Seismic design for enhanced building performance using rocking steel braced frames

Abstract

Performance-based seismic design has brought about innovative rocking and self-centering structural systems such as rocking steel braced frames (RBF). This lateral force resisting system has recently received focused attention in academic research however has seen limited application in practice to date. This may be due in part to the unconventional load path, plastic mechanisms, and unique dynamic characteristics of the system. The transfer of forces through a RBF with passive energy dissipating devices (steel yielding and viscous) is described and a simplified approach proposed to quantify peak dynamic deformation and force response. Enhanced performance can be achieved by including viscous damping devices over hysteretic devices and post-tensioning (proposed in previous research). The dynamic response of RBF are evaluated through nonlinear transient finite element seismic analyses with ground motion sets. Additionally, the demands placed on non-structural components contained on each building floor was investigated through the computational model by calculating critical response quantities such as inter-story drift, peak floor acceleration, and floor spectra. Structural and non-structural demands are compared with a buckling-restrained braced frame (BRBF) to illustrate the differences in seismic behavior and potential benefits of a well-designed rocking steel braced frame.