PEER Reports

PEER Reports

Behavior And Failure Analysis Of A Multiple-Frame Highway Bridge In The 1994 Northridge Earthquake, PEER Report 1998-08

Gregory L. Fenves
Michael Ellery

The Route 14/Interstate 5 Separation and Overhead bridge, a curved ten-span structural concrete structure, partially collapsed in the 1994 Northridge earthquake. The primary objective of this study is to ascertain the cause of failure by comparing estimates of the capacities and demands of various components in the bridge. A secondary objective is to examine earthquake modeling and analysis recommendations for highway bridges. As part of the examination, nonlinear static analysis (pushover analysis) is used to determine the capacity of a frame. Linearized analyses are compared with...

Empirical Evaluation of Inertial Soil-Structure Interaction Effects, PEER Report 1998-07

Jonathan P. Stewart
Raymond B. Seed
Gregory L. Fenves

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...

Capacity-Demand-Diagram Methods for Estimating Seismic Deformation of Inelastic Structures: SDF Systems, PEER Report 1999-02

Anil K. Chopra
Rakesh K. Goel

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...

Task 3: Characterization of Site Response General Site Categories, PEER Report 1999-03

Adrian Rodriguez-Marek
Jonathan D. Bray
Norman Abrahamson

Seismic site response and the amplification of ground motions are significantly affected by the combined effect of the dynamic stiffness of the soil and the depth of the soil. Current design practice, however, either uses an oversimplified approach to soil classification (e.g., "soil" vs. "rock"), or ignores the effect of depth by accounting only for the average shear wave velocity over the upper 100 feet of a site profile (e.g., 1997 UBC). The significant quantity of ground motion data recorded in the 1994 Northridge and 1989 Loma Prieta, California, earthquakes provides an opportunity to...

Adoption and Enforcement of Earthquake Risk-Reduction Measures, PEER Report 1999-04

Peter J. May
T. Jens Feeley
Robert Wood
Raymond J. Burby

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...

Seismic Evaluation of 550 kV Porcelain Transformer Bushings, PEER Report 1999-05

Amir S. Gilani
Andrew S. Whittaker
Gregory L. Fenves
Eric Fujisaki

Three 550 kV porcelain transformer bushings were evaluated for their response to severe earthquake shaking. The first bushing was similar to bushings currently in service in the United States; the other two bushings were modified versions of the first bushing. The modifications to the second and third bushings were intended to enhance seismic performance and included added tiers of springs, increased preload, and stiffer gaskets. The dynamic properties, vibration frequencies, and damping ratios of the bushings were evaluated from the experimental data. Tri-directional earthquake simulator...

Rocking Response and Overturning of Anchored Equipment under Seismic Excitations, PEER Report 1999-06

Nicos Makris
Jian Zhang

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...

Documentation of Strengths and Weaknesses of Current Computer Analysis Methods for Seismic Performance of Reinforced Concrete Members, PEER Report 1999-07

William F. Cofer

One of the future needs of the engineering community is a general computational platform for the seismic analysis of structures, structural components, and the interaction between structures and surrounding soil. However, before a large effort is expended, a thorough evaluation of current capabilities is required to establish the state of the art and to determine the direction that should be taken with regard to design needs and analytical approaches. A specific area of interest is the analysis of reinforced concrete components, including cracking and crushing of concrete and yield of...