冻融循环作用下混凝土的受拉本构特征

Experiment of tensile constitutive characteristics of concrete after freeze-thaw cycles

为了得出冻融循环作用下混凝土受拉应力-应变关系曲线上升段方程,对经过0,25,50,75,100,125次冻融循环的4个不同强度等级的普通混凝土抗拉试块进行了试验研究,结合现有普通混凝土受拉本构关系,建立了冻融循环次数、混凝土等级与混凝土受拉本构特征的关系.试验结果表明:随着冻融循环次数增加,混凝土的受拉应力-应变关系曲线上升段渐趋平缓,受拉峰值应力、受拉峰值应变降低,变化关系近似线性;冻融循环次数相同时,混凝土强度等级高的试件受拉峰值应力、受拉峰值应变降低程度小于混凝土强度等级低的试件,但下降速度没有明显变化.

In order to obtain tensile stress-strain curve and formula of rising part for concrete after freezethaw cycles, samples with four strength grades were subjected to uniaxial tensile experiment after 0, 25, 75, 100 or 125 freeze-thaw cycle times. Based on normal tensile stress-strain relationship, tensile stressstrain constitutive relationship of concrete after freeze-thaw cycles was proposed. The results show that the slope of the rising part of tensile stress-strain curve falls down gradually and the peaks of tensile stress and strain decrease linearly as cycle times of freeze-thaw increase. Samples with high strength grade express less decrease of peak tensile stress and strain than those with low strength grade for the same freeze-thaw cycles, while decreasina rate has slight difference.