Earthquake Simulations on a Self-Centering Steel Moment Resisting Frame with Web Friction Devices

Abstract

A self-centering moment resisting frame (SC-MRF) is a viable alternative to a conventional MRF with welded beam-column connections for seismic resistant buildings. An SC-MRF is characterized by gap opening and closing at the beam-column interface under earthquake loading. The beams are post-tensioned to columns by high strength post-tensioning (PT) strands oriented horizontally to provide self-centering forces when gap opening occurs. For the SC-MRF investigated in this research, energy dissipation is provided by beam web friction devices (WFDs) attached to the columns at the beam-column interface. Both the PT strands and WFD contribute to the moment capacity of the SC-MRF connections. The SC-MRF in this study is designed to meet several seismic performance objectives. These include no damage under the Design Basis Earthquake (DBE), leading to immediate occupancy performance following the DBE. In addition, under the Maximum Considered Earthquake (MCE) the structure is designed to have minimal damage and achieve the collapse prevention performance level. A 7-bay, 4-story SC-MRF prototype building located on stiff soil in the Los Angeles area was designed with WFDs using a performance-based design procedure with the above performance objectives. A 0.6-scale model of two bays of the SC-MRF was developed and tested under simulated earthquake loading at the NEES equipment site located at Lehigh University using the hybrid simulation method to include the remaining parts of the building in the simulation. This paper presents an overview of the performance-based design procedure, the test results, and an assessment of the design procedure.