• Earthquakes and Structures
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• v.16 no.4
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• pp.455-468
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• 2019

The behavior of pile-deck connections of pile-supported marginal wharfs subjected to earthquake loading is of key importance to ensure a good performance of this type of structures. Two precast-pretensioned pile-deck connections used in the construction of pile-supported marginal wharfs were tested under cyclic loading. The first is a connection with simple reinforcement details and light steel ratio developed for use where moderate pile-deck rotation demands are expected in the wharf. The second is specifically developed to sustain the large rotation, shear force and bending moment demands, as required for the shortest piles in a marginal wharf. Data obtained from the test program is used in the paper to calibrate an equivalent plastic hinge length that can be incorporated into nonlinear analysis models of these structures when prestressed pile-deck connections with duct embedded dowels are used.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.1
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• pp.93-102
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• 2006

In order to use a recycled aggregate concrete for precast concrete box structures, the structural behaviors should be analytically and experimentally evaluated. In this study, full-scale precast concrete box structures are manufactured using the recycled aggregate (30% replacement) and natural aggregate. Then, the flexural failure test and shear failure test as well as water leakage lest for the structures arc carried out. First of all, test results of compressive strength show that recycled aggregate concrete is only 4% lower than normal concrete. In the flexural and shear failure test, the structural performances of precast box using the recycled aggregate concrete are 95% of the capacities of normal precast concrete box or more. Especially, the water leakage test shows that leakage pressure of recycled concrete box is more than the critical value, 60kPa, as well as 9% higher than normal precast concrete box. These test results are analyzed and compared with results of finite clement analysis. The comparison shows that test results are more excellent than analytical results. Also, the comparison confirms the applicability of recycled aggregate concrete for the use as practical precast concrete box structure.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.667-675
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• 2012

Flat plate are being used more in buildings requiring a high level of technical installations or in buildings needing changeable room arrangements during their life time such as office buildings. The main problem in flat plate is its weak resistance against a punching failure at its slab-column connections. Therefore, in this research, an experimental study on full-scale interior slab-column connection was performed. Three types of shear reinforcements were tested to prevent brittle punching shear failure that could lead to collapse of the structure. A series of four flat plate specimens including a specimen without shear reinforcement and three specimens with shear reinforcements were tested. The slabs were tested up to failure using monotonic vertical shear loading. The presences of the shear reinforcements substantially increased punching shear capacity and ductility of the interior slabcolumn connections. The test results showed that a slab that did not have enough bond length failed before shear reinforcement yielded due to anchorage slip. Also, FEM analyses were performed to study an effect of slab thickness and concrete compressive strength on the flat plate slab. The analytical study results were used to propose a method to calculate performance capacity of shear reinforcement in slab-column connection.

• Steel and Composite Structures
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• v.16 no.2
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• pp.221-231
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• 2014

The purpose of this study was to evaluate the cyclic behavior of steel column-tree moment connections used in steel moment resisting frames. These connections are composed of shop-welded stub beam-to-column connection and field bolted beam-to-beam splice. In this study, the effects of beam splice length on the seismic performance of column-tree connections were experimentally investigated. The change of the beam splice location alters the bending moment and shear force at the splice, and this may affect the seismic performance of column-tree connections. Three full-scale test specimens of column-tree connections with the splice lengths of 900 mm, 1,100 mm, and 1,300 mm were fabricated and tested. The splice lengths were roughly 1/6, 1/7, 1/8 of the beam span length of 7,500 mm, respectively. The test results showed that all the specimens successfully developed ductile behavior without brittle fracture until 5% radians story drift angle. The maximum moment resisting capacity of the specimens showed little differences. The specimen with the splice length of 1,300 mm showed better bolt slip resistance than the other specimens due to the smallest bending moment at the beam splice.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.154-163
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• 2013

Adhesive bonding and plastic welding have been widely used to join two plastic materials together. The goal of this paper is to determine a proper joining technology of a pair of flat panel (FP) photobioreactor (PBR) case. The material of the FP PBR case is polycarbonate (PC) plate. Two types of adhesion, including acryl adhesive and two-part epoxy adhesive, as well as two types of plastic welding technology, including ultrasonic welding and thermal welding, are employed for joining of PC plates. In order to influence of the adhesion and welding conditions on the joining characteristics of the PC plates in operational conditions of the FP PBR case, the morphology in the vicinity of the joined region as well as the water and pressure resistance characteristic are investigated. In addition, the variation of the bonding strength of the joined region and deformation behaviors in the vicinity of the joined region according to the adhesion and welding conditions is examined via the lap-shear test. From the results of basic experiments, proper joining technologies are chosen. Using the chosen joining technologies, the FP PBR case are fabricated to perform full-scale durability experiment. The results of the full-scale durability experiment have been shown that the chosen joining technologies can be applicable to fabricate the FP PBR case.

