• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.413-420
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• 2014

The purpose of this study is to experimentally investigate the shear behavior of flat plate that reinforced by embedded GFRP(glass fiber reinforced polymer) plate with openings. Shape of the GFRP shear reinforcement is a plate with several openings to ensure perfect integration with concrete. The test was performed on 7 specimens to check shear strength of flat plate that reinforced by GFRP plate. The parameters include the spacing of the shear reinforcement and amount of the shear reinforcement. The result of test showed that when amount of shear reinforcement was increased, shear strength improved. The result of test showed that maximum shear strength was confirmed when spacing of shear reinforcement was 0.3d. The calculation of the shear strength of reinforced flat plate with GFRP plate based on the KCI was compared with the test results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.2
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• pp.1-9
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• 2015

In this paper, the RC column-based joint connection part carry out loading test by reinforced hollow or extended Base Plate in order to confirm that RC joint punching shear reinforcement effect of applying the Base Plate. Base Plate thickness, extension length, size, and type as the variable, Base Plate suitable for the stress distribution and shape and dimensions confirmed through experiment and then reinforcing effect was analyzed. Experimentally, vertical load transmitted to the Base Plate from column to foundation is effective to stress distribution and then, type of hollow reinforcement more efficient than a closed. Through experiment, improve performance and ductility due to reinforcement and relative to the thickness of the existing foundation reduced even showed better performance than the existing. The behavior of the reinforced specimens be able to induce from brittle to ductile. Experiment on loading to destroy performed the pattern of cracks, destruction aspect before and after reinforcement.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.455-479
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• 2015

This paper presents a numerical analysis of reinforced concrete slabs under missile impact loading. The specimen used for the numerical simulation was tested by the Technical Research Center of Finland. LS-DYNA, commercial available software, is used to analyze the model. The structural components of the reinforced concrete slab, missile, and their contacts are fully modeled. Included in the analysis is material nonlinearity considering damage and failure. The results of analysis are then verified with other research results. Parametric studies with different longitudinal rebar ratios, shear bar ratios, and concrete strengths are conducted to investigate their influences on the punching behavior of slabs under the impact of a missile. Finally, efficient designs are recommended.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.89-98
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• 2010

A method to design a critical height of embankments is presented so as to mobilize fully soil arching in pile-supported embankments. The behavior of the load transfer of embankment weights on pile cap beams was investigated by a series of model tests performed on pile-supported embankments with relatively wide space between cap beams. The model tests explained that the behavior of the load transfer depended very much on the height of embankments, because soil arching could be mobilized in pile-supported embankments only under enough high embankments. The measured vertical loads on cap beams coincided with the predicted ones estimated by the theoretical equations, which have been presented in the previous studies on the basis of load transfer mechanisms according to either the punching shear failure mode during low filling stage or the soil arching failure mode during high filling stage. The mechanism of the load transfer was shifted beyond a critical height of embankment from the punching shear mechanism to the soil arching mechanism. Therefore, in order to mobilize soil arching in pile-supported embankments, the embankments should be designed at least higher than the critical height. A theoretical equation to estimate the critical height could be derived by equalizing the vertical loads estimated by the load transfer mechanisms on the basis of both the punching shear and the soil arching. The derived theoretical equation could predict very well the experimental critical height of embankment.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.697-700
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• 2000

Fatigue damage to reinforced concrete bridge decks have been found in many bridges. Failure mode of most reinforced concrete decks is caused by local punching shear rather than flexural moment due to cumulated damage. In this study, mechanical degradation of unstrengthened and strengthened bridge deck specimens is experimentally investigated. The unstrengthened deck specimens were damaged under the pulsating loading condition. After the test, deteriorated deck specimens were strengthened with Carbon Fiber Sheet, then loaded to observe the improvement of the fatigue behavior. It is shown that fatigue damaged specimens are similar to real bridge rather than static damaged specimens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.10-21
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• 2014

