A Cyclic Backbone Curve for Shear-Critical Reinforced Concrete Walls

Backbone curves are used in seismic design standards as the basis for developing component models for nonlinear static and dynamic analysis. Herein, data from 240 tests of rectangular, barbell, and flanged shear-critical walls are assembled and analyzed to develop an improved cyclic backbone curve for use in nonlinear response-history analysis. Values of drift ratio and normalized lateral force at the control points on the cyclic backbone curve are identified. 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 the coordinates of the control points are addressed. The accuracy of equations for peak shear strength is assessed using the collected test data.