关键词: 碳纤维薄板, 钢筋混凝土梁, S-N 曲线, 疲劳寿命预测, 弯曲载荷

Abstract:

The fatigue behavior of RC (Reinforced Concrete) beams strengthened with FRP (Fiber Reinforced Polymer ) is an important subject in civil engineering in the world. In this paper , 18 RC beams (1850 mm x100 mm x 200 mm) strengthened with CFLs (Carbon Fiber Laminates) are divided into 4 groups and are tested to investigate their fatigue behaviors under bending loads. Based on the data of fatigue test and theoretical analyses , S-N and P-S-N curves of the RC beams strengthened with CFLs are obtained according to the new conceptions of permissive and extreme fatigue lives , finding that the ratios of the permissive and extreme fatigue strength to the ultimate static strength are respectively 65% and 67%. The relationships among the mid-span deflection , the loading cycle number, the individual fatigue life and the stress level are then deduced and validated. Afterwards , a new method that only needs some nondestructive experimental data of fatigue (the fatigue load cycles n recommended here is 100 - 1000) is proposed to predict the individual fatigue life. The proposed prediction method is finally validated by the fatigue tests of another three RC beams strengthened with CFLs.

Key words: carbon fiber laminate, reinforced concrete beam, S-N curve, fatigue life prediction, bending load