Effects of Local Denting and Fracture Damage on the Residual Longitudinal Strength of Box Girders

The residual strength of denting- and fracture-damaged box girders were experimentally and numerically investigated. The experiments were conducted under a pure bending moment using the four-point bending test method. The load, deflection, and strain were measured. The strains of the extension structures were also measured, and the frictional forces between the model and the supported round bar were estimated. Test models consisting of two groups were fabricated. These groups were designed to estimate the residual strength of denting- and fracture-damaged models. The damage was induced by releasing a striker using a drop-testing machine to consider the dynamic effect. Additionally, numerical analyses were performed via a nonlinear finite element analysis, where the measured initial imperfection data and welding residual stresses were considered. The ultimate longitudinal moments that considered the frictional force of the round bars were reduced by 12% (on average) compared with those obtained by neglecting the frictional forces.

Automated summary

The residual strength of denting- and fracture-damaged box girders was investigated through experiments and numerical analyses. The experiments were conducted using the four-point bending test method, measuring load, deflection, and strain. Strains of the extension structures and frictional forces were also measured. Two groups of test models were fabricated to estimate the residual strength, induced by striker release and considering initial imperfection data and welding residual stresses through numerical analysis. The inclusion of frictional forces reduced the ultimate longitudinal moments by an average of 12%.