冲击荷载作用下RC框架梁剪切破坏试验研究

Experimental research on the shear failure mechanism of reinforced concrete frame beam under impact load

通过对2个钢筋混凝土框架梁节点试件进行冲击荷载试验,研究了钢筋混凝土框架柱下支撑移去后框架梁的剪切破坏机理。试验中在两端固定的钢筋混凝土梁的1/4跨、1/2跨、3/4跨位置,通过施加荷载的方式来模拟次梁和现浇板传来的荷载,梁跨中通过自制的自动脱钩器移去等效柱来模拟结构在失去边跨中柱,框架梁跨度成倍增长时力学性能的变化。研究结果表明:当梁发生剪切破坏时,拱效应不能充分发挥,使得梁的极限承载力降低,所以在建筑结构抗倒塌设计时必须按照"强剪弱弯"的原则进行抗剪设计。

To study the shear failure mechanism of frame beam when the column damaged suddenly, tests on two re- inforced concrete frame beam joints under impact load were conducted. The loads coming from the secondary beam and cast -in -place plate were simulated by loading on 1/4 span, 1/2span, 3/4 span of the beam which is fixed at both ends. And the mechanical performance change of RC beams when the span was doubled because of losing the mid column at the sidespan was simulated by using self-release mechanism at the midspan. The test results indi- cate that： arching effect can not bring into action when shear failure occurs in the beam, which consequently makes the ultimate bearing capacity of beam reduced. Therefore when the building is designed to resist progressive col- lapse, the principle of stronger shear - weak bending must be satisfied in shear design.