Reliability-based evaluation of steel girder bridges

System reliability can be used as an important tool for the efficient evaluation of existing bridge structures. The traditional element-based approach to bridge design and evaluation does not allow for consideration of interaction between the components that form the structural system and, therefore, it can be conservative. The safety of the structural system also depends on the degree of redundancy (load sharing) and ductility. As a result, it has been observed that the load-carrying capacity of the whole structure can be much larger than that determined by the design of individual components. Therefore, this study was focused on system behaviour. The objective was to identify the load and resistance parameters, formulate the limit state function and develop a system reliability analysis procedure for the whole bridge as a structural system. The reliabilities were also calculated for individual components (girders) and compared with the system reliabilities of the bridge. The resulting system reliability can serve as a basis for the development of a rational bridge design and evaluation procedure.