• International Journal of Highway Engineering
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• v.15 no.1
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• pp.1-9
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• 2013

PURPOSES: The purpose of this study is to evaluate physical properties, durability, fatigue resistance, and long-term performance of poly-urethane concrete (PU) which can be possible application of thin layer on long-span orthotropic steel bridge and to check structural stability of bridge structure. METHODS : Various tests of physical properties, such as flexural strength, tensile strength, bond strength and coefficient of thermal expansion tests were conducted for physical property evaluation using two types of poly urethane concrete which have different curing time. Freezing and thawing test, accelerated weathering test and chloride ion penetration test were performed to evaluate the effect of exposed to marine environment. Beam fatigue test and small scale accelerated pavement test were performed to assess the resistance of PU against fatigue damage and long-term performance. Structural analysis were conducted to figure out structural stability of bridge structure and thin bridge deck pavement system. RESULTS: The property tests results showed that similar results were observed overall however the flexural strength of PUa was higher than those of PUb. It was also found that PU materials showed durability at marine environment. Beam fatigue test results showed that the resistances of the PUa against fatigue damage were two times higher than those of the PUb. It was found form small scale accelerated pavement test to evaluate long-term performance that there is no distress observed after 800,000 load applications. Structural analysis to figure out structural stability of bridge structure and thin bridge deck pavement system indicated that bridge structures were needed to increase thickness of steel deck plate or to improve longitudinal rib shape. CONCLUSIONS: It has been known that the use of PU can be positively considered to thin layer on long-span orthotropic steel bridge in terms of properties considered marine environment, resistance of fatigue damage and long-term performance.

• Journal of the Korea Concrete Institute
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• v.14 no.4
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• pp.615-622
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• 2002

To reasonably predict the behaviors for RC flat-plate structures, analysis model considering the flexural stiffness of slabs is required. FEMA 273 and ACI 318-99 refer to theoretical analysis models of two-way slab systems under lateral loading but the actual application method is not suggested. In this study, the modeling and application methods of the flat-plates using effective beam concept are suggested. The results of this study are as follows. 1) The effective beam width model suggested in this study is very useful to model flat-Plate structures subjected to seismic loading for three dimensional analysis 2) The result of analysis for idealized flat-plate example using the effective beam widths considering the effect of the slab crack is shown upper value for displacements. Whereas the model considering effective beam width coefficients only is shown upper value for unbalanced moments

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.297-303
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• 2010

The current encased-concrete deep corrugated steel plate has an arch type plate structure, which is a compressive strength-dominant structure that has a small moment due to its arch shape. Therefore, it increases the strength against compression by adding reinforcements to make concrete-filling spaces for increasing the compressive strength and forming cross sections that contain reinforced concrete. In this study, the safety factor of the new-concept encased-concrete bridge plate member was evaluated by comparing the compressive strength obtained from the compressive tests, flexural tests and the design compressive strength determined by using the Canadian Highway Bridge Design Code (CHBDC, 2003), which is a design standard for the encased-concrete bridge plate structures. The results of the safety factor evaluation using the design compressive strength and the test results showed that the safety factor was well above the appropriate value 2.0, which could be adjudged very conservative. If the safety factor based on this study results is considered and applied to the design, economical construction will be possible due to the reduced cross section and construction cost.

• Journal of the Korea Institute of Building Construction
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• v.12 no.5
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• pp.539-547
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• 2012

To manufacture laminated wood with improved mechanical properties by providing uniform adhesiveness, the adhesive was applied and the plate adhesive was laminated on the wood surface. Then, after laminating the wood on the top part of the adhesivebond, it was heated and dried while the adhesive was stiffened using microwaves, and the test piece was manufactured by compressing it with the press machine for thirty minutes. The temperature and the water content were examined according to the heating time of the wood heated with the microwave, and testing was conducted on the shear strength and flexural strength of the wood. In addition, the microstructure of the adhesive bond between the wood was recorded to confirm the penetrabilityinto the wood structure for the adhesive. After the test was conducted, it was found that the test piece manufactured with wood that has its water content leveled with the microwave heating showed improved shear strength and bending strength compared to the standard test piece. With regard to adhesives, liquefied polyvinyl acetate resin and plate's PVB resin were found to have superior adhesive strength. Also, after filming the cellular microstructure, it was found that when the laminated wood is heated with microwaves, the infiltration of the adhesive into the inside of the wood becomes easy, which makes it effective for improving adhesiveness.

