Nonlinear Seismic Interaction Behavior of Shear wall-Frame with Different Stiffness Ratio of Wall and Frame

Most codes recommend a minimum strength for frame, equal to 25% of total lateral force, as an acceptance criterion of shear wall-frame dual action. The purpose of this article is to study nonlinear seismic response of wall-frame structures with constant total stiffness and different stiffness ratio of wall and frames. Four, eight and twelve story RC structures, with different frame-wall stiffness ratio ranging from 10-90 to 80- 20, are analyzed nonlinearly under time histories. Stiffness and strength degradation, nonlinear behavior of reinforced concrete sections and their energy dissipation in cyclic loading are taken into account. This study tries to find stiffness ratios for frame in wall-frame structures which lead to safe and best nonlinear performance at different level of hazard. Methods are proposed to define wall, frame and wall-frame stiffness in multistory structures. Based on result of this study the minimum frame strength equal to 25% of lateral forces is not accurate and it could be decreased safely, however the best performance would be possible with higher frame stiffness and strength ratios.

Keywords:

Shear Wall , Concrete Frame , Frame-wall interaction , Seismic Design , Nonlinear Analysis