RC框桁式墙体破坏模式及地震损伤模型研究

Failure mode and seismic damage model of RC frame truss wall

文中提出一种由钢筋混凝土(RC)外边框和内部桁式杆件组合而成的新型框桁式墙体,为研究该新型墙体的地震损伤性能以实现损伤控制,进行了3个1:2模型比例的框桁式墙体试件的低周反复荷载试验,详细分析了试件从加载开裂直至破坏的各阶段裂缝发展规律与损伤积累过程。通过对既有损伤模型及框桁式墙体损伤特点的分析,引入基于延性和累计滞回耗能的双参数地震损伤模型,并通过非线性多元回归分析获得模型影响参数α和β。结果表明:该墙体首先在桁杆上出现裂缝且裂缝逐渐贯通,再以节点为中心开展裂缝,最终破坏发生在外框底部区域,该试件的破坏顺序明确;文中提出的双参数损伤模型能够较好地反映此类试件在地震作用下,损伤指数在加载初期增量较小、而在屈服后损伤指数增加迅速的实际情况。研究结果可为新型框桁式墙体的抗震设计提供参考。

In this paper,a new type of frame truss wall composed of reinforced concrete(RC)outer frame and inner truss members is proposed.In order to study the seismic damage performance of the new type of wall and achieve damage control,three 1:2 model scale frame truss wall specimens were tested under low cyclic loading.The development law of crack and damage accumulation process of the strucrure loaded from cracking to failure were analyzed in detail.Through the analysis of the existing damage model and the damage characteristics of frame truss wall,a double-parameter seismic damage model on account of ductility and cumulative hysteretic energy consumption is introduced.Further more,the influence parametersαandβare obtained by nonlinear multiple regression analysis.The results show that:cracks firstly appear on the truss and gradually run through,then develop near the panel,and ultimately the destruction occurs at the bottom of the outer frame,the failure sequence present is clear and regular.The double-parameters damage model proposed in this paper can better reflect that the initial increment of damage index is small while the damage growth rate is fast after yielding.The research results can provide a reference for the seismic design of the new frame truss wall.