CFL增强RC梁抗弯刚度的衰减规律

Degradation Rule of Bending Stiffness of RC Beams Strengthened with Carbon Fiber Laminates

在对4组共20根碳纤维薄板（CFL）增强钢筋混凝土（RC）梁进行三点弯曲疲劳试验的基础上，探讨了增强梁的抗弯刚度与损伤变量、荷载循环次数、荷载等级以及疲劳寿命之间的关系，得到以下结论：（1）抗弯刚度的衰减曲线包括初始的快速减小阶段、稳定衰减阶段和构件失稳后的快速减小阶段；（2）增强梁正则化抗弯刚度和循环次数在稳定衰减阶段有较好的线性关系；（3）线性刚度比介于0．55—0．79之间，平均值为0．67；（4）破坏刚度比介于0．53～0．73之间，平均值为0．63；（5）增强梁疲劳破坏时损伤变量约为0．37．

The three-point bending fatigue tests of 20 reinforced concrete （ RC ） beams strengthened with carbon fiber laminates （CFLs） in 4 groups were carried out to reveal the relationships between the bending stiffness and such parameters as the damage variable, the cyclic number of fatigue loading, the loading level as well as the fatigue life. It is concluded that （ 1 ） the degradation curve of bending stiffness includes a rapid decay phase, a uniform decay phase, and a rapid decay phase after the failure; （2） there is a good linear relationship between the normalized bending stiffness and the cyclic number of fatigue loading in the uniform decay phase; （3） the normalized linear stiffness varies from 0.55 to 0.79, with a mean value of 0.67 ; （4） the normalized fracture stiffness varies from 0.53 to 0.73, with a mean value of 0.63 ; and （ 5 ） the damage variable of the strengthened beams reaches about 0.37 at the fatigue failure point.