Seismic Behavior Of Hybrid Lateral Force Resisting Systems

Seismic codes and guidelines in the United States permit more than one type of lateral-force-resisting system to be used in an earthquake-resistant framing system. Multiple lateral-force-resisting systems in series, herein termed hybrid systems, are also constructed in the United States but have received little-to-no attention from the academic community. In such systems, flexible framing is typically constructed atop stiff framing. The expected performance of such systems for DBE and MCE shaking is unknown either in absolute terms or by comparison with framing systems composed of just one type of lateral-force-resisting system. Three types of lateral force-resisting systems are studied, namely, reinforced concrete shear walls, steel eccentrically braced frames and steel moment frames. Three building heights are considered, three, five and nine stories, to provide a robust dataset. The framing systems were designed for a site in Los Angeles and assessed by nonlinear response-history analysis.