Repair of concrete structures has been a focus of attention in recent years not only in Japan but also worldwide. Concrete structures have fallen short of expectations at the time of construction-they should have been perpetual and maintenance-free. However, investigation into their premature deterioration reveals the primary causes: Concrete was made using inadequate materials and/or inadequate mixture proportions due to insufficient consideration and was placed inadequately under insufficient execution control. The secondary causes include insufficient consideration at the time of construction for the environmental conditions to which the structures were to be exposed. In any event, in the current economic climate, structures cannot be demolished and rebuilt as soon as they are damaged, but instead are expected to continue to be in service as long as possible with appropriate repair or retrofitting. This paper analyzes the causes of deterioration requiring repair and introduces relevant repair techniques. At the end, the repair project of the Sanyo Shinkansen Line in which the author was involved through committee activities is reported.

Since bridge decks have many cyclic loadings by such as moving loads in a whole life, effects of cyclic loading as well as static loading should be considered. Particularly, in a view of serviceability and durability, structural performance under cyclic service loadings is very important. In this paper, experimental studies on flexural behavior of RC beams with loop joints under cyclic loadings were conducted. Then the structural behavior for serviceability and strength were discussed.

A prefabricated composite hollow slab with perforated I-beams was suggested for the replacement of deteriorated concrete decks or the construction of new composite bridges with long-span slabs. Composite slabs with embedded I-beams have considerably higher stiffness and strength. For the application of prefabricated composite slabs to bridges, joints between slabs should satisfy the requirements of the ultimate limit state and the serviceability limit state. In this paper, three types of the detail for loop joints were selected and their structural performance in terms of strength and crack control was investigated through static tests on continuous composite slabs. A main parameter was the detail of the joint, such as an ordinary loop joint and loop joint with additional reinforcements. Even though there was no connection of the steel beams at the joints, the loop joints showed good performance in ultimate strength. In terms of crack control, the loop joint with additional reinforcements showed better performance. In ultimate limit state, the continuous composite slabs showed good moment redistribution and ductility.

This paper discusses how steel cord and PVA hybrid fibers enhance the performance of high performance fiber reinforced cementitious composites (HPRFCC) in terms of elastic limit, strain hardening response and post peak of the composites. The effect of microfiber(PVA) blending ratio is presented. For this purpose flexure, direct tension and split tension tests were conducted. It was found that HFRCC specimen shows multiple cracking in the area subjected to the greatest bending tensile stress. Uniaxial tensile test confirms the range of tensile strain capacity from 0.5 to $1.5\%$ when hybrid fiber is used. The cyclic loading test results identified a unique unloading and reloading response for this ductile composite. Cyclic loading in tension appears not to affect the tensile response of the material if the uniaxial compressive strength during loading is not exceeded.

This experimental investigation was conducted to examine the seismic performance of reinforced concrete bridge columns. The columns were subjected to a constant axial load and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement (ps = 0.96, 1.44 per cent) and axial load ratio (0.05, 0.1, 0.2 P/Po) and strength $(350kgf/cm^2,\;600kgf/cm^2)$. Test results show that bridge columns with 50 per cent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. For bridge columns with axial load ratio(P/Po) less than 0.2, the ratio of Mmax over Mad, nominal moment capacity predicted by ACI 318-02 provisions, is consistently greater than 1 with approximately a 20 percent margin of safty.

This paper discusses the role of micro and macrofibers in the workability, compressive strength, and failure of cementitious composites. Workability(flow), compressive strength, splitting strength and fracture mechanism of hybrid fiber reinforced cement composites(HFRCC) have been investigated by means of Korean Standard (KS). The specific blend pursued in this investigation is a combination of polyvinyl alcohol(PVA) and steel cord. It was demonstrated that a hybrid combination of steel and PVA enhances fiber dispersion compared to only steel cord reinforced cement composites and that the brittle and wide cracking was much reduced in HFRCC as expected because in the matrix containing the PVA fiber around the steel cord, a multiple microcracking occurred and the steel cord could sufficiently work for bridging the cracked surface.

In recent years a number of catastrophic tunnel fires, the Euro tunnel, the Mont Blanc tunnel, the Tauem tunnel and the Gotthard tunnel, have occurred and inflicted serious damages to European countries. If a fire occurs in shield tunnels, the reinforced concrete segment linings playing as an important structural member is expected to damage severely and finally can be caused the collapse of tunnel. The purpose of this study is to evaluate the performance of concrete segment lining under heat exposure and to obtain information to assist a new technical approach to fighting fires in tunnels. In order to evaluate the fire-resistance performance of concrete segment by adding Polypropylene fibers, fire tests using the RABT heat-load curve is carried out. The temperature rise of this curve is very rapid up to $1200^{\circ}C$ within 5 minutes, and duration time of the $1200^{\circ}C$ exposure is 55 minutes. From the fire test, it was found that the explosive spalling was rapidly reduced by adding polypropylene fibers and this method is considered as an effective fireproof material to upgrade fire safety in tunnels economically.

In this study, effects of fluosilicate salt based chemical admixture(MZ) on the watertightness and hardening properties of concrete were investigated. Mix proportions for experiment were modulated at 0.55 of water to cement ratio and addition amount of MZ to $2.0\%$ at intervals $0.5\%$. Compressive strength, porosity and microstructure of hardened concrete cured at several days were executed to evaluate watertightness and hardening properties. It is ascertained that watertightness and hardening properties of concrete could be improved by an adequate addition of fluosilicate salt based chemical admixture.

A new design method for prestressed concrete girder is proposed in this study, which steps for manufacturing are; (1) the bottom part of concrete girder is placed and pretensioned by the first post-tensioning performed on the tendons located in the bottom part of concrete girder, and (2) the next step which consists of concrete placing and post-tensioning operation is followed by the previous step if required. This indicates that sufficient compressive stress can be effectively introduced at the bottom face in stepwise manner, when compared to conventional PSC girder. Two specimens are prepared and tested to investigate the short-term behavior of the PSC girders manufactured by the proposed method. Section Analysis results exhibit good agreements with the test results in terms of strain distribution across the girder section. In addition, flexural strength obtained from the tests is found to be similar to the expected based on Code(Korea). These demonstrate that the method proposed in this study is applicable to the design of PSC girders.

Since bridge decks have many cyclic loadings by such as moving loads in a whole life, effects of cyclic loading as well as static loading should be considered. Particularly, in a view of serviceability and durability, structural performance by cyclic service loadings is very important. In this paper, experimental studies on flexural behavior of RC beams with new types of loop joints under cyclic loadings were conducted. Then the structural behavior for serviceability and strength were discussed.

This paper is to study the response of flat plate slab-column connections consisting of various types of shear reinforcement and steel plate subjected to gravity loadings, mainly punching shear forces using the non-destructive testing, spectral analysis of surface waves and structural experiments. The base specimen failed due to punching shear generated from the gravity. The three other types of slab shear reinforcement and steel plate showed effective in resisting punching shear for these types of connections under gravity loading. This study has focused in evaluating the velocity response of a Surface wave during the early age as the poured concrete specimens have been hardened, the possibility of damage detection in the slab-column connection and the relationship between the punching shear forces and the surface wave velocities under the condition that the punching shear forces had gradually increased until the flat plate slab in slab-column connection had been failed.

Before incorporating the earthquake-resistance design in design code(998), most of existing residential buildings were built without having lateral resistance capacity in addition to their structural peculiarity such as exterior stair ways, exterior elevator room. For these reasons, the retrofitting research demands for existing buildings arise recently and many retrofitting methods are proposed. These tasks are important to reduce the enormous economic loss and environmental issues. In this study, Scaled residential buildings with/without lateral resistance were tested and monitored with external lateral load especially toward the longer side of the building. From these experiments, enhanced retrofitting methods of old shear wall system are proposed and also compared with structural analysis.

This paper presents the consideration of design guideline for underground HCS system, composite spancrete slab, under axial and bending force. Serviceability design requirements for continuous composite spancrete slab subjected axial force, which are allowable stress and deflection, are compared. Flexural strengths are evaluated by design guideline using strain-compatibility method. The results showed that stresses of spancrete and topping concrete, especially at the ends of beam, have much effect on design loads. Maximum service loads for tested specimens are proposed by allowable stress.

The paper deals with the damage assessment of the concrete beam using static displacements and the flexural stiffness reduction of the beam was evaluated. Simply supported concrete beams were loaded at the mid-span, and the applied load level ranged $20\%,\;40\%,\;80\%$ of the flexural strength of the beam. When the displacements from the tests were increased more than $10\%$ of the initial values, flexural cracks occured. Judging from the observed cracks, damaged area of the beams were assumed and the stiffness reduction using the smeared-cracking concept was estimated to minimize the error between the test results and analytical results. Four stages of the behavior of a RC beam, which are uncracked, initial cracking, stabilized cracking and post-yielding, can be considered to assess the damage of RC beams. Main parameters for the assessment were cracking area and the stiffness reduction ratio. In each stage, damaged elements and their stiffness reduction were estimated to minimized the error.

In recent years, the use of FRP composites to repair and strengthen existing reinforced concrete (RC) structures has been widely used. When the columns of existing RC structures are wrapped with FRP composites, the core concrete of such columns is confined not only by the FRP composites but also by the existing steel reinforcing ties (or spirals). Therefore, it is necessary to understand correctly the compressive response of concrete confined with both steel spirals and FRP composites in order to predict the behavior of such RC columns. This paper proposes a model to predict the compressive stress-strain curves of concrete confined with FRP and steel reinforcing ties.

In the shear strengthening with FRP sheets, beams are wrapped around the webs and tension face of critical shear span by fiber sheets. The shear strength of RC beam strengthened with FRP sheets must be calculated based on the effective strain that can be developed in the FRP sheets at ultimate stage because the final failure modes of beams are governed by premature debonding of FRP sheet due to the limitation of bonded length by beam depth. An experimental study is carried out to evaluate the shear strengthening effect of AFRP or GFRP sheets with respect to shear reinforcement ratio of rebar. From the test results, it was found that the additional shear strength provided by GFRP or AFRP can be estimated by $p_w{\cdot}f_w$ based on the maximum effective strain of FRP sheet $4,000m{\mu}$ proposed by ACI 440 committee.

Carbon Fiber Reinforced Polymer(CFRP) composites are widely applied to strengthen deteriorated concrete structures. This paper presents the experimental results of the performance of reinforced concrete(RC) beams strengthened with externally prestressed CFRP plates. Simple beams with 3 m span length were tested to investigate the effect of prestressing force of CFRP plates on the flexural behavior of externally strengthened RC beams.

The use of recycled aggregate concrete is increasing faster than the development of appropriate design recommendations. This paper is making advances in the recycling of waste concrete material for use as recycled aggregate to make secondary concrete product. Using recycled aggregates from demolished concrete, we manufactured concrete blocks to experiment overall performance in feasible performances. This paper reports limited experimental data on the structural performance of shear wall used concrete blocks made in recycled aggregates. Reinforced concrete frame and shear walls were tested to determine their diagonal cracking and ultimate shear behavior. The variable in the test program was the existence of infilled wall used concrete blocks Made in recycled aggregates. Based on the experimental results, Infilled wall has a high influence on the maximum strength and initial stiffness of reinforced concrete frame. Structural performance of specimen WSB1 and WSB2 is quite different from RCF specimen, particularly strength, stiffness and energy dissipation capacity.

The FRP plate or sheet bonding technology was widely used for strengthening deficient RC structures. The strengthened structure using FRP bonding scheme, however, experience the complex interfacial behaviour which is difficult to predict. Therefore, the unbonded scheme using some anchorage device can be is an alternative for more reliable design. In this study, wedge-type anchor for FRP plate is developed for the unbonded flexural strengthening scheme. Some parameter study using 2D finite element method is performed. The analysis parameters are taken as wedge-guide friction coefficients, wedge- FRP ,.friction coefficient and wedge inclination angle. Based on the parameter study, more efficient anchors are designed and tested. The test result show that the developed anchor assure about $80\%$ FRP strength, which is higher performance than typical bonding scheme. Last, 3D finite element analysis is performed.

Nominal flexural strength of RC members strengthened with FRP sheets is generally based on the tensile strength of composite materials obtained from coupon tests. This method is based on the assumption that bond failure does not occur until the FRP sheet reaches its rupture strength. According to the previous researches, however, bond failure often occurs before the FRP sheet reaches its rupture strength. Some attempts were made to control debonding failure by increasing the bonded length of sheet or wrapping the section around their side of the member(U-wrap). In this study, the flexural failure mechanism of RC beams strengthened with AFRP sheets with different bond lengths is investigated. Their strengthening details to prevent the premature debonding failure are also suggested and its effectiveness is verified.

It is generally known that the bonding strength of RC(Reinforced Concrete) flexural members strengthened by fiber sheet composites are sufficient and the bonding failure does not occur until the sheet failed. However, many researchers have been reported that, before the failure of the sheet, the bonding failure happens even though the bonding length is sufficient. This study was carried out to evaluate the effectiveness of shear key and U strip on flexural behavior of reinforced concrete beam structures. The ply number of CFS(Carbon Fiber Sheet), location of shear key, and existence or not of U strip were selected as the main test variables. Test results show that the behavior of a beam of which shear key is located in the nearby. of support and U strip is not existent, and having CFS of 1 ply is mostly improved.

The flexural strengthening effect of the RC beam strengthened with CFS under pre-loading condition was studied here. The beams were additionally strengthened at the each end with U type wrapping using the same CFS. Main variables considered were number of CFS plies(1,2) and pre-loading values(30,50,$70\%$ of the yield load of the control beam). The flexural strengthening effect was investigated through comparing the yield load, ultimate load, and ductility index of the specimens.

PSC bridges are deteriorated by many reasons and are difficult to measure residual prestressing forces. It is considered that one of the methods for measuring the prestressing forces is vibration test. This study reports on the change of natural frequency for damaged PSC beams using vibration test which have been carried out to evaluate the effects of cross-section and prestressing forces on natural frequency of PSC beams. According to the results of vibration test results, natural frequency is more sensitive to the changes of cross-section than those of prestress.

Bridges are deteriorating over service life due to over weight vehicles, environmental conditions and so on. In addition to that, those could be classified into low level bridges which are not fit for highway because of upgrade of the design load. Consequently, such reasons impel the bridges to be repaired or strengthened. Among the rehabilitating methods, FRP sheets and externally prestressing methods are preferred recently. This paper presents experimental results about the behavior of PSC beams strengthened by external tendons and CFRP sheets.

The crack widths of reinforced concrete flexural members are influenced by repetitive fatigue loadings. The bond stress-slip relation is necessary to estimate these crack widths realistically. The purpose of the present study is, therefore, to propose a realistic model for bond stress-slip relation under repeated loading. To this end, several series of tests were conducted to explore the bond-slip behavior under repeated loadings. Three different bond stress levels with various number of load cycles were considered in the tests. The present tests indicate that the bond strength and the slip at peak bond stress are not influenced much by repeated loading if bond failure does not occur. However, the values of loaded slip and residual slip increase with the increase of load cycles. The bond stress after repeated loading approaches the ultimate bond stress under monotonic loading and the increase of bond stress after repeated loading becomes sharper as the number of repeated loads increases. The bond stress-slip relation after repeated loading was derived as a function of residual slip, bond stress level, and the number of load cycles. The models for slip and residual slip were also derived from the present test data. The number of cycles to bond slip failure was derived on the basis of safe fatigue criterion, i.e. maximum slip criterion at ultimate bond stress.

