基于平面4节点单元的钢筋混凝土梁柱节点单元

Reinforced Concrete Beam-column Joint Element Based on Four-node Plane Element

基于平面4节点单元,提出了一个受循环荷载作用的钢筋混凝土梁柱节点单元,称之为超自由度单元.超自由度单元在梁与节点交界面和柱与节点交界面被划分成节点截面和梁柱截面,节点的力学性能由平面4节点单元描述,而梁柱受力钢筋与节点核心区的黏结滑移由节点截面和梁柱截面之间的8根弹簧控制.超自由度单元具有4个节点20个自由度,每个节点具有5个自由度,其中3个自由度与普通梁单元一致,从而确保其适合于同普通一维梁柱单元一起进行钢筋混凝土平面结构的非线性分析.通过3个梁柱组合体的实验和计算结果对比,验证了超自由度单元适合于进行循环荷载作用下平面框架结构的非线性响应分析.

Based on four-node plane stress elements,a new element, named super degree-of-freedom element,is developed to represent the response of reinforced concrete beam-column joints under reserved cyclic loading. Element edges are divided into ＂joint plane＂ and ＂beam-column plane＂ at the joint-column interface and joint-beam interface.The inelastic mechanism of joint core is represented by the four-node plane stress element. Anchorage failures of beam and column longitudinal reinforcement embedded in the joint are determined by eight springs between ＂joint plane＂ and ＂beam-column plane＂.The model is implemented as a four-node twenty-degree-of-freedom element.There are five degrees of freedom on each node.Three of them coincide with ones of typical beam element so that the element is appropriate for use with typical hysteretic beam-column line elements in two-dimensional nonlinear analyses of reinforced concrete structures. Comparison of simulated and observed responses for three sub-assemblages tested in the laboratory indicates that the proposed element is appropriate for use in simulating responses of building joints under cyclic loading.