抄録
This paper deals with the repair of the typical fatigue cracks initiated at the out-of-plane welded gusset joints in the steel bridge using externally bonded pre-tensioned CFRP strips. The specimens (L1,350×W400×t9 mm) with the real size out-of-plane welded gusset plates (L500×W300×t9 mm) were fabricated and the initial cracks (2a = 50 mm) occurred at the welded toes by the fatigue tests. In order to evaluate the effect of repair, the fatigue tests of three method types have been conducted as follows: the specimen without repair, with repair by non pre-tensioned CFRP strips and with repair by pre-tensioned CFRP strips. The value of the compressive force due to the release of the pre-tension is approximately 65 kN by four pre-tensioned CFRP strips. As the experimental results, under the nominal stress range of 60–120 MPa, the fatigue lives were improved drastically, and the effects of 6.5–8.9 times in the pre-tensioned CFRP strips and 3.5–5.5 times in the non pre-tensioned CFRP strips were obtained against the non repair. The predicted fatigue lives based on LEFM were evaluated.
