Abstract Thirty-two uncracked shear-friction specimens were tested to investigate the effect of elevated temperatures on the shear-friction behaviour of concrete. Exposure temperature and the shear reinforcement were the principal variables. Specimens were exposed to high temperatures of 350 °C, 550 °C, and 750 °C in a programmable insulated closed electric furnace and were cooled down to room temperature before testing. Shear-friction specimens were also tested at the ambient temperature. Exposure of shear-friction specimens to high temperatures resulted in the decrease of shear strength of concrete. An increase in shear reinforcement reduced the loss in shear strength when specimens were subjected to high temperatures. The post-ultimate strength of the specimens was not reduced up to an exposure temperature of 550 °C. After experiencing high temperatures, crack slip and crack width at the shear plane increased significantly at all the load levels. Two simple approaches, modified Zia failure analysis and a simple calculation method (SCM) were also suggested for the prediction of shear strength of concrete after high temperatures. Modified Zia failure analysis provided precise estimates of shear strength for all the temperature levels. SCM was found to be precise for shear strength predictions up to an exposure temperature of 550 °C. For an exposure temperature of 750 °C, SCM was found to be unconservative by 20–30%.

中文翻译：

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高温对混凝土剪切摩擦性能的影响：实验和分析研究

摘要 测试了 32 个未开裂的剪切摩擦试件，以研究升高温度对混凝土剪切摩擦行为的影响。暴露温度和抗剪钢筋是主要变量。试样在可编程绝缘封闭电炉中暴露于 350°C、550°C 和 750°C 的高温下，并在测试前冷却至室温。剪切摩擦试样也在环境温度下进行了测试。剪切摩擦试件暴露在高温下会导致混凝土的剪切强度降低。当试样经受高温时，抗剪强度的增加减少了抗剪强度的损失。试样的最终强度在高达 550 °C 的暴露温度下并未降低。经历高温后，剪切面的裂纹滑移和裂纹宽度在所有载荷水平下均显着增加。还提出了两种简单的方法，即修正的 Zia 破坏分析和简单计算方法 (SCM)，用于预测高温后混凝土的剪切强度。修正的 Zia 失效分析提供了所有温度水平下剪切强度的精确估计。发现 SCM 可精确预测高达 550 °C 的暴露温度的剪切强度。对于 750 °C 的暴露温度，发现 SCM 不保守 20-30%。还提出了改进的 Zia 破坏分析和简单计算方法 (SCM)，用于预测高温后混凝土的剪切强度。修正的 Zia 失效分析提供了所有温度水平下剪切强度的精确估计。发现 SCM 可精确预测高达 550 °C 的暴露温度的剪切强度。对于 750 °C 的暴露温度，发现 SCM 不保守 20-30%。还提出了改进的 Zia 破坏分析和简单计算方法 (SCM)，用于预测高温后混凝土的剪切强度。修正的 Zia 失效分析提供了所有温度水平下剪切强度的精确估计。发现 SCM 可精确预测高达 550 °C 的暴露温度的剪切强度。对于 750 °C 的暴露温度，发现 SCM 不保守 20-30%。