Load Rating and Evaluation of Railroad Bridges Based on Non-Destructive Testing and Finite Element Modeling

The Federal Rail Association (FRA) mandated an increase in freight railcar weight limits from 1170 kN (263,000 lb) to 1272 kN (286,000 lb). However, most of the railway bridges were built prior to World War II and are not designed to handle this increased railcar weight. Thus, there is a need for accurate and efficient methods to evaluate and load rate existing bridges that will reveal their actual capacities. In this study, the research approach adopted is aimed at providing an efficient method to load rate railway bridges. Three load rating methods were utilized and compared: (1) traditional method based on American Railway Engineering and Maintenance-of-Way Association (AREMA) specifications, (2) refined traditional method using data from field tests, and (3) load rating using testing data and finite element (FE) modeling. Various types of bridges were field tested and evaluated. Results from a typical railway bridge will be used to demonstrate and compare each one of the three load rating methods. For this bridge, non-destructive testing was performed. The collected responses were used to improve the traditional method and calibrate a 3-D FE model. The rating results indicated that method (1) can be relatively conservative and does not reflect the actual behavior of the structure while method (3) provided accurate results it was more tedious. It is suggested that the refined traditional method (2) be used since it provided similar accurate rating results without developing a detailed FE model.
Listed In: Mechanical Engineering, Other