Truss string structures (TSSs) are often prone to the risk of progressive collapse owing to critical member failures in accidental events. Moreover, the randomness of material properties, cross-sectional dimensions, and construction errors can inevitably lead to fluctuations in the collapse resistance of structures. Thus, to avoid catastrophic collapse of TSSs, it is essential to investigate the resistance to progressive collapse of TSSs considering structural uncertainties. In this study, three limit states of TSSs under key member failures are defined. In addition, a probabilistic evaluation methodology for the progressive collapse resistance of single TSSs considering structural uncertainties is proposed and extended to spatial TSSs. The analysis reveals that the external load of single or spatial TSSs reaching different limit states due to cable failure is less than that of the failure of the bottom chord of the support. Furthermore, the fragility analysis shows that the progressive collapse resistance of TSSs exposed to the failure of the bottom chord of the support is greater than that of cable failure, the cable failure should be given more attention than the failure of the bottom chord of the support in the structural design and post-maintenance of TSSs. The sensitivity analysis indicates that the performance of single TSSs against progressive collapse is more sensitive to the variability of random parameters. In addition, the spatial effect can considerably enhance the performance of TSSs against progressive collapse when the bottom chord of the support fails, whereas the improvement is marginal when the cable fails.

由于意外事件中关键构件失效，桁架弦结构 (TSS) 通常容易出现逐渐倒塌的风险。而且，材料特性、截面尺寸和施工误差的随机性不可避免地会导致结构抗倒塌能力的波动。因此，为了避免 TSS 灾难性崩溃，有必要研究考虑结构不确定性的 TSS 对渐进崩溃的抵抗力。在本研究中，定义了关键成员故障​​下 TSS 的三种极限状态。此外，还提出了考虑结构不确定性的单个 TSS 抗连续倒塌的概率评估方法，并将其扩展到空间 TSS。分析表明，单个或空间TSS因拉索破坏而达到不同极限状态的外荷载均小于支架下弦破坏时的外荷载。此外，脆性分析表明，支撑下弦破坏时TSS的抗连续倒塌能力大于拉索破坏，因此应更加关注拉索破坏而不是支撑下弦破坏。 TSS 的结构设计和后期维护。敏感性分析表明，单个 TSS 抗渐进式倒塌的性能对随机参数的变化更加敏感。此外，空间效应可以显着增强 TSS 在支撑下弦失效时抵抗渐进倒塌的性能，