考虑边界约束的多层组合框架抗倒塌性能研究OA北大核心

To accurately reflect the anti-collapse performance of multi-story composite frame structures under middle column removal scenario,a horizontal loading device considering the peripheral constraint stiffness was design.Through static loading,the resistance response,failure mode,internal force distribution,and mechanism resistance development of a 1/3 scaled three-story composite sub-frame specimen were investigated.The experimental results indicate that the boundary constraint device effectively reflects the decreasing axial constraint stiffness at the extended beams of each story.The axial forces in the beams of each story exhibit an uneven distribution characteristic,resulting in that the contribution of resistance supplied by the first-story to third-story accounts for 43％,37％and 20％of the total resistance,respectively.The presence of the vierendeel action mainly influences the development of catenary mechanism,whereas its influence on flexural mechanism resistance is relatively small.The effects of elastic boundary constraints,failure column positions,and span numbers on the collapse behavior of multi-story frame structures were investigated using numerical analysis methods.The analysis results indicate that the elastic boundary constraints overestimate the structural later resistance.The resistances provided by lower stories continuously decreases as the failed column position moves outward,while the resistance provided by the upper story continuously increases.With an increasing number of beam spans,the axial tension force is continuously transferred to the upper stories,and the resistant contribution provided by each story beam tends to be consistent.