Seismic resilience assessment of base-isolated structures with friction pendulum isolation bearings based on two-dimensional fragility

A seismic resilience assessment method based on multi-dimensional fragility is proposed for baseisolated structures with friction pendulum isolation bearings. Two-dimensional performance indexes representing the superstructure and the bearing are selected, and two-dimensional fragility is developed by considering the multi-dimensional correlated kernel density estimation theory and the multi-dimensional correlated performance limit state theory. Utilizing the conversion of two-dimensional fragility to the probability of various damage states as an initial point, seismic resilience is assessed in a total probabilistic manner. The rationality of the proposed method is examined through a typical base-isolated structure with such bearings. The case demonstrates discrepancies in fragility calculations, with differences of up to 5.2 %, 15.3 %, and 19.2 % respectively, due to the selection of two-dimensional performance indexes, the correlation of performance limit states, and the epistemic uncertainty in the probabilistic seismic demand model. The case also exhibits superior seismic isolation capability at peak ground acceleration greater than 0.4g. An increase in peak ground acceleration tends to diminish seismic resilience. The impact of the speed of post-earthquake functionality recovery on seismic resilience enhancement is limited. At the peak ground acceleration of 1.2g, a significant enhancement of 0.37 in seismic resilience assessment is observed when the speed varies from 0 to 0.41, but only a minor enhancement of 0.11 for the speed from 0.41 to 2.