基于频率的混凝土构件火灾损伤检测

Fire damage detection of concrete members based on frequency

火灾后混凝土构件残余力学性能的评估一直是火灾损伤检测中的难题。现有的检测方法多是针对受火后混凝土材性层面的损伤,缺乏对混凝土结构或构件层面的力学性能的评估。在借鉴相关研究成果的基础上,本文将建筑物频率变化的检测方法运用于火灾后混凝土构件的损伤评测,进行了4根混凝土连续梁的ISO834标准升温受火试验,检测、记录受火前后构件的频率变化,并进行了混凝土连续梁的承载力试验。试验结果表明,受火后混凝土构件的频率显著下降,并与构件力学性能之间存在明显的相关性,说明这种基于频率的检测方法能够有效地评估火灾后混凝土构件的损伤。

Evaluating the residual mechanical properties of concrete members after fire has always been a difficult problem in fire damage detection. Most of the current measuring methods are concentrated on detecting the changes of concrete material performance,but lack of the test of the mechanical properties of structural members. Based on the related research and results,this paper applies the measuring method of buildings＇ frequency to the fire damage detection of concrete members. 4 reinforced concrete continuous beams were constructed and tested under IS0834 standard fire. The frequencies of these beams were measured and recorded before and after the fire. Additionally,the bearing capacity tests of the beams were carried out after cooling. The result shows that the frequency of concrete members had a significant drop after fire,and this decrement is related obviously to that of the mechanical property. Thus it can be concluded the detection method based on frequency can effectively evaluate the damage of concrete members after fire.