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研究了火场最高温度、持续时间对混凝土材性的影响,采用逐层深入-劈拉法研究了沿深度方向的不同损伤情况。研究表明,混凝土力学性能,包括抗压强度、抗拉强度、弹性模量等,随温度升高而显著降低;抗压强度、抗拉强度均随持续时间的增长而下降。逐层深入-劈拉法试验表明,在最高受火温度基本相同的情况下,残余强度随受火时间不同而有较大的差别;受火时间短的试件强度曲线呈明显的非线性,而受火时间长的试件强度曲线则趋于线性。对于火灾后混凝土构件的检测,在钻芯法的基础上提出了多次横向劈拉法;基于混凝土受损趋势为双曲线模型的假定,提出了首波传播路径为抛物线的改进超声波检测法。
The influence of the maximum temperature and duration of fire on the concrete material properties was studied. The different damage along the depth direction was studied by layer-by-layer depth-splitting method. The results show that the mechanical properties of concrete, including compressive strength, tensile strength and elastic modulus, decrease with the increase of temperature. The compressive strength and tensile strength decrease with the increase of duration. The layer-by-layer depth-split test shows that the residual strength varies greatly with the fire time under the condition that the maximum fire temperature is basically the same. The strength curve of the specimen with short fire time is obviously nonlinear, However, the strength curve of the specimens exposed to fire for a long time tends to be linear. Based on the core drilling method, several times of transverse splitting method are proposed for the detection of concrete components after fire. Based on the assumption that the concrete damage trend is hyperbolic model, an improved ultrasonic detection method is proposed, in which the propagation path of the first wave is a parabola.