Blast-resistance performance and probabilistic vulnerability assessment of steel box arch ribs subjected to contact explosions

• Field blast experiments and residual capacity tests on three large-span steel box arch ribs evaluated their blast resistance and damage levels under contact explosions. • Empirical formulas were proposed to quantify stiffness and carrying capacity damage levels in the ribs. • Blast vulnerability curves integrating damage indices offer a comprehensive assessment, highlighting deformation and residual performance. To evaluate the blast resistance and vulnerability of steel box arch ribs under contact explosions, explosive and carrying capacity tests were conducted. A validated three-stage finite element model simulated the blast, free vibration, and residual carrying capacity stages. Multi-parameter analysis revealed that explosive mass, location, and rise-span ratio significantly influenced stiffness and carrying capacity damage, while preload had minimal impact. Explosions within the span range of L/6 to 5L/12 caused the most severe damage, and higher rise-span ratios (1/4) resulted in greater structural damage, suggesting an optimal range of 1/6 to 1/5 for improved stability. Damage levels were classified as slight, moderate, severe, or collapse, based on stiffness and capacity thresholds of 0.1, 0.3, and 0.5. Accounting for uncertainty, empirical formulas for damage levels were proposed, along with vulnerability curves for single and combined damage indices. The results revealed that, compared to single damage indices, blast vulnerability curves based on combined indices integrating stiffness and carrying capacity damage provide a more comprehensive assessment of steel box arch rib damage, particularly in terms of deformation and carrying capacity performance. This study provides key insights for improving the design and safety of steel box arch ribs.