Abstract: With the increase of span of arch bridges, ultimate load-carrying capacity has received more attention in design and construction. In this paper, three methods for evaluation of the ultimate load-carrying capacity of longspan bridges are reviewed. A long-span half-through steel arch bridge of 550m central span under construction in China is studied. Results show that the overall safety of a long-span arch bridge depends primarily on the material nonlinearity of individual bridge element. The effects of different load distributions on the ultimate load-carrying capacity of the bridge are investigated.