Seismic Response of Flexibly Supported Coupled Shear Walls

Abstract

Results from seismic analyses performed on 20-story ductile coupled-shear-wall models designed for Montreal, Canada, are presented. A two-dimensional model was used to idealize the structure including the supporting ground. Allowances were made for nonlinearities not only in the walls and the coupling beams, but also in the soil and foundation elements. The soil foundation was modeled by equivalent massless springs (hangers), located at the base of the structures, allowing for inelastic bearing of the soil and loss of contact (uplift) of base from supporting soil. The stiffnesses of massless foundation springs were obtained using the soil properties that were derived on the basis of strain-dependent shear moduli of real borings. The study showed that the model is capable of tracing the response of coupled shear wall, taking into account the soil-structure interaction effects. Results showed that allowing for foundation flexibility lengthened the fundamental period by a maximum of 33; it amplified deflections by a maximum of 81. However the stresses in the walls and the coupling beams attenuated particularly in lower stories. Finally, no substantial variations were observed in the rotational ductility demands of the coupling beams.