Numerical Study on the Blast Resistance of Cross-shaped Steel-reinforced Concrete Columns Subjected to Near-Field Explosion

Steel-reinforced concrete (SRC) columns are widely adopted in critical and high-rise buildings due to their high load-bearing capacity. The failure of SRC columns may trigger progressive collapse of the entire structure when subjected to blast loading. However, research on the blast resistance of SRC columns under near-field explosions remains limited. To fill this gap, a refined finite element model of a cross-shaped SRC column in a real high-rise building was established in LS-DYNA. The effects of scaled distance and axial load ratio on the blast resistance and damage level of SRC columns were investigated under near-field explosion scenarios. The numerical results indicated that, at an axial compression ratio of 0.2, the proportion of shock load distributed within 1300 mm of the mid-height of the SRC column decreased from 61.3% to approximately 42.5% with increasing scaled distance. If interfacial debonding occurred between the confined core region and the unconfined concrete, the SRC column would exhibit flexural-shear failure. Conversely, if no such debonding occurred, flexural failure would be observed in the SRC column, and the damage level could not exceed a medium level. A higher axial load ratio was detrimental to blast resistance when the scaled distance <italic>Z</italic> ≤ 0.6 m/kg ^1/3, whereas it became beneficial when <italic>Z</italic> ≥ 0.7 m/kg ^1/3. Finally, empirical predictive models were established to estimate the average cumulative impulse and damage index of SRC columns, thereby providing a quantitative basis for rapid post-blast damage assessment.