Arch bridges have been widely constructed in China owing to their versatile structural configurations and competitive costs.The concept of using high performance prestressed steel wires to withstand the huge horizontal thrust at arch ends has greatly encouraged the engineering practices of large span arch type bridges constructed on soft soil foundations where normally arch structure is an inappropriate selection.However,many technical challenges including the design details,structural behavior and construction method still need to be carefully investigated to ensure the bridge’s safety.As a new practice of such tied arch bridge with nonconventional thin-walled steel box rib and the longest span of this type in the world,this paper presents the innovative design concept and the corresponding studies in regard to its structural behavior compared with conventional single arch design,the shear lag effect of the thin-walled arch rib and its stress distribution via numerical analysis of different finite element models are also investigated.The results show that the current design can reach a very good structural behavior under design load cases,and moreover,provides another very useful engineering practice for long span arch bridge constructed on soft soil foundations.