Investigation into long-term behaviour and stability of concrete-filled steel tubular arches

• Analytical model is developed for long-term analysis of concrete-filled steel tubular arches.
• Mathematical expressions and closed-form solutions are derived to analyse both deep and shallow arches.
• New conclusions are drawn for the behaviour predication and stability assessment of concrete-filled steel tubular arches.
• Finite element model is established and numerical analyses are performed to validate the analytical results.

This paper presents the long-term structural behaviour analysis and stability assessment carried out on concrete-filled steel tubular (CFST) circular arches. Linear and non-linear analyses are herein conducted for pin-ended and fixed arches subjected to a central concentrated load. Accounting for the significant effects from creep and shrinkage in concrete core, in-plane deformations, internal forces and in-plane buckling loads are evaluated analytically and the adequacy is validated against the finite element results. The comparison of the results obtained by linear and non-linear analyses exhibits significantly different change scopes in deformation and loading capacity. For the sake of structural safety, non-linear analysis is found to be more reliable in long-term behaviour analysis and stability assessment for CFST arches. Hence, non-linear buckling analysis should be employed in assessing the long-term serviceability limit state of pin-ended and fixed CFST shallow arches in design practice, although linear buckling analysis is capable of predicting the in-plane buckling loads for pin-ended CFST deep arches.