Evaluation of Recorded Earthquake Response of a Curved Highway Bridge

The Landers and Big Bear earthquakes on June 18, 1992, triggered a strong motion instrumentation network on a curved highway bridge. System identification of the processed acceleration records show the vibration period of the fundamental mode lengthened from 1.56 sec to 1.75 sec between the two earthquakes. A three-dimensional, calibrated model of the bridge is used to investigate the effect of modeling assumptions on the earthquake response of the structure. Linear models, commonly used in design, adequately bound the earthquake response of the bridge. However, the linear models do not provide an upper bound on the forces in all the columns. Longitudinal hinge restrainers have minimal effect on the earthquake response. The non-uniform input motion recorded at four support points has a moderate effect on the response when compared with the assumption of uniform free-field motion.