Report No.: CCEER-93-10

Authors: M. "Saiid" Saiidi, D. N. O'Connor, and E. A. Maragakis

Date: September 1993

Sponsoring Agency: Nevada Department of Transportation

Performing Organization:

Department of Civil Engineering/258

University of Nevada, Reno

Reno, NV 89557

Abstract:

This study was undertaken to evaluate the highway bridges on 1-80 in the Reno-Sparks area for damagability potential during strong earthquakes. A data base consisting of a total of 22 bridges was formed. The focus of the study was on bridges with relatively thin, tapered columns. Three representative bridges were chosen for closer study: I-1000, I-1086N, and I-1171. These structures were analyzed to determine their displacement histories, abutment force histories, and column forces and displacement ductility demands in response to a suite of earthquake acceleration records which were provided by the Geotechnical Section of the Nevada Department of Transportation (NDOT). All the records corresponded to a bedrock acceleration of 0.4g. The nonlinear analyses were conducted using computer program NEABS. The foundation stiffnesses were determined using the soil modulus and a procedure specified by the Geotechnical Section at NDOT.

Results of the nonlinear analysis indicated that in bridges with one or two columns per piers, abutment soil yielding may occur and that the column shear forces and moments may exceed permissible values (Abstract by authors).