计算结果说明，世界贸易中心倒塌的直接原因是火灾导致的钢材软化和楼板塌落冲击荷载引起的连锁反应。

The numerical results also show that the softening of steel under fire and impact load of top floors are the two main reasons for the collapse.

youdao

计算结果说明，世界贸易中心倒塌的直接原因是火灾导致的钢材软化和楼板塌落冲击荷载引起的连锁反应。

The numerical results also show that the softening of steel under fire and impact load of top floors are the two main reasons for the collapse.

youdao