• Structural Monitoring and Maintenance
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• v.7 no.3
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• pp.167-193
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• 2020

In this paper, the behavior of interior steel fiber reinforced concrete beam - column joints (BCJs) under cyclic loading is investigated. An experimental program including tests on twelve reinforced concrete (BCJs) specimens under cyclic loading was carried out. The test specimens are divided into two groups having different geometry: group (G1) (symmetrical BCJs specimens) and group (G2) (nonsymmetrical BCJs specimens). The parameters considered in this study are the steel fibers (SFs) content by volume of concrete (V_f), the spacing of shear reinforcement at the joint region, and the area of longitudinal flexural reinforcement. Test results show that the addition of 0.5% SFs with stirrups spacing S=S_max has effectively enhanced the overall performance of BCJs with respect to energy dissipation, ductility ratio, spreading and width of cracks. The failure of specimens is governed mainly by the formation of a plastic hinge at the face column and outside the beam-column junction. Secondary shear cracks were also observed in the beam-column junctions.

• Computers and Concrete
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• v.8 no.1
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• pp.59-70
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• 2011

A theoretical model known as the modified rotating-angle softened-truss model (MRA-STM), which is a modification of Rotating-Angle Softened-Truss Model and Modified Compression Field Theory, is presented for the analysis of reinforced concrete membranes in shear. As an application, shear strength and behaviour of reinforced concrete exterior beam-column joints are analysed using the MRA-STM combining with the deep beam analogy. The joints are considered as RC panels and subjected to vertical and horizontal shear stresses from adjacent columns and beams. The strut and truss actions in a beam-column joint are represented by the effective transverse compression stresses and a softened concrete truss in the proposed model. The theoretical predictions of shear strength of reinforced concrete exterior beam-column joints from the proposed model show good agreement with the experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.1-9
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• 2015

This study is on the shear strength of the internal joints of RCS composite structure consisting of reinforced concrete column and steel beam. As a newly structure system, the composite system has been developed to fully utilize the advantages of reinforced concrete column and steel beam, which also include economic and practical joint detail. Nevertheless stress transfer mechanism and structural behavior of the joints had not been still clearly revealed and shown much difference from the proposed equation. In this study, by observing the crossing of reinforced concrete column through steel beam to the RCS structure beam type, thirty seven shear failure specimens were selected and applied to the 5 major equations which is used to calculate the shear strength of RCS joint. Through the regression analysis, modified equation which is more reliable and approximate results for shear strength of RCS joints was proposed.

• Steel and Composite Structures
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• v.37 no.1
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• pp.15-26
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• 2020

The top-and-seat angles with double web angles are commonly used in the design of beam-to-column joints in Asian and North American countries. The seismic behavior analysis of these joints with large cross-section size of beam and column (often connected by four or more bolts) is a challenge due to the effects from the relatively larger size of stiffened angles and the composite action from the adjacent concrete slab. This paper presents an experimental investigation on the seismic performance of exterior composite beam-to-column joints with stiffened angles under cyclic loading. Four full-scale composite joints with different configuration (only one specimen contain top angle in concrete slab) were designed and tested. The joint specimens were designed by considering the effects of top angles, longitudinal reinforcement bars and arrangement of bolts. The behavior of the joints was carefully investigated, in terms of the failure modes, slippage, backbone curves, strength degradation, and energy dissipation abilities. It was found that the slippage between top-and-seat angles and beam flange, web angle and beam web led to a notable pinching effect, in addition, the ability of the energy dissipation was significantly reduced. The effect of anchored beams on the behavior of the joints was limited due to premature failure in concrete, the concrete slab that closes to the column flange and upper flange of beam plays an significant role when the joint subjected to the sagging moment. It is demonstrated that the ductility of the joints was significantly improved by the staggered bolts and welded longitudinal reinforcement bars.

• Steel and Composite Structures
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• v.36 no.4
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• pp.427-446
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• 2020

This paper carries out the progressive collapse analysis of stainless steel composite beam-to-column joint sub-models and moment-resisting frames under column removal scenarios. The static flexural response of composite joint sub-models with damaged columns was initially explored via finite element methods, which was validated by independent experimental results and discussed in terms of moment-rotation relationships, plastic hinge behaviour and catenary actions. Simplified finite element methods were then proposed and applied to the frame analysis which aimed to elaborate the progressive collapse response at the frame level. Nonlinear static and dynamic analysis were employed to evaluate the dynamic increase factor (DIF) for stainless steel composite frames. The results suggest that the catenary action effect plays an important role in preventing the damaged structure from dramatic collapse. The beam-to-column joints could be critical components that influence the capacity of composite frames and dominate the determination of dynamic increase factor. The current design guidance is non-conservative to provide proper DIF for stainless steel composite frames, and thus new DIF curves are expected to be proposed.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.229-245
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• 2017

