CFRP筋的疲劳性能

进行了不同循环应力下CFRP筋的常温疲劳试验，选取CFRP筋70％的极限拉伸应力作为最大循环应力，在R=0．5（最小循环应力与最大循环应力的比）和R=0的应力率下，测量了CFRP筋的疲劳寿命曲线，研究了CFRP筋的疲劳性能．结果表明：CFRP筋的最大循环应力应控制在70％极限拉伸应力以下；在R=0．5应力率下，最大循环应力下降5％的极限拉伸应力时，CFRP筋的疲劳寿命增长10倍左右；最大循环应力分别为60％和50％极限拉伸应力时，R=0应力率下CFRP筋的疲劳寿命分别为R=0．5应力率下疲劳寿命的百分之一和十分之一．这说明CFRP筋具有很大的脆性，需要有足够的强度安全系数，才能发挥作用；根据试验拟合的疲劳寿命曲线，CFRP筋的疲劳性能远高于Q235光圆钢筋．

Experimental study on fatigue behavior of CFRP bars

The fatigue test of CFRP bars was carried out at the different cyclic stress,choose the 70% ultimate tensile stress of CFRP bar as the maximum cyclic stress,under the cyclic ratios of R-~0.5 (the minimum-to-maximum stress ratio) and R=0 and the fatigue behavior of CFRP bars was investigated. The results showed the maximum cyclic stress of CFRP bar should be under 70 percent of ultimate tensile stress;when the maximum cyclic stress decrease 5 percent of ultimate tensile stress,the fatigue life of CFRP bars increase generally 10 times;with the decrease of cyclic ratios,the fatigue life of CFRP bars decrease heavily;for the brittleness,CFRP bar should possess a higher reserve of strength,the margin of safety against failure is a necessity;according to experimental cyclic stress-fatigue life curve,the fatigue behavior of CFRP bar is much better than the fatigue behavior of Q235 steel.