Fatigue Performance of Orthotropic Steel Decks in Long-Span Cable-Stayed Steel-Box Girder Railway Bridges

Abstract

This study conducted preliminary finite-element analysis (FEA) of an orthotropic steel deck (OSD) with U-ribs and V-ribs for a long-span cable-stayed steel-box girder railway bridge using the hot-spot stress method to determine the behavior of the welded connections. The results of the FEA indicated that V-ribs exhibited better fatigue performance than U-ribs on four typical fatigue details, and the rib-to-diaphragm welded connections in the two rib types were the most unfavorable aspects. A full-scale 5.6 million cycle fatigue test was then conducted to determine and compare rib fatigue resistance. The rib-to-diaphragm joints in the U-ribs were more prone to fatigue cracks than those in the V-ribs, and crack formation and extension did not result in significant deterioration of rigidity. The fatigue life of the U-ribs was 62.5 years, whereas that of the V-ribs was in excess of 169 years. The results indicated that the FAT90 (a stress range of 90 MPa at 2 × 107 cycles) fatigue class was the most suitable for estimating the fatigue resistance of rib-to-diaphragm welded connections in a railway OSD.