Mixed Mode Fracture Assessment for Box Girder with Crack Damage under Combined Loads

The box girder is an important structure which is widely used in the ship and marine engineering but has not extensively investigated fracture problem. The paper adopts the stress intensity factor (SIF) as the crack tip parameter to carry out the mixed mode fracture assessment of the box girder structure with crack damage. The bending load, torsion load and side load are firstly introduced to study box girder crack propagation. And the related influencing factors of crack length, crack type, combined loads, etc. are investigated emphatically. In analysis, crack growth angle is also analyzed to evaluate the crack growth. The results show that different load types have different contributions to crack propagation. And combined bending and torsion loads effect may be considered adopting a linear superposition principle under transverse cracks and larger angle cracks. When the side load is added, the area near the crack upper surface will be easy to occur unstable expansion. These conclusions will provide a guiding significance to evaluate the crack propagation of box girder.