Seismic Response and Damage of Reduced-Strength Steel MRF Structures with Nonlinear Viscous Dampers

Abstract

An experimental investigation of the seismic response and damage of steel moment resisting frame (MRF) building structures with nonlinear viscous dampers was conducted using ground motions up to and beyond the maximum considered earthquake (MCE) level. The objective was to assess the response of MRFs designed with reduced strength (relative to current practice) but with added damping to achieve enhanced seismic performance. The MRFs were designed for 1%, 75%, and 6%, respectively, of the base shear strength required by the current standard. The experiments used a real-time hybrid simulation (RTHS) approach in which an MRF, together with a frame with nonlinear viscous dampers and associated bracing (called the DBF), was in the laboratory, and the seismic mass and gravity system associated with the MRF and DBF and the inherent damping of the building were numerically modeled. Experimental results, including inelastic energy dissipation, development of damage, and local response of the reduced-strength MRFs (focusing on the MRF with 6% base shear strength) to ground motions from the frequently occurring earthquake (FOE) level up to 1.4 times the MCE level are presented. The results show that steel MRF structures designed with reduced strength and added nonlinear viscous dampers have excellent performance for ground motions beyond the MCE level.