三跨连续板抗火性能的有限元分析

Numerical Analysis on Response of Reinforced Concrete Continuous Slab of Three-Span in Fire

采用有限元方法对三跨连续钢筋混凝土板局部受火和整体受火下的结构响应进行了数值模拟。结果表明,结构受火位置和受火范围不同时,产生的塑性区位置和范围不同,出现破坏铰的位置不同,但是经过模拟发现塑性区域都是在中间支座附近,破坏铰都是在负筋截断形成,因此结构的负筋长度对结构的耐火性能影响很大;结构在整体受火情况下由于整个结构绕塑性区的抬升作用,造成塑性区附近中跨的抬升,加温结束后整个中跨呈隆起形式,但是中跨局部受火时其中点始终产生向下的挠度,因此在局部受火与整体受火时结构的整体变形不同;在局部受火的时候,由于结构的整体作用使受火跨和未受火跨之间有很大程度的内力调整,这种内力重分布可以很好地提高结构的抗火性能,结构在局部受火的时候耐火性能比整体受火时好出很多。

The behaviors both in case of local span and whole span in fire were investigated by the finite element method.The result showed that： when the location of the fire was different,the location and scope of the plastic hinge were different, but in both cases the scope of plastic hinge appeared in the middle abutment;the destroy hinge appeared in the end of the negative moment reinforcement,so the length of the negative moment reinforcement had a significant effect on structural fire resistance;when the whole slab was fired,the middle span rose because of the whole structure′s plastic result and at last presented promontory,but when the slab was fired in local middle span the deflection of the middle span was descent always;when the structure was fired in local span there was a great degree of internal force adjustment,which could improve the fire resistance of structure,so the fire resistance of structure fired in local span was much better than the fire resistance of structure fired globally.