Assessment of the distortion-induced fatigue strength in steel-concrete composite bridges welded joints

Resumo

Highway bridges are known as structural systems permanently affected by random loads that can cause
significant damage to the structural elements. Nowadays, a challenging problem for structural engineers is
associated to the high-stress amplitudes related to the fatigue induced by distortion on the steel elements.
Therefore, in this research work, the hot-spot stress method was validated aiming to assess the distortion-induced
fatigue strength in welded joints of steel-concrete composite bridges. It is important to emphasize that for the
validation of the hot-spot stress method, a full-scale fatigue tests database was taken into account, designed
precisely to serve as a basis for the evaluation of the fatigue resistance induced by distortion. This way, the
investigated highway bridge finite element model, developed based on the use of the ANSYS program, was utilized
as a global model with a local sub model, aiming to perform the compatibility and interpolation of the
displacement’s fields of both models (global and local). The numerically obtained results based on the hot-spot
approach were compared with those calculated with the conventional methods, resulting, therefore, in a
considerable difference, showing that the hot-spot method is more realistic, in view of its effectiveness in terms of
capture of stress concentrations due to the geometry of welded details, over for evaluation of fatigue damage.