• Journal of the Korean Geotechnical Society
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• v.25 no.10
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• pp.5-15
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• 2009

This paper presents the results of full-scale uplift load tests performed on 24 passive anchors grouted to various lengths at Okchun and Changnyong site. Rock anchors were installed over a wide range of rock types and qualities with a fixed anchored depth of 1~6 m. The majority of installations used D51 mm high grade steel rebar to induce rock failure prior to rod failure. However, a few installations included the use of D32 mm rebar at relatively deeper anchored depth so as to induce rod failure. In many tests, rock failure was reached and the ultimate loads were recorded along with observations of the shape and extent of the failure surface. In addition to field tests, laboratory pullout tests were conducted to determine bond strength and bond stress-shear slip relation at the tendon/grout interface when a corrosion protection sheath is installed in the cement-based grout. The test results show that the ultimate tendon-grout bond strength is measured from 18~25% of unconfined compressive strength of grout. One of the important results from these tests is that the measured strains along the corrosion protection sheath were so small that practically the reduction of bond strength by the presence of sheath would be negligible.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.199-206
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• 2009

This paper presents full scale model tests on the various types of model piles carried out to estimate the behavior of laterally loaded steel-concrete composite piles. Subgrade-reaction spring system was developed to simulate the reaction of ground in laboratory condition. In addition, lateral behavior of piles under working load condition was estimated using composite loading system, which is available for independent loading in vertical and horizontal direction. Steel-concrete composite piles showed higher efficiency in lateral resistance rather than drilled shaft made of reinforced concrete. The lateral resistance of composite pile was larger than the summation of steel pile and concrete pile due to the composite effect by steel casing. The effect of shear key or strength of concrete on the behavior of composite pile was examined. The substitution of reinforcing bar by steel casing was also investigated.

• Journal of Korean Society of Steel Construction
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• v.19 no.3
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• pp.247-258
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• 2007

This paper describes the results of an experimental study on the new type of encased composite beams that use deep deck plates, which could reduce the story height of buildings by controlling the bottom flange of steel beams. The profiled steel beam was thus developed. It was advantageous to the long span of the buildings. Seven full-scale specimens were constructed, and simply supported bending tests were conducted on the encased composite beams with different steel plate thicknesses, with and without shear studs, reinforcing bars, and web openings. The test results showed that the encased composite beams that were developed in this study had sufficient composite action without additional shear connectors due to their inherent shear-bond effects between the steel beams and concrete.

• Earthquakes and Structures
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• v.3 no.6
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• pp.821-838
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• 2012

This paper proposes a new three-layer pillar-type hysteretic damper system for residential houses. The proposed vibration control system has braces, upper and lower frames and a damper unit including hysteretic dampers. The proposed vibration control system supplements the weaknesses of the previously proposed post-tensioning vibration control system in the damping efficiency and cumbersomeness of introducing a post-tension. The structural variables employed in the damper design are the stiffness ratio ${\kappa}$, the ductility ratio ${\mu}_a$, and the ratio ${\beta}$ of the damper's shear force to the maximum resistance. The hysteretic dampers are designed so that they exhibit the targeted damping capacity at a specified response amplitude. Element tests of hysteretic dampers are carried out to examine the mechanical property and to compare its restoring-force characteristic with that of the analytical model. Analytical studies using an equivalent linearization method and time-history response analysis are performed to investigate the damping performance of the proposed vibration control system. Free vibration tests using a full-scale model are conducted in order to verify the damping capacity and reliability of the proposed vibration control system. In this paper, the damping capacity of the proposed system is estimated by the logarithmic decrement method for the response amplitudes. The accuracy of the analytical models is evaluated through the comparison of the test results with those of analytical studies.

• Land and Housing Review
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• v.1 no.1
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• pp.67-73
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• 2010

Method of protruding steel bar embedded in PHC pile for connecting with foundation plate is an intermediate form of fixed and hinged connection and has often been used in architectural structures such as apartment complex. However, mechanical properties of this method have not been proved and its construction process is not simple. In this study, therefore, by analyzing previous research and by considering ratio of steel bar and concrete in PHC pile, which is minimum reinforcement of rebar, the newly optimized method of reinforcing joint of PHC pile and foundation plate is suggested with respect to PHC pile type (PHC 450, PHC 500, and PHC 600). To assess mechanical properties (ultimate tensile and shear strength) of joint of PHC pile and foundation plate, full scale experimental tests are performed. As a result, all cases are satisfied with required design criteria and can be practically applied. Our results indicate that reduction of rebar reinforcement compared to previous method would lead cost saving in PHC pile construction.