单层网壳结构非线性稳定的随机缺陷模态法研究

A Probe into Nonlinear Stability of Single-Layer Reticulated Shells by Means of Random Imperfection Modal Method

采用随机缺陷模态法对凯威特–联方型单层网壳进行非线性稳定分析,研究了随机缺陷空间样本数量、矢跨比等因素对网壳结构稳定极限荷载的影响,并将随机缺陷模态法计算结果与一致缺陷模态法计算结果进行了对比.结果表明:采用概率统计方法对该网壳进行稳定分析时,随机缺陷样本数量应不小于90;对于矢跨比较大的单层网壳结构,采用一致缺陷模态法计算稳定临界荷载的概率可靠度较低,需要采用随机缺陷模态法加以验证;当网壳结构的矢跨比小于1/6时,两种初始缺陷分布方法计算出的稳定承载力较为接近.

The nonlinear stability of Kiewitt-Lamella single-layer reticulated shells is analyzed by means of randomimperfection modal method, and the stable ultimate load of the reticulated shell structure, which is affected by boththe spatial sample number of random defect and the rise-span ratio, is investigated. Then, a comparison of calculatedresults is made between random imperfection modal method and consistent imperfection modal method. Theresults show that （1） the spatial sample number of random defect should be not less than 90 for the stability analysisof structures via statistical method; （2） for the reticulated shell structure with large rise-span ratio, the probabilisticreliability to calculate the critical load via consistent imperfection modal method is rather low, so that it is necessaryto verify the critical load with the help of random imperfection modal method; and （3） when the rise-span ratioof a single-layer reticulated shell is less than 1/6, the calculated stable bearing capacities obtained by the two above-mentioned initial defect distribution methods are nearly equal.