• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.5
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• pp.1-9
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• 2007

This study summarizes the results of a research project aimed at investigating the inelastic rotation capacity of beam-column connections of reinforced concrete moment frames. A total of 91 test specimens for beam-column joint connections were examined in detail, and 28 specimens were classified as special moment frame connections based on the design and detailing requirements in the ACI 318-02 Provisions. Then the acceptance criteria, originally defined for steel moment frame connections in the AISC-02 Seismic Provisions, were used to evaluate the joint connections of concrete moment frames. Twenty-seven out of 28 test specimens that satisfy the design requirements for special moment frame structures provide sufficient strength and are ductile up to a plastic rotation of 0.03 rad. without any major degradation in strength. Joint shear stress, column-to-beam flexural strength ratio, and transverse reinforcement ratio in a joint all play a key role in good performance of the connections.

• Earthquakes and Structures
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• v.21 no.6
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• pp.613-625
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• 2021

Non-seismically designed eccentric reinforced concrete beam-column joints were extensively used in existing reinforced concrete frame buildings, which were found to be vulnerable to seismic action in many incidences. To provide a fundamental understanding of the seismic performance and failure mechanism of the joints, three 2/3-scale exterior beam-column joints with non-seismically designed details were cast and tested under reversed cyclic loads simulating earthquake excitation. In this investigation, particular emphasis was given on the effects of the eccentricity between the centerlines of the beam and the column. It is shown that the eccentricity had significant effects on the damage characteristics, shear strength, and displacement ductility of the specimens. In addition, shear deformation and the strain of joint hoops were found to concentrate on the eccentric face of the joint. The results demonstrated that the specimen with an eccentricity of 1/4 column width failed in a brittle manner with premature joint shear failure, while the other specimens with less or no eccentricity failed in a ductile manner with joint shear failure after beam flexural yielding. Test results are compared with those predicted by three seismic design codes and two non-seismic design codes. In general, the codes do not accurately predict the shear strength of the eccentric joints with non-seismic details.

• Earthquakes and Structures
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• v.16 no.5
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• pp.533-546
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• 2019

This study presents an experimental investigation on six beam-column joint specimens under the lateral cyclic loading. The aim was to explore the effectiveness of steel fiber-reinforced concrete (SFRC) in reducing the transverse shear stirrups in beam-column joints of the reinforced concrete (RC) frames with strong-columns and weak-beams. Two RC and four SFRC specimens with different types of reinforcement detailing and steel fibers of volume fraction in the range of 0.75-1.5% were tested under gradually increasing cyclic displacements. The main parameters investigated were lateral load-resisting capacity, hysteresis response, energy dissipation capacity, stiffness degradation, viscous damping variation, and mode of failure. Test results showed that the diagonally bent configuration of beam longitudinal bars in the beam-column joints resulted in the shear failure at the joint region against the flexural failure of beams having straight bar configurations. However, all SFRC specimens exhibited similar lateral strength, energy dissipation potential and mode of failure even in the absence of transverse steel in the beam-column joints. Finally, a methodology has been proposed to compute the shear strength of SFRC beam-column joints under the lateral loading condition.

• Computers and Concrete
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• v.32 no.3
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• pp.339-349
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• 2023

Fast-built construction is a key feature for successful applications of precast concrete (PC) moment frame system in recent construction practices. To this end, by introducing some unique splicing details in precast connections, especially between PC columns including panel zones, use of temporary supports and bracings can be minimized based on their self-sustaining nature. In addition, precast wide beams are commonly adopted for better economic feasibility. In this study, three self-sustaining precast concrete (PC) wide beam-column connection specimens were fabricated and tested under reversed cyclic loadings, and their seismic performances were quantitatively evaluated in terms of strength, ductility, failure modes, energy dissipation and stiffness degradation. Test results were compared with ASCE 41-17 nonlinear modeling curves and its corresponding acceptance criteria. On this basis, an improved macro modeling method was explored for a more accurate simulation. It appeared that all the test specimens fully satisfy the acceptance criteria, but the implicit joint model recommended in ASCE 41-17 tends to underestimate the joint shear stiffness of PC wide beam-column connection. While, the explicit joint model along with concentrated plastic hinge modeling technique is able to present better accuracy in simulating the cyclic responses of PC wide beam-column connections.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.633-641
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• 2012