The polypropylene(PP) fiber is poised as a low cost alternative for reinforcement in structural applications in comparison with other high performance fibers, such as the polyvinyl-alcohol(PVA), polyethylene, carbon and aramid fiber. The mechanical properties of the composite are strongly determined by the interfacial behavior of fiber and cementitious matrix. The crack bridging mechanism contribute to composite toughness from activation of the fiber-matrix interface where energy is dissipated through debonding of the interface and fiber pullout. In this study, therefore, the pullout behavior of PP fibers is investigated. Experimental work includes the investigation of the interfacial properties, and the composite property. The quantification of interfacial properties, the frictional bond is achieved through single fiber pullout test. A study on the effect of inclination angle on fiber pullout behavior is also conducted.

Bond between reinforcing bar and surrounding concrete is supposed to transfer load safely in the process of design of reinforced concrete structures. Bond failure of reinforcing bar generally take place by splitting of the concrete cover as bond force between concrete and reinforcing bars exceeds the confinement of the concrete cover and reinforcement. However, the confinement force has a limitation. Thus, the only variable is the bearing angle corresponding to the change of bond force. Higher rib height bars possessing higher shearing resistance can maintain higher bearing angle and higher splitting resistance when bars are highly confined, and consequently higher bond strength, than lower rib higher bars. In this study, from the evaluate bond strength of high Relative Rib Area Bars Using beam-end test specimens are compared with the current provisions for development of reinforcement, and the improved design method of bond strength is proposed.

The use of higher strength materials frequently requires the change of design provisions. Following to the previous researches, high strength reinforcing bars have a weak point about the development and splice length. Based on the previous research about high relative rib area, bond strength between reinforcing bars and concrete can be improved by the control of rib height and spacing. But, the code provisions do not include these specific shape of reinforcing bars. So, the purpose of this paper is to determine the effect of relative rib area to the bond strength. This paper describes the experiment and analysis of 5 beam-spliced specimens containing D25 with relative rib areas ranging from 0.073 to 0.17. The test results are also analyzed to make a design formula about the calculation of splice length on the consideration of relative rib area.

The lap splice lengths of deformed steel reinforcing bars and GFRP bars were experimentally compared using beam specimens. The purpose was to evaluate the length required of the GFRP bar to develop strength at least equivalent to the conventional steel reinforcing bar. The main test variable was the lap splice length: 10, 20, 30 $d_b$ for the deformed steel bars and 20, 30, 40 $d_b$ for the GFRP bars. Two different types of GFRP bars were tested: (1) one with spiral-type deformation and (2) plain round bars. Elastic modulus was about 1/5 of the steel bars while the tensile strength was about 690 MPa for the GFRP bars. Nominal diameter of the GFRP bars and steel bars was 12.7 and 13 mm, respectively. Normal strength concrete (28-day $f_{cu}$ = 30 MPa) was used. For the conventional steel bars (SD400 grade), strength over 400 MPa in tension was developed using the lap splice length of 20 and 30 $f_{cu}$. Only $87\%$ of the nominal yield strength was reached with the lap splice length of 10 $d_b$. For the spiral-type deformed GFRP bars with $40-d_b$ lap splice length, 440 MPa in tension was determined. The maximum tensile strength developed of the GFRP bars with smaller lap splice lengths decreased. The plain GFRP bar was not effective in developing the tensile strength even with $40-d_b$ lap splice length. Development of the cracks on beam surface was clearly visible for the beams reinforced with the GFRP bars. Mid-span deflections, however, were significantly smaller than the comparable beams with conventional steel bars indicating potential ductility problem.

This study is to investigate the bond characteristics of glass fiber reinforced polymer(GFRP) reinforcing bars in concrete by pullout test experimentally. Three different types of GFRP bars with different surface deformations were considered in this study. Also, standard deformed steel reinforcing bar with or without epoxy-coating were included for the comparisons of bond strength. All test procedures including specimens preparation, test apparatus and measuring devices were made according to the recommendation of CSA(Canadian Standards Association) Standard S806-02. From the test results, it was found that small surface indentations contributed to increase the bond strength of GFRP bar significantly. Based on the limited test results till now, the bond strength of GFRP bar with sand-coated deformation commercially available in foreign market is around $80\%$ of that of steel deformed bars.

This paper is to investigate the mock up test results of mass concrete for transfer girder using setting time difference with super retarding agent(SRA) to reduce hydration heat. According to test results, the temperature history of plain concrete without placing lift had a steep rising curvature, and plain concrete had a big temperature difference between surface and middle section of mass concrete, which may result in occurrence of temperature crack. However, considering placing method B, because setting time of middle section concrete was retarded with an increase in SRA contents, higher hydration heat temperature was observed at surface section concrete compared with that at middle section concrete at early age, which can lower the possibility of hydration heat crack. In case of placing method C, although peak temperature of hydration heat was much lower, at early age, high crack occurrence possibility of the hydration heat attributable to the big temperature difference between middle section and bottom section of concrete was expected at bottom section concrete. Therefore, the structure above the ground like transfer girder is not applicable to consider the placing method C.

High-performance concrete (HPC) may be expected to differ from usual concrete with respect to shrinkage behavior, and it shows high autogenous shrinkage due to the use of very low water-binder ratio (w/b) and various admixtures. Therefore, in order to minimize the shrinkage stress and to ensure the service life of concrete structure, volumetric change of HPC should be understood. In this study, small prisms made of HPC with w/b of 0.32 and blast-furnace slag content of $0\%,\;30\%,\;and\;50\%$ were prepared to measure the volumetric changes such as autogenous shrinkage, drying shrinkage, and swelling under three different curing conditions. It was observed that the concrete cured. sealed condition showed only autogenous shrinkage while the concrete let to dry condition at temperature of $20^{\circ}C$ and relative humidity of $60\%$ during the test period showed both autogenous and drying shrinkage. Moreover, the concrete exposed to dry condition after 2-day water curing swelled and then started to shrink with age. The total shrinkage (autogenous+drying) of this concrete was smaller than that of the concrete cured dry condition, especially at early-age. Therefore, the early-age moisture curing is very effective to control or minimize the volumetric change and its induced stress of HPC.

The domestic concrete standard specification(l999) reports roughly about heat transfer analysis and thermal stress analysis for mass concrete. Engineers cannot but choice after all numerical method such FEM, FDM to escape review. It seems to us that the specification is room for reconsideration because above methods are vary expensive and without popularity. This study suggests thermal distributed function in mass concrete. The function consists of two independent variables, curing time and depth. It's results have been tested a sensitivity for unit cement content, form condition, curing condition, and shape(depth, width). Results of the function are made a comparison with analytical values of MIDAS/CIVIL and a few measurement values. The researchers could meet with coherent and good results for variable cases.

Heat of hydration of concrete under different curing temperatures can be characterized with knowledge of the thermal activity, the heat rate at the reference temperature, and the total heat of hydration of the mixture. The so-called multi-component hydration model incorporates the effect of following variables: cement chemical composition, cement fineness, secondary cementitious powders, mixture proportions, and concrete properties. However, the model does not consider the use of silica fume as a secondary cementitious powder. Therefore, the model that quantifies the heat of hydration due to the use of silica fume is needed. In this thesis, the effects of silica fume on heat of hydration are evaluated and the influence on the heat of hydration are also quantified to be included in the model, so that the analysis using modified multi-component hydration model for silica fume concrete provides more accurate results than normal concrete.

In this paper, field application of mass concreting using super retarding agent(SRA) are discussed based on setting. time difference with SRA in big discount market in Chongju. Mechanical and physical properties of .concrete are investigated. Temperature history of concrete is also measured. Slump and air content meet the requirement of target value. Compressive strength of concrete exceeded the nominal strength with 24MPa. Compressive strength of SRA concrete is higher than that of plain concrete by about $3\~4\%$. For temperature history, peak temperature of concrete at middle section at top concrete layer reached $49.6^{\circ}C$ within 24hours, and at bottom concrete layer, $54.6^{\circ}C$ within 42hours. Based on the naked eye's observation, no crack was found at mass concrete.

The hardening of concrete after setting is accompanied with nonlinear temperature distribution caused by development of hydration heat of cement. Especially at early ages, this nonlinear distribution has a large influence on the tensile cracking. As a result, in order to predict the exact temperature distribution in concrete structures it is required to examine thermal properties of concrete. In this study, the coefficient of air convection for concrete mix of nuclear power plant, which presents thermal transfer between surface of concrete and air, was experimentally investigated with variables such as velocity of wind and types of form. The coefficient of air convection obtained from experiment increases with velocity of wind, and its dependance on wind velocity is varied with types of form. This tendency is due to a combined heat transfer system of conduction through form and convection to air. The coefficient of air convection for concrete mix of nuclear power plant obtained from this study was well agreed with the existing models.

Recently constructions of large scale infrastructures have been tending upwards, due to continuous growth of economy and increase of demands. In addition, hydration heat occurs rapidly in early age just after casting of concrete owing to higher strength and massive structure of concrete. Consequently, cracks and residual stress are developed in accordance to field condition. Moreover, These have harmful influences on safety, durability, watertight, waterproof, and shape of concrete structure. In this study, hydration heat tests were conducted on three of self-compacting concrete and one of high strength concrete. Heat generation and temperature are compared and evaluated based on the test results.

The intention of this study is to reduce the plastic shrinkage of the polymer modified cement mortar using the PVA fiber. The durability of PVA fiber reinforced polymer cement mortar was also evaluated. The test results of PVA fiber reinforced polymer modified cement mortar were compared with plain polymer modified cement mortar(non-fiber). In conclusion, PVA fiber reinforced polymer modified cement mortar showed an ability to reduce the total crack area and maximum crack width significantly. Also. fiber reinforced polymer modified cement mortar show improved durability performance.

In domestic, various repair materials and method systems to keep up with these reinforced concrete deteriorated due to salt damage, carbonation, chemical decay et. developed and applied. However, on-site quality control of various repair materials and method systems isn't achieved desirably because it is depend completely on a men of experience' opinions above all else regardless of various on-site environments. In this background, mock up test with due regard to real on-site environments was performed to secure fundamental data for establishment of desirable on-site quality control. Mock up test using repair mortar analyzed from angles of construction methods, mechanical spraying pressures, W/M. Construction methods were designed manpower method and spraying method, spraying pressures were designed 32, 42, 52 psi, W/M were designed 14.4, 15.4, $16.4\%$. And compressive strength, Chloride ion diffusion coefficient, bond strength, SEM. of mock up test specimens were evaluated. In conclusion, we confirmed excellency of mechanical spraying pressures, fined extremely excellency of condition of spraying pressure 42 ps, W/M $14.4\%$ within this study. therefore the results of this study will be useful to provide fundamental data for establishment of desirable on-site quality control.

The purpose of this study is to investigate the properties of composite systems using polymer cement and epoxy resins for waterproofing and anti-corrosion to concrete structures such as water supply facilities and sewage-works. In this study these engineering properties of composite systems using polymer-modified mortar and epoxy resins were examined and could be confirmed to satisfy the guidelines of KS. Especially, it was turn out that the adhesion properties was excellent and high crack-resistance up to 1.49mm will be perform.

If a research trend present in and outside the country is often seen, the structure measurement method of having used PZT and the optical fiber (FBG) will be the actual condition which has accomplished the stock. In order to manage such cracks, time, efforts and expense are required. Such a method has many difficulties in application of a structure by the difficult problem of the measurement range, and the expensive sensor price. Progressive cracks were generated by fracture of glass pipe sensor. Moreover, the experiment which can detect damage propriety by external Light Emitting Diode by damaging a glass pipe by load change with the application of switch using strain gage of a glass pipe was conducted.

This study is to investigate the tensile properties of glass fiber reinforced polymer(GFRP) reinforcing bars with various kinds of anchor systems experimentally. Three types of anchor systems were examined: resin sleeve anchor adopted by CSA Standard, metal overlay anchor by ASTM Standards and wedge anchor normally used in prestressing tendons. Also, three different types of GFRP bars with different surface deformations were tested in this study. All test procedures including specimens preparation, test apparatus and measuring devices were made according to the recommendations of CSA Standard S806-02. From the test results, it was found that the highest tensile strength of GFRP bar was developed by resin sleeve anchor, and tensile strength of GFRP bar with CSA anchor system is $10\%$ higher than that with ASTM anchor system in the case of sand-coated GFRP bar.

The latest concrete structure has showed that the deterioration of durability has been increased by the damage from salt, carbonization, freezing & thawing and the others. Therefore, the measures for the concrete which has deteriorated durability have been taken. Among them, it has been often used that surface treatment which cuts off the deterioration factors of durability by protecting the surface of concrete. This study was evaluated the surface improving agent for permeability, watertightness, air-permeability, chemical resistance and elution resistance.

In general, the polymer is mainly used with the cement mortar with various admixtures for concrete repair. The properties of cement-polymer mortar was studied by the cement-polymer ratio only and ignored any influence of admixtures in the mortar. Therefore in this study, the test is carried out with 2 product of polymers(the same type produced by different companies) and various admixtures. It is found that the same type of polymers produced by different companies affect the properties of fresh and hardened concrete. As increasing the polymer proportion in mortar, the compressive strength and flexural strength are increased, and also drying shrinkages is increased.

There are many factors that generate the early deterioration of the concrete structure. As the one of the representative factors, we can think an invasion of the water, air and so on. The water and air invade in inside void along the capillarity and they become the cause that the durability like corrosion of layer department due to freezing and thawing, inside steel frame corrosion, and so on blacks. Therefore with covering permeability covering waterproofing material of fluid condition in outer wall, intercepting the deterioration factor due to the infiltration of water from outside and for salt damage of concrete layer department, freezing damage and neutralization, it needs to improve durability of structure. This study separately examined physical and chemical specific of quality liguid siliceous of waterproofing material. Therefore as this applys the construction site, it improves the durability of concrete structure. Further this presents the application plan from the construction market against the new material.

We experimented variables of four kinds(a/d=1.5, 2.5, 3.5, 4.5) of shear span ratio to consider a structural characteristic of high-strength lightweight concrete beam used industrial by-product. Through the research of serials, the more increase of shear span ratio, the more ductility is superior. Rating the capacity of high-strength concrete beam and the capacity of lightweight concrete beam, in existing lightweight concrete beam evaluation formula, if a shear strength formula for normal concrete multiplies 0.85(reduction factor), it is rated as safety side over shear span ratio 2.5, but it is riskful at low shear span ratio. Therefore it is important that these factors are considered as the evaluation.

