初始缺陷对三向张弦梁结构整体稳定性影响研究

STUDY ON THE INFLUENCE OF INITIAL IMPERFECTION ON THE STABILITY OF TRI-DIRECTIONAL BEAM STRING STRUCTURES

三向张弦梁结构是新广州站工程采用的一种新型张弦梁结构,因此有必要对三向张弦梁结构的整体稳定性能进行深入的研究。该文首先对随机缺陷模态法进行了改进,使其更适用于网壳与张弦梁混合结构的缺陷稳定性分析。然后分别采用改进的随机缺陷模态法和一致缺陷模态法对三向张弦梁结构的缺陷稳定性进行了研究。分析结果表明:改进后的随机缺陷模态法更适用于网壳和拱梁混合结构形式的缺陷稳定性分析;缺陷越大,该三向张弦梁结构对缺陷越敏感,整体稳定性能受缺陷的影响越大;与理想结构破坏模式最接近的特征值屈曲模态为最不利的特征值屈曲模态,按此模态施加初始缺陷后的结构承载力最低;按非线性屈曲模态对结构施加缺陷得到的结构极限承载力小于按特征值屈曲模态施加缺陷的情况,与随机缺陷模态法的结果最为接近。

Tri-directional beam string structure （TBSS） is a new type of beam string structure which is used in the new Guangzhou railway station. It is necessary to conduct stability analysis of this structure. Firstly the stochastic imperfection method was improved to make it more applicable to the structures mixed with grid shells and BSS. Then the imperfect stability of TBSS was studied with the improved stochastic imperfection method and the consistent imperfection method. The results show that improved stochastic imperfection method is suitable for the imperfect stability analysis of the structures mixed with grid shells and beam string structure. As the degree of imperfections becomes larger, the structure is more sensitive to the imperfections and the influence of the imperfections on its stability behavior becomes more obvious. The eigenvalue buckling mode which is the closest to the collapse mode of the structure is the most disadvantageous eigenvalue buckling mode, and the stability capacity of the structure with imperfections base on this eigenvalue buckling mode is the lowest. However, the stability capacity of the structure with imperfections based on the nonlinear buckling mode is lower than that based on eigenvalue buckling mode, and it is very close to the results given by the improved stochastic imperfection method.