Load Capacity Evaluation of Existing Railway Bridges based on Robustness Quantification

This paper presents a methodology for the load capacity evaluation of existing railway bridges based on the quantification of their robustness. The proposed technique uses the results of a non-linear structural analysis of a bridge system and couples the analysis with modified member and system reliability evaluations in order to assess the bridge's robustness and its overall system capacity. Bridge robustness is measured by the so-called redundancy factors, which serve to compare the system's capacity to member capacity. The application of the proposed approach to the safety assessment of an existing reinforced concrete railway bridge demonstrates its efficiency. The example shows that the proposed methodology is sufficiently accurate and simple for it to be used in the bridge assessment process on a routine basis. Also, the example indicates that the proposed redundancy factors provide an adequate and objective measure of robustness.