Safety assessment of existing concrete bridges with Gerber saddles through nonlinear analyses

Existing concrete bridges with Gerber saddles often suffer from degradation due to reinforcement corrosion and concrete deterioration, especially in the saddle area due to draining of water through the joint. The safety assessment of these bridges and the design of the retrofit intervention need to carry out nonlinear analyses, through reliable 2D or 3D finite element models, in the cracked phase of the structural elements up to the Ultimate Limit State. These analyses allow an evaluation of the structural behaviour of the bridge girders until failure, both in the original design configuration and in the hypothesis of the saddle degradation caused by corrosion of reinforcements. In the present study the results of numerical analyses on models of real case-study bridges and supporting experimental tests are reported, for the understanding of the structural behaviour of these bridges in the post-elastic phase.