Fatigue Performance Test and Numerical Analysis of Composite Girders with CSW-CFST Truss Chords

Abstract

Composite girders with corrugated steel webs and concrete-filled steel tubular (CSW-CFST) truss chords are a new type of structure and have been used in bridges. To study the fatigue performance of these composite girders, model tests and numerical analysis were con-ducted, and the results compared with those for composite girders with corrugated steel webs and steel tubular (CSW-ST) truss chords. The results indicated that concrete-filling the chords constrained chord radial deformation and relieved hot-spot stress in the intersecting weld zones of composite girders with CSW-ST truss chords by 18.5–60.1%. The crack growth rates along both depth and length directions in composite girders with CSW-CFST truss chords were lower than those of composite girders with CSW-ST truss chords during the crack propagation and failure stages. Under the same fatigue load, concrete-filling the chords increased the fatigue life of composite girders with CSW-ST truss chords by 61.5%. Under the condition that there is no fatigue design S-N curve, the fatigue design S-N curve given in API can be used to evaluate the fatigue life of composite girders with CSW-CFST truss chords with a deviation of less than 17.4%.