Experimental and numerical study on slender concrete-filled steel tubular arches subjected to tilting loads

Concrete-filled steel tubes (CFST) are economical for arch bridges because of their high compressive strength and efficiency in construction. Compared to the traditional concrete arches, the CFST arches usually have a large slenderness ratio, which makes the arches more prone to buckling. Despite this, limited experimental investigations have been performed on the buckling behaviour of CFST arches. In this study, a buckling test was performed on two 9 m long CFST parabolic fixed arches having a single circular cross-section with one arch subjected to a central concentrated tilting load and the other to half-span three-point tilting loads. Finite element (FE) models using solid elements were built and validated against the test results, with which the influences of the residual stress on the buckling behaviour of the composite arches were analysed and the confining pressure distribution was obtained. The FE models using beam elements were then built to investigate the confinement effects on the buckling behaviour of the CFST arches. Relatively significant confinement effects were found on the arches and were considered in the FE modelling. The residual stress had a fairly limited influence on the load-carrying capacity of the arches and was ignored in the FE models. Both the built FE models using solid and beam elements performed well in predicting the buckling behaviour of the CFST arches.