A STATE-OF-THE-ART BRIDGE LOAD RATING FOR THE SAFETY AND SUSTAINABILITY OF EXISTING BRIDGES

Highway bridges must be inspected periodically to ensure bridge safety for the public and bridge sustainability throughout service life. Along with the visual inspection, the load-carry capacity (bridge rating) must be evaluated to determine the maximum truck loads allowed on the structure. In the Load and Resistance Factor Rating (LRFR), the HL-93 design truck model is used as the rating truck. In fact, many states have their own state specific truck models. Very little research has been done on whether these state specific trucks are enveloped by the LRFR HL-93 design truck and what impact the LRFR could introduce on bridge rating. This paper will address various issues related to bridge rating, including the background and history of bridge rating in the United States, various bridge load rating methods/techniques. Several case studies of bridge rating will be presented, which include the evaluations for various types of bridges.