Recently, the development of construction materials is rapidly advancing. Especially, the rate of development of cement based construction materials is much quicker than steel or composite materials. In order to optimize the ductility and strength of cement based materials, Micro-mechanics based fiber concrete called Engineered Cement Composite (ECC) is developed and studied extensively by many researchers in the field. Due to ECC's remarkable flexural strain and strength capacities, many leading nation (i.e., US, Japan, and European countries) are currently using ECC in actual constructions. In this study, ECC with internationally competitive material capacities is manufactured using domestic materials. Then, unreinforced concrete beams are repaired using ECC with $10\%,\;20\%,\;30\%$ of concrete specimen height Using 4 point bending test, the flexural strength of repaired flexural members are determined. The results show that ECC manufactured with domestic materials can be effectively used for repairing materials.

Metakaolin is a cementitious material for producing high-strength concrete. This material is now used as substitute for silica-fume. In this paper, we tested the compressive strength of concrete according to the substitute ratio of metakaolin, silica-fume. And we did the durability test such as chloride ion diffusion and chemical attack. In the compressive strength test, the result shows that $10\%$ substitute of metakaolin & silica-fume for binder is optimum. In the chloride ion diffusion test, according to the increase of substitute of metakaolin & silica-fume for binder, the diffusion coefficient is more reduced. And in the chemical attack test, according to the increase of substitute, the resistance is more excellent. In the durability test, we recognized that metakaolin is able to used as a substitute for silica-fume.

In this study, it is examined the properties of flow and early strength of concrete according to superplasticizer. For this experiment, it is analyzed that the flow and strength properties according to the mixture factors, compared with naphthalene superplasticizer(normal & delay type) focused on polycarboxylate superplasticizer. (1) The slump loss of concrete used polycarboxylate superplasticizer showed $4\~8cm$, it is judged that slump loss according to the time lapse can be minimized. (2) The performance of polycarboxylate superplasticizer is about $70\%$ level of the normal naphthalene type, it is superior to the delay type, but the performance showed so lowly. The 28days, early strength didn't differ according to the kind of superplasticizer.

In this paper, mechanical properties of the high strength lightweight self-compacting concrete with simple mixed design method was investigated. Experimental tests were performed as such compressive strength, splitting tensile strength, modulus of elasticity and density of high strength lightweight self-compacting concrete. The 28 days compressive strength of high strength lightweight self-compacting concrete with the LC replacement ratio of $100\%$ reduces about $31\%$ but LF replacement ratio of $100\%$ increase about $20\%$ compared that of the control concrete. The structural efficiency of high strength lightweight self-compacting concrete increase with proportional to the replacement into of LF. The relationship between the splitting tensile strength and 28 days compressive strength can be represented by the equation $f_s=0.076f_{ck}+0.5582$. The modulus of elasticity was found to be lower than that of normal weight concrete, ranging form 24 to 33 GPa.

In order to obtain improved concrete mix proportion on nuclear power plant structures, the properties of normal concrete is compared with self-compacting concrete. In addition, various mixes of self-compacting concrete utilizing melaminic acid based admixture is mutually compared and estimated. Because existing normal concrete mixes might occur high temperature in concrete structure, A new multi-component concrete, which declines hydration heat, is demanded. Therefore, in this study, the possibility of manufacturing self-compacting concrete is verified and what influences melaminic acid and various powders have on the properties of self-compacting concrete are investigated.

While member sections of concrete structures of nuclear power plant are big, water-cement ratio is small. Consequently, the huge amount of heat generation and high viscosity could be occurred. These might reduce constructibility of nuclear power plant. In order to obtain improved concrete mix proportion on nuclear power plant structures, the properties of normal concrete is compared with self-compacting concrete. In addition, various mixes of self-compacting concrete utilizing polycarboxylic acid based admixture is mutually compared and estimated.

Due to the recent amazing achievements in nano technology. preparation of cement nano particles by mechanical method are examined to improve their properties. The experimental results show that the particle size after 3 hr milling were about 500nm. The SEM photographs of specimens also reveal that average sizes of cement particles are gradually decreased by milling time. And in the TG/DSC, influence of the alcohol is showed strongly. The value of TG of the crushed cement was larger than that of the non-crushed cement. That is also judged to be cause the alcohol.

It is fact that the cement is the most important material to harden the mortar and concrete, and Potland cement is used widely. Also, the chemical and physical properties of cement are different according to the kinds of cement. This is an experimental study to compare and analyze the influence of cement strength on the compressive strength of mortar to improve the quality of mortar and concrete. According to test results, it was found that correlation between cement strength and mortar strength was very high in all mixture.

The cement can be influenced by the temperature. Especially, when it is cold weather, it causes some problems in such properties as mixing, placing and curing of concrete. According to the Concrete Standard Specification(2003), in case of the average daily outdoor temperature below $4^{\circ}C$, it recommends to use the cold weather concrete. In this research, the on-site quality characteristics of the cold weather concrete using high early strength portland cement(Type III cement) were studied. As a result, the cold weather concrete using high early strength portland cement can obtain its excellent properties and benefit the cost of construction.

The purpose of this study evaluates possibilities of waste phosphogypsum into concrete by steam curing admixture. The waste phosphogypsums were classified into 4 forms(Dihydrate, $\beta-Hemihydrate$, III-Anhydrite and II-Anhydrite) which were changed to in low temperature of calcination. Also, various admixtures were made of waste phosphogypsum(PG) and pozollanic fine powderers (Fly-ash, Blast Furnace Slag), and the basic properties of the cement mortars incorporating with these admixtures were examined and analyzed under a verity of experimental conditions. As a result, III-Anhydrite, these is similar to II-Anhydrite from compressive strength and are great in the effect of strength improvement. also, it was proved that specimens made on type III-Anhydrite of waste phosphogypsum and blast furnace slag increased on the compressive strength of cement mortar. Therefore, III-Anhydrite phosphogypsum calcined at lower temperature could be used as steam curing admixture for concrete 2th production.

This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also investigates the basic physical properties and hydration reaction of NSC, and evaluates its reusing possibility as construction material. Results obtained from this study have shown that GBFS was affected by $So_4^{2-}$ in waste PG and stimuli under wet condition, left slag components, created Ettringite and CSH gels, and eventually started being hydrated. These hydrated creations formed dense structures like CSH based on Ettringite and contributed in allowing the mortar to reveal high strength.

The ternary blended cement(TBC) which the ability of resistance for seawater, the effect of decreation of hydration heat of concrete and long-age strength are known to be superior to other types was used to derive the estimation function of 91-age strength, 28-age strength with 28-age strength, 7-age strength respectively by analyzing the characteristics of statistics of compressive strength. The sample specimens was made after testing the variations of slump, air-contents during 30 minutes for consideration of transportation period. The functions might be expected to be useful for construction smoothness and reasonable quality control of concrete with TBC.

A new shear connection for the application of precast decks to PSC girders was proposed and push-off tests were conducted to evaluate the horizontal shear strength of the shear connection. Major parameters of the tests were connector type, shank area, vertical load, surface condition and bedding height. Judging from the test results, shear strength of the suggested shear connection was proportional to the shank area and yield strength of the connectors and was in inverse proportion to the bedding height. Shear connection with shear key at the surface showed better performance. An empirical equation for the evaluation of the shear strength of the shear connection without considering bond strength was proposed and it showed good correlation with the test results.

This study proposes the design method of the shear walls with openings using strut-and-tie models. Strut-and-tie models are constructed for opening near the middle of the wall and for opening near a wall boundary. These enables an admissible load path for the horizontal earthquake force. These models consider the size and position of opening effectively. Each model is suitable for the seismic response corresponding with lateral forces in a given direction to be considered. The proposed models are good agreements with nonlinear finite element analysis(DIANA) results.

This study was performed to propose the minimum thickness of RC slab that satisfies constructibility, fatigue safety, and serviceability requirements such as deflection control. Three different minimum thicknesses are calculated using concrete shear and rebar fatigue formulas, and deflection control, respectively, and checked by constructiblity. The maximum of these three minimum thicknesses is proposed as the minimum thickness of RC slab, which shows that the minimum thickness requirement of RC slab from Korean Bridge Design Code can be thinner than now.

The measured longitudinal reinforcement tensions in the shear-critical RC beams were significantly higher than the calculated values by the beam theory. This may be attributed to the reduction of the internal-moment arm length by the development of the arch action. In this paper, the measured longitudinal reinforcement tensions in the test performed by $Kim^4$ were compared with those predicted by the various truss model.

The objective of this experimental study is to understand the effects of horizontal and vertical shear reinforcement on the shear strength of concrete deep beams. Main variables were the horizontal shear reinforcement ratio $(P_{sh})$, vertical shear reinforcement ratio$(P_{sv})$ and shear span-to-overall depth ratio(a/h). Test results revealed that the effectiveness of shear resistance of shear reinforcement was greatly related to the a/h. For the beams with $a/h\geq1.0$, the vertical shear reinforcement was more effective than horizontal shear reinforcement.

The purpose of this study is to estimate the shear strength of SFRC beam that has stirrups. To achieve the goal of this study, two stage investigation, which is material and member level, is studied. From the reviewing of previous researches and analyzing of material and member test results, strengthening parameter of SFRC is defined as steel fiber coefficient. Based on above results, steel fiber strengthening factor is proposed. Therefore, shear strength equation of SFRC, which is considered the steel fiber strengthening factor, is proposed by regression analysis of test results.

It is well known that axial tension decreases the shear strength of RC beams without transverse reinforcement, and axial compression increases the shear resistance. What is perhaps not very well understood is how much the shear capacity is influenced by axial load. RC beams without shear reinforcement subjected to large axial compression and shear may fail in a very brittle manner at the instance of first diagonal cracking. As a result, a conservative approach should be used for such members. According to the ACI Code, the concrete contribution is calculated by effect of axial force and the vertical force in the stirrups calculated by $45^{\circ}$ truss model. This study was performed to examine the effect of axial force in reinforced concrete beams.

A strengthening technique for reinforced concrete beams using external unhanded reinforcement offers advantages in speed and simplicity of installation over other, established, strengthening techniques. The purpose of this paper is to investigate the capabilities of a new retrofitting technique, namely external prestressing out cable, for flexural strengthening of beams. The paper provides a general description of structural behavior of beams strengthened using the technique. Results of four physical tests on strengthened reinforced concrete beams are reported and compared. It is shown that the technique can provide greater strength enhancement to lightly reinforced sections and that provision of deflectors enhances efficiency.

This study is to propose a modified equivalent frame method under lateral loading. ACI 318-02 allows the equivalent frame method to conduct slab analysis subjected to lateral loads. However, current method can not predict the behavior of the slabs particularly under lateral loading because the equivalent frame method in the ACI 318 has been developed against gravity loads. This study provides more precise model for the analysis of the flat plate slabs under lateral loading. The model reflect the force transfer mechanism of slabs, column and torsional member more accurately than the existing model. The accuracy of this model is verified by compared with finite element method analysis results.

Concrete is one of the principal materials for the structure and it is widely used all over the world. but it shows extremely brittle failure under bending and tensile load. Recently to improve such a poor property. High Performance Fiber Reinforced Cementitious Composites (HPFRCC) have been developed. and it are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This study is to develop the hybrid HPFRCC with high ductility and strain capacity in bending and tensile load. and the three-point bending test on hybrid HPRFCC reinforced with micro and macro fibers is carried out in this paper. As the results of the bending tests. hybrid HPFRCCs reinforced with PVA40+SF and PVA100+PVA660 showed the high ultimate bending stress, multiple cracks and displacement hardening under bending load.

Today, the guide line of the SFRC mix design and the construction was not embodied, and the convenience of the practical application on the spot is not good. In this research, hence, the program which is optimized to result the mix proportion by the flexural strength and toughness, was developed to apply with ease SFRC on the practical spot. This program would minimize the number of trial mixes and achieve an economical and appropriate mixture. In addition, the theoretical background on which the program is based, will be the basis of the embodied method to mixing SFRC. New algorithm, in this research, was used to develop the mix proportioning program of SFRC. The new algorithm is the Harmony Search which is the heuristic method mimicking the improvisation of music players. And, beside to single fiber reinforced concrete, it was developed the program about the hybrid fiber reinforced concrete that two kinds of steel fibers, which have the different geometry, was reinforced. This will be able to keep the world trend to study, hence, offers the basis of the next generation research.

A high ductile fiber reinforced mortar has been developed by employing micromechanics-based design procedure. Micromechanical analysis was initially performed to properly select water-cement ratio, and then optimal mixture proportion was determined based on workability considerations, including desirable fiber dispersion without segregation. Subsequent direct tensile tests revealed that the fiber reinforced mortar exhibited high ductile uniaxial tension property, represented by $1.8\%$ strain capacity, which is around 100 times the strain capacity of normal concrete.

In this paper, to make ultra-high strength SFRCC with the range of compressive strength 180MPa, it was investigated the constitute factors of ultra-high strength SFRCC influenced on the compressive strength. The experimental variables were water-cementitious ratio, replacement of silica fume, size and proportion of sand, type and replacement of filling powder, and using of steel fiber in ultra-high strength SFRCC. As a result, in water-binder ratio 0.18, we could make ultra-high strength SFRCC with compressive strength 180MPa through using of silica fume, quartz sand with below 0.5mm, filling powder and steel fiber.

Recently, polymer-clay hybrid materials have received considerable attention from both a fundamental research and application point of view. This organ-inorganic hybrid, which contains a nanoscale dispersion of the layered silicates, is a material with greatly improved thermal and mechanical characteristics. Two classes of nanocomposites were synthesized using an unsaturated polyester resin as the matrix and sodium montmorillonite as well as an organically modified montmorillonite as the reinforcing agents. X -ray diffraction pattern of the composites showed that the interlayer spacing of the modified montmorillonite were exfoliated in polymer matrix. The mechanical properties also supported these findings, since in general, tensile strength, modulus with modified montmorillonite were higher than the corresponding properties of the composites with unmodified montmorillonite. Adding organically modified clay improved the tensile strength of unsaturated polyester by $22\%$ and the tensile modulus of unsaturated polyester was also improved by $34\%$.

The effects of polymer-cement ratio, antifoamer content and shrinkage-reducing agent content on the setting time and drying shrinkage of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As a result, the setting time of the high-fluidity polymer-modified mortars using redispersible polymer powder tend to delayed with increasing polymer-cement ratio, regardless of the antifoamer conten,. Irrespective of the antifoamer content, the drying shrinkage of the high-fluidity polymer-modified mortars using redispersible polymer powder tend to decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

In this study, the mixing contents of ceramic powder and of shrinkage-reducing agent (SRA) influencing on the strength properties of MMA-modified polymer paste were examined. Regardless of SRA content, the flexural. the compressive and the adhesive strengths of the MMA-modified polymer paste tended to increase as the mixing content of ceramic powder increased. On the other hand, those strengths of the polymer paste tended to decrease as the mixing content of SRA increased without regard to the paste content. Furthermore. the adhesive strength of MMA-modified polymer paste in a wet condition decreased about $30-40\%$ of that in an air-dry condition without regard to the mixing content of ceramic powder and SRA.

