反复荷载下碳化混凝土力学性能及本构关系研究

为研究碳化对反复荷载下混凝土力学性能及本构关系的影响,本文通过碳化混凝土棱柱体试件单调及反复荷载试验,得到各试件应力应变曲线及骨架曲线,考虑到碳化混凝土构件的截面尺寸效应,从混凝土碳化率的角度对比分析了单调及反复荷载下碳化对试件破坏形态、混凝土强度、弹性模量、峰值应变及极限应变的影响.试验表明:随着反复荷载下碳化混凝土内部损伤的积累,其应力应变曲线下降段比单调荷载下的更为陡峭,破坏较为突然,反复荷载碳化混凝土延性变差;反复荷载下随着碳化率的增加,混凝土碳化后的峰值应变有所降低,但变化不大;而峰值应力均有所提高,极限应变均有所降低.根据试验结果引入与碳化率相关的下降段参数修正系数建立了碳化混凝土反复荷载作用下应力-应变本构关系,通过与试验对比分析表明本文确定的本构关系与试验结果较为吻合.

Study on Carbonated Concrete Mechanical Property and Constitutive Relation under Cyclic Load

For better understanding of the mechanical property and constitutive relation of carbonated concrete under cyclic load, cyclic load and monotonic load tests were carried out on prism specimens. Considering the effect of section sizes on carbonated concrete member, the hysteresis loop and skeleton curve of the specimens were obtained, and the effects of carbonization on specimen failure mode, concrete strength, elasticity modulus, peak strain, and ultimate strain were analyzed from carbonation rate perspective. It''s revealed that, because of the accumulated internal damage under cyclic load, the stress-strain curve of carbonated concrete decreased significantly, and the ductility was less than that under monotonic load. Furthermore, the peak strain of carbonated concrete decreased a little, peak stress increased, and ultimate strain decreased with the increase of carbonization depth. Based on the test results, under the consideration of carbonation rate and the introduction of the parameters at stress-strain curve descending branch, the stress-strain constitutive relation of carbonated concrete under cyclic load was established, which agreed well with the experimental values.