火灾下大空间铝合金网架受力性能

针对铝合金空间结构抗火性能较差的问题,以正放四角锥铝合金空间网架为对象,基于实用大空间建筑火灾空气升温经验模型模拟火灾温度场,采用增量法对各构件的温度进行计算,利用ANSYS WORKBENCH构建铝合金网架遭受火灾温度场的有限元模型,研究铝合金网架在火灾下不同时间段的受力效应和变形特征;并利用有限元的手段,对比分析了铝合金网架和Q355普通钢网架在火灾下的受力性能。研究结果表明:铝合金网架在火灾升温60 min时温度达到峰值,最大温度应力主要集中在角部支座附近,其变形特征为整体向上起拱;铝合金网架从角部杆件发生局部破坏,随后造成整体变形过大而导致整个网架的坍塌破坏;铝合金网架在常温下受力性能优于Q355普通钢网架,但火灾下受力性能劣于Q355普通钢网架,工程实践中应根据结构的使用功能合理选择结构的材料。

Research on the Mechanical Performance of Large-space aluminum alloy truss under fire

For aluminum alloy space structure fire resistance poor problem, is to put four pyramid aluminum space frame as the object, based on practical experience model to simulate the large space building fire air warming fire temperature field, the increment method is adopted for calculation, the temperature of the components using ANSYS WORKBENCH builds finite element model of aluminum alloy grids by fire temperature field and the aluminum alloy frame under fire effect of different periods of stress and deformation characteristics; By means of finite element method, the mechanical properties of aluminum alloy grid and Q355 ordinary steel grid under fire are compared. The results show that the temperature of the aluminum alloy grid reaches its peak when the fire temperature rises for 60 minutes, and the maximum temperature stress is mainly concentrated near the corner support, and its deformation characteristics are overall upward arching. The partial failure of the aluminum alloy grid is caused by the corner bar, and then the overall deformation is too large, which leads to the collapse of the whole grid. The mechanical performance of the aluminum alloy grid is better than that of the Q355 ordinary steel grid at normal temperature, but worse than that of the Q355 ordinary steel grid under fire. In engineering practice, the materials of the structure should be reasonably selected according to the use function of the structure.