Direct tensile tests were carried out for the tensile members of MMA-modified polymer concrete with different steel kinds and steel diameters and steel ratios to figure out the effect of tensile strength of polymer concrete. In the experiments, MMA-modified polymer concrete with $1000\;kgf/cm^2$ of compressive strength, steel with $5200\;kgf/cm^2$ of tensile strength, and the tensile members with 100 cm of constant length were used. Experimental results showed that, regardless of steel kinds, diameters and steel content, the strain energy exerted by concrete till the initial crack was $14-15\%$ of the total energy till the point of yield: The energy was much larger than the one of high-strength cement concrete. The behaviors of tensile members of MMA-modified polymer concrete were in relatively good agreement with the model suggested by Gupta-Maestrini (1990), which was idealized by the effective tensile stress-strain relationship of concrete and the load-strain relationship of members, while those showed a big difference from CEB-FIP model and ACI-224 equation suggested for the load-displacement relationship that was defined as the cross sectional stiffness of effective axis. Modified ACI-224 model code about the load-displacement relationship for the tensile members of MMA-modified polymer concrete and theoretical equation for the polymer concrete tensile stiffness of polymer concrete suggested through the results of this study are expected to be used in an accurate structural analysis and resign for the polymer concrete structural members.

Many researchers have reported that adding steel fiber to concrete improved its tensile and flexural strength significantly, but relatively few studies have been made on the compressive behavior of SFRC(steel fiber reinforced concrete). It is still less in case of high strength SFRC. The main objective of this research is to examine the effect of adding steel fiber on the compressive strength of high strength SFRC using fiber reinforcing index$(RI,\;V_f(l/d))$. It was found from the study that compressive strength was noticeably increased in proportion to RI.

The effects of polymer-cement ratio, antifoamer content and shrinkage-reducing agent content on the strength of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As a result, the flexural and tensile strengths of the high-fluidity polymer-modified mortars using redispersible polymer powder tend to increase with increasing polymer-cement ratio, and tend to decrease with increasing shrinkage-reducing agent content, regardless of the antifoamer content. However, the compressive strength of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and shrinkage-reducing agent content.

Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. The purposed of this paper is to propose the model for the stress-strain relation of recycled-PET polymer concrete at monotonic uniaxial compression and is to investigate for the stress-strain behavior characteristics of recycled-PET polymer concrete with different variables(strength, resin contents, curing conditions, addition of silane and ages). The maximum stress and strain of recycled-PET polymer concrete was found to increase with an increase in resin content, however, it decreased beyond a particular level of resin content. A ascending and descending branch of stress-strain curve represented more sharply at high temperature curing more than normal temperature curing. In addition, results show that the proposed model accurately predicts the stress-strain relation of recycled-PET polymer concrete.

In general, polymer concrete has more excellent mechanical properties and durability than Portland cement concrete, but very sensitive to heat and has large deformations. In this study, the long-term creep behaviors was predicted by the short-term creep test, and then the characteristic of creep of recycled-PET polymer concrete was defined by material and experimental variables. The error in the predicted long-term creep values is less than 5 percent for all polymer concrete systems. The filler carry out an important role to restrict the creep strains of recycled PET polymer concrete. The creep strain and specific on using the CaCO3 were less than using fly-ash. the creep increases with an increase in the applied stress, but not proportional the rate of stress increase ratio. The creep behavior of polymer concrete using recycled polyester resin is not a linear viscoelastic behavior.

In this paper, fundamental properties of Polymer Concrete made from unsaturated polyester resin based on recycled PET and recycled aggregate(RPC) were investigated. Resins based on recycled PET and recycled aggregate offer the possibility of low source cost for forming useful products, and would also help alleviate an environmental problem and save energy. The results of test for resin contents and recycled aggregate ratio are showed that the strength of RPC increases with resin contents relatively, however beyond a certain resin content the strength does not change appreciably, and the relationship between the compressive strength and aggregate contents at resin $9\%$ has a close correlation linearly whereas there is no correlation between the compressive strength and the flexural strength of RPC with recycled concrete aggregate.

Recently, the study for practical construction application of recycled aggregate concrete is actively being proceeded, on the purpose of technical development for recycling on the construction waste concrete occurred at the time of destruction of building construction by the rapid increase of building wastes and exhaustion of natural aggregates. This study is performed to develop the permeable polymer concrete using recycled coarse aggregate and blast furnace slag for application of structures needed permeability. At 7 days of curing, compressive strength, flexural strength, water permeability and flexural load are in the ragge of $18\~20MPa,\;6\~7MPa,\;4.6\times10^{-2}\~6.9\times10^{-2}cm/s$ and $20\~25kN$, respectively. It is concluded that the recycled aggregate can be used in the permeable polymer concretes.

Polymethyl Methacrylate(PMMA) mortars using EPS solution-based binders are prepared with various unsaturated polyester resin(UP) contents of binder, and tested for working life. heat exothorm temperature, length change. compressive strength and temperature dependence of compressive strength. As a result, the working life of PMMA mortar is lengthened with raising UP content of binder. Length change of the mortar was condensed from expansion to shrinkage with increasing UP content, and non shrinkage of the mortar is obtained at about UP content of $2.5\%$. The compressive strength of the mortar is increased with an increase in the UP content and reach maximum at UP content of $5\%$. However thermal resistance improvement of the mortar by increasing UP content was not recognized. UP resin was recommended as an effective agent for shrinkage control and strength development of PMMA mortar.

This paper presents an experimental investigation examining water-cement ratio effects on fiber-matrix interface properties and on matrix fracture properties, which are used for designing mix proportion suitable for achieving strain-hardening behavior at a composite level. A single fiber pullout test and a wedge splitting test were employed to measure the bond properties in a matrix and the fracture toughness of mortar matrix, respectively. Test results showed that the properties tended to increase with decreasing water-cement ratio. Composite design using these test results will be discussed in the follow-up paper.

The cement-based composites have been used for construction industry because of their economy, suitability for architecture and structure function, fire resistance, low fee of repair, easiness for acquisition. but the limited strain capacity of these makes them tension-weak, brittle, and considerable notch-sensitive. As one of solution, FRC(fiber reinforced concrete) have been investigated for regulating weakness of the cement-based composites. In these day different fiber types are proposed for better performance such as HFRC(hybrid fiber reinforced concrete). This study shows experimental results to search the ultimate strength, the ultimate mean strain, and the tension toughness of HFRC. The tension toughness is proportional to the amount of steel fiber and carbon fiber. In this experimental program we kept the total of steel fiber and carbon fiber as $1.0\%,\;1.5\%$, respectively.

The amount of coal ash has been increasing and development of effective use is urgently needed. Various by-products and waste are expected to be used as resources from the point of reduction in environmental load. This is an experimental study to compare the properties of high volume coal ash concrete using the reclaimed coal ash. For this purpose, authors have started work to develop a production method of hardening coal ash concrete. Laboratory tests show that the optimum mixture of coal ash concrete can be determined from multiple regression analysis. According to test results, it was found that the compressive strength of the concrete can be determined by a single curve. And it is obtained from the analysis of the results tested for concrete with the ratio of total power to water and amount of land reclamation ash.

In this study, the recycled concrete aggregates crushed in-situ were used for the access road pcc (portland cement concrete) pavement. Based on laboratory results, the properties of materials, mixture proportioning, blend rates, and application conditions were investigated prior to trial application, and the various problems on recycled concrete aggregate under construction have been comprehensively checked.

Crushed sand is made by crushing the rocks artificially. With a wide shortage of natural river sand all over the region in Korea, demand for crushed sand are becoming increased. However, Informations as to crushed sand are insufficient. In this paper, the actual conditions of crushed sand related to producing and quality variation are investigated. 29 manufacturing company of crushed sand are reviewed. According to results, density of most crushed sand tested exceeded 2.5g/cm3, and absorption ratio meet the requirement of KS except one sample. For grain properties, passing amount of 0.08mm sieve satisfied the requirement of KS except one sample. Grain distribution of most crushed sand is estimated $54.26\%$. But 6 crushed sand sample did not meet the requirement of KS. Fineness modulus and grading are varied from manufacturing region. 18 samples of crushed sand among 29 samples deviated the minimum level of standard grading range by KS. Therefore, improvement of grain properties of crushed sand is urgently needed to manufacture better crushed sand.

Recently, owing to the deterioration of reconstruction and the construction, much of the construction waste is discharged in our construction field, and the amount of construction waste are rapidly increased. These waste are raised to financial and environmental problems, so the method of reusing waste concretes has been studied and carried out many direction. Especially being want of resources, if waste concrete could be recycled as aggregate for concrete, it will contribute to solve the exhaustion of natural aggregate, in terms of saving resources and protecting environment. This study is that the floating properties of concrete with recycled coarse aggregate were investigated for the substitution of recycled coarse aggregate. The result of this study, floating properties increases and strength development of concrete is showing a clear strength increase effect compare to blast furnace slag non-mixing according to age passing in case of use blast furnace slag. The Quality of recycled coarse aggregate concrete was improved by water reducing.

The effectiveness of Meta-Kaolin to prevent detrimental expansion due to alkali-silica reaction was investigated through the ASTM C 1260 method. Reactive aggregate used is a metamorphic rock. The replacement proportions of portland cement by Meta-Kaolin were 0, 5, 10, 15, 25 and 35 percent, respectively. The results indicate that 25 percent replacement of portland cement by Meta-Kaolin seems to be most effective to reduce alkali-silica reaction expansion under this experimental conditions.

The purpose of this study is to investigate quality of recycled fine aggregate manufactured by drying manufacturing system which is the manufacture method of high quality recycled fine aggregate, and to analyze on the fresh, hardened and durability properties of recycled concrete using it. Therefore it is to present the fundamental data for structural application of recycled concrete. The results of this study are as follows; Quality of recycled fine aggregate by drying manufacturing system is improved, and compressive and tensile strength of recycled concrete using high quality recycled fine aggregate are similar to those of normal concrete. But, durability such as carbonation, salt damage and dry shrinkage show decreased somewhat.

It analyzes the quality of the fine aggregate which is reproduced through a dry production process with cyclone and a wet production process. The conclusions of the study are as follows. 1. The recycled fine aggregate through the dry production process with cyclone shows the low rate of absorption and impurity content after the cyclone process. It shows that its density is 2.37, absorption rate is 4.8 and stability is $5.1\%$ and less. Therefore, it satisfies the standards of KS F 2573(recycled aggregate for concrete) as the first grade. 2. The recycled fine aggregate through the wet production process shows the low rate of absorption and foreign substance content after the process of wash and dehydration. It shows that its density is 2.40, absorption rate is 3.12 and stability is $3.2\%$ and less. Therefore, it satisfies the standards of KS F 2573(recycled aggregate for concrete) as the first grade.

Scaling deterioration and resistance to freezing of port concrete structures due to the combined effects of chemical actions by containning chlorides and the freeze-thaw action is also a problem which has not yet been fundamentally solved. Furthermore, deterioration of concrete surface was considered as accelerate factor of concrete durability tended to decrease. Therefore, we considered the scaling measuring method and decreasing influence of durability of concrete according to kind of binders, such as OPC, Slag, Slag+Fa, due to freeze and thaw of concrete by containing chlorides. As a results of this study, it was effective method of scaling deterioration and resistance freewing of concrete, and confirmed the salt deterioration resistance effect to use slag binder against to containing chlorides.

The objective of in this study makes investigation into the characteristics of concrete as to properties and blended ratio of crushed aggregates through experimental researches. In this study, river sand is blended with crushed sand as to investigate the quality change and characteristics of concrete with variation of blend ratio of crushed sand(50, 60, 70, 80, 90, $100\%$). Measured the air contents and slump to investigate properties of fresh concrete, and unit weight and compressive strength in age of 7, 28days to investigate properties of hardened concrete. The experimental results of crushed aggregates' qualities were all satisfied with Korea Standard's values.

The coarse and fine aggregates that make up the majority of concrete are resources. But, the raw naturals that make up concrete are our earth's resources and there is not a replenishable stock. Also industrial waste and life waste leaped into a pollution source. Therefore, as construction continue, quarries are exhausted and new sources must be discovered. The purpose of this paper is to investigate an application of recycled coal ash plastics in the construction field. The study examined the physical and mechanical properties of recycled coal ash plastics aggregate. In the results, although the absorption and specific gravity of SLAs increases slightly as the fly ash content increases, the compressive strength and modulus of elastic of concrete made with SLAs remains relatively constant when mortar type and volume fraction are also held constant. These values are always lower than natural-weight aggregate concretes.

Though recycled aggregate is useful resources for concrete, its application to structural frame is not frequent, because of low quality of recycled aggregate. Owing to the development of manufacturing technology to recycled aggregate, it is possible to produce high quality recycled aggregate. The purpose of this study is to confirm the applicability of the high quality recycled aggregate, instead of the natural aggregate, to normal concrete. Main factors of this study are substitute proportion of recycled aggregate, types of recycled aggregate, targeting compressive strength of recycled concrete. From the results of the study, we concluded that it is possible to use high quality recycled aggregate, to get the same strength as concrete using normal aggregate.

This research investigates how the fineness modulus of fine aggregates and the grain shape of coarse aggregates affects flow characteristics, packing characteristics and compressive strength characteristic. The experimental results, show that increase of the fine aggregate's fineness modulus improved concrete flow, but filling ability was high at over KS regulation extent due to segregation phenomena. It is considered that the improvement of 0.1 spherical rate was effective to concrete fluidity elevation by reducing about $6\%$ of fine aggregate ratio displays which the smallest gap rate of aggregate. Compressive strength was increased to about 0.6MPa everytime F.M. 0.1 of fine aggregate fineness is increased. However, it was decreased to about 9MPa at F.M. 3.5 compared to F.M. 3.0.

When a concrete member is damaged by fire accident, it can lose its strength. And the degradation rate of losing its strength affected by many environmental conditions. But there is few research for equation for strength evaluation of fire-damaged concrete. Besides, it is impossible to destruct structural member from the building for the evaluation. So, I will suggest a new equation for strength evaluation of fire-damaged RC beam using non-destructive test. For this purpose, the researchers are exploring the performance of non-destructive testing methods using Ultrasonic test, Schmidt Hammer test and Coring test against fire damaged concrete specimen.

This study was performed to develop necessary Visual Inspection System for the PSC Bridges precision safety diagnosis which to enhance the efficiency and accuracy of visual inspection by using mobile PC and adopted IT. This system was constructed to the automatic visual inspection map generating program and the Visual Inspection System using mobile PC that predicted high efficiency.

In conventional methods, the availability of floating crane has determined the size of a concrete caisson. However, this paper introduces a new method for larger caisson production that make it possible to complete caisson fabrication and launch out without use of floating crane. The new method carries out multi-step fabrication of caisson and horizontal transfer of caisson on a single casting bed which consists of collapsible soffit form, trough, aero go watercaster system or low frictional PTFE added jacking system, half-submergible floating dock. To make the new method successfully launched, the static and dynamic analysis is carried out to obtain the stability of caisson launching and experimental research is conducted in evaluating friction occurred between PTFE pad and steel track. Lastly, the comparison of the new method and the conventional method are detailed. With significant benefits in construction costs reduction and construction time reduction, this new method in this paper would be recommended for extensive application in large port and harbor construction projects.

