A cyclic backbone curve for squat reinforced concrete shear walls

Shear-resisting mechanisms generally dictate the seismic behavior of squat (low aspect ratio) reinforced concrete (RC) shear walls. Such walls are widely used in low-rise commercial buildings and energy-related facilities. A significant number of experimental studies have been performed over many decades to characterize the behavior of shear-critical RC walls. Analytical and numerical studies have also been performed but there are no a) validated analytical models for the analysis of shear-critical walls that are capable of reproducing cyclic backbone response to levels of lateral drift corresponding to failure, and b) validated cyclic macro models suitable for nonlinear dynamic analysis. In this paper, data from tests of 240 low aspect ratio RC walls are summarized to develop recommended backbone shapes for use in nonlinear seismic analysis in support of design and performance assessment. The effects of design parameters including wall aspect ratio, axial load, day-of-test concrete compressive strength, vertical and horizontal web reinforcement ratio, reinforcement ratio in the boundary elements, and yield strength of reinforcement, on nonlinear cyclic response are considered. The test data are used to update the values of the control points on the lateral load-deformation relationship for squat reinforced concrete shear walls.