Ultra-Long-Span UHPC-Filled Steel Tube Truss Arch Bridges: A Critical Review of Structural Design, Optimisation, Construction, and Stability

Abstract

Concrete-filled steel tube (CFST) truss arch bridges, by virtue of their large spanning capacity, low self-weight, high load-carrying efficiency and strong construction adaptability, have become one of the dominant bridge types for major crossings such as deep valleys and wide rivers, and their spans are being extended from the 500 m scale to the 700 m scale and even to the kilometre scale. The continuous increase in span dramatically amplifies the self-weight effect of the arch ribs and significantly raises the proportion of dead-load internal forces, so that reducing the self-weight of the arch ribs has consequently become key to extending the span limit. Ultra-high performance concrete (UHPC) possesses a compressive strength of over 150 MPa, an elastic modulus of no less than 40 GPa and excellent durability. Using it as the core concrete in steel tubes to form ultra-high performance CFST members provides a material-level solution for improving the load-carrying efficiency of sections and achieving structural lightweighting. Focusing on the topic of “optimal design of ultra-long-span ultra-high performance CFST truss arch bridges”, this paper systematically reviews the relevant research status in China and abroad: first, research on the development history, structural type selection, construction technology and structural optimisation of ultra-long-span CFST truss arch bridges; second, research on the material properties and member mechanical behaviour of ultra-high performance CFST, on hollow sandwich and composite section forms, and on the trial design of steel-UHPC composite truss arches; third, research on key detailing parameters of CFST arch bridges such as the reasonable arch axis, global and local stability, and lateral bracing layout. On this basis, it is pointed out that existing research remains deficient in four aspects, namely the systematic comparison and selection of the span limit and section forms at the 800 m scale, the coupling mechanism between UHPC and steel tubes as well as truss structures, the dual-nonlinear stability analysis of ultra-long-span bridges, and the detailing measures for prefabricated construction; accordingly, the research scope of this paper is defined as the trial design, static parameter optimisation and stability analysis of an 800 m-scale ultra-high performance CFST truss arch bridge. This review can provide a fundamental reference for further research on ultra-long-span CFST truss arch bridges.