A bi-directional load rating model of the flexural response of a prestressed concrete bridge beam element

It is essential that load rating capacity of bridges and their elements be monitored to preserve their structural integrity and ensure safety of the public. Load rating analysis, based on current design codes, is a basis used to identify bridges that should be earmarked for rehabilitation. Routine bridge inspections, which can identify a decrease in structural condition, are performed independently from load rating analyses. Thus, this research is motivated by a vision in which the inspections and load rating processes are integrated into a bridge management system.;The objective of the presented research is to develop a bi-directional element condition model that uses data typically obtained during routine bridge inspections. This model, developed for a prestressed concrete beam because it is the critical element in girder-supported bridge systems, has three main components. (1) The prognostic component is used to calculate bridge load ratings probabilistically considering random variables representative of load and resistance effects. (2) The deterioration component is used to evaluate the effects of deterioration on relevant random variables. (3) The diagnostic component helps to identify possible deficiencies that result in an undesirable bridge load rating.;Bayesian networks are used to implement prognostic and diagnostic features of the bi-directional model. Parent variables (input variables to the network) are assumed to be random and obtained from different data sources (random variables available in the literature and expert solicitation). Monte Carlo simulations are used to evaluate the conditional probabilities for use in the Bayesian network. Time-dependent corrosion effects are implemented as an example of considering deterioration in the b-directional model. The model is applied to the critical limit state (flexure at midspan) of the critical element (simply-supported prestressed concrete girder) of a prestressed concrete bridge at ten-year intervals throughout its service life.