中文摘要：

施工误差、材料性能不均匀等不可控制因素必然导致冷却塔结构具有一定的初始缺陷,本文主要研究了初始缺陷对冷却塔结构弹塑极限承载力的影响.通过弹性屈曲分析和自振特性分析,获得冷却塔结构的屈曲模态及振型,进而将结构初始缺陷视为由模态贡献系数调制的确定性函数（正交模态）的线性组合形式,在考虑材料非线性的前提下,采用修正的弧长法分析结构的弹塑性极限承载力.算例结果表明：冷却塔对振型初始缺陷构形较屈曲模态缺陷构型更为敏感,该方法可以有效地寻求结构初始缺陷的最不利分布形式,适用于大型工程结构的初始缺陷分析.

英文摘要：

The uncontrollable factors such as construction error,material inhomogeneity,etc.will inevitably lead to a certain initial imperfection.This paper mainly studies the initial defects of the cooling tower structure in the elastic-plastic stage influencing on the ultimate bearing capacity.Through elastic buckling analysis and the self-vibration characteristics of analysis,the buckling modes and the vibration modes multiplied by the modal contribution coefficients are introduced into the structure as the initial defects of hyperbolic cooling towers,taking into account the nonlinear material under the premise of the modified arc-length method in order to amend the elastoplastic ultimate bearing capacity of the structure.In the end,the numerical results show that： the super-large hyperbolic cooling tower with vibration mode initial imperfections is more sensitive than with buckling mode initial imperfections.The method can efficiently facilitate the search for the most unfavorable initial imperfection distribution form,so it can be applied to large-scale engineering structure initial imperfection analysis.