冻融损伤混凝土重复受压本构关系

摘要

In this paper, accelerated freeze⁃thaw tests and repeated loading tests on C40 and C50 concrete specimens were introduced to study the effects of freeze⁃thaw cycles on the mechanical performance of concrete under dynamic load. The test results showed that the mechanical performance of freeze⁃thaw damaged concrete under repeated loading decreased significantly and the characteristic curves of dynamic constitutive relation changed distinctly after freeze and thaw, the enveloping line and reloading curves before stress peak exhibited a concave shape due to the compaction effects, the strain hysteresis of unloading curve became more serious and the unloading curves tended to coincide gradually as the freeze⁃thaw cycles increased. The relationships between freeze⁃thaw cycles, strength grades of concrete and the characteristic value of stress⁃strain curve including mechanical properties parameters and constitutive model parameters were also studied to establish a dynamic constitutive relation for concrete with freeze⁃thaw damage.%为研究冻融损伤对混凝土重复受压力学性能的影响，完成了两种强度等级混凝土试块的快速冻融及重复受压试验。结果表明，冻融损伤混凝土重复受压力学性能显著降低，动力本构特征曲线也发生改变，包络线及再加载曲线在峰值应力之前因存在明显压实效应而表现出下凹形态，卸载曲线应变滞后现象严重且曲线逐渐趋于重合。在试验研究基础上，探讨了冻融循环次数、混凝土强度等级与冻融后混凝土力学性能参数及本构模型参数之间的关系，建立了冻融损伤混凝土动力本构模型。