单层球面网壳抗连续倒塌性能研究

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。

PROGRESSIVE COLLAPSE PERFORMANCE OF SINGLE-LAYER LATTICED SHELLS

In this study, a series of sensitivity assessment indicators were proposed for single-layer latticed shells, based on the bearing capacity of their components. The low redundancy and the stability of single-layer latticed shells were considered. Three single-layer latticed shells with different grid layouts were used to conduct progressive collapse analysis. The distribution patterns of sensitive components and key components of the three shell structures were investigated. The progressive collapse modes of the shells subjected to an extreme snow load were also studied. Results indicate that the grid layout has a great effect on the progressive collapse performance and the failure mode of single-layer latticed shells. The K8 latticed shell and the K8-lamella latticed shell totally collapsed after removing the sensitive components while the geodesic latticed shell with strong internal force redistribution ability remained intact. The progressive collapse performance of single-layer latticed shells can be improved effectively by increasing the sectional area of the key components rather than the sensitive components. The value of the importance coefficient was increased by a maximum of 3 times after considering the initial geometric imperfections, while the position of the sensitive components remained the same. The number of the sensitive components increased significantly and the value of the importance coefficient was enlarged by 1.2 to 5.6 times after considering the buckling of compression members.