Fatigue Strengthening for Rib-to-Deck Joint by Bonding Reinforcing Plates on the Deck Surface
Yang Deng, Taolei Liu, Bao-ya Cao, Aiqun Li
Abstract
Rib-to-deck welded joints of in-service orthotropic steel decks (OSDs) are prone to fatigue cracks, which usually lead to considerable repair costs and traffic interruption. To mitigate or avoid fatigue cracking, an easy-to-implement strengthening method of bonding reinforcing plates on deck surfaces was developed and investigated. The fatigue tests were carried out on four full-scale specimens. The first specimen was unreinforced and the other specimens were strengthened by using single-layer carbon fiber reinforced polymer (CFRP) plates (4 mm), double-layer CFRP plates, and 4 mm-thick steel plates, respectively. The strengthening time and thickness of the reinforcing plate were numerically investigated. The test results shows that the proposed strengthening method can significantly reduce the hot spot stress of the welded joints and prolong their fatigue lives. The steel plates are more effective than the same thick single-layer CFRP plates. The double-layer CFRP plates can further increase the fatigue life of the welded joint, if the bonding quality could be greatly improved to avoid or delay debonding. The test results also support that the FAT100 hot spot stress S–N curve is suitable to fatigue life evaluation for this type of joint before and after strengthening. The numerical investigation reveals that the implementation of the proposed strengthening method should be carried out at the early stage of fatigue crack propagation, namely the early phase of the service period, to obtain better strengthening effects. This study recommends that thicker steel plates should be used for fatigue strengthening without affecting the working performance of the bridge deck pavement. This study provided a reference to the design and application of bonding reinforcing plate on deck surface in fatigue strengthening of OSDs.