Seismic reliability analysis using a multi-fidelity surrogate model: Example of base-isolated buildings

Abstract

An approach is presented for conducting simulation-based seismic reliability analysis using a multi-fidelity surrogate model. To illustrate the approach, a base-isolated building is considered comprising a reinforced concrete frame for primary building and lead-rubber bearings for isolation devices. The high-fidelity model is a nonlinear finite-element model used in time history analysis. Ground motions are generated from a parametric power spectral density function that is compatible with a target response spectrum at the site of interest. The low-fidelity model uses a linear-elastic stick model for the superstructure, while stochastic linearization is used to capture the nonlinearity of the base isolation. Cokriging is used as a multi-fidelity surrogate model for fusing a large number of low-fidelity model evaluations with few high-fidelity model evaluations, in order to attain high-fidelity model accuracy while mitigating the computational cost. After training the Cokriging model, Monte Carlo simulation is carried out by sampling the cheap multi-fidelity surrogate, and the probability of failure is subsequently evaluated for different response thresholds. The relative error in failure probability prediction of Cokriging is shown to be in the range of 6% with a maximum of 10%, for a critical range of sample response variable threshold values, in contrast to errors as high as 60% provided by the low-fidelity model.