Report No.:CCEER-84-3

Authors: Mehdi Saiidi, James D. Hart, and Bruce M. Douglas

Date: July 1984

Sponsoring Agency: National Science Foundation

Performing Organization:

Department of Civil Engineering/258

University of Nevada, Reno

Reno, NV 89557

Abstract:

A multi-degree-of-freedom nonlinear analytical model for response analysis of highway bridges subjected to lateral static loads, free vibration, and earthquake motions is presented. The nonlinear effects are accounted for by incorporating translational and rotational springs at abutments, pier foundations, and at the base of piers. The deck and piers are treated as line elements.

Two hysteresis models are used to represent the cyclic behavior of the nonlinear components: the Ramberg-Osgood model (for abutment springs) and the TQ-Hyst model (for pier and foundation springs). The latter is a modified version of a previously developed model called Q-Hyst.

The analytical model is used to determine the static and free vibration response of a bridge in Northern Nevada (Rose Creek Interchange). The calculated results are compared with the measured values to evaluate the idealizations and the assumptions made in the model. A reasonably good correlation between the calculated and measured results is noted. It is pointed out that, due to lack of data for bridges with extensive nonlinearity, the correlation studies could be done only for small loads producing a limited degree of nonlinearity.

Finally, the model is used to evaluate the seismic performance of the Rose Creek Bridge based on the recently developed Applied Technology Council Guidelines for the seismic design of highway bridges and by analyzing the bridge for a variety of input earthquake records with different peak accelerations. It is shown that the Rose Creek Bridge performed well in resisting the loads specified by the seismic code used in the design of the bridge (Abstract by authors).