• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.241-244
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• 2008

In general, RC flat plate frames have been used as a gravity load resisting system(GLRS) in building. This system should be constructed with lateral force resisting system(LFRS) such as shear walls and brace frames. When lateral loads such as earthquakes occur, LFRS undergo displacement by which connected gravity systems experience lateral displacement. Thus, flat plate system designed as GLRS should be predict unbalanced moments and punching failure due to lateral deformation. This study developed an analytical mode for predicting nonlinear behavior of RC slab column connection for the seismic performance evaluation of RC flat plate frames. For verifying the analytical model, the test results of two flat plate specimens having two continous spans with the difference gravity shear ratio($V_g/{\phi}V_c$) were compared with the results of analysis. The developed model can predict the failure modes and punching failures.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.341-346
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• 2002

이 연구는 게르버 보 형식의 포스트텐션 PC 골조 구조 시스템의 실용화를 위해 골조 전체의 구조 성능 시험을 수행하며, 여기서 보-기둥 접합부 및 내민 보-단순 보 접합부의 구조 성능과 골조의 안전성을 확인한다. 시험은 400 mm$\times$800 mm 단면의 경간 3 m 보와 500 mm$\times$600 mm 단면을 갖는 높이 3 m 기둥의 실물 크기 시험체를 제작하여, 기둥에 80 톤의 축 하중을 준 상태에서 단순 보 중앙에 하중을 가력하여 기둥-보 접합부와 단순 보-내민 보 단면 축소 연결부의 구조성능을 파악한다. 시험 결과, 보 - 기둥 접합부는 예상 설계 하중 40톤 이상에서도 강 접합에 가깝게 거동하였고, 단순 보- 내민 보의 단면 축소 연결부는 경사철근의 사용으로 초기 균열 및 균열 확산에 대한 억제 효과가 있었으며, 예상 설계 전단력 40톤에서 안전하다는 것이 확인되었다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.181-184
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• 2002

In this research, a basis test on steel fiber concrete's material property was carried out and optimum design as well as material property was examined. In corroboration of it, the compressive strength was compared with the tensile strength and this paper tried to get the initial load of flexural cracking and the ultimate load in the positive-negative moment section through the static test of beam. The addition rate of the steel fiber, 0.75 SFRC specimen was failed at $65{\sim}75%$ of the static ultimate strength and it could be concluded that fatigue strength to two million cycle was around 75.2%.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.10a
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• pp.120-127
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• 1998

This paper deals with the dynamic responses of the multi-span continuous bridge with longitudinal shear keys. It is motivated by a need to understand the effects of longitudinal shear keys which may be used for the reduction of the longitudinal seismic force in continuous bridges. The results show that (1) The force reduction of fixed pier is proportional to the ratio of gap size and elastic maximum displacement of the bridges without shear keys ; (2) The thermal movement has little effect on the response of the continuous bridges with shear keys. Also the simplified equation is proposed to calculate the maximum response of the continuous bridges with longitudinal shear keys. The equation requires only the elastic analysis results of the bridge and the gap size between superstructure and shear keys.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.1
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• pp.119-129
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• 2002

Reinforced concrete haunched beams have been used for enhancement of shear resistance of beams to avoid the stress concentration. But American and British codes do not give my formula for the design of haunched beams. The purpose of this research is to experimentally investigate the shear failure of reinforced concrete punched beams for various haunch inclinations and shear span-to-depth ratios. The experimental results showed that even though shear behavior of haunched beam were similar to that of resembled rectangular beams, shear span-to-depth ratios and inclinations of haunch had effects on shear cracking strength.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.3
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• pp.9-16
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• 2019

