Confidence factor assessment for bridge structures under seismic loading

Abstract

Mexico City area is considered as a vulnerable zone for seismic events. Recently, a 7.1 Mw seismic event occurred in 2017 that left economical and live loses, while in 2022, a 6.9 Mw left structural damage, including some damage to a bridge on the outskirts of Mexico City. The above highlight to study the structural reliability of this kind of structural systems. An approach to estimate the confidence factor by means of simplified close-form expressions is presented. The confidence factor is expressed in terms of both the original formulation proposed by Cornell and collaborators and based on a normalization index called IDC. The uncertainties related to geometric, mechanical properties and the variability of seismic events are considered. In addition, the epistemic uncertainties are estimated based on a prior approach. An application example is exposed for a reinforced concrete bridge designed to complain with a 0.003 drift radio. The bridge of study has two-lane roadway of 10 m width, 80 m long with two lateral spans of 25 m and a central span of 30 m. The system is located on transition soil Mexico City. Design recommendations are made based on the results.