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钢筋混凝土框架结构在使用期内遭遇爆炸、撞击等突发事件时,可能引起结构承重柱失效,从而导致结构倒塌。当失效柱为内柱时,失效柱上方与其相连的两跨梁将形成双跨梁,双跨梁的承载能力决定剩余结构的抗倒塌能力。为分析双跨梁的受力特征和破坏机理,进行了3根1/4缩尺钢筋混凝土双跨梁的静力加载试验。结果表明:梁端存在轴向约束时,梁产生压拱效应,其竖向承载力得到提高;基于试验结果,根据双跨梁关键截面满足的内力平衡方程、考虑压拱效应时满足的变形协调方程,推导出梁的竖向荷载与中柱竖向位移之间的关系式;通过不断增大竖向位移,得到最大竖向荷载(对应的梁轴向力为压力)即为双跨梁考虑压拱效应的竖向承载力。理论分析结果和试验结果比较表明,所提计算方法有较高精度。
Reinforced concrete frame structure in the event of explosion, impact and other emergencies, may cause the structural load-bearing column failure, resulting in structural collapse. When the failure column is the inner column, the two spans connected with the two spans above the failure column will form double spans. The bearing capacity of the double spans determines the anti-collapse ability of the remaining structures. In order to analyze the stress characteristics and failure mechanism of the two-span beam, three 1/4-scale RC double-span beams were subjected to static loading test. The results show that when the axial constraint exists on the beam end, the beam produces arching effect, and the vertical bearing capacity of the beam increases. Based on the test results, according to the internal force balance equation satisfied by the key cross-section of the double-span beam, the deformation coordination Equation, derive the relationship between the vertical load of the beam and the vertical displacement of the column. By increasing the vertical displacement, the maximum vertical load (the corresponding beam axial force is the pressure) Vertical bearing capacity of arch effect. The comparison between theoretical analysis and experimental results shows that the proposed method has higher accuracy.