ABSTRACT
Fatigue cracking is a primary factor that affects the service life of an orthotropic steel deck. Cracks in the welds between the U-ribs and the deck plate account for 18.9% of all the fatigue cracks in an orthotropic steel deck and are the type of cracks with the most significant impact. This study presents a new thickened-edge U-rib (TEU) developed based on the conventional U-rib (CU). The TEU requires the same amount of material and welding process as the CU. An effective notch stress analysis finds that the maximum effective notch stress in the TEU is over 25% lower than that in the CU and that the TEU exhibits higher tolerance to weld imperfections than the CU. At penetration depths greater than 50%, the maximum effective notch stress in the TEU remains basically the same. Fatigue model test results show the following. At 2×106 loading cycles, the equivalent fatigue strength of the TEU was 17.4% and 23.1% higher than that of the CU based on nominal and hotspot stresses, respectively. At an equivalent fatigue strength of 71 MPa, the equivalent number of loading cycles for the TEU was 1.62 times that for the CU. Based on the above analysis, the TEU is capable of extending the service life of an orthotropic steel deck to a relatively large extent. Moreover, based on the results of this study, the TEU was also applied in the Yushan Bridge, the Wuyi Bridge, the Fenghuangshan Viaduct, and the Yangsigang Bridge.
