Experimental study on the fatigue behavior of the orthotropic steel deck rehabilitated by UHPC overlay

The orthotropic steel deck is widely adopted in a number of large span steel bridges for its light self-weight and high load-bearing capacity. In China, due to the heavy load traffic, the fatigue cracks have been observed in many steel decks. If fatigue cracks were not repaired properly, the performance of steel decks will deteriorate rapidly. In order to improve the fatigue behavior of the cracked orthotropic steel deck, the UHPC (Ultra-high performance concrete) overlay is proposed to cast on the steel deck for decreasing the stress range. In this study, a full-scale specimen was used to investigate the rehabilitation process of the cracked steel deck. Firstly, the specimen without pavement developed a crack at the rib-to-deck welded connection during the cyclic load test. Then the crack was repaired and the UHPC overlay was casted on the specimen. After the 28 days curing on site, for comparison, the specimen with the UHPC overlay was investigated at the same cyclic load cases of the second stage test. At the end of the cyclic load test, no crack was observed, and the effectiveness of the UHPC overlay improving the fatigue life was demonstrated by the equivalent standard axle cycles according to the Miner's linear accumulative damage rule.