Multi-objective Performance-Based Design Optimization of a Controlled Rocking Steel Braced Frame System

Abstract

This chapter seeks to determine the optimal structural design parameter values for a 6-story controlled rocking steel braced frame (CRSBF) building that minimizes the upfront (initial construction) and earthquake-induced economic and environmental impacts. The dead load on the rocking frame, initial post-tensioning force, fuse strength and frame aspect ratio are the considered parameters. Earthquake-induced economic losses are assessed using the FEMA P58 methodology and the Economic Input-Output Life Cycle Assessment is used to quantify greenhouse gas emissions associated with initial construction and repair and replacement activities following earthquake damage. Surrogate models are developed as compact representations of the statistical relationship between the structural design parameters and economic and environmental impacts. Once validated, the surrogate models are used to perform single- and multi-objective optimization using the desirability function approach. Differences in the sensitivity of the two impact categories (environmental and economic) to variations in the individual structural design parameters are also highlighted.