Dynamic response and damage mode of H-section steel columns subjected to combined axial and near-field blast loads: Experiments and numerical simulations

As primary load-bearing members in steel frames, H-section steel columns are vulnerable to blast loads, particularly in the near field. The axial force, signifying vertical compression on the column, introduces additional complications for the estimation of the blast response. However, only limited studies have been devoted to the dynamic response and damage mode of H-section steel columns subjected to combined axial and near-field blast loads. To address this issue, four blast tests were conducted to investigate the effect of the scaled distance and the axial force on the blast response of steel columns. It was shown that the damage mode of steel columns varied from global bending to local web breaching as the scaled distance decreased. The columns bent primarily globally about the weak axis, accompanied by local web dishing and flange spreading for large scaled distances, whereas web breaching occurred near the charge for small scaled distances. Due to the presence of the axial force (500 kN, about 35% of the ultimate resistance of the column), the maximum displacements in the column web were significantly amplified, i.e., by 33.2%-61.9%. Furthermore, the maximum residual displacements along the center line of the left and right flanges were increased by 191.8% and 216.3%. Moreover, local flange buckling was observed in the breaching region. High-fidelity numerical models, which are based on the structured Arbitrary Lagrangian–Eulerian (S-ALE) method, are developed for the steel columns and validated against the experimental data recorded using a variety of measuring devices. After validation, the damage evolution of the blast-loaded columns is illustrated for the scenarios involved in the tests.