火灾全过程作用下钢-混凝土组合楼盖力学性能有限元研究

Research on mechanical behavior of steel-concrete composite slabs exposed to overall stage fire

为分析火灾全过程作用下钢-混凝土组合楼盖的力学性能,利用有限元分析软件ABAQUS,合理选取钢材和混凝土材料本构模型,并考虑不同构件之间相互接触等基础上,建立了考虑火灾和荷载共同作用下的钢-混凝土组合楼盖热-力耦合有限元模型,并与现有相关试验数据进行了模型验证。在此基础上,对经历常温、火灾升温、降温作用以及火灾后等不同阶段的组合楼盖受力性能和工作机理进行了研究,并对影响火灾全过程作用后钢-混凝土组合楼盖力学性能的影响因素进行了分析。分析结果表明:火灾高温作用使得组合楼盖的承载力相对于常温下有所降低,由于组合楼板的吸热作用,整个楼盖温度较低,受火后仍然具有较高的承载力;火灾升温时间比、钢梁的屈服强度、混凝土抗压强度和板厚度对火灾全过程作用后钢-混凝土组合楼盖的力学性能影响较显著。

In order to properly analyze the mechanical behavior of steel-concrete composite slabs exposed to overall stage fire,using the finite element software ABAQUS,on the basis of reasonable selection of material constitutive models of steel-concrete composite slabs and the contact modeling among different components,the steel-concrete composite slab thermal-mechanical coupled finite element model was established.Some existing tests results were also used to verify the proposed finite element model.The performance and the working mechanism of steel-concrete composite slabs were analyzed at room temperature,fire temperature,cooling effect,and the combination of the different stages of the fire and parametric analysis was performed to investigate the mechanical behaviors of steelconcrete composite slabs after exposure to overall stage fire.The results show that the ultimate bearing capacity of composite slabs decreases relative to the room temperature because of the high temperature.Due to the endothermic action of composite slabs,the temperature of the entire slabs is lower and the composite slabs still have a high bearing capacity after fire;heating time ratio,the yield strength of steel beams,the concrete compressive strength and the thickness of the concrete have great influence on the mechanical behavior of steel-concrete composite slabs after exposure to overall stage fire.