碳纤维加固钢桥面板U肋对接焊缝疲劳试验

Fatigue Test of CFRP-strengthened U-rib Butt Weld in Steel Bridge Decks

摘要:

为探究钢桥面板U肋对接焊缝的疲劳开裂机理与修复加固方法，设计了2个带嵌补段的足尺单U肋试件模型，通过模型试验研究了该细节的疲劳破坏模式和实际疲劳抗力。随后，基于线弹性断裂力学方法建立碳纤维增强复合材料（CFRP）加固对接焊缝裂纹模型，通过数值模拟分别研究了CFRP布层数、CFRP布尺寸对疲劳性能的影响。最后，针对U肋对接焊缝介绍粘贴CFRP布无损修复方法和施工工艺流程，并对CFRP布粘贴修复后的裂纹试件进行疲劳测试。结果表明：U肋对接焊缝的疲劳易损点均出现在U肋圆弧过渡处，平均疲劳强度仅为59.7 MPa。经3层CFRP布修复后，不同损伤程度的焊缝疲劳强度约为未加固试件的0.8~2.6倍。粘贴CFRP布能够有效改善钢桥面板U肋对接焊缝的疲劳性能，且满足实桥无损修复的需求。

Abstract:

In order to explore the fatigue cracking mechanism and strengthening methods of U-rib butt welds in steel bridge decks， a total of two full-scale single U-rib specimen models with embedded sections were designed， and the fatigue failure modes and actual fatigue resistance of the detail were investigated through model tests. Then， based on the linear elastic fracture mechanics method， a butt-weld cracked model repaired by CFRP strips was established， and the effects of the number of layers and the size of CFRP cloth on the fatigue performance were investigated through numerical simulation. Finally， the non-destructive repair methods and construction process of pasting CFRP strips were introduced for the U-rib butt welds， and the fatigue test of the cracked specimens repaired by CFRP strips was carried out. The results indicate that the fatigue vulnerable points of the U-rib butt welds all appear at the arc transition of U-rib， and the average fatigue strength is only 59.7 MPa. After being repaired by three layers of CFRP strips， the fatigue strength of the welds with different damage degrees is about 0.8 to 2.6 times of unrepaired specimens. Pasting CFRP strips can effectively improve the fatigue performance of the U-rib butt weld details of the steel bridge decks， and meet the demand for the non-destructive repair of actual bridges.