Joint elimination retrofits and thermal loading analysis in plate girder bridge using health monitoring and finite element simulations

Abstract

Degradation of United States' public infrastructure has attracted attention from the public and governing agencies alike. A challenge facing transportation departments is management of leaking and clogged expansion joints in bridge structures, which result in significant deterioration to bridge substructures and superstructures. Some agencies have started eliminating these joints. However, technical understanding of which retrofit methodology to employ based on thermal loading and specific characteristics of the structure is lacking. In this study, this problem is investigated with both numerical modeling and analysis of field measurements. Various sensors were installed on the bridge including thermocouples, strain gauges, and linear differential displacement transducers. Following sensor installation, controlled load testing was conducted and the collected data evaluated against numerical and analytical predictions. The installed sensors will allow for long-term monitoring of the bridge to evaluate the effect of seasonal temperature profiles that are characteristic of Colorado on bridge behavior. In addition to gaining technical understanding of site-specific bridge characteristics that influence joint movement using field-testing, numerical finite element analysis was conducted. Specifically, a 3D finite element model was developed and used in a parametric study to assess the effect of various parameters on the stresses occurring in the bridge. The stresses occur due to 1) variation in thermal loading and thermal gradient, 2) clogging of the joint with different materials including gravel and sand, and 3) employment of various repair techniques in eliminating the expansion joints. The results of the numerical models show that clogged joints induce some localized stress but do not significantly affect the global performance of the superstructure. The results also show that a reduction in moment demand on the superstructure is not apparent until a Full-Moment Splice connection is utilized. This study will help engineers to choose the most appropriate method of designing a retrofit for expansion joint removal.