• Computers and Concrete
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• 제23권3호
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• pp.203-215
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• 2019

Precast reinforced concrete structure (PRCS) consists of prefabricated members assembled at worksites and has more connections limitations in comparison with the equivalent in-situ reinforced concrete structure (IRCS). As a result of these limitations, PRCSs have less ductility in comparison with IRCSs. Recent studies indicate that the most noticeable failure in PRCSs have occurred in their connection zone. The objective of this study is introducing a type of precast beam-to-column connection (PBC) which in spite of being simple is of the same efficiency and performance as in-situ beam-to-column connection (IBC). To achieve this, the performance of proposed new PBC at exterior joint of a four story PRCS was analyzed by pseudo dynamic analysis and compared with that of IBC in equivalent IRCS. Results indicated that the proposed connection has even better performance in terms of strength, energy dissipation and stiffness, than that of IBC.

• Structural Engineering and Mechanics
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• 제85권3호
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• pp.353-367
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• 2023

An extended parametric study based on nonlinear finite element analyses is performed to assess the key factors affecting the shear behaviour of exterior beam-column joints of unbraced reinforced concrete frames. Extensive results are presented, the major conclusion being that the few shear behaviour models for exterior reinforced concrete beam-column joints available in the literature do not properly account for some of the most influential factors. The present results are also compared with recently published results for interior joints, showing that while some factors have a similar influence on interior and exterior joints others are relevant for only one of these types of joints. This also confirms, numerically, that some resisting mechanisms of exterior joints differ from those of interior joints.

• 한국지진공학회논문집
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• 제26권2호
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• pp.83-93
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• 2022

In this study, to verify the structural performance of the Composite Joint System (CJS) hybrid structural model, a cyclic load test was performed and evaluated and verified through the test. To verify the structural performance of the CJS hybrid structural systems' joint and evaluate the seismic performance, four three-dimensional real-size specimens were developed with three internal beam-column specimens and one external beam-column specimen. The three interior column specimens were classified by different methods of joining the upper column and lower column, and the same bonding method as the primary specimen was used for the exterior column. The structural performances in terms of drift, strength, and energy dissipation capacity were analyzed and compared based on the experimental results. From the displacement-based loading experiment, all specimens showed a lateral drift of 4.0% without any significant strength drop and stable energy dissipation capacity.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.123-133
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• 2013

This paper presents experimental and numerical tests on a recently developed timber column concealed base joint. This joint was designed to replace the wood-wood connection found in the post-and-beam structure of Hanok, the traditional Korean timber house. The use of metallic connectors provides an increased ductility and energy dissipation for a better performance under reversed loading, especially seismic. In this study, we investigate the performance of the joint under pseudo-static reversed cyclic moment loading through the study of its ductility and energy dissipation. We first perform experimental tests. Results show that the failure occurs in the metallic connector itself because of stress concentrations, while no brittle fracture of wood occur. Subsequent numerical simulations using a refined finite element model confirm these conclusions. Then, using a practical modification of the joint configuration with limited visual impact, we improve the ductility and energy dissipation of the joint while retaining a same level of rotational strength as the originally designed configuration. We conclude that the joint has a satisfying behavior under reversed moment loading for use in earthquake resistant timber structure in low to moderate seismicity areas like Korea.

• Steel and Composite Structures
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• 제23권1호
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• pp.17-29
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• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.

• Steel and Composite Structures
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• 제45권1호
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• pp.101-118
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• 2022

The seismic performance of the reinforced concrete (RC) special-shaped column to steel beam connections with steel jacket used in the RC column to steel beam fabricated frame structures was investigated in this study. The three full-scale specimens were subjected to cyclic loading. The failure mode, ultimate bearing capacity, shear strength capacity, stiffness degradation, energy dissipation capacity, and strain distribution of the specimens were studied by varying the steel jacket thickness parameters. Test results indicate that the RC special-shaped column to steel beam connection with steel jacket is reliable and has excellent seismic performance. The hysteresis curve is full and has excellent energy dissipation capacity. The thickness of the steel jacket is an important parameter affecting the seismic performance of the proposed connections, and the shear strength capacity, ductility, and initial stiffness of the specimens improve with the increase in the thickness of the steel jacket. The calculation formula for the shear strength capacity of RC special-shaped column to steel beam connections with steel jacket is proposed on the basis of the experimental results and numerical simulation analysis. The theoretical values of the formula are in good agreement with the experimental values.

