PEER Reports

Strong motion data obtained over the last decade from sites with instrumented structures and free-field accelerographs has provided an unprecedented opportunity to evaluate empirically the effects of soil-structure interaction (SSI) on the seismic response of structures. Strong motion data were gathered for 58 sites encompassing a wide range of structural systems, geotechnical conditions, and ground shaking levels. System identification analyses were employed with these records to quantify the effects of inertial interaction on modal parameters of structures. Simple indices of free-field...

The ATC-40 and FEMA-274 documents contain simplified nonlinear analysis procedures to determine the displacement demand imposed on a building expected to deform inelastically. The Nonlinear Static Procedure in these documents, based on the capacity spectrum method, involves several approximations: The lateral force distribution for pushover analysis and conversion of these results to the capacity diagram are based only on the fundamental vibration mode of the elastic system. The earthquake-induced deformation of an inelastic SDF system is estimated by an iterative method requiring analysis...

These combined studies explore the socio-political implications of the seismic provisions of local building codes. Based on results from a national survey of building code officials, these three complementary studies explore (1) making building codes effective tools in earthquake hazard mitigation at the national level (2) the policy challenges of seismic mitigation in the western U.S., and (3) the role of policy entrepreneurs in the adoption of seismic-related provisions by local governments within California.

The conclusions of these studies are diverse, exploring various aspects...

This report investigates the transient rocking response of anchored electrical equipment and other anchored structures that can be approximated as rigid blocks. Practical issues that control over-turning, such as the effect of the vertical component of ground accelerations and the effect of the coefficient of restitution during impact, are also addressed.

The anchorages of equipment are assumed to have a pre-yielding linear behavior, a finite post-yielding strength, and some ductility. The nonlinear behavior of the restrainers in conjunction with the nonlinear dynamics of a rocking...