混凝土早龄拉伸徐变的试验与理论研究

EXPERIMENTAL AND THEORETICAL RESEARCH ON TENSILE CREEP OF EARLY-AGE CONCRETE

研究了混凝土在早龄期自身水化温升和自收缩引起的内部拉伸应力作用下的徐变规律。研究以具体的工程应用为背景,首先利用混凝土温度应力试验机为基本手段,对早龄期混凝土在收缩约束状态下的徐变变形进行了试验研究;然后利用试验结果对普遍采用的混凝土双幂徐变模型针对早龄拉伸进行了参数识别;最后利用得到的适用于拉伸徐变规律的双幂模型进行了混凝土结构早龄内应力的计算。试验与计算都表明,混凝土早龄拉伸徐变有不同于压缩徐变的规律,结构早龄内应力计算直接使用压缩徐变规律总体上偏于不安全。

This paper investigates the tensile creep of early-age concrete subjected to intrinsic hyclration temperature rise and autogenous shrinkage. Through a temperature stress test machine （TSTM）, the tensile creep of early-age concrete is studied experimentally. Then, a double power law is attributed to the tensile creep with the model parameters identified fi＇om the test results. The calibrated tensile creep model is used to calculate the internal stress of a concrete structure at early-age. Both experimental data and numerical results show that the tensile creep is very different from compressive creep and the direct use of compressive creep in early-age stress evaluation of concrete stress would give unsafe results.