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该文结合单层球面网壳冗余度较低、稳定性问题突出等特点,提出了一种基于构件承载能力的敏感性评价指标,对采用不同网格布置形式的单层球面网壳进行了连续倒塌分析,明确了结构在极端雪荷载作用下的连续倒塌破坏模式以及敏感构件和关键构件的分布规律,分析了初始缺陷和压杆屈曲对构件敏感性的影响。分析结果表明:网格布置形式对单层球面网壳的抗连续倒塌性能以及破坏模式有很大影响,K8型网壳以及K8-联方型网壳在撤除敏感构件后均发生了整体倒塌破坏,而短程线型网壳的内力重分布能力较强,未发生连续倒塌破坏。增大关键构件的截面尺寸比增大敏感构件的截面尺寸更能有效提高单层球面网壳的抗连续倒塌性能。考虑初始缺陷后,构件重要性系数最多增大3.0倍,敏感构件的分布位置基本不变;而考虑压杆屈曲后,结构敏感构件的数量明显增加,重要性系数增大了1.2倍~5.6倍。
In this paper, based on the characteristics of low redundancy and outstanding stability problems of single-layer spherical lattice shells, a sensitivity evaluation index based on the bearing capacity of components is proposed, and single-layer spherical lattice shells with different grid layouts are used. Continuous collapse analysis confirmed the continuous collapse failure modes of the structure under extreme snow loads and the distribution of sensitive components and key components, and analyzed the influence of initial defects and buckling on the component sensitivities. The analysis results show that the grid layout has a great influence on the continuous collapse performance and failure mode of the single-layer spherical lattice shell. The K8 type lattice shell and the K8-joint type lattice shell all collapse after the removal of sensitive components. However, the reproducible internal force of the geodesic reticulated shell is strong and continuous collapse failure has not occurred. Increasing the cross-sectional size of the key member can effectively improve the continuous collapse resistance of the single-layer spherical reticulated shell, compared with increasing the cross-sectional size of the sensitive member. Considering the initial defect, the importance coefficient of the component increases by a factor of 3.0 at most, and the distribution position of the sensitive component remains basically unchanged. After considering the buckling of the pressure bar, the number of structural sensitive components increases significantly, and the importance coefficient increases by 1.2-5.6 times. .