Analysis of Ordinary Bridges Crossing Fault-Rupture Zones

Abstract eng:
Rooted in structural dynamics, two procedures for estimating peak responses of linearly-elastic “ordinary” bridges crossing fault-rupture zones are presented: response spectrum analysis (RSA) procedure and a static analysis (SA) procedure. These procedures estimate the peak response by superposing peak values of quasi-static and dynamic responses. The peak quasi-static response in both procedures is computed by static analysis of the bridge with peak values of all support displacements applied simultaneously. In the RSA procedure, the peak dynamic response is estimated from the dynamic analysis including all significant modes, which is simplified in the SA procedure to static analysis of the bridge for appropriately selected forces. Both procedures are shown to provide estimates of peak response that are close to those from the “exact” response history analysis. Furthermore, it is shown that usually only one mode – the most dominant mode – is sufficient in the RSA procedure. These procedures utilize the “effective” influence vector that differs from that for the spatially-uniform excitation. Furthermore, the RSA procedure uses the response spectrum for the reference support excitation (including permanent offset of the ground due to fault rupture) that differs from the standard California Department of Transportation (CALTRANS) spectrum. The presented procedures idealize the spatially varying support excitation by proportional multiple-support (PMS) excitation in which motions at various supports of the bridge crossing a fault-rupture zone are proportional to the motion at a reference location.

• Export as: BibTeX | MARC | MARCXML | DC | EndNote | NLM | RefWorks
• Add to your basket