火灾下钢筋混凝土双向板失效概率评估

Failure probability assessment of two-way reinforced concrete slab in fire

探究不确定性参数对火灾下钢筋混凝土双向板变形行为的影响.首先,建立火灾下钢筋混凝土双向板的有限元分析模型;然后,考虑钢筋强度、混凝土强度、板厚、保护层厚度、活荷载、钢筋截面面积和钢筋间距等7种主要不确定性参数,采用拉丁超立方体抽样与有限元模型相结合的随机有限元法,得到火灾下钢筋混凝土板的随机跨中挠度-受火时间曲线;接着,定义受火时间90,180 min和跨中挠度达到跨度的1/20为3个典型的性能点,并确定各性能点的概率分布特性;最后,采用龙卷风图法对不确定性因素在不同性能点的灵敏度进行了计算.结果表明:不确定性因素对钢筋混凝土板跨中挠度的影响较明显,其中活荷载、板厚的灵敏度较大;正态分布可以较好地描述3个性能点的概率分布特性.

The influence of uncertainty factors on the deformation behavior of reinforced concrete two-way slab in fire was explored.Firstly,a finite element analysis model of reinforced concrete two-way slab in fire was established.Secondly,a total of 7 kinds of main uncertainty factors were considered,such as steel strength,concrete strength,slab thickness,concrete cover,live load,steel bar section area and the bar spacing.The random finite element method combining Latin hypercube sampling and finite element model was used to obtain the random mid-span deflection-time curve of reinforced concrete slabs in fire.Then,three typical performance points were defined as duration time of 90 min and 180 min and mid-span deflection reaching 1/20 of span.The probability distribution characteristics of each performance point were determined.Finally,the sensitivity of uncertainty factors at different performance points was calculated by using tornado diagram method.The results showed that the influence of uncertainty factors on the mid-span deflection of reinforced concrete slab cannot be ignored.The sensitivity of live load and slab thickness is greater than others.Normal distribution can better describe the probability distribution characteristics of the three performance points.