The construction of high-rise buildings is increased. The Vertical Member of tall buildings is inherently shortened and it causes several seriously problems such as tilting of slab, crack within partition wall, deformation of curtain wall. This also affects structural stability by inducing unexpected stress to the structural members such as outrigger. In this study, the column shortening according to revised field information and to compare the analysis results the actual field measurement. Pusan The $\#$, a 51-story apartment building which is currently under construction was chosen for the case study.

The presence of voids behind tunnel linings results in their deterioration. One proposed method of effectively detecting such voids by non-destructive means is radar. This research is devoted to quantitatively evaluating the efficiency of such non-destructive tests with radar. As a foundation to this ongoing research, which aims to acquire directional information and estimate the shape of specific voids using radar of three-dipole antenna type, an investigation of microwave polarization methods is carried out with various void orientations and void geometries. As the results, it is clarified that the response of microwave polarization modes depends on void geometry and thus there is a possibility of identifying the geometry and orientation of specific voids using radar of three-dipole antenna type.

This study was performed to verify the behaviors of fiber Bragg grating (FBG) sensors attached to the containment structure in the nuclear power plant as a part of structural integrity test which demonstrates that the structural response of the non-prototype primary containment structure is within predicted limits plus tolerances when pressurized to $115\%$ of containment design pressure, and that the containment does not sustain any structural damage.

The kinetic energy during ship collision with bridge piers is released as the permanent deformations of structure and friction between the impact surfaces. So the ship collision energy is estimated from the equations of motions for ship-pier collisions which include the influence of the surrounding water, different impact angles and impact locations. The normal impact energy and tangent impact energy at a collision location and angle can be transformed into the normal impact force and friction force acting on the structure. Also the kinetic energy after collisions is calculated from the linear and angular impulse of ship collisions. The collision energy absorption system such as the protective structures for bridges is designed by evaluating the damage portions of ship and structure during the ship-structure collisions varying from the soft impact to hard impact and then the estimation of it will be suited for the design of protective measures.

This paper reports the results of performance verification tests of the base isolated RC building with the laminated rubber bearings which is manufactured by Dongil Rubber Belt Co.. The shaking table tests were performed using a scaled 3-story model scaled to 1/3 of the prototype RC apartment building. Several major earthquake records were scaled to different peak ground accelerations and used as input base excitations. Through the verification tests, the validity of the applied base isolation device and the response reduction effect against earthquakes are confirmed.

Smart structural system is defined as structural system with a certain-level of autonomy relying on the embedded functions of sensors, actuators and processors, that can automatically adjust structural characteristics, in response to the change in external disturbance and environments, toward structural safety and serviceability as well as the extension of structural service life. In this study, carbon and glass hybrid fiber materials were investigated fundamentally for the applicability of self diagnosis in smart concrete structural system as embedded functions of sensors.

In this study, Pavement Management System(PMS) was developed to overcome the unscientific pavement management limitations of the past. PMS program is economic, efficient and scientific. Also, it produces the best maintenance method through exact judgement and logical analysis of pavement condition. First of all, the logical algorithm, that is such as investigation and analysis of pavement, detailed naked eye investigation and the estimation for whole system etc., was composed on the basis of the domestic and the outside data on PMS and pavement condition data of Seoul metropolitan. And then it was verified that this algorithm is suitable through the research examples of PMS data and the results of detailed naked eye investigation. Also, Geographic Information System(GIS) was integrated on PMS program. Therefore, PMS program was developed so as to use easily on the basis of the logical algorithm.

This paper presents the results of the experimental study on the performances of reinforced concrete beams rehabilitated by external unbonded high tension steel-bar. Design variables for the experiment in this study includes the position of anchorage zone of the high tension steel bar, the anchorage length of the reinforcing steel bar and the types of the shear strengthening measures. 5 specimens were tested with one point monotonically increased loads and structural performances such as strength capacities, ductility capacities and failure modes were analysed. It is found that the structural performance of the rehabilitated beams are strongly depended on the location of anchorage zone of the high tension steel-bars. In the case that anchorage zone is located near the critical shear zone, it is observed that the rehabilitated beam is failed in brittle failure mode and the additional shear strengthening is necessitated. But if anchorage zone is properly located or additional shear strengthening device is provided properly, it is also observed that the strength capacity of the rehabilitated beams could be increased more than $200\%$ by the proposed method.

The mock-up test was carried out to solve several problems of the hot weathered high strength concrete. The workability of concrete could be guaranteed by using high range water reducer containing polycarboxylic acid. The compressive strength calculation by rebound value of Schumidt hammer underestimated the actual strength of concrete structure. The temperature of concrete should be lowered by control of raw material temperature and transportation.

Traditional prediction models have been developed with a fixed equation from based on the limited number of data and parameters. If new data is quite different from original data, then the model should update not only its coefficients but also its equation form. However, artificial neural network dose not need a specific equation form. Instead of that, it needs enough input-output data. Also, it can continuously re-train the new data, so that it can conveniently adapt to new data. Therefore, the purpose of this study is to verify faith and application of prediction system of concrete strength using artificial neural networks through mock-up test.

The present study is a basic experiment on the estimation of the compression strength of high strength concrete, aiming at estimating the compression strength of mass test pieces of high strength concrete by giving the temperature hysteresis of the mass test pieces to managerial test pieces. Thus, this study made concrete test pieces in an optimal mix ratio for each strength level, and also created adiabatic curing tank and managerial test pieces. Then it carried out comparative analysis in relation to core strength and suggested equipment and a technique that can control the strength of high strength concrete mass more conveniently and accurately.

Due to social problems such as the increasing of land price and the expanding of city, buildings require more complex and bigger components and structure. However, the complex and massive building projects need new technology to solve effect of local buckling and the needs for more space. Hence, Concrete Filled Tube Steel (CFT), the tube steel to hold concrete during pouring and curing of concrete procedure, which helps to reduce local buckling and space, was developed. Most researches on CFT might not be focused on the characteristic of concrete 'filled in tube but structural analysis. However, it is the essential factor to increase the strength of concrete on CFT for having efficient results. Therefore, this paper will describe how to apply CFT into the construction site through examining High Strength Concrete $(800kg/cm^2)$, the strength of core, and bleeding during pouring strategy.

The column for Steel Framed Reinforced Concrete Structure (SFRCS) and the column for Reinforced Concrete Structure (RCS) could be the most common building structure. The increasing of the need for massive space hasaffected the size of building components for supporting the massive structure. However, the changing of components size makes inefficient space of building. Hence. to meet the need for acquiring efficient space comparing the budget and cost the new structure method, Concrete Filled Tube Steel (CFT), was developed. CFT is the structure for which steel tube instead of other materials such as wood for holding concrete is used. The most benefit of this one is to help in reducing the size of the building components and local buckling because of tube steel holding concrete. For this reason, this research will examine the probability of applying CFT on construction sites by using the concrete $(800kg/cm^2)$ especially for CFT through the data from the real size mock-up.

Since quasi-brittle materials like concrete show strain localization behavior accompanied by strain softening, a numerical drawback such as mesh sensitivity is appeared in the finite element analysis. In this paper, the so-called homogenized crack model which was introduced for three dimensional finite element analysis of fracture in concrete is studied for the mesh size dependence problem in fracture analysis. A homogenized crack element having a velocity discontinuity. is averaged to remove the mesh sensitivity in finite element analysis of concrete fracture. Numerical examples show that softening behavior of concrete fracture is successfully predicted without mesh sensitivity using the homogenized crack model.

Efficient numerical finite element analysis of creeping concrete structures requires the use Kelvin or Maxwell chain model, which is most conveniently identified from a continuous retardation or relaxation spectrum, the spectrum in turn being determined from the given compliance or relaxation function. The method of doing that within the context of solidification theory for creep with aging was previously worked out by Bazant and Xi, but only for the case of a continuous retardation spectrum based on Kelvin chain. The present paper is motivated by the need to incorporate concrete creep into the recently published microplane model M4 for nonlinear triaxial behavior of concrete, including tensile fracturing and behavior under compression. In that context. the Maxwell chain is more effective than Kelvin chain. because of the kinematic constraint of the microplanes used in M4. Determination of the continuous relaxation spectrum for Maxwell chain. based on the solidification theory, is outlined and numerical examples are presented.

A new earthquake design method performing iterative calculations with secant stiffness was developed. Since basically the proposed design method uses linear analysis, it is convenient and stable in numerical analysis. At the same time, the proposed design method can accurately estimate the inelastic strength and ductility demands of the structural members through iterative calculations. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. The proposed method, as an integrated analysis and design method, can directly address the earthquake design strategy intended by the engineer, such as limited ductility of member and the concept of strong column - weak beam. Through iterative calculations on a structural model with member sizes preliminarily assumed, the strength and ductility demands of each member can be determined so as to satisfy the given design strategy. As the result, structural safety and economical design can be achieved.

An experimental investigation on the relationship between corrosion of reinforcement and bond strength in pull-out test specimen has been conducted to establish the allowable limit of rust of reinforcement in the construction field. The reinforcing bars used in this study were rusted before embedded in pull-out test specimen. The first component of this experiment is to make reinforcing bar rust electrically based on Faraday's theory to be 2, 4, 6, 8 and $10\%$ of reinforcing bar weight. For estimation of the amount of rust by weight, Clarke's solution and shot blasting were adopted and compared. Parameters also include 24 and 45MPa of concrete compressive strengths and diameter of reinforcing bar (16, 19 and 25mm). Pull-out tests were carried out according to KS F 2441 and ASTM C 234. Results show that up to $2\%$ of rust increases the bond strength regardless of concrete strength and diameter of reinforcing bar. As expected, the bond strength increases as compressive strength of concrete increases and the diameter of bar decreases.

A Performance Based Design procedure for retrofitting the RC frame with friction dampers is described. The Capacity Diagram Method procedure is used to estimate the inelastic response of the example model. The example models were retrofitted using SBC dampers and the retrofitted example models were computation ally modeled. The results show that the performance of the retrofitted frame satisfies the target objective.

In this paper, we try to detect the peel out effect and find the strain difference between the main structure and retrofitting patch material when they separate from each other. In the experiment, two fiber optic Bragg grating sensors are applied to the main concrete structure and the patching material separately at the same position. The sensors show coincident behaviors at the initial loading, but different behaviors after a certain load. The test results show the possibility of optical fiber sensor monitoring of beam structures retrofitted by the composite patches.

In the analysis of early-age concrete behavior, the fresh concrete is considered as a structural element immediately after mixing. But for the activation of real structural behavior in the fresh concrete, the so-called setting time is necessary a few hours after the beginning of hydration reaction. In this paper, analysis on the setting behavior is carried out by proposing an analytical model based on the percolation theory as well as the expanding cluster model by defining the setting as a microstructure formation in fresh concrete. An experimental investigation is also carried out to show the influences of curing temperature, mineral admixtures and chemical admixture on setting behavior of fresh concrete. Finally, the analytical results using proposed model are compared with the experimental results for the sake of verification.

This paper presents the analysis results predicted by the upper bound approach in the limit analysis of concrete incorporating the original plastic and crack sliding solutions for short high-strength concrete beams that varied the compressive strength of concrete, and the shear span-to-depth and vertical shear reinforcement ratios. The significance of the distance away from the support to define the location where the yield line starts and the properties of cracked concrete, particularly related to high-strength concrete, is identified.

A new slab design using secant stiffness, Direct Inelastic Slab Design, was developed. Since basically the proposed design method uses linear analysis, it is convenient and stable in numerical analysis. At the same time, the proposed design method can accurately estimate the inelastic strength and ductility demands of slab because it can analyzes the inelastic behavior of structure using iterative calculations for secant stiffness. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. Design examples using the proposed method were presented, and compared with traditional nonlinear analysis, and experiments. The Direct Inelastic Slab Design, as an integrated analysis/design method, can directly address the design strategy intended by the engineer, such as moment strength and ductility limit. As a result, economical and safe design can be achieved.

Now for the first time in Korea pilot project on application of base isolation system to the RC building is carrying out by collaboration with KNHC and DRB dongil. The hybrid-type base isolation system, which is composed of sliding bearings and laminated rubber bearings and can make the resonance period of base isolated buildings comparatively long up to 4 or 5 seconds, is applied to this building. In this paper the overview of this project, the dynamic characteristics of this particular building and the response reduction effect against earthquakes are presented.

This paper proposes Headed bar as reinforcement of beam-column joint, and proves seismic performance and reduction of reinforcement congestion. In these case, the use of Headed bars have obvious advantages. The greatest benefit of using Headed bars is not only improved structural performance of beam-column joints, but also the ease of fabrication, construction, and placement. Three-dimensional finite element analysis model is compared with test program which was fulfilled by the proposed model with Headed bar. Also, the plastic hinge region is relocated to the center of the longitudinal beam length according to the strong column-weak beam design philosophy, so Headed bar is used as the joint reinforcement. Therefore, this paper presents results of a computer analysis of a practical solution for relocating potential beam plastic hinge regions by the placing of straight - Headed bar.

The objectives of this research are to evaluate the effect of the compressive strength of concrete, reinforcing bar size, spacing of column transverse bars related to the concrete confinement effects on anchorage bond strength and bond behavior of beam-column joints subjected to cyclic loading and to predict the bond behavior of beam-column joints according to the variables by Finite Element Analysis appling the interface element between concrete and reinforced bar surface in a three-dimensional configuration. This paper shows that to verify the results by three-dimensional nonlinear finite element analysis appling a interface element, the test results that were already conducted are compared with analytic results. The behavior of bond and anchorage of beam bar is expressed by a local bond stress-slip relationship and the failure mode of bond is predicted by principal stress contour.

The paper discusses the general behavior of fire-damaged slender reinforced concrete columns on the basis of results obtained from parametric studies. Effects of slenderness ratio, concrete strength, cover thickness, reinforcement ratios, exposed time to fire, and eccentricity on the ultimate capacity of fire-damaged column are theoretically observed. With the increase of slenderness ratio, similar tendency of relative strength reduction was observed between fire-damaged columns and columns at room temperature.

The finite element method(FEM) models were developed for the reinforced concrete flexural walls and analysed under constant axial and monotonic lateral load using ABAQUS. The major objective of the present study is to determine if the ABAQUS finite element program can be used to accurately model the post-cracked mode of failure in plastic regions of walls, and, if so, to develop practical failure criteria in the plastic range of the material response. The research comprises constitutive models to represent behavior of the materials that compose a wall on the basis of experimental data, development of techniques that are appropriate for analysis of reinforced concrete structures, verification, and calibration of the global model for reinforced concrete walls of increasing complexity. Results from the analyses of these FEM models offers significant insight into the flexural behavior of benchmark data.

Recently, precast concrete products have been increasingly used in the construction of bridges except for special bridges like long-span bridge due to their easy and high-quality construction. Specially the use of precast prestressed concrete hollow box slab bridges is also increased due to the merits in their construction. Thus, an experimental evaluation of flexural behavior of the precast PSC hollow box slab bridges and a development of effective analytical technique for the behavior are necessary. For the development, experimental study on the flexural behavior of the precast bridges up to ultimate states is needed. In this study, two full-scale precast PSC hollow box slab girders are manufactured and full-scale flexural failure tests of the girders subjected to cyclic loading are carried out. For the failure analysis of the girders, the so-called volume control method is applied to finite element analysis of the precast PSC hollow box slab girders discretized using multi-layered shell elements. The analytical results by the volume control method is verified by comparing with test results.

