Fatigue testing and analysis of peened highway bridge welds under in-service variable amplitude loading conditions

A laboratory study is presented wherein needle peened structural steel weld specimens are fatigue tested under simulated in-service loading histories typical of highway bridges. A strain-based fracture mechanics model is then validated by comparison with the test results and used to perform additional studies, wherein similar welds are analyzed under loading histories encompassing a wider range of influence lines and bridge spans. It is concluded that the employed model is well suited for studying the effects of peening on the fatigue performance of highway bridge welds under in-service loading conditions. The consideration of tensile dead load stresses and periodic overload trucks is seen to decrease the predicted benefit of peening. This benefit can still be substantial, however, for a wide range of loading conditions likely to be seen in highway bridges.