Study of creep effects in a long-span concrete-filled steel tube arch bridge

This paper reports how modelling experiments, theoretical analysis, finite-element analysis and in situ measurement were employed to research the effects of creep in a long-span concrete-filled steel tubular arch bridge in China. First, a creep experiment using a 1 : 2·5 scaled model of the arch-foot segment was carried out to investigate time-dependent behaviours. Experimental results showed that the creep strains of the arch developed very rapidly at the start of loading, but grew very slowly later. Subsequently, two theoretical analysis methods were used to determine creep coefficients of the arch members, considering the steel tubular confining effects and stress distribution, as well as the effects of the ratio of sectional areas and elastic modulus of steel and concrete. The calculated values of the two theoretical methods were in general agreement with the experimental results. It can be concluded from the in situ measured stress data that concrete stresses reduced and steel stresses, conversely, increased with time. Concrete compressive stresses from the in situ measurement were smaller, with some even being negative.