大空间钢网架结构的性能化抗火分析

大空间钢网架结构常作为人员密集场所建筑的屋盖,火灾下一旦发生坍塌,将可能造成重大人员伤亡和财产损失,因此对其抗火性能有必要深入研究。本文运用FDS(Fire Dynamics Simulator)火灾模拟软件对某工业厂房进行火灾模拟,得到火灾发生发展的时间—温度曲线。在此基础上,运用ANSYS有限元软件对火灾下网架结构的不同位置进行了热—力耦合的位移和内力分析。结果表明,采用计算机模拟得到的升温曲线,要比一概采用ISO834标准求得的升温曲线更符合实际情况;火灾发生在中间位置更为不利,必须采取防火保护措施;火灾下结构会发生内力重分配,但距离火源越远处的杆件内力和位移变化越小。本文结论可供该类型结构的抗火设计和灭火救援参考。

Analysis on Fire-resistance of Large-space Grid Structures of Steel

A large-space grid structure of steel is often used as a roof of a building with a dense occupation. Once the structure collapsed,it may cause heavy casualties and property losses.Therefore,it is necessary to launch further research on its performance of fire-resistant.In this paper,a fire simulation of the facto- ry workshop was carried out with FDS to obtain the time-temperature curves.On this basis,the coupled thermo-mechanical system was analyzed with the finite element software ANSYS,which can supply the in- ternal forces and displacements of a grid structure when fire occurred in different places.The results indi- cate:temperature field calculated with the computer simulation is more consistent with the real situation than with the ISO834 standard heating curve.A fire occurred in the middle of the structure is more dan- gerous than one on the edge of the structure.When some bars yield or retreat to work,the stresses will be redistributed in the whole structure,the farther away from the fire source,the less the variation of bar stress.Conclusions in this paper could offer a useful reference for future fire-resistance designs and rescue of this type of structure.