不同跨依次受火混凝土连续板试验研究及理论分析

为研究不同跨依次受火工况下混凝土连续板力学行为，对三块混凝土连续板进行火灾试验，分析不同跨受火顺序、受火时间间隔、配筋率和配筋方式等对试验板各跨温度、变形、板角约束力和破坏模式等影响规律；在此基础上，采用6种混凝土板极限承载力理论，对连续板各跨承载力进行计算分析。试验表明，每跨炉温及板截面温度分布主要取决于自身跨受火情况；不同跨受火工况和边界条件对连续板各跨跨中变形趋势、裂缝分布和破坏机理有重要影响，进而两边跨和中跨具有完全相反的跨中变形趋势，且中跨裂缝较多，易出现完整性破坏。此外，理论表明相比边界作用和受拉薄膜影响，不同跨受火工况及其配筋率对连续板各跨极限承载力变化趋势和数值有决定性影响。总之，对于任一火灾蔓延工况，提高配筋率和采用连续配筋方式有助于提高混凝土连续板各跨抗火性能。

Experimental study and theoretical analysis of concrete continuous slabs with different spans subject to fire in order

To investigate the mechanical behaviors of different spans subjected to fire in order, fire tests were conducted on three concrete continuous slabs. The influence laws of some parameters, such as the fire subsequences, time interval, reinforcement ratios and reinforcement layout, on the temperature, deflection, corners’ reaction forces and failure mode of the continuous slabs, were analyzed. In addition, the limit load-bearing capacity of each span in the continuous slabs were calculated and compared based on six theoretical methods. Experimental results show that the furnace temperature of each span and the temperature of slabs were mainly dependent on the self-furnace temperature. Meanwhile, the fire scenarios and the boundary conditions have important effects on the mid-span deflection trend, crack patterns and failure mechanism of the continuous slabs. The deflection trends in edge spans and middle spans were different. Compared to that of the edge spans, the cracks in the middle span were relatively more, and the integrity failure easily occurred in the middle span. Theoretical results show that compared to the effects of the boundary condition and the tensile membrane action, the fire sequences and reinforcement ratio have more critical effects on the limit capacities of different spans in the continuous slabs. In all, for any fire scenario, increasing reinforcement ratio and using the continuous reinforcement are beneficial to enhance the fire resistant performance of the concrete continuous slabs.