Near fault ground motions and their incorporation in performance based design

The main objective of Performance Based Design is determining the structural demands for earthquake loadings. For a good estimation of structural demands, the relation between ground motion parameters and structural demands must be known. Near fault ground motions are significantly different from far field ground motions. Depending on the fault mechanism, ground motions may contain distinct pulse in velocity and permanent displacement in displacement records. These are increase the near fault ground motions damage potential.In this thesis the incorporating of near fault ground motion in performance based design was studied. For this purpose the relation between ground motion characteristics and the shift periods of response spectrum were obtained by using 307 records.Forward directivity occurs in faults normal direction. But for all records, it is not possible to determine the fault-normal direction. To overcome this complexity the maximum velocity direction has been proposed. In this thesis in addition to maximum velocity direction two new directions were determined which are very effective as fault-normal direction.The main stage of performance based design is to estimate the inelastic displacements by inelastic modification factors. This study reveals that most inelastic modification factors are not applicable for near fault ground motions and a new empirical formula was developed. In this study, it was shown that the strength reduction factors are related to pulse periods and in acceleration sensitive region these factors are very small than codes strength reduction factors. When the codes factors are used in near fault, the unconservative results are inevitable. For near fault ground motions two well known strength reduction formulas was modified by nonlinear regression analysis.