Global sensitivity analysis of soil structure interaction system using N2-SSI method

Abstract

This paper applies the Sobol’s variance-based global sensitivity analysis to determine the contribution of input parameters to the structural lateral displacement considering damping and taking into account soil structure interaction (SSI) process. This method includes the main effect, the total effect and provides specific parametric interaction for each input. The considered input parameters are soil Poisson’s ratio, soil density, shear wave velocity, soil damping and structural damping. The N2-SSI simplified procedure is used to estimate the lateral displacement and damping of SSI model of RC structure. This simplified nonlinear method allows the assessment of the seismic performance considering the SSI. The results of the sensitivity analysis indicate that soil damping and structural damping greatly affect on the overall damping and can vary according to soil type. Whereas, the maximum lateral displacement is most sensitive to shear wave velocity and soil damping for very soft and soft soils, and it is sensitive to shear wave velocity and structural damping for hard and rock soils. This study reveals the importance of considering more than one output in the sensitivity study for the same input parameters. A same parameter can be considered as deterministic if it has a small influence on the output and it can be considered as probabilistic if it has significant influence on another output.