混凝土双轴抗压疲劳损伤特性的超声波速法研究

对混凝土在双轴压疲劳荷载作用下超声波波速的变化规律进行了试验研究。结果表明，穿透混凝土试件自由面的横向波速随着荷载循环次数的增加而发生明显的3阶段衰减，即初始迅速衰减，稳定衰减与临近破坏的急速衰减3阶段，它们分别约占疲劳寿命的10％，80％和10％，而且受侧压水平及疲劳应力水平的影响。基于超声波速定义了损伤变量，建立了混凝土疲劳累积损伤的演化方程，最后提出了在实际工程中运用无损的超声检测法评定混凝土疲劳损伤与结构耐久性的一般方法。

RESEARCH ON FATIGUE DAMAGE OF CONCRETE UNDER BIAXIAL COMPRESSIVE LOADING USING ULTRASONIC VELOCITY METHOD

This paper presents a study on the histories of ultrasonic velocity variations of concrete specimen during biaxial cyclic compressive loading tests. Results show that the attenuation of the transverse ultrasonic velocity follows S-shape line,which can be divided into three phases,lasting about 10%,80% and 10% of the sample life,respectively. The effects of the level of stress on the sample are investigated,too. A damage variable is defined based on the transverse ultrasonic velocity and used to describe the growth law of fatigue damage. The general method to evaluate the fatigue damage of the concrete and residual life of structure is presented.