Shear lag is the phenomenon that occurs when a supported slender member undergoes deformation from lateral loading, causing in-plane non-uniform distribution of stresses that results in reducing the member’s minimum strength capacity. This paper investigates the behaviour of shear distribution in steel I-section and box girders when subjected to both static and impact loadings. Three-dimensional finite element analysis models were prepared in Strand7 and validated against experimental results providing a basis for further comparison research into shear lagging effects. A parametric study was conducted comparing the effects of impact loading through certain specified velocities at the midspan of restrained ends. It provided new insights into the distribution of shear lag and prevalence of loading locality when considering unique impact scenarios. Impact loads provided different shear-lag results compared to static loads as the material’s properties absorb energy through deformation and distribution of stress. Furthermore, the study highlights the need for additional investigation into a variety of impact scenarios and possible factors for designers to consider when implementing members in structures.
