Influence of wall load-displacement shape on seismic performance of wood-frame shear wall structures

Abstract

The research presented in this paper investigates the influence of varying load-displacement shape on the computed FEMA P-695 seismic performance metrics including collapse margin ratio (CMR) for a subset of the woodframe shear wall building designs that were developed for the FEMA P-695 wood-frame example. Variation of loaddisplacement shape is accomplished by modification of three key parameters in the familiar 10-parameter CASHEW model: peak strength, displacement at peak strength and post yield stiffness. These parameters are varied to gain insight into trends in seismic performance for wood shear walls exhibiting different load-displacement shape compared to baseline assumptions of the FEMA P-695 wood-frame example. Investigation is conducted without P-Delta to reproduce the baseline evaluation and also with P-Delta effects included. For the range of parameters variations evaluated, it is generally observed that improving the peak strength parameter and post yield stiffness parameter has a greater effect on improving the collapse performance, as measured by CMR, than does an increase in the displacement at the peak strength parameter.