Experimental Research Of The Reinforcement Technology Based On Orthotropic Plate Of Steel Box Girder With Fatigue Damage

Nowdays, maintenance technology of orthotropic plate of steel box girder suffering from fatigue damage mostly focuses on the way to improve the pavement structure, and rarely makes a further exploration to locally repair the tiny fatigue crack of orthotropic plate with complex fabric cloth(FRP). Therefore, based on HIROX 3D micro nondestructive detection technology which is able to capture subtle fatigue crack, this thesis conducts fatigue tests of 13 full-scale components and theoretical research on three different reinforcement forms. Ultimately, the result gives reasonable advice on the way to choose reinforcement time and strengthening method, which can provide reference for maintenance application of steel bridge. The main research contents and conclusions are as follows.1. Through the application of HIROX 3D micro nondestructive detection technology, the time of anti fatigue reinforcement can be determined. The experimental results show that the components will get into a deeper state of fatigue, when the crack exceeds a critical value.2. Fatigue tests are carried out, including 1 static load test, 2 non-reinforced fatigue tests and 10 reinforced fatigue tests. The results of the experiment indicate that the three kinds of reinforcement pieces show almost the same fatigue damage form as the unreinforced. In the early stage of fatigue, the structure keeps a linear state; in the final stage, the stiffness is significantly decreased,which presents a brittle failure characteristic.3. In contrast, the fatigue properties and reinforced effect of the three repair methods are presented. The tests show that the fatigue life of the three ways nearly keeps in the same gradient as the pre damage level is low; the fatigue life of the piece which takes repair welding is much longer than the other two ways as the pre damage level gets into deeper.4. The hot spot stress analysis of different forms of reinforcement technology is carried out by ANSYS. The analysis results show that the same fiber layers, the reinforcement effect of whole paste way is better than the local way. With continuously increasing fiber layers, the promotion keeps in a low degree whicn makes single-whole paste form have much more economic benefits.