Diagonally reinforced concrete coupling beams (DRCBs) have been widely adopted in reinforced concrete (RC) bearing wall systems. DRCBs are known to act as a fuse element dissipating most of seismic energies imparted to the bearing wall systems during earthquakes. Despite such importance of DRCBs, the damage estimation of such components and the corresponding consequences within the knowledge of performance based seismic design framework is not well understood. In this paper, drift-based fragility functions are developed for in-plane loaded DRCBs. Fragility functions are developed to predict the damage and to decide the repair method required for DRCBs subjected to earthquake loading. Thirty-seven experimental results are collected from seventeen published literatures for this effort. Drift-based fragility functions are developed for four damage states of DRCBs subjected to cyclic and monotonic loading associated with minor cracking, severe cracking, onset of strength loss, and significant strength loss. Damage states are defined in a consistent manner. Cumulative distribution functions are fit to the empirical data and evaluated using standard statistical methods.

Diagonal reinforced coupling beam of coupled shear walls can provide sufficient strength and stiffness to resist lateral force. However, the reinforcement details for coupling beams required by ACI 318 (2011) are difficult to construct because of the reinforcement congestion and confined interior area. This study presents experimental results about the seismic performance of coupling beams having bundled diagonal reinforcement to improve the workability. Experiments were conducted using half scaled precast coupling beams having an aspect ratio of 2.0. It was observed that the bundled diagonal reinforced coupling beams can develop seismic performance similar to the coupling beams with requirement details specified in ACI 318 (2011).

콘크리트 부재의 내진설계에 있어 강도와 더불어 변형 능력은 중요한 요소이다. 연결보는 전단 지배 부재임에도 항복 이후 소성 변형을 요구하는 부재인데 본 연구에서는 연결보의 변형 능력에 대한 실험을 통해 변형 모형을 제시하였다. 일반적인 배근 형태를 가진 철근 콘크리트 연결보를 대상으로 단조하중실험을 수행하였다. 경간-깊이비, 휨 철근비, 전단 철근비를 변수로 하여 연결보의 거동을 평가하였다. 전단 지배 부재인 연결보는 아치작용과 트러스 작용으로 전단력에 대해 저항하는데 실험 결과를 통해 전단력을 두 작용의 구분과 항복 강도 발현 이후 소성 변형에 따른 두 작용의 구성비 변화에 대해 분석하였다. 실험결과에 기초한 전단 철근과 휨 철근의 변형률 분포 모형을 이용하여 휨 철근의 응력 상태를 산정하였다. 휨 철근의 부착-미끄러짐에 의해 결정되는 균열폭을 고려하는 연결보의 변형 모형을 제시하였다. 항복 상태는 휨 철근의 항복 시점으로 정의하였고, 극한 상태는 변형 증가에 따른 스트럿의 압축 강도 저하에 의해 결정되었다. 이 변형 모형은 변위기초설계에 활용될 수 있을 것으로 기대된다.

This experimental study showed that the shear friction strength that the joint regions of hybrid steel-reinforced concrete beam systems was increased by the dowel bars.

This paper describes the experimental results for the structural performance of full-scale coupling beams with different reinforcement layout (diagonal and horizontal). For the reinforcements of the coupling beams, high-strength steel bars(SD500 and SD600) were used in order to improve workability and economic feasibility. The rigid steel frames and linked joints were used to maintain the clear span length (distance between both shear walls) of the coupling beam during the cyclic loading. Experimental results indicated that the diagonally reinforced coupling beam specimen could exhibit more ductile behavior compared to horizontally reinforced specimen. ACI318-14 code is applicable to design of coupling beam with diagonally reinforcement, however, that is overestimating the strength of horizontally reinforced coupling beam. It is remarkable that effective elastic stiffness values of both reinforcement details coupling beam significantly lees than ASCE 41-13.

Coupled shear wall systems, which consist of two or more in-plane shear walls interconnected with link beams, are frequently used in medium and high-rise buildings. In this study, an innovative type of replaceable steel angle for link beam, was conceived and studied.

As viable substitutes for reinforced concrete link beam, the use of alternlate link beam and composite coupling beams have also been investigated by several researchers. In this study to enhance the post-damage repair capability of the link beam, a different type of replaceable link beam with angle connection was investigated.

In this study aims at exploring the use of steel frame as an innovative method of improving the seismic performance of link beams. Also, the effect of diagonal reinforcement in link beam is evaluated in comparison to conventional reinforcement.