高温后静置混凝土力学性能试验研究

混凝土经高温、冷却并静置若干时间后,其主要力学性能指标将随着静置时间发生变化。本文综合考虑受火温度、冷却及养护方式和静置时间等因素的影响,通过大量试验,研究了高温后静置混凝土的抗压强度、弹性模量和应力-应变关系等力学性能随上述各因素的变化规律,给出了各力学指标的拟合回归公式,分析了高温后静置混凝土抗压强度达最低值的时间,提出了混凝土结构火灾后实施补强加固的合理时间。高温后静置混凝土的力学性能变化明显,为火灾后建筑结构的鉴定提供了理论依据。

Experimental study on mechanical properties of long standing concrete after exposure to high temperature

After high temperature, cooling and then standing for a certain length of time, the main mechanical properties of concrete will be changing along with standing time. Based on a lot of tests, in consideration of the influential factors, including fire temperature,cooling, curing process and standing time etc., the regularities of variation of compressive strength, elastic modulus and stress strain relationship of standing concrete along with above mentioned factors were studied. The empirical formulas, which can be easily used for predicting mechanical indexes, are given by regression on the test results. The standing time corresponding to lowest compressive strength of standing concrete after high temperature had been analyzed. The proper time for strengthening concrete structure after fire is suggested. The study shows that the mechanical properties of the concrete have obvious transformation, and the study results offer a theoretic basis for appraisement of concrete structure after fire.