竖向加载模式对结构连续倒塌Pushdown分析的影响

Effects of vertical loading patterns on Pushdown analysis of structures in resisting progressive collapse

作为评估结构抗连续倒塌能力的一种有效方法,Pushdown分析方法已得到广泛应用。基于Pushdown方法采用的满跨加载、受损跨加载以及局部加载三种竖向加载模式,研究不同竖向加载模式对二维和三维钢筋混凝土框架结构模型Pushdown分析结果的影响。通过对二维和三维钢筋混凝土梁-柱子结构在中柱失效后的拟静力加载试验进行模拟,验证有限元模型的正确性。以一栋8层4跨钢筋混凝土框架结构作为研究对象,对比不同竖向加载模式下的Pushdown曲线。对比结果表明:在满跨加载和受损跨加载模式下,结构的Pushdown曲线基本一致。在局部加载模式下,结构移除柱上方节点的变形更大。

As an effective method for the evaluation of the performance of structures in resisting the progressive collapse,the Pushdown analysis method has been widely employed for the progressive collapse studies. There were three vertical load patterns used in Pushdown analysis,namely,the full-bay loading pattern,the damage-bay loading pattern,and the local loading pattern. The effects of adopting different vertical load patterns on the Pushdown analysis were evaluated by using 2D and 3D reinforced concrete( RC) frame modelling. The finite element model was validated by simulating the quasi-static tests of the 2D and 3D RC beam-column subassemblies subjected to the loss of midcolumn scenario. A RC frame structure was selected as the case study structure and the Pushdown curves in accordance with different vertical loading patterns were compared. Results show that the full-bay loading pattern may achieve similar Pushdown curves to the damage-bay loading pattern. However,the local loading pattern always generates larger deformation at the joint beyond the missing column than the other two.