带上盖物业地铁车辆段盖板结构耐火性能研究

摘要

Through the investigation of codes and engineering cases, the fire endurance limit and the design measures of the main components of the cover plate upon metro depot were determined. Based on the thermal elasto-plastic constitutive model, a nonlinear element analysis program was developed to numerically simulate the transient temperature field and the mechanical behavior of the most unfavorable slab and beam in the cover plate structure. The calculation results show that the design measures of the beam and slab of the cover structure could meet the requirements of 3.00 h fire resistance. According to the comparative study of the thermal stress and deformation of the two-way slab and unidirectional slab under fire, the relationship between the membrane effect and the length-width ratio was obtained. By regression analysis, the relationship curve between the temperature rise of the unexposed surface and the thickness along the direction of temperature gradient is proposed and the minimum thickness of the cover plate is defined. The results could provide reference for the fire protection design of this kind of structure.%通过对规范和工程案例的研究,确定地铁车辆段盖板结构主要构件的耐火极限及设计措施.基于热弹塑性本构模型编制非线性有限元分析程序,对钢筋混凝土盖板结构中的最不利楼板和主梁的瞬态温度场以及火灾下的力学行为进行数值模拟,计算结果验证了盖板结构中的梁和楼板的设计措施能够满足3.00 h耐火极限的要求.对比研究火灾下双向板与单向板的温度应力和高温塑性变形,得出薄膜效应的特征与板件长宽比的关系.通过回归分析,提出受火3.00 h时背火面温升与沿温度梯度方向厚度的关系曲线,明确盖板结构厚度最小取值.研究结果可为此类结构的防火设计提供参考.