• Journal of the Korea Institute of Building Construction
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• v.8 no.5
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• pp.43-51
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• 2008

This study examines shear capacity performance and structural characteristics of reinforced concrete beam using carbon fiber sheet(CFS), g)ass fiber sheet(GFS), glass fiber steel plate(GSP) and carbon fiber bar CB) which are reinforcing materials for reinforced concrete beam in order to produce similar condition to repair and reinforce actual structure and aims to provide data available In designing and constructing reinforced concrete structures under the structural damage. This study obtains the following conclusions. After considering the shear experiment results. it was indicated that the CB reinforced test object was the best in the shear capacity improvement and ductility capacity as it was contained in the concrete and was all operated, Also, GFS reinforced test object indicated the reduced flexural capacity but good shear capacity. GSP reinforced test object had bigger reinforcing strength than other reinforcing test objects. On the other hand, it showed the lowest reinforcement effect as compared section thickness of reinforced material because it showed the bigger relativity a section thickness of reinforced material. If the adherence to the concrete is improved, it will seem to show bigger reinforcement effect.

• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.243-251
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• 2016

Longitudinally structural cracks are sometimes observed in the pavement on steel plate deck bridges because traffic truck loadings can cause large local deformations of the thin deck plate stiffened by longitudinal and transverse beams. In this study, an improved finite strip method using flat-shell strip, prism, and link elements is presented to investigate local deformations of steel decks with pavements in which flexural and torsional stiffness effects of thin floor beams are rigorously taken into account. A simplified deck model extracted from steel plate-girder bridges is analyzed using the developed FSM and the commercial FE program, ABAQUS and also, their numerical results are compared and discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.447-454
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• 2012

Considering that the weight of a hollow slab system is not increased with an incremental increase in its thickness, and that the flexural stiffness of a hollow slab is not significantly lower than that of a general slab, there has been a growing need for hollow slab system, because long span structures are in great demand. In a long span structure, the problem of vibration of floor slabs frequently occurs, and the dynamic characteristics of a hollow slab system are quite different from the conventional floor system. It is required to investigate the safety and the serviceability of hollow slab. Therefore, there exists a necessity for accurate vibration analysis. Hollow slab should be modeled by refined mesh for accurate vibration analysis. For the efficiency of the Eigenvalue Analysis, an equivalent plate slab model when can relatively precisely represent the dynamic behavior of a one-way hollow slab system is used. In conclusion, equivalent plate models relatively precisely presented the dynamic characteristics of one-way hollows.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.553-558
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• 2000

In this study, a numerical simulation that can effectively predict the interfacial fracture behavior in repaired structures is developed using the axial deformation link elements. In repaired structures, concrete and interface are considered as quais-brittle materials, and steel plate as a repair material and reinforcement are modeled as elasto-plastic materials. The behavior of repaired reinforced concrete structures under flexural loading conditions is numerically simulated, and compaired with experimental results. The strengthening effect according to the length and thickness of the repair material is studied and rip-off, debonding and rupture failure mechanism of interface between substrate and repair materials are detected. It is shown that the interface properties affect on the mechanical behavior of repaired structures. Therefore, the developed numerical method using axial deformation link elements can be used for determining the strengthening effects and failure mechanism of repaired structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.159-160
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• 2014

The floor impact noise arising between upper and lower households in residential houses has been known as one of major causes worsening residential environment and still led to serious social troubles in a residential community. It is known that the heavy weight floor impact noise is induced by flexural vibration modes in the relatively lower frequency ranges. In this study, a procedure is examined to evaluate the relations between the vibration modes and the corresponding noise of the slab. In the process, for simplicity of the numerical analysis, it is assumed that the slab is simply supported plate-like structure and the acoustic mode formed in the lower room by acoustic boundary conditions is ignored.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.317-322
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• 2001

A mathematical modelling technique is proposed for estimating the additional bending stresses of tube(s)-in-tube structures due to tube-tube interaction, which has a significant effects on the shear-lag phenomenon. The proposed method simulates the framed-tube structures with multiple internal tubes as equivalent multiple tubes, each composed of four equivalent orthotropic plate panels. Hence, the tube(s)-in-tube structure can be analysed by using an analogy approach where each tube is individually modelled by a continuous beam that can account for the flexural and shear deformations as well as the shear-lag effects. The numerical analysis is applicable for the structural analysis of framed-tube structures with single and multiple internal tubes, as well as those without internal tubes. The shear-lag phenomenon of such structures is studied with additiona] bending stresses and shear-lag reversal points.