Performance of Conventionally Reinforced Coupling Beams Subjected to Cyclic Loading

The behavior of coupled-wall buildings primarily depends on the performance of coupling beams. Existing coupled-wall buildings designed and built prior to the 1970s contain coupling beams reinforced with horizontal and vertical bars. Seismic evaluation of these older buildings is commonly performed using nonlinear static or dynamic analyses techniques. Results from nonlinear analyses depend on the quality of backbone curves that characterize the behavior of the individual coupling beams. Backbone curve construction must, therefore, focus on reliable estimates of the strength and deformation values used to characterize the behavior of the structural component. This paper presents experimental results of four conventionally reinforced coupling beams designed to exhibit different behavior modes during cyclic loading. The effect of different amounts of longitudinal and transverse reinforcement on behavior is highlighted. The measured shear strength of the beams is compared with values calculated using existing equations. The deformation components that contributed to chord rotation are identified and discussed in light of response parameters, such as measured strains and observed cracking. The tests also highlight the importance of accounting for reduction in shear stiffness to accurately determine the deformation response of coupling beams.