CFL增强RC梁抗弯刚度衰减规律试验研究

在对4组20根碳纤维薄板(CFL)增强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、损伤变量、载荷循环次数、载荷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0.63；（5）增强梁的平均疲劳寿命随着载荷水平的增大而降低，平均抗弯刚度衰减速率随着载荷水平的增大而增大，平均疲劳寿命随着抗弯刚度平均衰减率的增大而降低；（6）增强梁疲劳破坏时损伤变量D≈0.37。

Experimental Study on Stiffness Degradation Rule for CFL Strengthened RC Beams

Fatigue tests for 20 RC beams strengthened with carbon fiber laminates (CFLs) under cyclic loads divided into 4 groups were carried out. The relationships among bending stiffness, damage variable, fatigue cycles, loading levels and fatigue lives were investigated. Conclusions can be drawn as follow: (1) the stiffness degradation curves include a rapid decay phase, a uniform decay phase and a rapid decay phase until fail; (2) there is a good linear relationship in the uniform decay phase between normalized stiffness and cycles; (3) the value of linear normalized stiffness points varies from 0.55 to 0.79, the mean value is 0.67; (4) the value of fracture normalized stiffness points varies from 0.53 to 0.73, the mean value is 0.63; (5) the mean value of fatigue lives decrease as the load levels increase, the mean value of stiffness degradation velocity elevate as the load levels increase and the mean value of fatigue lives reduce as the mean value of stiffness degradation velocity elevate; (6) the value of damage variable is 0.37 when the strengthened beams fail.