Overview
When evaluating existing bridges, the application of the dynamic coefficient in the codes to actual loads, frequently leads to a violation of structural safety criteria for bridge decks. This may lead to costly bridge strengthening measures. Consequently it is of interest to better determine the actual dynamic coefficients for the bridge decks in order to perform more realistic evaluations.
Existing knowledge on dynamic coefficients is based primarily on measurements taken on the principal structural elements of bridges. It is difficult to interpret these coefficients to determine the values that should be used for bridge decks and other secondary elements carrying loads in the transverse direction. In addition, due to difficulties linked to data acquisition, there are few studies where the dynamic coefficients have been measured in a systematic way over the entire structure.
The numerical models that simulate the passing of a vehicle on a bridge allow identification of the most important parameters that influence the dynamic behaviour of the system. The results obtained by these means are influenced by the degree of sophistication of the model of the bridge as well as the vehicle and the roughness of the wearing surface.
The research work proposed involves analysing the dynamic behaviour of a system consisting of one bridge and one vehicle. The bridges will be typical concrete highway bridges in Switzerland. The vehicles will be representative of the heavy vehicles found on Swiss roads with respect to their load and dynamic characteristics. The majority of work will be on determining the most appropriate dynamic model to represent the behaviour of the bridge-vehicle system using the results of existing analysis and of future, to be defined, in situ tests
Using the calibrated model, analysis on the bridges will be carried out to establish the spatial repartition of the dynamic coefficients for evaluation of the serviceability and the structural safety of a bridge.