RELIABILITY OF HIGHWAY GIRDER BRIDGES

Reliability procedures are developed for girder bridges. Load models are based on the available statistical data. The derivation of load models is described in other papers. Resistance models are developed by simulations using the available test results for materials and components. The girder behavior is described by a moment curvature relationship. Bridge capacity is determined in terms of the maximum truck load before failure. The analysis is performed for a single unit truck, a semitrailer, and combinations of these trucks. For a given truck position, the load is gradually increased until the deformation (maximum deflection) exceeds the critical level. The developed resistance models are used in the reliability analysis. Reliability indices are calculated for noncomposite and composite steel girders, reinforced concrete T-beams, and prestressed concrete girders. The calculations are performed for girders and structural systems. Reliability indices for the system are higher than for girders. The effect of correlation between girder strengths is analyzed. Girder bridges behave as parallel systems. Sensitivity functions are developed for various parameters related to the considered girders. The developed approach is demonstrated on typical girder bridges.