现浇楼板对RC框架结构“强柱弱梁”破坏机制的影响及措施

Effect and Measure of Cast-in-place Floor Slab on Strong Column Weak Beam Mechanism of RC Frame Structures

以地震中倒塌的汶川漩口中学教学楼为原型,设计了两个具有不同形式现浇楼板的钢筋混凝土框架结构对比模型,分别为普通现浇楼板模型和四角设缝楼板模型,运用DIANA进行了非线性有限元数值模拟。动力时程对比分析表明:忽视现浇楼板的贡献使RC框架结构很难实现“强柱弱梁”破坏机制,现浇楼板四角设缝的措施,可以有效减少框架结构柱端的塑性铰数量,使结构呈现出“强柱弱梁”破坏机制,提高了RC框架结构的延性和抗震性能。

Taking Xuankou Middle School building in Wenchuan collapsed in the earthquake as the prototype,two RC frame comparison models were designed,namely,the ordinary cast-in-place floor frame model and the frame model with gaps at four corners of the floor.The nonlinear finite element time history comparison analysis was carried out by DIANA.The analysis shows that the RC frame structure is difficult to realize the failure mechanism of“strong column and weak beam”due to the existence of cast-in-place floor slab.The measure of slotting at four corners of the floor slab,making separate between slab and beam,can effectively reduce the number of plastic hinges at the column end of the frame structure,so that the structure presents a failure mechanism of“strong column and weak beam”and improves the ductility and seismic performance of the RC frame structure.