Nowadays, many of PSC bridges has constructed because high performance and long span bridge is required. Therefore, it is required that the evaluation of PSC bridges which retain various structure performance. In this study, nonlinear FEM analysis was performed with two parameter, concrete compressive strength and effective prestress force which is dominant factor for evaluating structural behavior of PSC bridge. Concrete compressive strength was adapted between 30Mpa and 100Mpa and effective prestress force was used the value which is considered effective rate for time-dependant effect. In the result of this study, it was showed that concrete compressive strength and effective prestress force is important factor for evaluating structural behavior of PSC bridge.

This paper presents a nonlinear finite element analysis procedure for the prediction of shear strength of reinforced concrete deep beams. A computer program, named RCAHESTC(Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile. compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The proposed numerical method for the prediction of shear strength of reinforced concrete deep beams is verified by comparison with the reliable experimental results.

This paper focues on the flexural behavior of RC beams externally reinforced using Carbon Fiber Reinforced Plastics plates. (CFRP) A non-linear finite element (FE) analysis is proposed in order to complete the experimental analysis of the flexural behaviour of the beams. This paper is a part of a complete program aiming to set up design formulate to predict the strength of CFRP strengthende beams, particularly when premature failure through plates-end shear or concrete cover delamination occurs. An elasto-plastic behaviour is assumed for reinforced concrete and interface elements are used to model the bond and slip.

In this study, the validity of the grid softened strut-tie model method suggested for concrete member analysis is examined through the ultimate strength evaluation of the reinforced concrete beams. The evaluated results of ultimate strength by the grid softened strut-tie model method were compared with those by the ACI 318-02 and the modified compression field theory, and European codes.

Predicting the failure modes of reinforced concrete corbels is difficult because the reinforced concrete corbels show the shapes of sudden shear failures at even slight deflection. For this reason, an exact analysis method is demanded highly. In this study, the validity of the grid softened strut-tie model method suggested for concrete member analysis was examined through the ultimate strength evaluation of the reinforced concrete corbels tested to failure. The evaluated ultimate strengths by the grid softened strut-tie model method were compared with those by the ACI 318-02 and the softened strut-tie model method.

The main purpose of this study is to estimate the internal temperature of RC beam under fire. For this purpose, the finite difference method was used. In the previous studies, the structural behavior of fire damaged RC beams was investigated through experiments. The result was concluded that The high temperature affects the properties of concrete such as the elastic modulus, the compressive strength. The internal temperature Estimation of the concrete is helpful for understanding the structural behavior of fire damaged RC beams. Especially, high strength concrete has more spalling than normal strength one. So, this study is performed analysis of internal temperature of RC beam considering spalling.

For the estimation of the load effects of the slab-an-girder type structures, the applicability of FEM analysis for RC T-type girder bridges using orthotropic plate elements has been studied in the present study. The present study indicates that the analysis by orthotropic plate elements for RC T-type girder bridges gives reasonable results for sectional force, including moments and shear. The results from the present method gives the values in between full composite and non-composite cases, which are reasonable when compared with actual test results.

In this Paper, concrete durability, coefficient variation of compressive strength, and hydration heat development characteristics of concrete using different types binder for 2nd Phase Construction in IIA were investigated. The experimental results show that the coefficient variation of compressive strength decreased with the slag cement when compared with the replacement of granulated blast furnace slag powder. And the diffusion coefficient of chloride ion decreased with use of a blended cement when compared with using a only portland cement. Also the type of low heat cement is very suitable to reduce the thermal crack caused by hydration heat development.

This study reports the site application of concrete using AE Water Reducing Agent of Early-Strength Type. According to the lab test results, we have made plans of batch plant pilot test, and we have analyzed the erly aged compressive strength and workability of the concrete. We applied the early-strength development concrete to the construction site. We accomplished the slump test in order to evaluate the workablity and air contents, we made site curing mold to evaluate the early strength of members. As a result, we judgeed the superior property of early strength development of the concrete, and thought that we can reduce the time of form stripping more $40\%$ than ordinary strength concrete. We thought that we can reduce the term of works and finally we can accomplish the economical construction.

FAs and BAs indicated different chemical compositions and physical properties. Leaching of Pb in FAl and Cu in FA2 were 33.2mg/L and 5.92mg/L, these were high concentration above 30 and 2 times respectively in compared to permit level. Leaching of Hg and Cr were about 1/2 of permit level. When diatom was complexly mixed with portland cement, the 28 days compressive strength of mortar with FA2 was similar with that of control mortar. Furtherfore, leaching of heavy metal ions like as Pb, Cu, Hg, Cr was highly reduced.

This research estimated the physical. mechanical characteristic and the character of sound absorption according to target void ratio of porous concrete and the mixing ratio of recycled aggregate for the valid utilization of recycled aggregate using waste concrete and sound reduction out of a road, a railway, a residential street, and a downtown area. As a result of the test, compressive strength tended to be a radical strength fall when target void ratio was $25\%$ and contents of recycled aggregate exceeded over $50\%$. Also, the character of sound absorption of porous concrete which used recycled aggregate using waste concrete was the most excellent when target void ratio was $25\%$, and the influence by contents of recycled aggregate was trivial. Therefore, when the strength and the character of sound absorption of porous concrete are considered, it is proved valid that proper target void ratio was $25\%$ and contents of recycled aggregate using waste concrete was $50\%$ or so.

A fundamental study was executed in order to evaluate quantitatively the effect on strength characteristic of concrete or mortar by fly ash. As a result, it was confirmed that the appropriate usage of fly ash is in existence comply with mix condition and characteristic of fly ash. And, we could evaluate the activity factor of fly ash. But, there are many problem in actual application because that the object of this study is only Method(2) out of the evaluation methods of activity factor proposed by CEN. Therefore, it is necessary to keep up an additional study.

In order to offer the condition of plant survival, present the method to reduce pH of porous concrete. Water curing is the most suitable method for reducing pH. Water/cement ratio is lower pH in $25\%$ than $30\%$, and to reduce pH, the larger size of coarse aggregate is more proper in the same water/cement ratio, neutralization management after becoming solid than early.

Due to the tendency of increase in demolished-concrete produced by alteration and deterioration of concrete structures, recycling of those demolished-concrete is necessary to solve the exhaustion of natural aggregate, in order to save resources and protect environment. In this an experimental study herein, the Chlorine-ion and Carbonation resistance of the recycled aggregate concrete was investigated. Coarse aggregate was replaced with $100\%$ of the recycled aggregate and cement and fine recycled aggregate was replaced with various amount. It was shown that the concrete can obtain resistance of chlorine-ion, when fly ash replaced with up to $30\%$ of cement.

This research investigates the rheological behavior and the confined water ratio of the cement paste and binder condition in order to predict mix design proportion of the high flowing concrete. The purpose of this study is to determine the optimum replacement ratio of binders including fly ash, and lime stone powder by the cement weight. For this purpose, belite cement, blast furnace slag cement and ordinary portland cement are selected. As test results, the confined water ratio shows the following range ; OPC>blast furnace slag cement>belite cement. Therefore, belite cement is proved very excellent cementitious materials in a view point of the flowability. The optimum replacement ratio of lime stone powder is shown over $30\%$ in case of belite cement and about $10\%$ in case of slag cement type. Also, the optimum replacement ratio of fly ash is shown $30\%$ by the cement weight considering the confined water ratio and deformable coefficient of the paste condition.

Generally, $TiO_2$ powders absorb ultraviolet rays and make oxidation/reduction reactions on its surface. Hydroxide radical(OH), a product of photocatalyst reactions, has so strong oxidation/reduction electric potential that it can oxidize noxious gas like VOCs(Volatile Organic Compounds) and NOx. In this study, $TiO_2$ was substituted for exposed concrete to investigate the purifying degree of VOCs(Benzene, Toluene) and NOx. Anatase types of $TiO_2$ were used as photocatalyst. The sun rays and the ultraviolet were used as a light source. Anatase type $TiO_2$ was better than rutile type in purifying performance. The sunray showed the best purifying performance among the light sources. $3\%$ substitution of $TiO_2$ with the sunray was enough to purify VOCs(Benzene, Toluene) and NOx efficiently.

This Study discusses the properties of drying shrinkage of concrete slab with W/B, water content, fiber and anti-shrinkage agent. According to results, drying shrinkage is reduced with decrease of water content and W/B. Also, compared with plain concrete, drying shrinkage is reduced by using of fiber, anti-shrinkage agent and adding ratio of anti - shrinkage agent. Therefore, in the range of workability if water content and W/B are reduced and using of fiber and anti-shrinkage agent are performed properly, crack by drying shrinkage can be prevented effectively.

The purpose of this study is to investigate properties of porous concrete according to rheological properties of binder and compaction factor. The results of this study, the rheological property of binder is stabilized when a mixing time is over 240 seconds in case of target flow values are $175\%\;and\;200\%$. The void ratio of specimen has a very near value by target void ratio on the whole according as the rheological properties of binder and compaction energy are changed when target flow value is $200\%$, compaction energy is $75kN{\cdot}m/m^2$. The specimen has the excellent compressive strength when compaction energy and target flow value are $100kN{\cdot}m/m^2$ and $200\%$ respectively.

Recently, the river sands are in short supply. Gathering sea-sand will be faced with difficulty. Alternative aggregates for concrete are estimated by many researchers. The aggregates are blast furnace slag, steel slag, copper slag, ferro-nickel slag and recycled aggregate and etc. Nevertheless steel slag has been limited in practical use due to its expansibility which is occurred reaction with water and free CaO in slag. Most recently stable management method is to minimize the expansibility researched and developed. First of all, slump, air content, compressive strength and flexural strength are measured in concrete. An estimate is made of the segregation of concrete containing atomized steel slag by Image Analyser program.

Concrete structures in the marine environment often deteriorate in the early stage of their service life because of contact with various aggressive conditions. In recent years, the study on the concrete in the marine environment are carried out to increase their service life. In this experimental study, the concrete specimens were prepared with various adding contents of inorganic antifouling agent$(0\~3.0wt\%)$ composed to some fluosilicate solution. For evaluatin of the physical and chemical properties of concretes containing inorganic antifouling agent, various tests such as setting time, slump loss, compressive strength, water absorption rate, freezing and thawing resistance and SEM micrographs of concrete, were conducted. As the results, physical and chemical properties of concretes were improved with an adding of inorganic antifouling agent. From the results of various tests, the optimal adding contents of antifouling agent was $1.0wt\%$.

As the use of various electronic equipments has been increased recently according to industrialization and information network establishment, concern about electromagnetic wave exposed environment has also been increased. Therefore, this study aims to verify electromagnetic wave absorbing effects of inorganic paint that is made of carbon, electro-conductive materials with regard to its physical characteristics, its electromagnetic wave absorbing rate through a mock-up test for proving its effects in the indoor condition. The results are as follows: The results of running tests on electromagnetic wave absorbing inorganic paints for checking their requirements as painting material such as adherence degree, resistance to fine crack, resistance to washing, alkali-resistance, discoloration-resistance, etc. show that inorganic paints have the physical characteristics meeting the requirements for painting materials. In addition, it shows that the electromagnetic wave absorbing effect, in line with the number of paintings and the thickness of paintings, secures $75\~89\%$ of efficiency. And the mock-up test shows that the electromagnetic wave absorbing effect inside building is directly proportional to the distance from the source of electromagnetic wave such as electronic equipments.

The objective of this experimental study was to understand inelastic strain of concrete incorporating hwangtoh or combination of hwangtoh and slag. Main variables were replacement level of admixtures, hwangtoh and slag. We studied the properties of concrete such as heat of hydration, drying shrinkage and creep according to the replacement level of hwangtoh and slag. Test results showed that the heat of hydration of concrete decrease with increasing hwangtoh and slag replacement. Also drying shrinkage and creep of concrete increase with increasing hwangtoh replacement.

This study has focused on the possibility for recycling of tailings from the Sangdong tungsten mine as powder. The experimental tests for entrapped water ratio were carried out in accordance with the specificed method by Okamura. The rheological measurements of cement paste were conducted by using a commerically digital Brookfield viscometer (Model LVDV-II+) equipped with cylindrical spindles. The results of this study, in case of cement paste mixed with tailings, entrapped water ratio was decreased with increasement of mixing ratio. Thickness of pseudo water film was increased, and mean plastic viscosity was decreased with increasing replacement.

Waste concrete powder(WCP) has been estimated with a great value-added material as by-product of waste concrete manufactured to fine and coarse aggregate for concrete, because it is able to utilized for cement clinker and concrete admixture. In the experimental results for this study, chemical composition of WCP was similar to that of cement, and specific gravity of WCPs were 2.46 and 2.48 due to internal micro-void of WCP. Final setting of paste with WCP was delayed, and flow value of mortar with WCP was tendency to reduced in comparison with that of paste and mortar with only ordinary portland cement as replacement ratio of WCP increased. Furthermore, sorptivity of mortar with WCP was increased as replacement ratio of WCP increased. Compressive strength of mortar with $15\%$ WCP was developed about 27MPa at 28days.

Most concrete is recently made of an aggregate which is properly absorbed, and carried in it according to its capability at every fields. We have been close to demand new capability of high flowing and enduring for specific concretes. That is difficult to cope with claiming the efficiency on deterioration from lack of a high Quality aggregate. Therefore, For solving the problems we apply to method of packaged dry combined materials for concrete using dried materials. That is to say that it is a kind of making into an instant. In this study, There is a purpose to present fundamental data, comparing and analyzing a phenomenon of aggregate's absorption following the rate of adding water, for using existing materials.

In this paper, mechanical properties of concrete incorporating CKD are discussed with W/B and fluidity. For setting properties, an increase in W/B retarded setting time greatly in $5^{\circ}C$, while accelerated in $20^{\circ}C$. For fluidity, an increase in slump delayed the setting time with dosage of SP agent. The presence of CKD has little influence on setting time compared with plain concrete. For compressive strength, an increase in maturity enhanced compressive strength. Fluidity had no relation to compressive strength. At low curing temperature, concrete with CKD has slight strength loss compared with plain concrete. However, remarkable strength loss at low curing temperature in early stage was not found, which can be applicable to low temperature environment concrete placing.

In this paper, material property of fiber reinforced concrete(FRC) according to the steel fiber, glass fiber and carbon fiber blended ratio. The fiber reinforced concretes are increased mechanical strength, because the fibers are dispersed with randomly direction and disturb crack progression in concretes. Adhesive fracture is occurred slowly at interface between fiber and concrete, and the fracture energy is absorbed due to softening phenomenon.

Reinforced concrete structures have been used for a long time. However, corrosion problem in reinforcing steel is inevitable, which results in the degradation of performance and the shortening of the life of structures. To overcome such problems, FRP(Fiber Reinforced Polymer) rebars have been developed. Due to their corrosion resistance and their superior mechanical properties, FRP rebars are increasingly applied to concrete structures in other countries. To obtain the composite action between FRP rebars and concrete, sufficient bond between two materials must be secured. But, the behavior of FRP rebars is different from that of steel rebars. Therefore, it is necessary to understand and develop the proper bond mechanism of FRP rebars to use them in concrete structures. This paper presents analytical results to investigate the bond-slip relationship between FRP rebars and concrete based on pull out tests.

