Fatigue Performance of Butt-Welded Tensile Plate Cable-Girder Anchorages of Long-Span Cable-Stayed Steel Box Girder Railway Bridges

Abstract

The fatigue performance of a new type of butt-welded tensile-plate cable-girder anchorage that requires higher load-bearing capacity and lower stress concentration compared with normal tensile-plate anchorages for a long-span cable-stayed railway bridge was evaluated using a finite-element analysis and full-scale laboratory model. The test results show that the stresses remained constant over the first 2 million fatigue cycles, stress redistribution occurred at the end of the butt weld after 2.75 million cycles, and no surface cracks were observed after 3 million cycles. Anatomical milling tests found a fatigue crack originating from a microscopic welding defect in the end of the butt weld. The fatigue properties of butt welds of the anchor plate combined effect of tensile and shear forces are lower than the common butt welds. The fatigue details at two ends of the butt weld are crack vulnerable for the relative weak weldability of 40-mm-thick anchor plate. However, the measured minimum fatigue life of 2.75 million cycles (or 137.5 years) for the butt weld is larger than the bridge design requirement of 2 million cycles (or 100 years), indicating satisfied fatigue performance of the anchorage. The addition of leading and blowout plates is suggested to reduce butt weld residual stresses and defects, improving the fatigue performance of the anchorage.