Stochastic seismic response and failure probability of story isolation structure

The dynamic analytic model of story isolation structure is established. The seismic ground motion is assumed to be a hybrid model combining low frequency simulation and high frequency simulation, in order to reflect the frequency spectrum characteristics of seismic ground motion. Pseudo excitation method is used to calculate the stochastic seismic response of story isolation structure. The statistical quantity of the maximum story displacement of each layer is also obtained. The maximum story displacements of isolation layer and other layers are adopted as the performance index to establish the performance equation. The failure probability is calculated using first-order reliability method by MATLAB. The total reliability of structure is derived by regarding the stories to be of series relation. A 20-story frame shear-wall structure in high intensity zone in Suqian city is taken as an example. Stochastic seismic displacement responses and failure probabilities of isolated and non-isolated structure are compared. The results show that the superstructure's failure probability of the isolated structure is much smaller, and each layer's failure probability is well distributed. The failure probability of story isolation structure is much smaller than non-isolated structure. So the dynamic reliability of story isolation structure is increased rapidly.