Modeling inelastic shear lag in steel box beams

This paper describes a study of inelastic shear lag behavior in steel box beams. Shear lag effects in flanged flexural members are usually recognized as the uneven longitudinal deformation and normal stresses along the flanges. Elastic shear lag behavior has been extensively studied and considered in structural design while the study of inelastic shear lag is limited. Knowing that flanged flexural members likely have plastic deformation at their ultimate limit state, a least-work based method was developed for modeling inelastic shear lag behavior. An effective modulus was formulated and the Poisson’s ratio following the theory of plasticity was used in the inelastic shear lag model. The analytical method was verified using laboratory tests of two steel box beams. Comparison with experimental data indicates the proposed variation method can accurately predict the plastic normal strain distribution and the deflection of steel box beams.