装配整体式混凝土梁-柱子结构角柱失效后承载能力试验研究

Experimental assessment on bearing capacity of monolithic precast concrete beam-column subassemblages under corner column removal scenarios

钢筋混凝土框架结构在角柱失效后,与失效角柱相连的两边梁处于弯剪扭复杂受力状态,其承载能力不同于纯弯构件。为评估装配整体式混凝土框架结构在角柱失效后边梁的承载能力,对5个装配整体式梁-柱子结构试件与1个整体现浇梁-柱子结构试件进行单调静力试验。对于装配整体式子结构,考虑了3种节点连接形式(90°弯钩连接、开槽水平搭接、锚固板焊接)和3种扭弯比受力状态(0、0.127、0.254)。通过对比各子结构的破坏形态、承载能力与延性,分析了扭弯比及节点连接形式对边梁承载能力的影响,对比了装配整体式子结构与整体现浇子结构在复杂受力状态下的性能差异。结果表明:在弯扭作用下装配整体式叠合梁承载力随着扭弯比的增加而降低;扭弯比为0.127∶1与0.254∶1时,结构承载力比纯弯结构分别降低了15.9%与40.4%;节点连接形式为90°弯钩连接时,装配整体式叠合梁在复杂受力状态下的性能可以认为与整体现浇梁的相同。

When a reinforced concrete frame structure is under a corner column removal scenario, its edge beams connected to the removed column are subjected to combined bending, torsion and shear actions, which are different from ideal bending beams. In this study, five monolithic precast concrete beam-column subassemblages and one cast-in-place concrete beam-column subassemblage were tested to assess the bearing capacity of frame edge beams under corner column removal scenario. Three different types of beam-column connections(90° hooks connections, lap-splice connections and headed bars connections) with three different torsion-bending ratios(0,0.127,0.254) were included in this test program. The effects of beam-column connections and torsion-bending ratios on the loading capacity of edge beams were investigated by analyzing the failure modes, the bearing capacity and the ductility. The differences between precast concrete members and reinforced concrete members under combined loading were also investigated in this paper. From the test results, it is observed that the sectional bearing capacity of monolithic precast concrete beams under bending and torsion decreases with the increase of torsion-bending ratios. The applied peak loads were reduced by 15.9% and 40.4% respectively compared with that of bending specimen when the torsion-bending ratios of the specimens were 0.127∶1 and 0.254∶1. The cast-in-place concrete beams and monolithic precast concrete beams with 90° bent-up rebars had similar behaviors under complicated stress conditions.