INFLUENCE OF INPUT MOTION SCALING METHODS ON DECOUPLED SSI DYNAMIC ANALYSIS

Abstract

Propagation of seismic waves through soil deposits may considerably alter theircharacteristics at surface. This ultimately influences the seismic performance of structures.The influences of soil deposits are included in seismic codes (e.g. Eurocode 8, EC8) by meansof proposed design response spectra for different soil classes used in design or retrofittingof structures. Nevertheless, a smooth design response spectrum cannot always representspectral response of an actual input motion over an engineering period of interest due toits irregular spectral shape. Subsequently, the seismic performance of a structure may beinsufficient when a design response spectrum is used. The interaction between soil andstructure may also affect the structural behaviour. This study aims to demonstrate theimpact of adoption of input motions and soil deposits with soil classes B, C and D on theseismic behaviour of one-bay, 1-storey structure modelled in OpenSEES For this purpose,two different approaches are chosen; (i) seven input motions recorded on ground surfaceare modified and applied to the model, (ii) seven outcrop motions are scaled according toEC8 and processed through the ideal soil deposits by conducting nonlinear site responseanalysis, then applied to the model. The results indicate that the model is exposed to moredrift responses when it is on softer soil deposit. In addition, imposing input motionsobtained at surface from nonlinear site response analysis cause higher drift responses thandirectly applying input motions.

Keywords

• soil classes
• design response spectrum
• outcrop/surface motion
• zemin sınıfları
• tasarım davranış spektrumu
• outcrop ivme hareketi