爆炸荷载作用下钢筋混凝土双跨梁子结构连续倒塌机制试验研究

Experimental study on progressive collapse mechanism of reinforced concrete sub-assemblage with two-span beams under blast loading

为了研究爆炸荷载作用下钢筋混凝土双跨梁子结构抗连续倒塌机制,对3榀钢筋混凝土框架双跨梁子结构的中节点进行竖向冲击加载,以模拟爆炸荷载作用下承重柱失效对子结构产生的轴拉效应。结果表明:在加载瞬间,由于惯性效应,梁受力呈现出显著的反拱机制,随着惯性效应的减弱以及中节点竖向位移的增加,梁表现出压拱机制;在试验冲击工况下,子结构没有出现纵筋断裂,梁的破坏模式均表现为梁端弯曲破坏;顶部纵筋通长配置可以减轻跨中混凝土的开裂,并减小子结构在动力加载时的峰值位移响应。

To investigate the progressive collapse mechanism of reinforced concrete(RC) sub-structure with double-span beams under blast loading,three vertical impact tests on middle-joint of the RC substructures with double-span beams are carried out,which is aimed to consider the axial tension effect on the remaining sub-structure from the bearing column in failed process under blast loading.The results showed that,at the moment of loading,an obvious reverse arch action appeared in beam due to inertial effect,compressive arch action appeared with decrease of inertial effect and increase of middle joint displacement.Under the impact condition in test,no fracture occurred in the longitudinal bars.The damage mode of beam exhibited a flexural damage at the beam ends.Continuous longitudinal bars at the top of the beam can mitigate the crack development in beam span,and reduce the peak displacement of middle joint in dynamic response of substructure.