飞机撞击引起爆炸-火灾后建筑坍塌过程模拟

为了解飞机撞击超高层建筑后致使建筑坍塌或倾倒过程,基于颗粒流理论进行了该过程模拟,包括飞机撞击、油箱爆炸、火灾和建筑坍塌过程。模拟分4个阶段:初始至撞击、撞击至油箱爆炸、爆炸至火灾、建筑坍塌至结束。引入了颗粒流爆炸模型和考虑钢混等效结构的火灾模型。分别在建筑高程250 m和100 m处实施了撞击模拟。结果表明,不同的撞击高度所造成的建筑破坏效果和过程有同有异。共同点是飞机的撞击并不是建筑破坏的直接原因。飞机油箱爆炸破坏了外围框架,也造成核心筒结构的损伤,因此爆炸是建筑破坏的起因。不同点是250 m撞击时爆炸引起的火灾加速了上部建筑的倾倒,但最终撞击处下部建筑结构仍完整,这个过程时间较长。100 m时火灾几乎未起到任何助力坍塌的作用,建筑便已经开始不可逆的坐塌过程,该过程时间较短。

Simulated study on the collapse process of the high-rise buildings under the aircraft impact after the busting fire-flame

The paper is intended to present its simulated modeling of the collapse process of the high-rise building as a result of the aircraft impact,like those in the 9/11 terrorist attacks,based on the PFC3D of the particle flow theory,including:the aircraft crash,the fuel tank burst,the fire flame puffing and the process leading to the building collapse.The simulation can be divided into four stages,that is,the initial stage of impact by hitting;the hit leading to the fuel tank explosion;the explosion to the fire;and the building collapse due to the violent shocking and vibration.While introducing to the particle splitting explosion model and considering the steel structure fire-bursting types,we have decided to proceed with the bumping simulated explosions at the two heights,respectively,that is,at the heights of 250 m and 100 m.The high-rise building of the frame-core tube is simulated as a height of 480 m.The results of our simulation indicate that:the destructive damages of the building and the process are various because the impacts took place at the different heights.It is common that the aircraft impact on the building may not account for the destruction of buildings.Rather,it is the explosion of the aircraft fuel tank that has destroyed the peripheral frame of the building,and then damaged the structure of the heart-core tube,which makes the building tilted,and leads to the vibrations of the core tube stress center,which may bring about further compression damages of the core tube components.The serious bumping impact of the upper part of the high-rise construction has now been tending to tilt further,eventually resulting in the building collapse.Therefore,the explosion serves merely as the original cause to lead to the destruction of the high-rise building,whereas the other points,the fires that are caused by the explosion that took place at the 250 m height has accelerated or pushed up the dumping of the upper part of the structure,and eventually toppled.down the lower parts of the building bit by bit with the process of the collapse going on much longer.Thus,it can be seen that the fire at about the height of 100 m didn't make any contribution to the collapse of the building,for it has already begun to be irreversible in the base collapse process,which takes place very shortly.The simulation program can thus be expected to roughly embody the destructive process after the aircraft hit the building in the same way as that of the 9/11 terrorist attack.