火灾可能导致高层混凝土结构倒塌么？

火灾可能导致高层混凝土结构倒塌么？这是一个很受关注的问题。

我们最近的研究结果表明，想引起高层混凝土结构火灾倒塌，其实难度还是蛮大的。新论文：

Progressive collapse analysis of a typical super-tall reinforced concrete frame-core tube building exposed to extreme fires 

Fire Technology, 2016. DOI: 10.1007/s10694-016-0566-6

图a 分析对象超高层建筑

图b 倒塌破坏模式

图c 倒塌机理

图d 内力重分布机制

Abstract: A number of disastrous incidents have indicated that extreme fires can act as a trigger event to initiate the progressive collapse of reinforced concrete (RC) structures. Hence, research on progressive collapse risks of RC structures under extreme fires is most important. However, limited studies have been undertaken in the fire-induced progressive collapse of tall and super-tall RC buildings. Hence, a high-performance finite element (FE) model was developed for this study to simulate the mechanical behavior of RC members in fire-induced progressive collapse. Fiber beam and multi-layer shell elements were used, in conjunction with appropriate material constitutive laws and elemental failure criteria under high temperature conditions. Extreme fire scenarios were also considered, based on the actual fire-induced progressive collapse events of the WTC towers and the Windsor Tower. The simulation results indicated that a progressive collapse of a super-tall building was triggered by the flexural failure of the peripheral columns, approximately 7 hours after being exposed to fire. The bending deformations of the peripheral columns increased significantly, due to the outward thermal expansion of the upper floors and the inward contraction of the lower floors, a result of the fire-induced damage. The results also revealed that, when multiple stories are subjected to fire, the internal forces in the components are redistributed in the horizontal and vertical directions by way of the Vierendeel truss mechanism, leading to a maximum increase (of approximately 100%) of the axial forces in the columns. The present work identified the mechanisms of the fire-induced progressive collapse of a typical RC super-tall building, and provided an effective analysis framework for further research on the fire safety of tall and super-tall RC buildings.

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