• 한국공간구조학회논문집
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• 제8권1호
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• pp.89-97
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• 2008

본 논문은 유닛 모듈러를 구성하는 주구조체인 각형강관 기둥과 냉간성형 LEB C-형강 보로 볼트 접합된 접합부의 거동을 실험적으로 평가하는 것이 연구의 목적이다. 접합부에서 기둥과 LEB C-형강 보를 접합하기 위한 브라켓의 두께변화, LEB C-형강 보와 브라켓 접합부 볼트 개수 등의 주요변수에 대한 실험을 통하여 기둥-보 접합부의 내력증대와 변형성상 및 파괴모드 변화 등을 고찰하였다. 실험결과, 접합부의 보강형상과 관계없이 또한 접합부의 파괴 없이 LEB C-형강 보의 국부좌굴강도가 지배하는 것으로 파악되었으며, 브라켓 두께 크기에 따라 내력과 강성이 조금 높게 나타남을 알 수 있었다. 또한 접합부에 사용된 볼트 수량에 관계없이 강성면에서 큰 차이를 나타내지 않았으며 LEB C-형강과 브라켓을 볼트접합으로 반강접합의 역학적 거동 가능성을 확인하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제4권3호
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• pp.197-204
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• 2000

Tensile strength (stress) of bar splice is important in the research of mechanical behavior of reinforced concrete structures-beam, column etc.- with bar splice. The purpose of this research is to evaluate the flexural behavior - deflection of beam specimens, strain of main bars - of reinforced concrete beam with Lock Joint Coupler. To make a comparative research, reinforced concrete beam specimens with normal deformed bar and lap splice are tested and analyzed. Test results, Comparing a deflection of three types flexural specimens, a flexural specimen with Lock Joint Coupler is 40% greater than the other flexural specimens. At the center of flexural specimen, the strain of main bar(D29) with lock joint coupler is 50% less, and vice versa, at the point of 14cm far from the center of flexural specimen, the strain of main bar(D29) with lock joint coupler is 9% larger than the strain of main bar(D29) which calculated using the classical flexure theory. A discords, between a deflection behavior of the flexural specimens and a strain of the main bar, are caused by the difference of strain between the lock joint coupler and main bar, near the lock joint coupler. So, additional research is need to verify as stated above discords.

• Earthquakes and Structures
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• 제26권1호
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• pp.31-48
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• 2024

In order to get a better understanding of seismic performance of exterior beam-column joint, reciprocating loading tests with variable loading speeds or axial forces were carried out. The main findings indicate that only few cracks exist on the surface of the joint core area, while the plastic hinge region at the beam end is seriously damaged. The damage of the specimen is more serious with the increase of the upper limit of variable axial force. The deflection ductility coefficient of specimen decreases to various degrees after the upper limit of variable axial force increases. In addition, the higher the loading speed is, the lower the deflection ductility coefficient of the specimen is. The stiffness of the specimen decreases as the upper limit of variable axial force or the loading speed increase. Compared to the influence of variable axial force, the influence of the loading speed on the stiffness degradation of the specimen is more obvious. The cumulative energy dissipation and the equivalent viscous damping coefficient of specimen decrease with the increase of loading speed. The influence of variable axial force on the energy dissipation of specimen varies under different loading speeds. Based on the truss model, the biaxial stress criterion, the Rankine criterion, the Kent-Scott-Park model, the equivalent theorem of shearing stress, the softened strut-and-tie model, the controlled slip theory and the proposed equations, a calculation method for the shear capacity is proposed with satisfactory prediction results.

• 한국구조물진단유지관리공학회 논문집
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• 제2권3호
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• pp.188-193
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• 1998

An experimental study was performed on the pull-out behavior of 90-deg standard hooks from exterior beam-column connections. The effects of lateral confinement and fiber reinforcement of joint area were investigated. It was concluded ; (1) Substitution of the transverse column (confining) reinforcement with steel fibers at the joint region effectively reduces the extent of cracking in exterior joints caused by pull-out of hooked bars; and (2) The strength and ductility of hooked bars under pull-out forces are positively influenced by substituting the conventional confining reinforcement of exterior joints with steel fibers. Application of steel fibers to exterior joints seems to be an effective technique for improving the anchorage conditions of hooked bars, and also for reducing the congestion of reinforcement in exterior beam-column connections.