Comparisons of anti-progressive collapse performance between straight and curved concrete beam-column structures

The progressive collapse behavior of reinforced concrete curved beam–column substructures was investigated through experimental tests, finite element simulations, and theoretical analysis. The structural response was characterized by three stages: flexural action (FA), compressive arch action (CAA), and incomplete catenary action (ICA). A theoretical resistance calculation method considering bending–torsion interaction was developed for the CAA stage, and parametric analyses were conducted to investigate the effects of central angle, reinforcement ratio, and strength ratio. The results indicate that (1) A theoretical bearing capacity model for curved beam–column substructures under compressive arch action is proposed, accounting for bending–torsion coupling effects. Good agreement with numerical results confirms its reliability in predicting progressive collapse resistance. (2) Significant differences in progressive collapse behavior between straight and curved beam–column substructures are identified. Curved members exhibit pronounced bending–torsion interaction, leading to non-uniform internal force distribution and asymmetric reinforcement stresses. (3) The bending–torsion effect inhibits full development of catenary action, resulting in an incomplete tensile mechanism in curved structures, whereas straight beams can form a more complete catenary response. (4) Compared with straight beam–column systems, curved structures show reduced load-carrying capacity and ductility due to less efficient load-transfer mechanisms under torsional effects. (5) Increasing central angle enhances bending–torsion coupling and reduces structural resistance, while higher reinforcement ratio and material strength improve capacity but remain limited by torsional effects.