Fatigue test and life evaluation of rib-to-deck connections in orthotropic steel bridge decks

Abstract

This study presents an experimental and analytical investigation of the fatigue performance of novel double-welded rib-to-deck (RD) connections in orthotropic steel bridge decks (OSDs). To better evaluate the fatigue of this kind of novel RD connection, eleven specimens with both outside grooves and inside fillet welds were fabricated and tested, and five specimens with only a single outside groove weld were fabricated and tested for comparison. First, the effects of the internal fillet weld, test stress amplitude, and penetration of the groove weld on the fatigue lives and crack form of the specimens were analysed. The test results showed that internal fillet welding could enhance the fatigue life of the specimens. The test stress amplitude had a considerable influence on the fatigue life and crack mode, while the penetration of the outside groove weld of the double weld had a moderate influence. Then, the master S-N curve method was used to evaluate the fatigue lifetimes of the specimens, and the results were compared with the measured values. The results show that most of the measured lifetimes were distributed in the scattering band of the master S-N curve, but the distributions were relatively scattered. Therefore, for most double-ribbed specimens with double-welded connections, the lifetimes were evaluated directly using the mean value, while for double-ribbed and single-ribbed specimens with single welded connections, the fatigue lives were estimated using the scattering band boundary lines that offset ±2 and ±3 times the standard deviation (σ) from the master S-N curve, respectively.