箱板装配式钢结构火灾下的热力耦合响应分析

Thermo-Mechanical Coupling Response Analysis of PrefabricatedBox-Plate Steel Structures Under Fire

通过建立箱板装配式钢结构的热力耦合分析模型,计算得到了整体结构在火灾下的热力学响应,并对关键构件和关键测点进行力学响应分析,结合箱板式钢结构的结构特点,探明了箱板装配式整体结构在火灾下的破坏模式,并得到了7种火灾场景下的耐火极限。研究表明:对于一层结构,火源位置是影响其耐火极限的主要原因,火源位于中心时,板的中面屈服后产生薄膜应力可提供屈曲后强度,有效提升了耐火时间,火源位于墙板附近时,结构因受力不均,应力重分布后墙板承受过大的应力,导致耐火时间大大降低;对于三层结构,火源位于结构中间楼层时耐火时间会缩短,火源位于中心位置时也会更早达到耐火极限。各工况下耐火时间达到了1 000 s以上,各方向最大位移处无明显突变,表明箱板装配式钢结构具有刚度大、耐火性能和整体性能优良的特点。

By calculating the thermo-mechanical coupling analysis model of prefabricated box-plate steel structures,the thermodynamic response was obtained,and the mechanical response analysis of key members and key measuring points was carried out.Combined with the structural characteristics of the prefabricated box-plate steel structure,the failure mode of the structure under fire was proved,and the fire resistance limit of seven fire scenarios was obtained.The results showed that,in single-story structure,the location of fire sources had a great impact on the fire resistance endurance,and when the fire source was in the center,the film stress produced after the middle surface yield of the plate could provide the post buckling strength,which effectively improved the fire resistance time.When the fire source was near the wall,the structure was under uneven and redistributed stress,and the wall bore too much stress,which caused a great reduction of fire resistance time.For a three-story structure,the fire resistance time would be shortened when the fire source was at the bottom,which would achieve earlier when the fire source located in the center position.The fire resistance time of each working condition had reached more than 1000 s,and there was no obvious mutation at the maximum displacement in each direction.The prefabricated box-plate steel structure showed great stiffness,excellent fire resistance and superior overall performances.