Progressive deterioration is a problem that affects road infrastructure, especially bridges. This requires the development of methods to determine its influence on structural behavior, one of them being load testing. Within load testing, finite element analysis (FEA) models are used as part of the preparation process. This study focused on the modeling and analysis of the static response of the bridge over the Lili River in Cali, Colombia, a prestressed girder bridge programmed to undergo a diagnostic load test. A linear FEA model was created, and variations were applied to the stiffness of diaphragms and elastomeric bearings. The analysis included obtaining the critical position for the design vehicles, the transversal distribution of stresses, and the influence of the variation parameters in the structural response. Results showed that the critical responses were with loads close to the exterior girders and that the variation of parameters did not significantly influence the structural response of the bridge. Girder Distribution Factors (GDF) were contrasted with previous research, finding similarities in shape and value. Finally, an instrumentation plan was proposed. The findings show how linear FEA models provide relevant information regarding the critical position, the distribution of stresses and the expected response under design loads.

In this study, a prestressed concrete girder bridge without plans and with severe levels of deterioration, located in Cali, Colombia, was load-tested to quantify, experimentally, its live-load behavior. The bridge consists of seven prestressed I-girders covered with a reinforced concrete deck, and four diaphragm beams. A geometric survey was performed to obtain the dimensions for a shell-based linear finite-element model (FEM) representing the bridge superstructure. In this survey, it was observed that the diaphragm beams in the span are geometrically inadequate to contribute to the structural system. Based on the experimental modal properties and the design regulations enforced at the time of bridge design and construction, a first update was made. Modifying the effective stiffness of selected elements to model girder deterioration, a second update was performed based on strain-gauge data from three load tests and visual inspection (VI) of the elements. The three models (basic, modal updated, and load-test/VI updated) were compared with the load distribution factor (DF) obtained from the load test and AASHTO distribution factor estimations. Visual inspection, dynamic characterization, and load testing response of this structure indicated severe deterioration of the girders and the absence of the effect of the diaphragms in the overall structural behavior. The results show that the AASHTO recommendations overestimate the LDF in comparison with the FEM without girder deterioration. When girder deterioration is included in the model, the LDFs change drastically, showing that AASHTO estimations are not in line with the experimental results. As such, for cases of bridges with severe levels of deterioration, it is recommended to use field data to estimate the distribution factors.