Post-earthquake observations revealed that seismic performance of beam-column connections in precast concrete structures affect the overall response extensively. Seismic design of precast reinforced concrete structures requires improved beam-column connections to transfer reversed load effects between structural elements. In Turkey, hybrid beam-column connections with welded components have been applied extensively in precast concrete industry for decades. Beam bottom longitudinal rebars are welded to beam end plates while top longitudinal rebars are placed to designated gaps in joint panels before casting of topping concrete in this type of connections. The paper presents the major findings of an experimental test programme including one monolithic and five precast hybrid half scale specimens representing interior beam-column connections of a moment frame of high ductility level. The required welding area between beam bottom longitudinal rebars and beam-end plates were calculated based on welding coefficients considered as a test parameter. It is observed that the maximum strain developed in the beam bottom flexural reinforcement plays an important role in the overall behavior of the connections. Two additional specimens which include unbonded lengths on the longitudinal rebars to reduce that strain demands were also tested. Strength, stiffness and energy dissipation characteristics of test specimens were investigated with respect to test variables. Seismic performances of test specimens were evaluated by obtaining damage indices.

• Land and Housing Review
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• v.3 no.4
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• pp.433-449
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• 2012

An experimental investigation was conducted to study the behavior of RC wide beam-column joints with slab subjected to reversed cyclic loads under constant axial load. Six half scale interior wide beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including three specimens without slab and three specimens with slab. The primary variables were the ratio of column-to-beam flexural capacity ($M_r={\Sigma}M_c/{\Sigma}M_b$ ; 0.77~2.26), ratio of the column-to-beam width (b/H ; 1.54, 1.67). Test results are shown that (1) the current design code and practice for interior joints(type 2) are apply to the wide beam-high strength concrete column. (2) the presence of a slab have an effect on the performance of the wide beam-high strength concrete column interior joints(type 2). therefore in the design of the wide beam-high strength concrete column interior joints(type 2), the width of slab effective as a T beam flange should be considered. It was show that the case of the ratio of column-to-beam flexural capacity is more than 2.0, the effective width of slab are 2 times of an effective depth of wide beam, however if the ratio of column-to-beam flexural capacity is 1.4~2.0, the effective width of slab are not able to be considered.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.3
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• pp.97-105
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• 2013

In this paper, the a static experiment of on two reinforced concrete (RC) frame sub-assemblages was conducted to evaluate the seismic behaviors of existing RC frames that were not designed to support a seismic load. The specimens were a one span and actual-sized. One of them had two columns with the same stiffness, but the other had two columns with different stiffness values. As Regarding the test results, lots of many cracks occurred on the surfaces of the columns and beam-column joints for the two specimens, but the cover concrete splitting hardly occurred was minimal until the test ends. In the case of the specimen with the same stiffness offor the two columns, the flexural collapse of the left-side column occurred. However, in the case of the specimen with different stiffness values for of the two columns, the beam-column joint finally collapsed, even though the shear strength of the joint was designed to be strong enough to support the lateral collapse load. The nonlinear Nonlinear static analysis of the two specimens was also conducted using the uniaxial spring model, and the analytical results successfully simulated the nonlinear behaviour of the specimens in accordance with the test results.

• KCI Concrete Journal
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• v.11 no.3
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• pp.191-199
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• 1999

A Precast frame system with hybrid beam-column connections was proposed in this study. An analytical study evaluated the system under seismic loadings. Four buildings with different heights were modeled in which each building had three types of joint details (A. B, C). Thus, twelve buildings were examined with variables such as building height and joint detail. Four earthquake records were applied to the buildings as input ground motions. All the records were normalized to the intensity of 0.25g to assess behavior under the same intensity of seismic excitation. All the joint types showed almost identical results except for the Mexico earthquake which was scaled up from 0. 1g to 0.25g. Buildings with the type C joint exhibited the largest deflection for the Mexico earthquake. It was concluded that type B joint could be used in a high seismic zone and the type C joint could possibly be used in the regions of low to medium seismic activity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.8-14
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• 2019

In Korean traditional wooden architecture, joint performance varies with the material characteristics of timber, the form of joint, the precision of timber-trimming and the like. Case studies prove that the beam-to-column joint type has large influence on the degrees of deformation and spacing. This is not only true of single-story buildings, but also of large-scale multi-story buildings more apparently. Therefore, this study followed the process of examining to joint types, producing their specimens and testing their structural performance. As a consequence of structural test, the dovetail joint specimen showed the best outcomes of the maximum load and rigidity. Synthesizing the structural performances by respective forms of joints, the Doraegeoji dovetail joint specimen showed the higher performance, followed in order by the Doraegeoji mortise joint specimen and the Tongneoko dovetail joint specimen. The structural performance of a building varies with the characteristics by the shouldering forms of penetrating beams and with the joint types within the columns. This should be considered for the new construction or restoration of multi-story buildings, and be continuously researched henceforth.