基于四点弯曲力学模型的半刚性节点弹性转动刚度研究

Research on the Elastic Rotational Stiffness of Semi-Rigid Joints Based on Four-Point Bending Mechanical Model

半刚性节点的弹性转动刚度对单层网壳整体稳定承载力分析的准确性至关重要。四点弯曲试验是广泛应用于获取半刚性节点力学性能的测试方法,但存在转角测量误差较大的缺陷。本文首先利用能量法原理和挠曲线微分方程,推导出基于四点弯曲力学模型的半刚性节点转角和位移关系的理论公式,进而得到半刚性节点弹性转动刚度公式;随后,利用理论公式将四点弯曲试验测得的荷载-位移曲线转化为节点弯矩-转角曲线(即公式曲线),并与试验直接测得的节点弯矩-转角曲线(即试验曲线)进行对比。结果表明,本文提出的理论公式能够准确的根据荷载-位移曲线计算出弯矩-转角曲线,用位移测量替代转角测量,从而准确计算半刚性节点的弹性转动刚度值,为单层网壳稳定承载力分析时考虑节点的弹性转动刚度提供了依据。

The precise determination of the elastic rotational stiffness of semi-rigid joints is of significant importance in evaluating the overall stability capacity of single-layer latticed shells.The four-point bending test is commonly employed to obtain the mechanical properties of semi-rigid joints,but it has the drawback of significant errors in measuring the rotation angle.Based on the four-point bending mechanical model,this paper firstly derives the relationship formula between the rotation angle and displacement of the semi-rigid joint using the principle of energy method and the differential equation of the deflection curve,and then obtains the formula for calculating the elastic rotational stiffness of the semi-rigid joint;Subsequently,the moment-rotation curve(i.e.,the formula curve)is obtained by the load-displacement curve measured by the four-point bending test according to the relationship formula and compared with the moment-rotation angle curve measured by the test(i.e.,the experimental curve).The results show that the theoretical formula proposed in this article can accurately calculate the bending moment-rotation curve based on the load-displacement curve,and replace the angle measurement with displacement measurement,thereby accurately calculating the elastic rotational stiffness value of semi-rigid joint,this provides a basis for considering the elastic rotational stiffness of joint when analyzing the overall stability capacity of single-layer latticed shells.