In this study, the effects of the inelastic shear behavior of beam-column joint on the response of RC OMRF are evaluated in the inelastic time history analysis. For an example, a 5-story structure for site class SB and seismic design category C was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was evaluated using fiber model and bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship. The hysteretic behavior was simulated using three-parameter model suggested in IDARC program. The inelastic time history analysis with PGA for return period of 2400 years showed that the model with inelastic beam-column joint yielded smaller maximum base shear force but nearly equivalent maximum roof displacement and maximum story drift as those obtained from analysis using rigid joint. The maximum story drift satisfied the criteria of KBC2009. Therefore, the inelastic shear behavior of beam-column joint could be neglected in the structural design.

• Steel and Composite Structures
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• v.32 no.5
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• pp.583-594
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• 2019

In recent years, composite concrete-filled steel tubular (CFST) members have been widely utilized in framed building structures like beams, columns, and beam-columns since they have significant advantages such as reducing construction time, improving the seismic performance, and possessing high ductility, strength, and energy absorbing capacity. This paper presents a new composite joint - the composite CFST beam-column joint in which the CFST member is used as the beam. The main components of the proposed composite joint are steel H-beams, CFST beams welded with the steel H-column, and a reinforced concrete slab. The steel H-beams and CFST beams are connected with the concrete slab using shear connectors to ensure composite action between them. The structural performance of the proposed composite joint was evaluated through an experimental investigation. A three-dimensional (3D) finite element (FE) model was developed to simulate this composite joint using the ABAQUS/Explicit software, and the accuracy of the FE model was verified with the relevant experimental results. In addition, a number of parametric studies were made to examine the effects of the steel box beam thickness, concrete compressive strength, steel yield strength, and reinforcement ratio in the concrete slab on the proposed joint performance.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.599-604
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• 2000

The analytical studies for the test results are presented. From experimental envelope curve, hysteretic behaviors under cyclic loading are modelled for beam-column subassemblages. Modelled curves show relatively good reproduction or experimental curves. finally, seismic performances are investigated for 7 story plain framed structure by nonlinear dynamic analysis. The resulting responses are different by each beam-column joint design.

• Journal of the Earthquake Engineering Society of Korea
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• v.21 no.3
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• pp.115-123
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• 2017

To investigate the cyclic characteristics of the retrofitted exterior joints of RC frame with haunch, 70% scaled 6 beam-column exterior joint subassemblies were designed according to design guideline according to 1988 and tested with cyclic loading up to 3.5% story drift ratio. During the experiments axial forces are applied to columns to simulate gravity load. Experimental results shows that the strength of retrofitted specimens was increased steadily until 2.5% story drift ratio and their strengths increased more than 1.7 times of the non-retrofitted in case that main bar was bent away from exterior joint. The joint strength and effective stiffness of the retrofitted specimen was increased and results in more deformation capacity compared to the non-retrofitted.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.13-20
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• 2012

In this study, 5-story structures were designed in accordance with KBC2009 for inelastic time history analysis of RC IMRF. Bending moment-curvature relationship for beam and column was identified with fiber model and bending moment-rotation relationship for beam-column joint was calculated with simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The hysteretic behavior was simulated with three-parameter model suggested in IDARC program. The analytical results showed that the inelastic shear behavior of the joint could be neglected in the structural design for seismic design category C but the structure of category D did not satisfy the criteria of FEMA 356 for collapse prevention performance level.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.4
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• pp.189-196
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• 2020

In this study, two full-scale gravity load-designed reinforced concrete corner beam-column joints were tested by being subjected to uniand bi-directional cyclic lateral loading. The test variable was loading type: uni- or bi-directional loading. To investigate the effect of the loading type on the cyclic behavior of joint specimens, damage progression, force-deformation relation, contribution of joint deformation to total drift, joint stress-strain response, and cumulative energy dissipation were investigated. The test data suggest that bidirectional loading can amplify damage accumulation in the joint region.