Fatigue test on aluminium bridges

Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge loaded by heavy traffic. The S-N curves of a welded detail that is often applied in the deck of aluminium bridges were determined by testing and the test results were compared to the standard S-N curve prescribed by standard prEN 1999-1-3 (1). Additional tests were carried out in which the passage of vehicles was simulated on a model of the entire bridge, in order to obtain a better approximation of the real fatigue load on the bridge. The fatigue lifetimes resulting from these tests are compared to the arithmetical lifetimes, determined by using the S-N curve and Miners's summation. The paper shows that aluminium is suitable as structural material for heavily loaded bridges