地铁车辆基地盖板耐火性能数值模拟

Numerical simulation study on fire resistance of slab in metro vehicle base

为提高土地利用效率,地铁车辆基地顶部进行上盖物业开发已成为一种趋势。地铁车辆基地与上盖物业之间的分隔盖板耐火极限要求至少为3.0 h,而相关规范中没有关于盖板3.0 h耐火极限的设计方法。利用有限元分析软件ABAQUS,研究了在标准火灾条件下盖板配筋率、厚度和含水率对盖板温度分布的影响,并研究了钢筋保护层厚度和荷载比对盖板耐火极限的影响。结果表明:配筋率对盖板温度分布影响较小;不同厚度盖板的温度在传递到背火面之前,沿厚度方向的温度分布一致;温度传递到背火面后,改变了背火面边界的换热状态,使背火面附近温度升高并向受火面反馈;盖板越厚,背火面温度越低;随盖板含水率增大,盖板内部温度降低;根据温度分布规律提出了盖板温度分布预测模型,与有限元分析结果吻合较好;盖板满足3.0 h隔热耐火极限要求的厚度不小于170 mm;底筋保护层厚度越大,荷载比越小,盖板耐火极限越大。给出了不同保护层厚度、不同荷载比条件下车辆基地盖板的耐火极限,为地铁车辆基地盖板3.0 h耐火极限设计提供了参考。

To improve the efficiency of land use,the development of the superstructure on the top of the metro depots has become a trend.The fire-resistance rating of the separated floor slab between the metro depot and the superstructure is at least 3.0 h,and there is no design method for the 3.0 h fire-resistance limit of the floor slab in the relevant codes.In this paper,ABAQUS finite element analysis software,the effects of a fire under standard conditions floor slab reinforcement ratio,thickness and moisture content of the slab temperature distribution,and the effects of protective layer thickness and the load ratio of the floor slab fire resistance.The results show that the reinforcement ratio has little effect on the temperature distribution of the floor;The temperature of floor slabs of different thicknesses has the same temperature distribution along the thickness direction before being transferred to the side unexposed to fire;After the temperature is transferred to the side unexposed to fire,the heat transfer state of the boundary of the side unexposed to fire is changed,and the temperature near the side unexposed to fire rises and feeds back to the side exposed to fire;With the increase of floor slab thickness,the temperature of the side unexposed to fire becomes lower;With the increase of the moisture content of the floor slab,the internal temperature of the floor slab decreases;According to the temperature distribution law,a prediction model for the temperature distribution of the floor slab is proposed,which is in good agreement with the results of the finite element analysis;the thickness of the floor slab meeting the 3.0 h heat insulation and fire resistance limit requirement is not less than 170 mm.The greater the cover thickness of the bottom is,the smaller the load ratio is,and the greater the fire resistance limit of the floor slab is.The fire resistance limit of the vehicle base under the conditions of different cover thickness and different load ratios is given,which provides a reference for the 3.0 h fire-resistance limit design of the subway vehicle base.