Retrofitting of R.C. Frame Buildings With Double Con-Cave Curved Surface Isolator Sliders Characterized by Over-Stroke Displacement Capacity

Abstract

Base isolation system is one of the most widespread passive control system techniques currently used for seismic protection of buildings and bridges. At the ultimate limit state, isolating devices are designed to attain the design displacement at the Maximum Credible Earthquake (MCE), while the superstructure remains in the elastic range for earthquake intensity corresponding to the Design Basis Earthquake (DBE). Among various isolation devices the friction pendulum sliders and elastomeric bearings are the most economical and practical system. Acceptable probabilities of collapse for seismically isolated frame structures could be achieved by a suitable isolator displacement capacity. This study considers the effects of restraining rings and of the over-stroke displacement capacity of double concave curved surface slider (DCCSS) isolators on the structural seismic response. The seismic behaviour of base isolated six-storey reinforced concrete frame building case study retrofitted for seismic site of L'Aquila has been evaluated considering earthquake intensity levels at Collapse Limit State. Different configurations of the base isolation system, with end-stops placed at maximum isolator displacement capacity or with extra-stroke displacement capacity, have been investigated. In this paper, the results of non-linear static and dynamic analyses at the MCE are compared.