Load Measurement and Control of Auxiliary Bridge Supports During Passage of Oversized Vehicles

Actual live loads on bridges can be categorized into ordinary loads and loads exceeding standard limits induced by abnormal transport. A bridge structure subjected to a heavy load may behave differently than under a light load. Selected analyses performed as part of an assessment regarding the presence of a vehicle weighing 620 tons on the bridge are presented in the paper. The decision on the structural safety for the passage of such a vehicle is made after a structural check, taking into account the current technical condition of the structure. The bridge discussed here was strengthened to achieve a load-bearing capacity significantly higher than its original rating. Two additional steel frame supports were installed beneath the existing span, which originally functioned as a simply supported beam. These supports are engaged only when the bridge is subjected to exceptionally heavy, overweight loads. Consequently, the support system of the bridge span is variable, depending on the loads applied and the structural deflections. It has been found that the results of measurements taken during the previous overweight transport are very useful for proper structural modeling. The main aim of this work is to present a methodology for determining or modeling the structural behavior of nontypical bridges under very exceptional loads.