T形截面钢压杆几何初始缺陷测量方法研究

Measurement Method of Initial Geometric Deflections of T-Section Steel Struts

几何初始缺陷是影响钢压杆整体稳定承载力的重要缺陷因素之一。T形截面钢压杆的常见几何初始缺陷包括构件初弯曲、荷载初偏心及构件初扭转。在压杆整体稳定承载力研究中,为了更加精确便捷地测量出构件的几何初始缺陷大小,基于传统弹性稳定理论,利用T形截面钢压杆几何初始缺陷与荷载、截面应变、侧移及扭转等参数之间的关系,推导出几何初始缺陷的计算式,提出利用压杆弹性阶段的荷载与变形关系获得几何初始缺陷的参数反推测量法。借助ANSYS建立具有几何初始缺陷的T形截面钢压杆三维模型,并对其进行几何非线性分析,将模型初设的几何缺陷值与按照新方法计算所得的结果进行对比,验证所提出的几何初始缺陷计算式的正确性。结合T形截面钢压杆整体稳定承载力试验,获得弹性阶段荷载、截面应变、侧移及扭转实测值,基于新提出的参数反推测量法,计算钢压杆实际几何初始缺陷大小,并将结果与传统光学仪器测量法获得的结果进行对比,验证参数反推测量法的正确性。分析结果表明:T形截面钢压杆几何初始缺陷的参数反推测量法具有正确性和可行性;该方法不需要另设测量设备、可减小人为测量误差,具有高效性和精确性;同时,该方法考虑了实际压杆在整体稳定承载力试验过程中,因端部约束作用影响而产生的杆件临界力大小,不仅可获得构件初弯曲及荷载初偏心之和,还可获得构件初扭转缺陷值。基于新参数反推测量法获得的几何初始缺陷值,可作为初参数直接引入后续的T形截面钢压杆整体稳定承载力分析,为钢压杆整体稳定承载力研究提供重要参考。

Initial geometric deflection is one of the important factors impacting on the overall stability bearing capacity of steel struts.The common initial geometric deflections of the steel strut with T-section include the initial bending deformation of the component,the initial eccentricity of the load and the initial torsional deformation of the member.In the process of the study on the overall stability bearing capacity of steel struts,in order to measure the initial geometric deflection more accurately and conveniently,the relationship between the initial geometric deflection of steel struts and the parameters such as load,strain,lateral displacement and torsion deformation of the section are utilized.Based on the traditional theory of elastic stability,the calculation formulas of the initial geometric deflections are derived,and the inverse parameter measuring method is put forward to obtain the initial geometric deflections by using the relationship between the load and deformation of the compression member in the elastic stage.Using ANSYS,the 3 D model of a T-section steel strut with initial geometric deflections was created,and the geometric nonlinear analysis of the strut was performed.Comparing the data of the initial geometric deflections of the 3 D model with the results calculated by the inverse parameter measuring method,the accuracy of the calculation formula to get the initial geometric deflections was verified.Finally,based on the overall stability capacity test of T-section steel struts,the measured values such as load,strain,lateral displacement and torsion deformation of the section in the elastic stage were obtained.By the inverse parameter measuring method,the actual initial geometric deflections of the steel strut were calculated.The results were compared with those obtained by the traditional optical instrument measuring method,and the correctness of the inverse parameter measuring method was verified.It is shown that the inverse parameter measuring method of the initial geometric deflections of T-section steel struts was correct and feasible.Since the deflections can be measuring with the equipment in the overall stability capacity test without extra devices,the artificial measurement errors are reduced.Moreover,the influence of the end constraint on the critical force of actual struts is taken into account during the process of the overall stability bearing capacity test.Most of all,the common initial geometric deflections of the steel strut with T-section,not only the initial bending deformation of the component and the initial eccentricity of the load,but also the initial torsional deformation of the member can be obtained.The initial geometric deflections,which are obtained by the inverse parameter measuring method,can be directly used in the subsequent finite element analysis,that it can provide an essential reference for the study of the overall stability bearing capacity of the steel struts with T-section.