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一、前言 在九江长江大桥钢筋混凝土箱形梁和郭溪桥钢筋混凝土柔性墩的温度应力试验研究中,需要混凝土材料的热膨胀系数。为此,我们于1981年6月在混凝土试件表面粘贴普通电阻应变片,用低膨胀材料石英玻璃作为补偿以测量热膨胀,用铜—康铜热电偶测量温度,从而求得混凝土在10°～60°C范围内的热膨胀系数α值。在这之前,还曾采用在混凝土试件内部埋设差动电阻式应变计测量热膨胀的方法,为室内二个混凝土自由板的温度应力模型试验测定过混凝土材料的热膨胀系数。由于差动电阻式应变计价钱较贵,且不能重复使用,故改用
I. Introduction In the temperature stress experiment of reinforced concrete box girder of Jiujiang Yangtze River Bridge and GuoXiQiao reinforced concrete flexible piers, the thermal expansion coefficient of concrete material is needed. To this end, in June 1981 we pasted ordinary resistance strain gauges on the surface of concrete specimens, quartz glass with low expansion material as compensation to measure thermal expansion, with copper - Kang Tong thermocouple temperature measurement, so as to obtain concrete at 10 ° ~ 60 ° C within the range of thermal expansion coefficient α value. Prior to this, the method of measuring the thermal expansion by laying a differential resistance strain gauge inside a concrete specimen was also used to determine the thermal expansion coefficient of the concrete material for the thermal stress model test of two concrete free plates in the room. As the differential resistance strain gauge expensive, and can not be reused, it switched