An AAT technique based fatigue evaluation of composite corrugated steel web girders under coupled flexural load and temperature gradient

Medium-to-long spanned composite corrugated steel web (CSW) girders have recently been extensively constructed in the hot-humid terrains. Their degraded structural behavior in service has been concerning due to the presence of surface cracks under vehicle load-induced fatigue and repeated temperature fluctuation as coupled loads. This paper presents an experimental coupled loading study for such a structure with a CSW dimensional scale factor comparable to contemporary research work. An innovative artificial acceleration testing (AAT) technique was developed to fulfill the fatigue experimental test under controlled periodic variation of temperature. The structural deterioration modes during the whole fatigue loading progress have been analyzed. A new equation was proposed for the calculation of the coupled stress field incorporating the compatible strain condition at the steel-concrete interface under coupled loads. The resultant S-N relations based on fracture mechanics are demonstrated to be reasonably consistent with codified detail categories. The stress intensity factor allowing for crack geometry and the heat flux due to the prescribed temperature difference was developed and justified for the analytical remaining fatigue life analysis. The results can provide a reference for the development of AAT technology and the basic theory of thermal-structural analysis for these girders in the future.