Optimal Evolutionary Seismic Design of Three-Dimensional Multistory Structures with Damping Devices

Abstract

Current seismic codes do not incorporate a well-established methodology for the properties and topological distribution of damping devices in three-dimensional multistory structures. The issue is further exaggerated when structures are subject to extreme events and operate well within their inelastic range. To overcome the previous shortcomings, this study develops an evolutionary computational framework for the seismic design of regular and irregular three-dimensional multistory structures that incorporates hierarchical multiscale megabrace architectures. Design examples include an 8-story irregular and a 14-story regular steel three-dimensional building with moment resisting frames (MRFs) retrofitted with friction dampers. The seismic environment consists of 25 synthetic ground motions with 5% of probability of exceedance in 50 years. Identified optimal designs result in novel three-dimensional multiscale megabrace architectures that yield more uniformly distributed ductility demand throughout the height of the structures when compared to the base structures. Optimal 8-story structure designs include damping devices with properties progressively reducing toward the top, while optimal 14-story structure designs favored layered architectures with nonretrofitted stories at the upper stories in an attempt to attenuate the seismic wave travelling toward the top of the structure.