Extension of direct displacement‐based design for quantifying higher mode effects on controlled rocking steel cores
Navid Rahgozar, Navid Rahgozar, Nima Rahgozar, Nima Rahgozar
Abstract
Summary Direct displacement‐based design (DDBD) procedure utilizes an equivalent single‐degree‐of‐freedom model to predict seismic demands while neglecting the higher mode effects. Controlled rocking steel cores (CRSCs) vibrate in the first mode of vibration; however, higher modes greatly influence the member forces. Previous studies, in which DDBD has been utilized, have not quantified the contribution of higher mode demands to CRSC's assemblies. This paper aims to extend the DDBD (EDDBD) procedure for low‐damage buildings, equipped with CRSCs. Modal responses are combined with modified SRSS at the design displacement. Design is formulated for the strength and stiffness of the CRSC components. The application of the proposed design approach is illustrated by 3‐, 9‐, and 15‐story archetypes. Results verified by nonlinear dynamic analyses demonstrate the high precision of EDDBD in the design of low‐ to mid‐rise CRSCs. The proposed procedure is applicable to commercial software.