Civil Engineering, Urmia University
In the present work, the effect of Soil-Structure Interaction (SSI) in low frequency structures resting on loose soil, through numerical modelling and shaking table tests have been studied. In theoretical studies two types of models namely fixed base and flexible base structure were subjected to three selected earthquake records. Nonlinear dynamic analysis was employed for all of the numerical models. Geometrical and material nonlinearities were considered in all models and finite element method was used for soil modelling. To verify the outputs of the numerical modelling, shaking table tests were carried out. For experimental tests, scaled form of the main structure according to scaling laws, and laminar shear box as a container of the soil, was built. By comparison between the numerical modelling and the shaking table tests results, good agreement was observed. Therefore, the numerical modelling approach was validated. In next step by implementing this approach, comparison between the fixed base and the flexible base results was carried out. In this study, it was demonstrated that considering the SSI effects on structures resting on loose soils increases the lower story drifts. Besides if the structure is located in sites which is susceptible to experience strong earthquakes, this increase is dominant. Therefore negelecting SSI effects leads to unsafe design of the structure.