双向受力下钢筋混凝土框架节点抗剪承载力计算方法

《建筑抗震设计规范》(GB 50011-2010)规定框架结构设计应保证其在两个方向分别满足抗震要求。但地震作用是多维的、随机的,框架节点可能在两个方向同时受力,使其抗震能力相比于单向地震作用可能会降低。目前对钢筋混凝土框架节点在两个方向同时受力时的抗剪承载力计算未见详尽报道。该文分析了钢筋混凝土框架节点在双向同时受力时的抗剪机理,双向受力下,节点内作用合成剪力,节点端部形成斜向受压区,节点内形成不同于单向受力下的斜向斜压杆。基于拉压杆模型建立了双向受力下框架节点的抗剪承载力计算方法,其计算结果与已有试验结果吻合良好。

SHEAR CAPACITY CALCULATION METHOD OF PANEL ZONE IN REINFORCED CONCRETE FRAME UNDER BIDIRECTIONAL LOADING

According to the provisions of the Chinese Code for Seismic Design of Buildings(GB50011-2010),the anti-seismic capability of a frame structure in two horizontal directions are designed respectively.However,earthquake action is multi-dimensional and random,which will make a panel zone in a frame structure be loaded by bidirectional actions at the same time.Thusly,its anti-seismic capability may be lower than the designed capability based on a unidirectional earthquake action.So far,the detailed calculation methods of shear capability for a panel zone in a reinforced concrete(RC)frame subjected to bidirectional loading have not been reported.In this work,the shear mechanism of a panel zone in a RC frame under bidirectional loading was analyzed.It demonstrated that a synthetic shear force is imposed on a panel zone,the oblique compression zone comes into being at the end of a panel zone,and the diagonal strut is formed in a panel zone,which is different from the shear mechanism under unidirectional loading.A shear capacity calculation model was established based on the strut and tie model,and the predicted values by this work are in a good agreement with the reported experimental results.