中文摘要：

对62组混凝土标准立方体试块进行劈裂抗拉强度试验，考察受火温度、冷却方式、养护龄期及静置时间对高温作用后混凝土劈裂断面形态和抗拉强度的影响规律，并针对不同情况建议了高温作用后混凝土抗拉强度的计算式．结果表明：受火温度对高温作用后混凝土劈裂断面的破坏形态和抗拉强度影响很大．当受火温度在300℃以内时，劈裂断面较为平整；随着受火温度的提高，劈裂断面越来越粗糙，当受火温度超过600℃时，劈裂断面主要经过硬化水泥浆，断面处粗骨料未发生破坏．喷水冷却后，高温作用后混凝土的抗拉强度总体上比自然冷却后的低．养护龄期越短，高温作用后混凝土的抗拉强度越低．高温作用后混凝土的抗拉强度总体上随静置时间呈先下降后上升的发展趋势，且当静置时间为28d时，混凝土的抗拉强度最低．

英文摘要：

The splitting tensile strength of 62 groups of concrete standard cubic specimens was investigated. The effects of temperature, cooling mode, curing age and standing time on the failure pattern of splitting section and the tensile strength of concrete were discussed, and the related calculation formula of the tensile strength was proposed in different conditions. The results show that there is a great influence of temperature on splitting sectional failure pattern and tensile strength of concrete. The splitting section is smooth at the temperature 〈300℃, and becomes rougher at higher tempera- ture. When the temperature exceeds 600℃, the splitting occurs at the edge of coarse aggregates which are nearly undam- aged. The tensile strength of the concrete after fire with spray cooling is smaller than that with natural cooling. The shor- ter the curing age is, the lower the tensile strength of the concrete after fire. With an increase in standing time, the ten- sile strength of the concrete after fire decreases initially and then increases, the minimum strength locates at 28 days standing time