钢管混凝土柱-钢梁延伸式端板连接节点初始转动刚度计算模型

延伸式端板连接节点是钢管混凝土结构中常见的梁柱节点形式，基于组件法建立了钢管混凝土柱-钢梁延伸式端板连接节点初始转动刚度的计算模型，考虑了端板受弯、端板受剪、螺栓受拉、钢管柱腹板受剪、柱核心混凝土受剪变形对节点转动刚度的影响，对于节点锚固件，采用贯通螺栓或单边螺栓。通过确定对节点初始转动刚度有贡献的组件将其简化为弹簧模型，提出了各组件的刚度计算公式，建立了节点初始转动刚度的计算模型。根据建立的计算模型对已有试件进行理论计算并与试验结果对比，得到理论值与试验值之比的平均值为1.02，标准差为0.12，验证了其正确性，且该计算模型简单，便于在实际工程中应用。分析了节点初始转动刚度的影响因素，结果表明：适当增大端板厚度，可有效提高节点初始转动刚度；增大螺栓直径、钢管柱厚度和提高混凝土等级对节点初始转动刚度的提高不及增大端板厚度显著。

Calculation model for initial rotational stiffness of steel beam to concrete-filled steel tube column joints with extended end-plate

The joint with extended end-plate is a common joint form in the concrete-filled steel tube (CFST) structures. An calculation model for the initial rotational stiffness of steel beam to CFST column with an extended end-plate was proposed based on the component method. The model takes into consideration the effects of the following deformations on the rotational stiffness of the joint: the end-plate in bending, the end-plate in shear, the bolts in tension, the steel tube column web in shear and the core concrete surrounded by steel tube column in shear. The through bolts or blind bolts are used as anchorage components of the joint. The components that contribute to the initial rotational stiffness of the joint are determined and simplified to spring models, respectively. Then, formulas for the stiffness of each component are given. Finally, the calculation model for the initial rotation stiffness was proposed. The theoretical calculations based on the proposed model were compared with the existing experimental results. The average and the standard deviation of the ratio between the theoretical value and the experimental value are 1.02 and 0.12, respectively, which verifies the validity of the proposed model. In addition, the calculation model is simple and convenient for application in practical engineering. The factors affecting the initial rotational stiffness of the joint were analyzed. The analysis results show that the increase of the end-plate thickness can improve the initial rotation stiffness of the joint effectively. The improvement of initial rotational stiffness of joints with increasing the bolt diameter, the thickness of the steel tube, and the concrete grade is not significant as increasing the end-plate thickness.