随机风荷载下单层球面网壳的整体疲劳分析

对随机风荷载下K6型单层球面网壳的整体疲劳问题进行了研究。用AR法模拟Kaimal谱多点互相关的脉动风风速时程,确定结构所承受的荷载谱,通过有限元时程分析和雨流计数法得到杆件的应力循环历史,采用疲劳设计方法中的总寿命法计算杆件的疲劳损伤度,分析结构在不同矢跨比、不同平均风速下结构的抗疲劳性能。研究发现,结构中出现疲劳的杆件数随矢跨比的减小而逐渐增加,结构中杆件最大疲劳损伤度D随着矢跨比的减小而逐渐增大。网壳的疲劳薄弱区域主要与结构的振型有关;矢跨比较大时,结构中环向杆件易出现疲劳,随着矢跨比的减小,结构径向肋两侧的斜杆易出现疲劳。

Integral Fatigue Analysis of Single-1ayer Spherical Reticulated Shells under Stochastic Wind Loads

The problem of integral fatigue of single-layer spherical reticulated shells under stochastic wind loads was studied.By simulating fluctuating wind speed in time history according to Kaimal power spectrum with AR methods,load spectrums were obtained.After time history analyses of FEM and statistics of stress cycles history by rainflow counting algorithms,the total life method was adopted to obtain the fatigue damage of members.Fatigue performance of the single-1ayer spherical reticulated shells was analyzed under different rise-span ratios and average wind velocities.It was shown that the number of fatigue members increased gradually with the decrease of the rise-span ratio;the maximum fatigue damage of members increased with the decrease of the rise-span ratio.Fatigue regions of single-layer spherical reticulated shells were related to the structural vibration mode;when the rise-span ratio was high relatively,circular members in the structure came about fatigue damage easily,when the rise-span ratio became small,the members of both sides of radial ribs came about fatigue damage easily.