大型钢-混凝土组合楼盖系统的连续倒塌试验与失效机理研究

为研究钢-混凝土组合楼盖系统在连续倒塌工况下的抗力机制和破坏过程，按照中国现行规范设计了1个典型的组合楼盖钢框架原型结构，并从该原型结构中提取出两个单层2×1跨钢-混凝土组合楼盖子结构。分别开展了移除边中柱和角柱侧边柱两种工况下的足尺连续倒塌试验研究，并得到了相应的荷载-位移曲线、破坏模式、裂缝分布等。在移除边中柱时，破坏主要集中在梁端负弯矩区，且峰值荷载出现在梁悬链线抗力充分发展的大变形阶段。而在移除角柱侧边柱时，破坏主要集中在正弯矩区，峰值荷载出现在梁翼缘断裂前的抗弯阶段。两个试件后期承载力的差别主要由梁悬链线抗力引起。组合楼盖系统中楼板受拉薄膜作用的发展不易受边界水平约束条件的影响，但梁悬链线抗力的发展明显受边界水平约束条件的影响。在边柱失效工况下，塑性铰线法可以用来预测组合楼盖系统在抗弯阶段的承载力。

Progressive collapse tests and failure mechanism of large-scale steel-concrete composite floor system

To investigate the load-resisting mechanisms and failure process of typical steel-concrete composite frames under the progressive collapse scenario, two full-scale single-story two-bay by one-bay steel-concrete composite floor systems were quasi-statically tested. The tested floor systems were extracted from a prototype steel-concrete composite moment-resisting frame building, which was designed according to Chinese codes. Two column removal scenarios were considered, including the middle edge column removal scenario and the penultimate edge column removal scenario. The load-displacement responses,failure modes, and crack distributions of these tested floor systems were compared. For the middle edge column removal scenario, the damage is concentrated in the hogging moment region, and the ultimate capacity is achieved at the catenary stage. For the penultimate edge column removal scenario, the damage is concentrated in the sagging moment region, and the ultimate capacity is achieved at the flexural stage before the fracture of beam flange plate. The difference between the two specimens in ultimate capacity is mainly caused by the catenary action. The tensile membrane action developed in the composite floor system is insensitive to the horizontal boundary constraints, while the development of catenary action is highly affected by the horizontal boundary constraints. Under the edge column removal scenario, the yield line theory can be used to evaluate the load-carrying capacity of the composite floor system in the flexural stage.