EVALUATION OF SOIL-STRUCTURE INTERACTION EFFECTS USING SEISMIC CODES

Seismic codes nowadays include design requirements in order to taking Soil-Structure Interaction (SSI) into account for realistic modelling of structures. This study is conducted to assess the behaviour of steel structure-soil systems using Standard No. 2800 and FEMA-440. Steel frame buildings are assumed to have various heights and different lateral resistant systems. The buildings are supported by shallow foundation resting on soft and also very dense soil. The strong ground motions are selected and scaled according to 2800 code. Both kinematic and inertial interaction effects are considered. SSI is investigated through the equivalent spring-dashpot method on the basis of nonlinear Winkler beam concept in the OpenSees framework. Numerical results show that period lengthening have overall agreement in both simulations and regulations. In addition, It is observed that when SSI is considered, base shear and interstory drift demand reduces; indicating a beneficial effect of the foundation flexibility. However, the story displacement demand is observed to increase with SSI. In addition, depending on the structural building and soil type, the obtained results may differ from each other and the most significant SSI effects are related to braced frame structures on soft soil.