Nonlinear Seismic Response of a Coupled Wall System

Elastic and nonlinear dynamic analyses were performed on a coupled wall model based on the Banco de America building in Managua, Nicaragua. The general seismic behavior of coupled walls is examined, and the factors that must be considered in their design or repair are identified. Results of nonlinear dynamic analyses obtained for several accelerograms are compared with results of comparable static inelastic and dynamic elastic analyses. Three types of nonlinear behavioral characteristics were considered for the coupling girders: (1)Brittle shear failures; (2)ductile bilinear flexural yielding; and (3)ductile flexural yielding with stiffness degradation. Seismic response was very sensitive to the ground motion.Brittle girder failures had a detrimental effect on the lateral deflections. Improved behavior was obtained with ductile girders, but very large numbers of inelastic curvature reversals occurred in the girders due to higher mode effects, and very high girder shears and large fluctuations in the wall axial forces were developed.