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为了解超高层建筑发生火灾后变形特征及失稳后的非连续坍塌过程,掌握引起变形和坍塌的原因,将三维颗粒流软件(PFC3D)作为模拟平台,设置核心筒-框架结构的超高层建筑火灾区域,并模拟坍塌过程。在考虑钢筋和混凝土共同作用结果的基础上,提出火灾区域中构件属性设置方法及模拟步骤。分析得到造成建筑结构摆动的3种原因,一是火区位置不同导致上部结构对火区的压力不同,二是火区位置不同导致结构受到的约束不同,三是受热膨胀性使构件产生不同程度变形。结果表明:燃烧温度为500℃,3 h后建筑发生摆动,表现出对火区位置和燃烧时间敏感的特征。1 000℃下1 h内,建筑物首先发生破坏的是梁构件,然后是承重柱。即建筑一旦进入结构破坏阶段,坍塌将是迅速且不可逆的。
In order to understand the post-fire deformation characteristics and instability of non-continuous collapse process in super high-rise buildings and to understand the causes of deformation and collapse, three-dimensional particle flow software (PFC3D) was used as a simulation platform to set up the core tube- Fire zone and simulate the collapse process. On the basis of the result of the interaction between steel bar and concrete, the setting methods and simulation steps of component attribute in fire area are proposed. Three kinds of causes of building structure swinging are analyzed. One is that the pressure of the upper structure is different to the fire area due to the different location of the fire area. The other is the different restraint of the structure caused by the different location of the fire area. Thirdly, Deformation. The results show that the building oscillates at a combustion temperature of 500 ℃ for 3 h and shows the characteristics of the fire area in terms of location and combustion time. Within 1 h at 1000 ° C, the first failure of a building is a beam member followed by a load-bearing column. That is to say, once the building enters the stage of structural destruction, the collapse will be rapid and irreversible.