Synthetic lightweight aggregates are manufactured with recycled plastic and fly ash with 12 percent carbon. Nominal maximum-size aggregates of 9.5mm were produced with fly ash contents of 0 percent, 35 percent, and 80 percent by total mass of the aggregate. An expanded day lightweight aggregate and a normal-weight aggregate were used as comparison. Mechanical properties of the concrete determined included density, compressive strength, elastic modulus, and splitting tensile strength. Compressive and tensile strengths were lower for the synthetic aggregates; however, comparable fracture properties were obtained. Relatively low compressive modulus of elasticity was found for concretes with the synthetic lightweight aggregate, although high ductility was also obtained. As fly ash content of the synthetic lightweight aggregate increased, all properties of the concrete were improved.

Modulus of rupture (MOR) and flexural toughness in hybrid fiber reinforced cement pastes mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume according to the fixed ratio were researched. Reinforcing efficiency in specimens were estimated by two factors, such as strengthening factor $(F_s)$ and toughening factor $(F_t)$, which were calculated from the analysis of variance (ANOVA) of the response values, such as MOR and absorbtion energy $(W_0)$. According to the experimental design by the fractional orthogonal array, nine hybrid fibrous reinforced paste series and one non-reinforced control paste were manufactured. Specimens of each series were tested by the INSTRON Inc. 8502(model) equipment in three-points bending and then measured the load-deflection response relationships. Considerable strengthening of cement pastes resulted in' the case of other factors without carbon fiber and toughening of cement pastes about all factors showed high. Based on the significance of factors related to response values from ANOVA, following assessments were available; $F_s$ or MOR: silica fume $\gg$ steel fiber $\gg$ carbon fiber; $F_t\;or\;W_0$: steel fiber > carbon fiber > silica fume. Optimized composition condition was estimated by steel fiber of $1.5\%$, carbon fiber of $0.5\%$ and silica fume $7.5\%$ in side of strengthening and steel fiber of $1.5\%$, carbon fiber of $0.75\%$ and silica fume $7.5\%$ in side of toughening.

Many damage models has been developed to express the degradation of materials. However, only minor damage model for concrete has been developed because of the heterogeneity of it unlike metals. To model the damaged behavior of concrete, this peculiarity as well as a load-induced anisotropic feature must be considered. In this paper, basic concepts of the thermodynamic theory is investigated to model the behavior of the damaged concrete in the phenomenological viewpoint. And the general constitutive relations and damage evolution equations are investigated too.

In these days, repair materials for leakage cannot help but being taken in temporary way without any noticeable countermeasure. This kind of repair is socially criticized many times that is defective construction even if tills costs a lot. It was not arrange the standard for performance evaluation test method and quality maintenance for materials, even it has been used various injection repairing agent. In conclusion, We suggest that the test method for repair materials for leakage to establish the leakage repairing technology as increase of structure demand, so that the necessity of the establishment of the quality control standard and the performance testing way on the relevant water-proof seal is increasing a lot to regulate the water-proof technology and the leakage repair technology.

In this research, the properties of porous concrete by pressurized compaction, such as compressive strength, coefficient of permeability, void ratio of the porous concrete are measured. These results suggest the fundamental data of porous concrete properties.

This paper investigate the qualities variety of concrete using recycling water under various kinds and contents of saccaric based stabilizing agent(SSA). Fluidity had little changes with the kinds and contents of SSA. Air contents of concrete with recycled water only shows the tendency. With an increase in SSA contents, air content recovered. For bleeding properties, bleeding shows to be decreased with an increase in SSA contents. The use of recycled water accelerated the setting time. However, with an increase in SSA, setting time showed the similar level of plain concrete. SSA (Btype) had better performance in enhancing compressive strength owing to loss of air content. Although the use of recycled water increased the drying shrinkage compared with that of plain concrete, it tended to decrease with an increase in SSA.

It may have to establish the definite standard for performance evaluation basis about cementitious waterproofing material in job site that applied the method of construction formed cement waterproof course on concrete surface In present paper shows the effective selection method of waterproof layer of optimum thickness for economic performance as evaluating of the need thickness on waterproof property of penetrating waterproofing material.

Recently, the concern for mechanical properties at early age concrete are increasing because of the importance of the thermal stress and the determination of removal time of form work and prestressing work. In this study, an estimation for the development of compressive strength and elastic modulus with age in concretes isothermally cured $(10^{\circ}C,\;20^{\circ}C)$ and having W/C ratio of 30, 40, and $50\%$ were investigated. According to experiment results, the development of compressive strength and elastic modulus shows higher values at early ages as the W/C ratio decreases and curing temperature increases. When the maturity concept, for estimation of the strength, is adopted, a modification for W/C ratio is required at early ages.

The objective of this study was to understand the effect of hwangtoh and slag on various properties of concrete. Main variables were replacement level of admixtures, hwangtoh and slag, and curing temperature. Test results indicated that the compressive strength of concrete replaced by either hwangtoh and slag was significantly influenced by curing temperature. The elasticity modulus and compressive peak strain of concrete showed a small increase with increasing hwangtoh replacement.

In this study, we considered the characteristic of drying shrinkage from age of high strength concrete with garnet minute powder to be industry by-product. The factors of experiment are unit water content$(160kg/m^3)$, water-binder ratio(30, $35\%$), fine aggregate ratio(40, 42, $44\%$), admixture replacement ratio(0, 10, $20\%$), admixture type(garnet minute powder, fly ash, blast-furnace slag). We make a comparative study of shrinkage about concrete with a passage of age(1, 3, 7, 14, 28, 56, 91 days). As a result of experiment, we reach a conclusion as follow. In the same mix condition, as unit water content and fine aggregate ratio go up, the drying shrinkage ratio increase. In the drying shrinkage ratio according to admixture replacement ratio, it goes up when admixture replacement Ratio increase in case of fly ash and blast-furnace slag. But, drying shrinkage ratio decrease when admixture replacement ratio increase in case of garnet minute powder.

This study is to obtain basic data concerned with properties of foam for foamed concrete and foaming method. Main factors of this study are types of foaming agents, temperature of solution with foaming agents, and types of foam generator. Testing items are size distribution of foam, foaming ratio to solution, and stability of foam. The results of this study were shown as follow. It is optimum condition of foam generator that length/diameter of foaming tube is 2.0, bead size within foaming tube is $4\~6mm$, and nozzle size of foaming tube is 10mm. AES and AOS are good results to produce high quality foam, and stability of foam is good in foaming temperature of $20^{\circ}C$.

The purpose of this study is to obtain basic data on the properties of the development of lightweight mortar contained foam agent for various applications in the field. In the experiment, as a result of measurement the specific gravity by the change of the W/C and the foam agent into a variable and measuring the compressive strength of mortar, specific gravity checked that a compressive strength therefore increased. Mortar is using lightweight foam agent having the change of specific gravity, the water cement ratio $50\%,\;40\%,\;30\%$. This paper present extensive data on the characteristics of strength of the lightweight mortar and also presents the mechanical characteristics of the lightweight according to specific gravity.

This study summarizes results of a research project aimed at investigating the inelastic rotation capacity of beam-column joints of reinforced concrete moment frames. A total of 28 specimens were classified as special moment frame connections based on the design and detailing requirements in the ACI 318-99 provisions. Then, the acceptance criteria, originally defined for steel moment frame connections in the AISC-97 Seismic Provisions, were used to evaluate the joint connections of concrete moment frames. Twenty seven out of 28 test specimens that satisfy the design requirements for special moment frame structures provided sufficient strength and are ductile up to a plastic rotation of $3\%$ without any major degradation in strength.

Seismic performance of reinforced concrete(RC) column bent piers to bidirectional seismic loadings was investigated experimentally. RC column bent piers represent one of the most popular forms of piers used in highway bridges. Further to series of previous experimental researches for the performance of single bridge columns subjected to seismic loadings, four column bent piers were constructed in 400 mm diameter and 2,000 mm height. Each pier has two circular supporting columns. These piers were tested under lateral load reversals with axial load of $0.1f_{ck}A_g$. Bidirectional lateral loadings were applied. The test parameters included: different transverse reinforcement contents and lap-spliced longitudinal reinforcing steels. Test results indicate that lap-splices of longitudinal reinforcing steels have significantly influence on hysteretic response of column bent piers. Column capacity changed with the level of transverse confinement, and bidirectional repeated loadings induced more strength and stiffness degradation than unidirectional repeated loading.

Generally, the time history analysis among seismic response analyses of a structure needs more times than static analysis. Therefore the mechanical model of a structure has been used as a simple lumped parameter model in time history analysis. For the most cases, the simple mechanical model shows the similar results to that of detailed finite element model. so it is reasonable to use the simple mode] in preliminary analysis. In seismic design of liquid storage tank, such as LNG storage tank, the lumped parameter mode] also is being used in preliminary analysis, however sometimes shows the differences to the results of detailed finite element model. Therefore in this study, the dynamic characteristics between lumped parameter model and detailed finite model is compared for the variables such as height/diameter of liquid-storage tank and thickness of wall, then the applicability of beam mode] to the seismic response analysis are evaluated for some liquid storage tanks.

The purpose of this study is to present the design methodology of base isolated buildings. To achieve the goal of this study, time-history analysis was performed with seismic performance level and recorded seismic data. From the analysis results of MDOF system, the maximum. displacement and base shear were evaluated as 25 cm and $4\%$ by the input level which is maximum velocity of 50 kine. By introducing hybrid isolation system, seismic energy can be concentrated consequently high seismic capacity of the total building is secured.

The structure should be designed to be safe to any direction of earthquake input. However, the reference axes whereby the structure is analyzed and designed against earthquake may influence the design member forces. This study is concerned with the effect of the choice of the reference axes on the seismic design member forces. The analytical results on member forces using the principal axes suggested by Wilson and the global axes generally adopted in design offices show that the values of member forces by the principal axes be about $15\%$ smaller than those by the global axes in the example structure.

A typical structure was selected for a prototype and four 1:2.5 scaled models, representing the subassemblage including the interior column and the deep beam, were constructed. The transverse reinforcement was designed according to ACI procedure and the procedure proposed by Sheikh. In this study, the correlation between the experimental and analytical responses of the subassemblages subjected to the cyclic lateral displacement were evaluated through investigation of lateral load-lateral deformation, local deformation characteristics by using a nonlinear FEM analysis program RCAHEST.

Five RC piers were tested under a constant axial load and a cyclically reversed horizontal load to investigate the behavior of RC piers used in the high-strength concrete and the high-strength rebars. Seismic design of piers were conducted under the same design, according to the current Korean Bridge Design Standard. The parameters of the test were concrete compressive strength and steel strength, steel ratio. The test results indicated that RC piers of the high-strength concrete and high-strength rebars exhibited ductile behavior and seismic performance.

This study proposes an algorithm for recognition of crack patterns, which includes horizontal, vertical, diagonal$(-45^{\circ})$, diagonal$(+45^{\circ})$, and random cracks, based on image processing technique and artificial neural network. A MATLAB code was developed for the proposed algorithm, and then numerical tests were performed on thirty-eight crack images to examine validity of the algorithm. Within the limited tests in the present study, the proposed algorithm was revealed as accurately recognizing the crack patterns when compared to those classified by a human expert.

This study is intended to propose a systematic approach for determining optimum Life-Cycle Cost (LCC)-effective seismic design for continuous PSC bridges considering lifetime expected seismic risks. In the paper, a set of cost function for LCC analysis of bridges is proposed. The total LCC functions consist of initial cost and direct/indirect damage costs considering repair/replacement costs, human losses and property damage costs, road user costs, and indirect socio-economic losses. The damage costs are expressed in terms of Park-Ang median global damage indices (Park and Ang, 1985) and lifetime damage probabilities. The proposed approach is applied to model bridges of both moderate seismicity regions like Korea and high seismicity regions like Japan. Since, in case of bridges, a number of parameters may have an influence on optimal target reliability, various sensitivity analyses are performed in this study. It may be expected that the proposed approach can be effectively utilized for the development of cost-effective performance criteria for design and upgrading of various types of bridges as well as continuous PC bridges.

The purpose of this study is to investigate the strength and ductility improvement of columns retrofitted with Fiber-Steel Composite Plate, compared with Steel Plate, and Carbon Fiber Sheet. Test specimens strengthened with 3 different materials--- carbon fiber sheet, steel plate and fiber-steel composite plate --- were tested under cyclic lateral force and a constant axial load equal to $20\%$ of the column's axial load capacity. The hypothetical equivalent value of the strengthening among three materials is introduced to evaluate.

Three Hollow RC piers were tested under a constant axial load and a cyclically reversed horizontal loadto investigate the structural behavior of hollow RC piers using the high strength concrete and the high strength rebars. The test variables include concrete compressive strength, steel strength, and steel ratio. The test results indicate that RC piers using the high strength concrete and high strength rebars exhibit ductile behavior and appropriate seismic performance, in compliance with the design code. The present study allows more realistic application of high strength rebars and concrete to RC piers, which will provide enhanced durability as well as more economy.

The synthetic fibers such as polypropylene(PP) and polyvilyl-alcohol(PVA) fiber are poised as a low cost alternative for reinforcement in structural applications. It has been reported that synthetic fiber in cement composites can control restrained tensile stresses and cracks and increase toughness, resistance to impact, corrosion, fatigue and durability. High performance fiber reinforced cementitious composite(HPFRCCs) shows ultra high ductile behavior in the hardened state, because of the fiber bridging properties. Therefore, a variety of experiments have being performed to access the performance of HPFRCCs recently. The research emphasis is on the flexural behavior of HPFRCCs made in synthetic fibers, and how this affects the composite property, and ultimately its strain-hardening performance. Three-point bending tests on HPFECCs are carried out. As the result of the bending tests, HPFRCCs showed high flexural strength and ductility. HPFRCCs made in PVA or Hybrid fiber were, also, superior to PP of singleness. On the other hand, effect of sand volume fraction on HPFRCCs made in PP was insignificant.

This study is concerning on modeling to predict the flexural behaviors of FRP-confined concrete structural members. For compressive behaviors of confined concrete by FRP jackets, the hypoelasticity-based constitutive law of concrete has been presented under the basis of three-dimensional stress states. The strength enhancement of concrete wrapped by FRP jackets has been determined by the failure surface of concrete in tri-axial states, and its corresponding peak strain is computed by the strain enhancement factor. The behavior of FRP jackets has been modeled using the mechanics of orthotropic laminated composite materials in two-dimensional stress states. To be based on the three-dimensional constitutive laws, an algorithm for the prediction of flexural bending behaviors of FRP-confined concrete structural member has been presented.

