龄期混凝土损伤特性研究

Study on damage properties of age concrete

对尺寸ф150 mm×300 mm的混凝土试件进行了不同龄期（28、112、183、345、810、1 248、1 550 d）和不同应变速率（10^-5、5×10-5s^-1）下的单轴压缩试验并定义了损伤变量D,研究了龄期和加载速率对混凝土的损伤特性的影响。结果表明：（1）在相同应变速率下,随着龄期的增长,混凝土的强度增强,损伤变量值降低,但损伤发展越来越迅速。（2）选用了Weibull-Lognormal损伤本构模型,当应变为0～1×10^-3时混凝土出现初始损伤;当应变为1×10^-3～2×10^-3为损伤稳定发展阶段;当应变为2×10^-3～4×10^-3混凝土的损伤变量D随应变的增长迅速加快;当应变超过4×10^-3时,损伤变量D随应变的增长速率逐渐减小。（3）混凝土峰前曲线形状控制参数m值随龄期的变化趋势服从Lognormal统计分布。

Uniaxial pressure tests for concrete of size φ150 × 300 mm was carried out under different age （28,112,183,345,810, 1 248,1 550 d） and different strain rates（ 10 ^-5,5 × 10 ^-5 s ^-1 ） ,and the effects of age and loading rates on damage characteristics of con- crete was studied and the damage variable D was definedl The results show that （1）At the same strain rate, the strength of concrete in- creases with age and the value ofconcrete＇s damage variabledecreases with age,but development of damage is more and more rapidly. （ 2 ） Weibull - Lognormal damage constitutive model wasselected as experimental study, when the strain is between 0-1 × 10 ^-3, the con- crete initial damages. When the strain is between 1 × 10 ^-3 -2 × 10 ^-3 ,the development of damage becomes stable. When the strain is be- tween 2 × 10 ^-3 ~4 × 10^ -3 ,damage variable＇D grows rapidly with strain. When the strain surpasses 4 × 10^-3 ,the damage variable D de- crease with strain rate. （3）The control parameter m of concrete＇s shape of the curve before the peak trends with age obedience lognor- real statistical distribution.