Dual‐Level Approach for Seismic Design of Asymmetric‐Plan Buildings

Buildings should be designed to resist moderate ground motion without structural damage and resist intense ground motion with controlled damage. However, most codes do not consider both these requirements explicitly and specify a single design earthquake that generally corresponds to intense ground motion. Investigated in this study is the response of one‐story, asymmetric‐plan systems designed according to torsional provisions of seismic codes to the two levels of ground motions with the objective of evaluating whether such systems satisfy these requirements. The presented results demonstrate that such systems may not remain elastic during moderate ground motion resulting in structural damage and may experience ductility demand in excess of the design ductility, causing excessive damage during intense ground motion. Therefore, the dual‐design approach, proposed earlier for symmetric‐plan systems, is extended to asymmetric‐plan systems. In this approach, the design earthquakes and the design eccentricities corresponding to the moderate and intense ground motions are considered to be different; for the latter ground motion, the values of design eccentricity are considered to depend on the design ductility of the system. It is shown in this exploratory investigation that systems designed by this extended dual‐design approach would satisfy the design requirements for both levels of ground motion.