考虑杆件失稳的初始缺陷单层网壳极限承载力分析

Ultimate Bearing Capacity Analysis of Single Layer Latticed Shell with Initial Imperfection Considering Member Buckling

建立了考虑失稳效应的杆件计算模型.采用正态分布随机变量描述单层网壳结构的初始几何缺陷,考虑杆件失稳效应,计算初始几何缺陷结构的极限承载力.假设初始几何缺陷单层网壳的极限承载力服从正态分布,通过非参数假设检验方法进行了验证,利用极大似然估计法推导了该正态分布均值与方差估计量的表达式.针对随机缺陷模态法无法计算出稳定的、可靠度统一的结构设计极限承载力,一致缺陷模态法不适用于非线性效应明显的结构,提出了基于统一可靠度的单层网壳结构设计极限承载力计算方法,并推导了其在一定置信水平下的误差表达式.承载极限状态下单层网壳结构部分杆件发生失稳,不考虑杆件失稳效应会高估结构承载力.

The member calculating model considering the buckling effect was founded. The initial geometrical imperfection of single layer latticed shell was described by normal random variable, and ultimate bearing capacities of imperfect structures were calculated considering the member buckling effect. Ultimate bearing capacities of imperfect structures were first assumed to obey the normal distribution, which was then proved by the nonparametric test, and the expressions of the mean and variance estimators were deduced by the maximum likelihood method. As random imperfection model method fails to calculate the stable ultimate bearing capacity with uniform reliability and uniform imperfection model method is inapplicable to structures with significant nonlinearity effect, the design ultimate bearing capacity of single layer latticed shell based on the uniform reliability was presented, whose error expression under a certain confidence level was deduced. Some members get buckled when structure is in an ultimate bearing state. The structural bearing capacity can be overestimated if member buckling effect is ignored.