Recently, precast PSC girder bridges have been widely applied for short and middle span bridges. The construction of the spliced girder bridges has been increasing to overcome the length limit of girder and transportation restrictions. In case of the spliced girder, the integrity of the segmental joints is very important to secure the structural soundness of bridge because the discontinuity on the segmental joints between adjacent segments could be vulnerable point. The study of segmental joint behavior with different influence factors of joint type, shear key installation, confining force is very important. In this research, finite element analysis and scaled model test with different shear key shapes and confining forces were carried out and the comparative study was performed to evaluate the segmental joint behavior of precast spliced PSC girder bridge. It was confirmed that the installation of shear key with height and depth ratio of 1/2~1/3 and applying of confining force of 1/2 of the concrete strength at the joint was effective in improving the integrity of segmental joint. In addition, the field loading test for existed precast spliced PSC girder bridge was performed and the measurement of the difference of deflection between adjacent segments at segmental joint was proposed as the assessment solution of the integrity of segmental joint.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.93-101
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• 2012

Bridge deck has a role in a comfortable and safe passage of vehicles. At the same time, it preserves upper structure against the abrasion and shearing due to impact of traffic loads in bridges or has a role to protect the plate from off adverse effect of climatic process as rain, chemicals. Currently, the total number of inspected bridges is 6,248 in the general national road and to maintain effectively, Introduction of GPR system mounted in the vehicle has been considered. In this research, the comparison and analysis of bridge deck condition on general national road has been performed with major variations of superstructure type, span lengths, located region and ages by using 'the current status of road bridge and tunnel' that is provided by MLTM(Ministry of Land, Transport and Maritime Affairs). As a result, Condition assessment grade, superstructure type, age and length were derived as a major factor to determine priority for the condition assessment.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.259-269
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• 2005

This paper describes the application of genetic algorithm for the discrete optimum design of reinforced concrete continuous beams. The objective is to minimize the total cost of reinforced concrete beams including the costs of concrete, form work, main reinforcement and stirrup. The flexural and shear strength, deflection, crack, spacing of reinforcement, concrete cover, upper-lower bounds on main reinforcement, beam width-depth ratio and anchorage for main reinforcement are considered as the constraints. The width and effective depth of beam and steel area are taken as design variables, and those are selected among the discrete design space which is composed with dimensions and steel area being used from in practice. Optimum result obtained from GA is compared with other literature to verify the validity of GA. To show the applicability and efficiency of GA, it is applied to three and five span reinforced concrete beams satisfying with the Korean standard specifications.

• Journal of the Korea Concrete Institute
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• v.20 no.2
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• pp.203-212
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• 2008

The cyclic behavior and energy dissipation mechanism of short coupling beams with various reinforcement layouts were studied. For numerical analysis of coupling beams, nonlinear truss model was used. The results of numerical analysis showed that the coupling beams with conventional reinforcement layout showed pinched cyclic behavior without significant energy dissipation, whereas the coupling beams with diagonal reinforcement exhibited stable cyclic behavior without pinching. The energy dissipation of the coupling beams was developed mainly by diagonal reinforcing bars developing large plastic strains rather than concrete which is a brittle material Based on this result, simplified equations for evaluating the energy dissipation of coupling beams were developed. For verification, the predicted energy dissipation was compared with the test results. The results showed that the simplified equations can predict the energy dissipation of short coupling beams with shear span-to-depth ratio less than 1.25 with reasonable precision, addressing various design parameters such as reinforcement layout, shear span-to-depth ratio, and the magnitude of inelastic displacement. The proposed energy equations can be easily applied to performance-based seismic evaluation and design of reinforced concrete structures and members.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.549-559
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• 2005

A railway bridge with a double composite section is proposed to enhance the structural performance of existing two-girder bridges because the governing design parameter of railway bridges is the flexural stiffness. The concrete deck in negative moment regions is neglected in the design of continuous composite bridges assuming the concrete slab has no resistance to tension. Therefore, the flexural stiffness of the composite section in the negative moment region is reduced resulting in the increase of the depth of the steel section. In order to resolve this disadvantage, several methods are suggested and the double composite section is one of the excellent solutions for extending the span length and increasing the flexural stiffness. In this study, push-out tests on lying studs and mixed stud shear connection with lying and vertical studs were performed to investigate the behavior of the shear connection in the double composite section. Static strength of the shear connection was evaluated through the test results and numerical analyses.