Seismic response of friction damped and base-isolated frames considering serviceability limit state

The present study evaluates the seismic performance of steel moment resisting frames (MRFs) upgraded with different structural protective systems. For this, three 5 storey steel MRFs (Ordinary moment frame (OMF), intermediate moment frame (IMF) and special moment frame (SMF)) and two 10 storey MRFs (IMF and SMF) were studied. As structural protective systems, friction dampers (FDs), base isolation with lead rubber bearings (LRBs), and a combination of them were considered. The structures were modeled using a finite element program and evaluated by the nonlinear time history analyses. In the nonlinear time history analyses, seven natural accelerograms, namely, 1976 Gazlı, 1978 Tabas, 1986 San Salvador, 1987 Superstition Hills, 1992 Cape Mendocino, 1994 Northridge and 1999 Chi-Chi were taken into account. Roof drift, roof absolute acceleration, relative displacement, interstorey drift ratio, base shear, top storey moment, and hysteretic curve were employed to compare the elastic and inelastic responses of all frames. The results clearly highlighted that the application of FDs with LRB had remarkable improvement in the earthquake performance of the case study frames reducing the local/global damages in the main structural systems and satisfied the serviceability (i.e., fully operational, FO and operational, OP) limit states as well.