Reliability analysis of highway bridge structures considering ultimate load effects

In the reliability analysis of bridge structures, it is often assumed that the bridge responds elastically to the highway loads it is subjected to. In this work a nonlinear material response of a three span beam and slab bridge structure is assessed using a nonlinear finite element model. The bridge is subjected to a lifetime of simulated traffic: 100 years annual maximum truck traffic loads determined from Monte Carlo Simulation of Weigh in Motion (WIM) data are used. A load factor for bending failure for each annual maximum event is established. Extrapolations are carried out to determine the load factor at the level of characteristic loading using a 1000-year return period, in order to determine if linear elastic response is appropriate at this level. Furthermore the reliability index for this indeterminate structure is also established using the First Order Reliability Method.