Investigating asymmetric spatial butterfly-shaped steel arch bridges: a case study

Abstract

Jiusha Bridge in Hangzhou city, China, is an asymmetric spatial butterfly-shaped steel arch bridge. The bridge deck and steel arch rib form a half-through structure at one end and a through structure at the other. The bridge sits on a soft soil foundation with poor thrust resistance; therefore, different force transmission structures adopted at the asymmetric ends to balance the large arch thrust during internal force transmission of the structure were researched. The mechanical behaviour of the asymmetric steel arch bridge under dead load and live load was compared with that of a symmetric half-through and through steel arch bridge. Subsequently, a full-bridge finite-element (FE) model was established in order to adjust the stiffness contribution of the middle arch and side arches to the bridge, optimise the hanger forces in the finished bridge state and analyse the bridge's stress, stiffness, stability and dynamic characteristics. The stresses in some key members and joints were calculated by means of a refined FE model consisting of beam elements, truss elements and plate elements. Some of the special construction technologies used on Jiusha Bridge are also briefly discussed.