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已有的混凝土受热力学性能研究重点集中于500℃以上的高温区段,小于500℃的亚高温区段的混凝土强度则直接按常温处理,这不符合实际温度作用的受力情况。长期处于亚高温作用下的混凝土结构也需要了解其材料受力性能的变化规律。通过亚高温区段混凝土的受压强度试验,考察了不同亚高温及温度持续时间对其的影响。结果表明,不同温度持续时间的混凝土受压强度随温度升高的变化趋势相似,在100～250℃波动较大,且在100℃附近形成一个强度的低谷,250℃后则呈急剧下降趋势。而当试件温度分布均匀后,温度持续时间对混凝土受压强度的影响很小。通过试验还给出了亚高温下混凝土受压强度的计算公式。
The existing research on the thermomechanical properties of concrete focuses on the high temperature above 500 ℃. The concrete strength in the sub-high temperature range of less than 500 ℃ is directly treated at room temperature, which is not consistent with the actual temperature. Long-term under the action of sub-high temperature concrete structure also need to understand the changing law of its material properties. Through the compressive strength test of sub-high temperature concrete, the effects of different sub-high temperature and temperature duration were investigated. The results show that the compressive strength of concrete with different temperature duration tends to change with increasing temperature, fluctuating between 100-250 ℃, forming a trough of strength near 100 ℃, and dropping sharply after 250 ℃. When the specimen temperature distribution is uniform, the temperature duration has little effect on the compressive strength of concrete. The compressive strength of concrete under sub-high temperature is also given through the test.