高温环境下钢筋混凝土结构温度传播规律研究

Study on the Pattern of Temperature Propagation of Reinforced Concrete Structure under High-Temperature Environment

高温环境下钢筋混凝土结构的力学性能会出现不同程度降低,严重影响结构的使用寿命,而钢筋混凝土结构内的温度分布规律是分析构件抗火性能和维修加固的依据。鉴于此,文章依托成都市某装配式隧道工程,基于该隧道工程钢筋混凝土衬砌实际情况,采用室内耐火试验,研究高温环境下钢筋混凝土结构内温度传播规律。根据室内试验成果,采用数值模拟方法对混凝土相关热工参数进行优化,获得更适合于工程实际的数值模拟参数,并对实际工程装配式隧道进行热力耦合分析。研究结果表明:(1)单面受火条件下,钢筋混凝土梁距离受火表面越近,升温速率越快温度越高;(2)基于有限元方法修正导热系数计算公式,可为仿真计算参数选取提供参考;(3)顶板与中墙、侧墙相连接的边角处易产生热应力集中,对结构损伤较大,在隧道防火设计时应考虑加强。

The mechanical properties of reinforced concrete structures under high-temperature environment will be reduced to different degrees,seriously affecting the service life of the structures,however the temperature distri⁃bution pattern within the reinforced concrete structures is the basis for the analysis of the fire resistance of the com⁃ponents as well as for repair and reinforcement.In view of this,this paper carries out the indoor fire test to study the temperature propagation pattern within reinforced concrete structures under high-temperature environment based on the actual condition of the reinforced concrete lining of a prefabricated tunnel project in Chengdu.According to the indoor test results,this paper uses the numerical simulation method to optimize the concrete-related thermal pa⁃rameters and obtains numerical simulation parameters more suitable for actual project condition,and also conducts a thermal coupling analysis on the prefabricated tunnel.The study results show that:(1)under single-sided fire con⁃dition,the closer a reinforced concrete beam is to the fire surface,the faster the heating rate and the higher the tem⁃perature will be;(2)the calculation formula of thermal conductivity is modified based on the finite element method,providing a certain level of reference for the selection of parameters for simulation calculation;(3)at the corners be⁃tween the roof and the middle wall,sidewall it is prone to thermal stress concentration,which will cause greater dam⁃age to the structure and should be considered for strengthening in the tunnel fire protection design.