The joint of prefabricated steel grid composite deck is composed of concrete shear key and high-tension bolts. The flexural and shear strength of the joint were experimentally evaluated only by the bending and push-out test of the joint element. In this study the lateral load transfer behavior of the joint in deck structure system is experimentally evaluated. Several decks connected by the joint are prefabricated and loaded centrically and eccentrically. In the case of centrically loaded specimens, the analysis results show that for the same loading step the rotation angle of the joint with 4 high-tension bolts is larger than the case of the joint with 9 high-tension bolts. Consequently, flexural stiffness of deck and lateral load transfer decrease in the case of specimen with 4 high-tension bolts. But, in the case of eccentrically loaded specimens, it is found that there are no significant differences in the load transfer behavior. The further analysis results about the structural behavior of the joint show that lateral load transfer can be restricted by the load bearing capacity of the joint as well as punching shear strength of the slab. Furthermore, considering that high-tension bolts in the joint didn't reach to the yielding condition until the punching shear failure, increase in the number of high-tension bolts from 4 to 9 has a greater effect on the flexural stiffness of the joint and deck system than the strength of them.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.1-6
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• 2011

New methods for joining sheet of metal are being sought. One of the most promising methods is MPJ (mechanical press joining). It has been used in thin metal work because of its simple process and relative advantages over other methods, as it requires no fasteners such as bolts or rivets, consumes less energy than welding, and produces less ecological problems than adhesive methods. In this study, the joining process and static behavior of single overlap joints has been investigated. During fixed die type joining process for SPCC plates, the optimal applied punching force was found. The maximum tensile-shear strength of the specimen produced at the optimal punching force was 1.75 kN. The FEM analysis result on the tensile-shear specimen showed the maximum von-Mises stress of 373 MPa under the applied load of 1.7 kN, which is very close to the maximum tensile strength of the SPCC sheet(= 382 MPa). This suggests that the FEM analysis is capable of predicting the maximum tensile load of the joint.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.467-470
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• 2005

This study was performed to evaluate the static strength of long-span PSC deck slabs. In the previous study, the minimum thickness of PSC deck slabs in the composite two-girder bridge was proposed. To examine the structural behavior and safety of the PSC deck slabs designed in accordance with the proposed minimum thickness, 1/3 scaled PSC deck slabs in the composite two-girder bridge were tested under the static loading. The test results were compared with the predicted values proposed by the code and Matsui. Test results showed ultimate static strength of the PSC deck slabs designed in accordance with the proposed minimum thickness have enough margin of safety. The static failure mode of each test specimen was punching shear mode.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.757-762
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• 2001

This study was performed experiment for strengthened bridge decks with isotropic carbon fiber sheets received fatigue loading, and compared with fatigue behavior of unstrengthened bridge decks. By the results, this study was examined effect of increasing strengthened to phase life cycles of bridge deck for fatigue loading and application of the punching shear theory of bridge deck strengthened by carbon fiber sheet.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.137-147
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• 2012

In the steel-free bridge concrete deck, steel straps are generally used instead of conventional steel rebar while laterally restrained in the perpendicular direction to the traffic in order fir the arching effect of concrete deck. In this paper, the minimum amount of FRP bar is to be suggested based on the structural strength, crack propagation, stress level and others in order to control cracks. As a result of laboratory tests, the structural strength of deck with 0.15 percentage of steel strap showed improved structural strength including ductility. The long-term serviceability of steel strap deck with FRP bar proved to satisfy the requirements and to be structurally stable while showing the amount of crack and residual vertical displacement within the allowable limits after two million cyclic loadings. The structural failure of RC bridge deck is generally caused from the punching shear rather than moment. Therefore, the ultimate load at failure could be estimated using the shear strength formula in the two-way slab based on ACI and AASHTO criteria. However the design criteria tend to underestimate the shear strength since they don't consider the arching effects and nonlinear fracture in bridge deck with lateral confinement. In this paper, an equation to estimate the punching shear strength of steel strap deck is to be developed considering the actual failure geometries and effect of lateral confinement by strap while the results are verified in accordance with laboratory tests.