Fatigue performance of composite trough-girders with corrugated-steel-webs

A new composite trough-girder with corrugated-steel-webs (CTG-CSWs) is proposed to solve the problems of ordinary trough-girders: complex construction process, easy cracking at the intersection of concrete web and bottom plate, and poor mechanical performance. Also, the self-weight is reduced. First, this study experimentally investigated the flexural fatigue performance of a CTG-CSWs. Based on the compressive strain changes of the top concrete flange and mid-span deflection, the influence of fatigue load on the static mechanical properties of the girder was studied. Correspondingly, the fatigue performance was characterized. Furthermore, numerical studies were performed using finite element model. Parametric study was conducted by equivalent structural stress method. Experimental results showed the CTG-CSWs has similar degradation process of fatigue mechanical properties as that of ordinary reinforced concrete beams. The mid-span deflection and compressive strain of the top concrete flange increased obviously in the early stage of the fatigue test, and then increased slowly around an approximately straight line. In the whole process, the test beam was in the stage of slow connection and expansion of internal microcracks and further developed into micro-fracture, indicating good fatigue perfor-mance. Numerical studies verified the insensitivity of equivalent structural stress method to mesh size and element type. Also, it showed significant stress concentration existed at the connection between the corner of the corrugated web and lower flange plate. In practical application, it recommends determining a reasonable corner radius as required, and applying a turning angle of 50 degrees to obtain the best fatigue performance of the whole weld.