Seismic Response Comparison of Fixed-Base and Base-Isolated 8-Story Buildings with Frame and Shear Wall Systems

This study investigates the effects of different lateral load-resisting systems on engineering demand parameters (EDPs) and evaluates the suitability of spectral acceleration (Sa) as an intensity measure for predicting their seismic response. Eight-story reinforced concrete buildings with four configurations—fixed-base moment-resisting frame, fixed-base dual system with shear walls, base-isolated moment-resisting frame, and base-isolated dual system with shear walls—were analyzed. The seismic responses are obtained through nonlinear time-history analyses using 11 ground motion records scaled to match the site conditions. Four key response parameters are examined: maximum lateral displacement, interstory drift, floor acceleration, and base shear. Overall, the base-isolated dual system exhibited the best performance across all response parameters. In addition, Sa can be reasonably used to estimate floor acceleration in frame structures. However, the use of Sa to estimate floor acceleration in dual systems with shear walls tends to underestimate the actual response.