Sensitivity Analysis of Site Response Effect on Stochastic Responses of Two-Span Beam

Abstract

In this paper, a numerical sensitivity analysis of the spatial variability of ground motions due to site response effect on the stochastic response of a two-span structure subjected to this phenomenon is presented. The site response effect is due to the difference in local soil conditions at different support points. The transfer functions of the soil profiles under each support are analytically formulated. Kanai-Tajimi spectrum parameters are estimated and expressed analytically from the soil profile model. The example structure is intentionally taken to be a simple one as to allow a comprehensive sensitivity analysis. Interesting results in term of mean maximum responses (displacement, bending moment and shear forces) obtained from the spatial variability of ground motion are given and compared to those induced by uniform excitation. Each component of the responses (pseudo static, dynamic and dynamo static) is differently influenced by the site response effect, it is therefore essential to incorporate this effect in the analysis of long span structures to be more realistic.