控制竖向几何缺陷的特征缺陷模态法

Eigenvalue Imperfection Modal Method for Controlling Vertical Geometric Imperfections

为了准确快速地分析带有初始几何缺陷的单层网壳结构静力稳定性,通过分析特征缺陷模态法和随机缺陷模态法的初始几何缺陷值,并对1/4、1/5、1/6和1/7矢跨比的K8凯威特单层网壳结构进行线性屈曲分析,发现特征缺陷模态法的竖向几何缺陷值小于随机缺陷模态法,在矢跨比较大时会更明显,进而分析了特征缺陷模态法在矢跨比较大时可靠度较低的原因,提出控制竖向几何缺陷的特征缺陷模态法。运用所提出的方法和N阶特征缺陷模态法对网壳结构进行了弹塑性荷载-位移全过程分析。结果表明,控制竖向几何缺陷的特征缺陷模态法与N阶特征缺陷模态法的计算结果接近,误差在工程允许的5%以内,控制竖向几何缺陷的特征缺陷模态法较N阶特征缺陷模态法可以更安全地评估网壳结构的稳定性能。

In order to accurately and quickly analyze the stability bearing capacity of single-layer reticulated shells with initial geometric defects,through analyzing analysis the initial geometric imperfection values of eigenvalue imperfection modal method(EIM)and random imperfection modal method(RIMM),and conducting the linear buckling analysis of K8 Kaiweite single-layer reticulated shell structure with 1/4,1/5,1/6,1/7 rise-span ratio,it was found that we found the vertical geometry imperfection value of the EIM was smaller than that of the RIMM,and it would be more obvious when the rise-span ratio was relatively large.Furthermore,the reason for the low reliability of the EIM when the rise-span was relatively large was analyzed,and the eigenvalue imperfection modal method for controlling vertical geometric imperfections(EIM-CVGI)was proposed.Using the proposed method and the N-order eigenvalue imperfection modal method,the elastoplastic load-displacement whole process analysis of the above four kinds of rise-span ratio reticulated shell structures was carried out.The results showed that the errors of the calculation results of the EIM-CVGI and the N-order eigenvalue defect modal method were within 5%of the engineering allowable.Compared with EIM,the stability performance of the reticulated shell structure could be evaluated more safely.