预应力钢纤维混凝土板弯曲疲劳弹性模量试验研究

Experimental study on the fatigue elastic modulus of steel fiber reinforced prestressed concrete slabs

对三种不同钢纤维掺量(0%、1%、2%)的预应力钢纤维混凝土板在不同应力水平(0.80、0.85)下的疲劳弹性模量衰减规律进行研究,得到了预应力钢纤维混凝土板跨中下表面弹性模量衰减曲线以及同钢纤维掺量、同应力水平的跨中上表面弹性模量衰减曲线。揭示了预应力钢纤维混凝土板的弹性模量在弯曲疲劳过程中呈现三阶段衰减并且衰减曲线在第二阶段基本呈线性,当板发生疲劳破坏时其弹性模量衰减至初始弹性模量的59.9%左右的规律。在此基础上根据Miner累积损伤原理建立了疲劳寿命预测模型并提出了采用微损试验来预测疲劳寿命的方法,用该方法预测的疲劳寿命与实测寿命在三倍离散范围内。

The attenuation of elastic modulus of Steel Fiber Reinforced Prestressed Concrete Slabs （SFRPCS） with different steel fiber contents （0%, 1%, 2%） and under different stress levels （0.80, 0.85） is investigated through flexural fatigue experiments. Three types of attenuation curves in the middle of slabs are obtained, and these curves reveal that the elastic modulus attenuation of SFRPCS could be divided into three stages during the fatigue process and the second stage is nearly linear. The elastic modulus is about 59.9 percent of its initial value when the SFRPCS fails.A model for fatigue-life prediction is proposed according to the Miner cumulative damage theory, and a method of micro-damage experiment is provided to predict the fatigue-life. The model predicted fatigue-life is within three times of the experimentally measured fatigue-life.