钢筋混凝土柱-钢梁盒式节点抗剪机理及抗剪承载力计算

Research on shear behavior and bearing capacity of box joints for a RC column-steel beam

为研究钢筋混凝土柱-钢梁(reinforced concrete column and steel beam,RCS)盒式节点的抗剪承载力,基于低周反复荷载试验结果,采用理论和有限元方法分析了该类节点的内部钢腹板、外部钢侧板和节点区混凝土的抗剪机理及其对节点抗剪承载力的贡献,推导了该类节点的抗剪承载力计算公式。盒式节点的剪力由内部钢腹板、外部钢侧板和节点区内、外侧混凝土所形成的斜压杆机构共同承担,其中内部钢腹板和内侧混凝土为主要承力组件,对节点抗剪承载力的贡献分别占比为50%,30%左右;基于盒式节点中外部钢侧板承担剪力较小且与内部钢腹板抗剪承载力之比相对稳定的特点,引入放大系数β反映外部钢侧板对节点抗剪承载力的贡献,推导了盒式节点中钢组件的抗剪承载力计算表达式;基于混凝土斜压杆原理和内、外侧混凝土对节点抗剪承载力的贡献,推导了盒式节点中混凝土组件的抗剪承载力计算表达式;最后将处于承载力极限状态的钢组件、内侧混凝土与尚未屈服的外侧混凝土进行叠加建立了RCS盒式节点的抗剪承载力计算公式,计算结果与相应试验结果及有限元分析结果均吻合良好。

In order to study the shear capacity of reinforced concrete column and steel beam(RCS)box-type joints,based on the results of quasi-static tests,the shear mechanism of internal steel webs,external steel side plates and concrete in the joint area and their contribution to the shear capacity were analyzed by theories and the finite element method,and the calculation formula of shear capacity of the joints was derived.The shear force was jointly borne by the internal steel webs,the external steel side plates and the diagonal bar mechanism was formed by the inner and outer concrete.The internal steel webs and the inner concrete are the main bearing components,and the contribution to the shear capacity of the joint is about 50%and 30%respectively.Based on the characteristics that the shear force of the outer steel side plates is small and the ratio of the bearing capacity of the inner steel webs to that of the outer steel side plates is relatively stable,the amplification factorβis introduced to reflect the contribution of the outer steel side plates to the shear capacity,and the shear capacity formula of the steel components is derived;based on the principle of concrete diagonal strut and the contribution of the inner and outer concrete to the shear capacity of the joints,the shear capacity formula of the concrete components was derived.Finally,steel components,the inner concrete in the ultimate bearing capacity state,and the outer concrete which have not yet yielded were superimposed to establish the shear capacity calculation formula of RCS box-type joints.The calculation results are in good agreement with the results of quasi-static tests and finite element analysis results.