基于承载力拟合的钢拱不利几何缺陷分析  

ANALYSIS OF UNFAVORABLE GEOMETRIC DEFECTS OF STEEL ARCH BASED ON BEARING CAPACITY FITTING

作　　者：蒋友宝 尹倩倩 罗军 付涛 JIANG You-bao;YIN Qian-qian;LUO Jun;FU Tao(School of Civil Engineering, Changsha University of Science and Technology,Changsha 410004, China;Hunan Academy of Building Research, Changsha 410011, China)

机构地区：[1]长沙理工大学土木工程学院,长沙410004 [2]湖南省建筑科学研究院,长沙410011

出　　处：《工程力学》2019年第B06期203-209,共7页Engineering Mechanics

基　　金：国家自然科学基金项目(51678072);“湖湘青年英才”支持计划项目(2016RS3030)

摘　　要：几何缺陷会显著降低钢拱结构的稳定承载能力。为合理确定钢拱不利几何缺陷,该文采用基于子空间划分的多响应面方法对承载力函数进行了拟合,然后根据函数极值的拉格朗日乘子法求解承载力最低时的几何缺陷分布。以两铰圆弧钢拱结构为例,考虑荷载比、偏差节点数量等参数的变化,对比了按上述不利缺陷法和一致缺陷法确定的缺陷拱结构受力性能。结果表明:1)基于子空间的多响应面方法拟合承载力函数的精度较高,承载力预测值与有限元分析结果较为接近;2)采用对承载力拟合函数求极值的方法得到的几何缺陷对承载力更为不利,在参数分析范围内其对应的结构承载力和初始刚度较一致缺陷法分别平均偏低约10%和约22.8%;3)随着偏差节点数量增多,基于承载力拟合的不利缺陷分布与一致缺陷分布的差别进一步增大,且基于承载力拟合的不利缺陷分布对应的节点正负偏差的波动性更为明显。Geometric defects will significantly reduce the stability bearing capacity of a steel arch structure.In order to reasonably determine the unfavorable geometrical defects of a steel arch,the multiple response surfaces method based on subspace division is used to fit the bearing capacity function.Then,according to the Lagrange multiplier method of the extremum of the function,the geometric defects distribution with the lowest bearing capacity is solved.Taking the two hinged circular steel arches as examples,and considering the changes of parameters such as the load ratio and the number of deviation nodes,the mechanical properties are investigated for defective arch structures obtained by the proposed unfavorable defects method and the consistent mode imperfection method.The results show that:1)the multiple response surfaces method based on subspace is more accurate in fitting the bearing capacity function,and the prediction value of the bearing capacity is close to the result of the finite element analysis;2)the geometric imperfections obtained by using the fitting function to calculate the extremum are more unfavorable to the bearing capacity,and within the parameters in analysis,the corresponding structural bearing capacity and initial stiffness is averagely about 10%and 22.8%,respectively,lower than that obtained by the consistent mode imperfection method;3)with the increase of the number of deviation nodes,the differences are increasingly large between the distribution of unfavorable defects based on bearing capacity fitting and the distribution of the consistent defects,and the positive and negative deviations of nodes are more obvious for the unfavorable defects distribution based on bearing capacity fitting.

关 键 词：钢拱结构 不利几何缺陷 极限承载力 多响应面法 一致缺陷法 

分 类 号：TU391[建筑科学—结构工程]