A theoretical method for scaling the dynamic response of steel beams subjected to blast loads

Conducting experiments using scaled models is a highly efficient and cost-effective approach to predicting structural dynamic responses to blast loads. However, accurate representation of the prototype in a scaled model is hindered by the strain rate effect of the materials, thus limiting the application of scaled model tests. To address this issue, this paper proposes a theoretical correction method for scaling the dynamic response of steel beams subjected to blast loads. This method allows for direct and quantitative evaluation of the error caused by the strain rate effect on the similarity of the maximum mid-span displacement of the beam without the need to modify the charge mass or stand-off distance. In addition, the proposed method eliminates the need for extensive model tests. The accuracy of the proposed method is verified through numerical simulations. The results demonstrate that the strain rate effect scarcely influences the geometric similarity of the maximum mid-span displacement of the beam in the elastic response stage. However, in the plastic response stage, the maximum mid-span displacement of the beam does not conform to geometric similarity. Accordingly, the similarity of the maximum mid-span displacement of the beam can be expressed as the product of the geometric scale factor and calculated strain rate correction coefficient. These theoretical innovations can significantly enhance the reliability of scaled-model tests, help extrapolate scaled-model test results back to the prototype, and reduce the difficulty and consumption of field blast tests.