The FRP-concrete composite deck system has advantages of corrosion free and easy construction. The system is, however, comprised of two brittle materials, so that it suffers from inherent disadvantage of lack of ductility. In this study, some conceptual design is presented for preventing the brittle failure of FRP-concrete composite deck at ultimate load level. 4-point bending tests are performed for FRP-concrete composite beams using FRC(Fiber Reinforced Concrete). The specimens use the box-shape FRP member in the lower portion. Four types of concrete with different compressive strengths and ductilities including normal mortar and 3 FRCs are placed in the upper portion. Typical failure mode in the test is identified; Concrete compressive failure occurs first at the maximum moment region, and the interfacial debonding between FRP and concrete member proceeds. Finally, the tensile rupture of FRP member occurs. The specimen using FRC with the high compressive ductility of concrete fails with less brittle manner than other specimens. The reason is that the ductility from the concrete in compression prevents the sudden loss of load-carrying capacity after compressive concrete failure.

A new-type of FRP-concrete composite bridge deck system is proposed and its behaviors are experimentally studied. The new-typedeck consists of FRP as a permanent form and main tension resisting member and concrete as a compression resisting member. A suitable bonding method such as silica coating is applied to the interface between FRP and concrete to ensure composite behavior. The proposed deck system uses the box-shape FRP member, while a typical FRP-concrete composite deck uses the I-shape FRP member. Theproposed deck system has inherent advantages of a FRP-concrete composite deck like corrosion free and easy construction. The new-type deck shows the equal performances compared to a previous one, and has the advantage of reducing self-weight. In this study, the static tests on 3-span FRP-concrete decks in full scale are carried out, so that load-displacement relation, stress distribution, failure mode and design criteria are analyzed. The test results show that the deflection design criterion (L/800, L: span length) is satisfied at the service load state. No concrete tensile crack occurs in the negative moment region above the main girder, regardless of no tensile reinforcement at upper concrete portion.

In this paper, experimental test on the full scale model of steel and concrete composite plate girder with prefabricated slabs under hogging moments was conducted cautiously and observed in order to study cracking in precast decks. Details of prefabricated slab transverse joints were determined from previous research. A test specimen was overhanging simple support beam, totally 28 meter length. Through the 4-point flexural test, the behaviour of the composite girder under hogging moments was observed. From the test results, crack development and crack widths were observed.

This study was performed to propose design bending moment formula for long-span slab on a composite two-girder bridge. FEM models representing slab spaning between 4m and 12m were analyzed, and parameters such as girder flexibility and orthotropy of slab were considered. By regression of the parametric analyses results, the moment formula that can predict the design moment with reasonable margin of safety and correctness was developed. The research also showed that the design bending moment from Korean Bridge Design Code overestimated the design moment for the span length under gm, and underestimated for the span length over 9m.

Prestressing tendons of the nuclear containment building dome are arranged in a non-axisymmetric manner. However, simple axisymmetric modeling of the containment building is often employed to estimate the structural behavior for, e.g. the ultimate pressure, which requires the axisymmetric approximation of the actual tendon arrangements of the dome. A procedure is proposed that can devise the actual 3-dimensional tendon stiffness and prestressing effect into the axisymmetric model. A numerical example of the CANDU type is presented to verify the procedure and to estimate the amount of approximation.

The main objective of this study is to provide a parametric evaluation of the pull-out response of steel fibers embedded in cementitious matrices. The various parameters controlling the behavior of the bond stress versus end slip relationship are analyzed; their effects on the entire pull-out load versus end slip response and the corresponding pull-out energy up to total pull-out are investigated. Also discussed are the effects of the fiber length, the water/binder ratio of the mixtures and embedded length.

This paper presents 3D nonlinear analysis considering the slip of composite section as well as the static load tests of PSC-Steel hybrid girders. According to the slip modulus, the nonlinear analysis shows that the behavior of hybrid girders could be divided into three parts as full-composite, partial-composite and non-composite. However, the experimental results show that the PSC-Steel hybrid girders with shear connectors take the part of partial composite action in ultimate load stage. In addition, the load test results give that stud shear connectors and welded reinforcements have contributed to improve the ultimate strength of hybrid girders for about $20\%$.

The full-width, full-depth precast panel system is very efficient for the rehabilitation of deteriorated decks as well as for new bridge construction.. The horizontal bond strength at the interface between the two interconnected elements is of primary importance in order to achieve composite action. The strength of the bond between the two precast members should be high enough to prevent any progressive slip from taking place. However, the case when both of the interconnected elements are precast members bonded by means of grout, is not currently addressed by KBDC or AASHTO. This is the main impetus for this study. A total 43 push-off tests were performed to evaluate the horizontal bond strength and to recommend the best practice for the system. Test parameters included different interface surface conditions, different amount and different types of shear connectors. The presence of the shear keys at the top surface of the beam increased the interface bond capacity tremendously compared to the bond capacity with a different surface conditions.

This study was performed to evaluate joint behavior for the application of hybrid bridges by experiment of 14 beams according to penetration length, amount of reinforcing steel and stud and prestressing stress. By tests results, prestressing stress was more effective than amount of stud or reinforcing steel. And the spacing of stud is also more effective than penetration length. Especially, all beams were failed by turns desertion of reinforcing steel, stud, and steel plate.

This paper summarizes the results of push-out test specimens with a new type of shear connector called ㄱ type perfobond rib. This connector is a flat steel plate with a number of holes punched through and strengthen rib's head part. According to experiment result, ㄱ type perfobond rib shear connector appeared that resistance force is increased than stud shear connector by $108\%$ and perfobond rib shear connector by $26\%$. The results obtained indicate that the perfobond rib connector is a viable alternative to the headed studs. An appreciable improvement in the shear capacity of the connection was observed when additional reinforcing bars were passed through the perfobond rib holes. For composite beams with concrete filled steel tubes, ㄱ type perfobond shear connectors exhibit adequate ductility and substantially higher capacities.

Salt attack is one of the serious deterioration factor with respect to the durability of concrete structure. Especially, in case of exposed rebar concrete structure in marine environment, corrosion of rebar is accelerated by penetration of $Cl^-$ from exterior. Through this path, volume of corroded rebar is increased about two and half times due to increased inner pressure originated from rust. As a consequence, the overall deterioration of concrete structure, namely, cracks, reduction of adhesive strength and pop-out is followed. In this paper, the effect of structure treatment of concrete on chloride resistance has been investigated. At the same time, the relationship among several characteristics, such as resistance to chloride, water absorption coefficient and surface hardness of concrete has been investigated. It is believed that surface performance improvement by the application of penetrative hardening agent influences on positively water absorption coefficient, surface hardness of concrete and resistance to chloride ion penetration.

Corrosion of reinforced concrete structures in marine environment is one of the most important mechanism of deterioration. However, conventional rehabilitation techniques in tidal zone, which consist of removing delaminated areas of concrete, cleaning affected steel and patching with portland cements mortar, have proven to be ineffective for marine structures. Also, repairs are often repeated every several years. The purpose of this report is to announce appropriate repair method of highway bridge damaged by chloride attack in marine environment (application of cathodic protection) using FRP and antiwashout underwater mortar.

The factors influencing concrete deterioration in marine environment can be generally divided into the physical and chemical action. The physical attack due to drying and wetting would increase the internal stress of concrete. The chemical attack resulting from the diffusion of ions$(i,e,\;Cl^-,SO_4^{2-},Mg^+)$ from seawater through the pores in concrete. The objective of this study is to evaluate corrosion characteristics of steel when using the various concrete materials under marine exposure environment. After 3 years of exposure, concrete specimen incorporating $40\%$ blast-furnace slag as replacement for type I cement with low w/c ratio of 0.42 and using the inhibitor shows excellent performance.

In this study, tensile adhesive strength(TAS) test was carreid out for evaluated the effects of temperature conditions (-20, -10, 0, 5, 10, 20, 30, $40^{\circ}C$) on the tensile adhesive characteristics about 4 type waterproofing membranes which were commercially used in bridge decks. And, failure appeariences of waterproofing systems in each temperature after TAS test were observed the sawing surfaces of waterproofing systems for whether or not damaged of waterproofing membranes. Also, correction coefficient of TAS with temperature were calculated using 4 type waterproofing membrane. It could be shown that the higher TAS and shear adhesive strength, the lower temperature, regardless of the type of waterproofing membrane. Temperature sensibility of TAS was especially remarkable in epoxy membrane. Failure type was occurred the ductile failure in $30^{\circ}C\;and\;40^{\circ}C$. From these results, it was shown that if ambient temperature above $30^{\circ}C$ maintains for a long time, waterproofing membrane will be deformed by softening. Otherwise, waterproofing membrane in temperature below $20^{\circ}C$ shown that occurred the brittle failure. From the results of visual observation of cutting surface for specimen, the thin waterproofing membranes shown indented by hot aggregate of the asphalt mixtures. Therefore, it could be known that the specification of waterproofing membrane thickness is necessary by waterproofing membrane type. As temperature change varied with pavement depth, the interface temperature was more important than ambient temperature in TAS test. Now, TAS test results were limited only in $-10^{\circ}C\;and\;20^{\circ}C$ temperature, but correction coefficient of TAS by ambient temperature could be used as a solution to deal with this problem.

Silver nitrate colored method that measure easily penetration depth of chloride ion has been used, recently. But, characteristics of silver nitrate colored method hasn't examined well. Therefore, we are aim to examine characteristics of colored method. According to experiment results, when the colored method was applied in concrete, it is reasonable that $AgNO_3$ solution more than 0.05N concentration was sprayed. Chloride concentration difference in colored parts was about 20ppm when $AgNO_3$ of two concentration (0.05N, 0.1N) in concrete was sprayed.

This study was performed to investigate the effect of mineral admixture' type and replacement ratios on the chloride penetration resistance of concrete which was immersed in the artificial chloride solution. The chloride penetration resistance was evaluated by penetration depth and chloride diffusion coefficient. As a result, all of the mineral admixtures were effective on the chloride penetration resistance of concrete compared to ordinary portland cement only.

The early-age cracks have bad effects on the diffusion movement of chloride ions and oxygen. In this study, a corrosion analysis algorithm for cracked concrete is proposed to examine the influence of early-age cracks on corrosion of RC structures. For different environmental exposure conditions of RC structures, a corrosion model is combined with models for activation polarization and concentration polarization. From the finite element corrosion analysis using the proposed algorithm and the models, the effects of early-age cracks to the corrosion is simulated.

Air void systems in hardened concrete has an important influence on concrete durability such as freeze-thaw resistance, water permeability, surface scaling resistance, and etc. Linear traverse method and point count method described at ASTM have been widely used to estimate the air void system in hardened concrete. These methods, however, are rarely used at present, because they require many efforts, are time consuming works, depend on each person's decision, and are not repeatable. Thus, new image analysis method using microscope and computer processes has been approached for analyzing air void system in hardened concrete. However, it is just in initial step. The purposes of this study were to develope an effective and reliable image analysis technique for estimating air void system in hardened concrete. The developed technique was proved to be accurate, reasonable and repeatable.

Deterioration due to de-icer salt occurs in practice in concrete pavement, dike, barrier and similar structure. This paper reports the results of effect of de-icer salt on. durability of concrete structure in winter. To protect concrete structure from damage by de-icer salt in winter, the exposure test was performed using three countermeasures such as increase in design strength upto $350kg/cm^2$, application of ggbf slag powder, and concrete sealer. Of these, the method of increase in design strength upto $350kg/cm^2$ showed better durability for deterioration by de-icer salt.

Generally, the high performance concrete of drying cracking and autogenous shrinkage are tend to be increased. In the previous study, it was found that the using method in combination with expansive additive and shrinkage reducing agent was more effective than the separtely using method of that. This study is to investigated the durability of high performance concrete using expansive additive and shrinkage reducing agent. Test results showed that the high performance concrete using expansive additive and shrinkage reducing agent had very good not only the durability performance such as salt injury, carbonation, resistance to freezing-thawing and permeability but also the resistance to shrinkage.

Corrosion of reinforced concrete structures in marine environment is one of the most important mechanism of deterioration. The conventional repair techniques of concrete structure damaged by chloride attack consist of removing damaged concrete, cleaning rebar and patching with cement-based materials. However, recently, this method was considered to be ineffective for marine concrete structure in tidal zone. It is necessary to select proper repair method for domestic marine environment which shows broad tidal zone. This paper reports the results of repair of highway concrete bridge damaged by chloride attack in domestic marine environment.

An increasing interest in fire safety engineering can currently be identified in Korea and overseas. The fire-resistant characteristics of spray coating material for fire protection with or without nano $Al(OH)_3$ colloid has been experimentally investigated and the results are presented in this paper. The fire-resistance characteristics of spray coating material with nano $Al(OH)_3$ were superior to those without $Al(OH)_3$. Especially, spray coating material with nano material showed that thermal characteristic in the early days was remarkably excellent.

Hydraulic structures have been constructed with low cost concrete so as to increase the investment efficiency. But, it has caused to produce structures having excess internal voids inside concrete. As the construction of agricultural irrigation and drainage project is concentrated on off-farming season and scattered in wider area, variation of quality of structures is big and it caused increase of internal voids. Due to that reason, hazardous substance is passing rather freely through the voids causing occur of crack and accordingly life time of structures is getting shortened. It is necessary to make a thesis of design criteria for design strength to increase life time, range of variation of quality, strength of ready-mixed concrete proper to design strength, and water-cement ratio and air content.

In this study, the electric accelerated reinforcing bar corrosion test was carried out to estimate the coefficient of electrolytic corrosion based on the concept of Faraday's law according to rebar corrosion rate and concrete compressive strength which had an effect on the actual corrosion mass loss. The results of this paper allow the prediction of corrosion amount in the electric accelerated reinforcing bar corrosion test method.

This paper presents the experimental results on the penetration of chloride. ions to ordinary portland cement concrete which is subjected to 2 different artificial environments; consecutive digestion, wetting at $3\%$ NaCl for 1 day and then drying at $40^{\circ}C$ oven for 4 days. The water-cement ratio was $35\%,\;45\%,\;55\%$. Test results showed that the intrusion depth and concentration of chloride ions penetrated into concrete in repeated wetting-drying environments were respectively deeper and higher than those of consecutive digestion environment. The penetration of chloride ions deeply depend on the effect of water to cement ratio.

When the concrete structures are in contact with seawater, concentration of chloride for estimating chloride diffusion coefficient can be defined as the chloride concentration of sea water. However, in case the concrete structures, constructed in the seashore, aren't directly in contact with seawater, it is difficult to establish the interface concentration of chloride. In addition, marine concrete structures are greatly affected by salt attack such as rebar corrosion, among the cause of salt attack, airborne sea salt is primary factor. Therefore, in this study, salt attack environment by airborne sea salt was investigated in terms of the distance from seashore at 33 spots, 6 areas in East, West, South coast for 1 year. Results indicated that airborne sea salt is decreased by $y=a{\cdot}x^{-b}$ equation to the distance from seashore.

It is important to decide the precise chloride diffusion coefficient in order to predict the durability plan of concrete structure chloride and prediction of remaining lifetime. However, the inland references are limited to the rapid test in laboratory. The purpose of this study is to examine and analyze the established data, which are restricted by chloride diffusion coefficient, and to examine the prediction of the concrete structure durability by an FEM interpretation and the chloride diffusion coefficient as a variable.