Seismic vulnerability and load carrying capacity studies of a steel bridge based on structural reliability

Abstract

In this document, seismic vulnerability and load carrying capacity analyses are presented for a bridge in Colombia after monitoring by means of reliability of structures. Results of this work are part of a new methodology to evaluate existing bridges carried out though a partnership among University – Private Companies – and Goverment. This study helps in decision making on the priority of rehabilitation tasks. This study included: dynamic characterization of natural vibrations of the bridge; data logging of inner forces due to traffic by using LVDT´s and strain gages technology; evaluation of actual forces to be compared to allowed stresses, dynamic and static structural modelling. Also, a seismic hazard and dynamic response of the local area of the bridge was developed and nine (9) different response spectra were obtained, each one varying its return period. It was found that the bridge towers have a larger failure probability than that allowed by the Codes. This produced an inmediate strengthening of the bridge.