Fatigue behaviour of composite girders with concrete-filled tubular flanges and corrugated webs-experimental study

This paper is devoted to experimentally and analytically evaluate the fatigue life behaviour of composite girders with concrete-filled tubular flanges and corrugated webs. Typical fatigue crack manner and stress distribution under repeated bending moment are analyzed and compared between the first and subsequent cycles. The fatigue life results are evaluated with S-N curves related to codified detail classes which are analogous to those dealing with the corrugated web girders with plain flange plates consisting of similar critical welded details. The remaining fatigue life analytical model is also developed to offer supplementary data for general fatigue behaviour of test girders. To this end, a formulation permits the tensile stress gradient along the depth and length of flange surface and combined correction factors is developed in the determinations of stress ranges. Also, the fatigue crack initiations are properly accounted at the upper surface of the bottom tubular flange where the longitudinal stress concentrates at the welded toes close to the end of the inclined fold adjoining longitudinal fold of the corrugation. The proposed formula is demonstrated to be effective in the remaining fatigue life assessment of test girders with multiple cracks based on a consistent trend between the predicted results and the test data.