A case study on correlations of axial shortening and deflection with concrete creep asymptote in segmentally-erected prestressed box girders

Abstract

Large-span prestressed concrete bridges are sensitive to concrete creep which has a profound effect on bridge safety and serviceability. In this study, 3D computational simulations based on different concrete creep and shrinkage models are employed to investigate the long-term deformation of a prestressed concrete bridge. An improved rate-type algorithm powered by the continuous spectrum method and exponential algorithm is utilised to enhance the computational accuracy and efficiency. The asymptotic behaviours of the deflection and shortening at the main cantilever tip are captured. Compared to deflection, the asymptotic slope of the shortening curve is more systematically correlated with the asymptotic trend of creep models containing logarithmic time functions and this close correlation can be established at a relatively young age after construction. Thus, it can be used to realistically predict long-term deformation, as well as approximate the governing parameters in the compliance functions. Sensitivity studies based on Latin hypercube sampling are employed to explore the scatter band of the deflection and shortening due to material randomness, prestress fluctuation and environmental variations. Its effect on the correlation between deformation and creep asymptote is comprehensively examined. Furthermore, the influence of individual tendons on the deflection is probed based on the sensitivity investigation.