Numerical analysis of fatigue behavior of welded cfchs T-joints

Fatigue life assessment of welded joints made of circular hollow sections (CHS) with concrete filled (CF) chord member subject to vehicle load is vital in designing of CFCHS arch truss bridge. A key issue in fatigue life assessment of such joints is how to accurately estimate the stress intensity factor. This paper describes a methodology for calculating the stress intensity factor of the hot spot region in the welded CFCHS T-joints based on a finite element analysis which considers weld modeling, crack modeling and nonlinear interface element between steel and concrete. A procedure for fatigue life estimation of welded CFCHS T-joints is also established. Discussions are made on the effect of the initial crack size and concrete strength on fatigue life and hot spot stresses. The majority of crack propagation life is found to be associated with the shallow crack stage. The proposed method gives reasonable estimation of fatigue life of welded CFCHS T-joints.