Creep of Concrete Core and Time-Dependent Non-Linear Behaviour and Buckling of Shallow Concrete-Filled Steel Tubular Arches

摘要

This paper presents a theoretical analysis for the time-dependent non-linear behaviour and buckling of shallow concrete-filled steel tubular (CFST) arches under a sustained central concentrated load. The virtual work method is used to establish the differential equations of equilibrium for the time-dependent behaviour and buckling analyses of shallow CFST arches, and the age-adjusted effective modulus method is adopted to model the creep behaviour of the concrete core. Analytical solutions of time-dependent displacements and internal forces of shallow CFST arches are derived. It has been found that under a sustained central concentrated load, the deformations and bending moments in a shallow CFST arch are time-dependent and they increase with time significantly owing to the creep of the concrete core, which lead to the change of equilibrium configurations of the arch with time. When the time is sufficiently long, the stable equilibrium configuration of the arch under the sustained load in the short-term continues to change until its buckling configuration corresponding to the sustained load is attained. In this case, the arch may buckle in a bifurcation mode or a limit point instability mode. The analytical solution of the prebuckling structural life time is also derived. Comparisons of the analytical solutions with the finite element results show that the analytical solutions of the present study are effective and accurate.