火灾后混凝土结构损伤检测方法研究与探讨

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。

Study and Discussion on Inspection of Fire-damaged Concrete Structures

The influence of the elevated temperature and fire duration on material characteristics of concrete was studied in this paper.The damage along the vertical direction was examined by testing the splitting tensile strength layer by layer.Results show that the concrete mechanical properties,including compressive strength,tensile strength and elastic modulus,decrease sharply as temperature rises.Compressive strength and tensile strength decrease as fire duration increases.The results also show that the residual strengths for different fire durations are of great difference even treated with the same elevated temperature.The curves of strength along the depth show nonlinear presentation with short durations,while show linear presentation with long durations.Multiple transverse splitting method based on the core drilling method,and modified ultrasonic testing method which assumes that the damage model was hyperbolic and the propagation path of the head wave was parabola were presented for concrete testing.