薄壁钢-轻质混凝土组合楼板的受火后力学性能及评估模型研究

对5块内置钢骨架的轻集料混凝土组合楼板在火灾后的受力性能进行了试验研究,并基于试验结果给出了火灾后组合楼板综合承载力的评估模型。结果表明,该组合楼板在火灾作用后仍具有较高的剩余承载力和整体刚度,其主要影响参数包括轻骨料混凝土预制板中的配筋数量、受火时的荷载分布方式与荷载值以及火灾升温后所采用的冷却方式。受火时组合楼板试件中钢骨架主、次构件正上方的混凝土表面首先出现裂缝,且火灾后加载时进一步发展。火灾下均匀堆载的组合楼板试件的名义刚度较局部堆载的试件刚度提高18.5%;采用人工喷淋冷却方式较之自然冷却,其火灾后组合楼板试件静载试验的残余位移增大23.9%;所建立的综合指标模型可用于评估火灾后组合楼板试件的综合承载力。

Study of post-fire mechanical performance and evaluation model of thin-walled steel-lightweight concrete composite slab

Based on the static test results of five lightweight aggregate concrete composite floors after fire,the evaluation model of the post-fire comprehensive bearing capacity of the slab specimens after fire is given.The results show that the composite slab still has high residual bearing capacity and overall stiffness after fire,and its main effect parameters are the number of reinforcement in the lightweight aggregate concrete precast slab,the load distribution mode and load value in case of fire,and the cooling mode adopted after fire temperature rise.The test results show that the concrete surface rightly above the main and secondary components of the steel frame in the composite floor specimen cracks first in fire,and further develops in post-fire loading test.The post-fire nominal stiffness of the composite floor specimens after fire for the uniformly distributed load in fire is 18.5%higher than that for the locally distributed load near center area of the specimen;the residual displacement of the composite floor after fire caused of static loading is increased by 23.9%by artificial spray cooling compared with natural cooling;the post-fire comprehensive index model presented here can be used to evaluate the comprehensive bearing capacity of the composite floor after fire.