Seismic response analysis of structures equipped with uplift-restraining sliding isolation bearings: A case study

This paper concentrates on the seismic response analysis of structures equipped with uplift-restraining sliding isolation bearings (XY-FP). The study involves nonlinear response-history analysis of a seismically isolated building, the new Acropolis Museum in Athens, Greece, subjected to bi-directional horizontal seismic excitation. The analysis was performed with an enhanced version of program 3D-BASIS-ME, which was modified to include an element representative of the mechanical behavior of the XY-FP isolators. Upon identifying the uplift-prone isolators through analysis of the seismically isolated structure equipped with solely conventional Friction Pendulum (FP) isolators, 3D-BASIS-ME analysis was performed on the structure with isolators prone to uplift being replaced with XY-FP isolators. The input motions used in the analysis were arbitrarily scaled so that they cause significant uplift in the FP isolators or significant tension in the XY-FP isolators, in order to ascertain the impact of using the XY-FP isolators in a real structure. The results demonstrate that tension in individual XY-FP isolators, and by extension the increase of isolation system friction force, did not have any appreciable effect on either the total isolation system response or the superstructure response.