Design Technology Innovations in China’s Railway Hybrid Box Girder Cable-Stayed Bridges

Before 2014, cable-stayed bridges with steel box girders were rarely used in railways worldwide as their stiffness was deemed insufficient for train operation. Hence, hybrid box girder technology was introduced to railway cable-stayed bridges, making hybrid box girder cable-stayed bridges (HBGCBs) one of the most widely adopted railway cable-stayed bridge types in China. The introduction of HBGCBs has eliminated the heavy reliance on steel truss and prestressed concrete girders in railway cable-stayed bridges worldwide, especially in China. This review aims to illustrate how the rapid development of railway HBGCBs in China over the past decade was achieved through innovative stiffness enhancement technologies and key design considerations. This article first provides a valuable review of the development of railway HBGCBs and the factors that limited their international adoption prior to 2014. It then comprehensively highlights key stiffness control criteria and presents innovative stiffness enhancement strategies tailored to railway HBGCBs. It reveals that key design parameters, including the side-span–mid-span ratio, the position and form of the steel–concrete joint (SCJ), girder height, auxiliary pier configuration and pylon layout, are also important for the mechanical performance of railway HBGCBs. Typical construction methods for railway HBGCBs are also described. Finally, the article introduces a series of long-span bridge types derived from SCJ and girder technologies and discusses the feasibility of further span extension using the above technologies. The research results are conducive to the transformation of bridge design concepts and promote the further development and application of railway HBGCBs and related innovative technologies worldwide.