火灾下钢筋混凝土梁热力学性能演化试验及数值研究

Experimental and numerical study on evolution of thermodynamic properties of reinforced concrete beams under fire

为研究荷载状态、受火时间等对钢筋混凝土梁热力学性能的影响规律,设计10根T梁分别开展受火试验及静载试验。考虑混凝土高温爆裂、钢筋/混凝土粘结滑移退化等影响,采用Abaqus建立混凝土梁的数值分析模型,并与试验实测和理论计算结果进行对比分析,验证数值分析模型的可行性和合理性。研究结果表明:截面温度,跨中挠度分别随受火时间和荷载比的增大而逐渐升高,基频随受火时间增长呈波动式下降;数值模拟温度与实测温度基本吻合,抗弯承载力的模拟值比试验值稍高,但相对误差均小于10%;模拟频率曲线与实测频率的波动衰减趋势整体较为吻合。研究结果可为混凝土结构火灾损伤评估提供参考。

In order to study the influence of load state and fire exposure time on the thermodynamic properties of reinforced concrete beams,10 T-beams were designed for fire tests and static load tests,respectively.Considering the effects of concrete high-temperature spalling and bond-slip degradation between reinforcement and concrete,a numerical analysis model of concrete beam was established by Abaqus,and the feasibility and rationality of the numerical model were verified by comparison with the test and theoretical calculation results.The results show that the sectional temperature and mid-span deflection increase with the increase of fire exposure time and load ratio respectively.The fundamental frequency presents fluctuating decrease with the increase of fire exposure time.The numerical simulation temperature are in good agreement with those measured in the experiments.The simulated value of flexural capacity is slightly higher than the test value,but the relative error of both is less than 10%.The simulation frequency curve is in good agreement with the wave attenuation trend of measured frequency.The research results can provide reference for fire damage assessment of concrete structures.