Probabilistic seismic performance assessment of the soil-structure interaction effect on seismic response of mid-rise setback steel buildings

Abstract

This is a study to evaluate the soil-structure interaction effect on the seismic response of setback steel buildings in a probabilistic framework. A group of ten-story steel buildings with different setback ratios was analyzed under simultaneous action of two orthogonal earthquake ground motions. The soil-foundation system was modeled by using the beam on nonlinear Winkler foundation approach. The structural performance of flexible-base steel moment frames was evaluated from the elastic range of behavior to the inelastic region and up to the global instability of the structures by using incremental dynamic analysis. The soil-structure interaction effect was assessed on the probabilistic seismic performance of setback buildings by evaluating the limit-state capacities, performance-based ductility factors, mean annual frequencies of exceeding performance limit states and confidence levels to meet performance objectives. Results show that soil-structure interaction reduces the structural seismic capacities, ductile deformation and life-safety confidence level. On the other hand, soil-structure interaction increases the drift demand and exceeding the annual frequencies from a limit state. Meanwhile, soil-structure interaction shows a beneficial role in moderating the reduction rate of the structural seismic capacity of flexible-base setback buildings compared to that of the regular structure.