Life-cycle based structural performance of long-span CFST hybrid arch bridge: A study on arch of Pingnan Third Bridge

Abstract

Long-span concrete-filled steel tubular (CFST) hybrid arch bridge is one of the optimal solutions for large-span bridge construction, where the construction process and long-term sustained loading may affect the structural performance during its life-cycle. The trussed CFST hybrid arch of the Pingnan Third Bridge in China with a main span of 575 m was taken as a benchmark case to numerically determine the life-cycle based structural performance of long-span CFST hybrid arch bridge, and the construction process and long-term service period were considered. The accuracy of the numerical method was validated with the in-situ measured records of the real bridge and a series of available laboratory tests. Thereafter, the life-cycle based working mechanism of the trussed CFST hybrid arch was investigated. Parametric investigations were also carried out to evaluate the influence of key parameters on the load-bearing capacity of the hybrid arch structure. Furthermore, the resistance of the structure was examined using GB/T 51446–2021. It is shown that the simulated results agree well with the in-situ measured and experimental data. The stress redistribution exists in the CFST chord during construction and long-term service phases. The influence of CFST chords is significant to the load-bearing capacity of hybrid arch as the core concrete plays a prominent role, while the effects of the web (brace) strength and web (brace) - to - chord diameter ratio are limited. It is recommended to use GB/T 51446–2021 for resistance prediction of the long-span CFST hybrid arch bridge.