AMPLIFICATION FACTORS TO ESTIMATE INELASTIC DISPLACEMENT DEMANDS FOR THE DESIGN OF STRUCTURES IN THE NEAR FIELD

The effects of rupture directivity at near-fault sites on the ratio of maximum inelastic displacement demand to maximum elastic displacement demand are investigated. Inelastic displacement ratios are computed for single-degree-of-freedom systems undergoing different levels of inelastic deformation when subjected to 82 earthquake ground motions recorded at distances closer than 15 km from the surface projection of the rupture. It is found that in addition to increments of linear elastic spectral ordinates in the long period spectral region previously identified by seismologists, forward directivity effects can affect the ratio of maximum inelastic displacement demand to maximum elastic displacement demand.…