Influence of Material Time-Dependent Performance on the Cantilever Construction of PSC Box Girder Bridge

This study investigated the influence of material time-dependent performance on a PSC box girder bridge. We prepared 24 sets of standard prismatic concrete specimens in the construction site and synchronous maintenance in the deck for 3, 5, 7, 14, 28, and 60 days of concrete specimen mechanical test. The relationship among early-age concrete axial compressive strength, elastic modulus, and curing time was established, and then the function equation among them was optimized. The state of stress and deflection of the main beam in the maximum cantilever stage of the PSC box girder bridge considering time-dependent performance were analyzed by using the finite element software Midas civil, and the analysis results were compared with the calculation results of the standard value. Data show that the growth of the elastic modulus of early-age concrete lags behind the development of axial compressive strength. In consideration of the material's time-dependent performance, the maximum stress variation on top of the box girder is 2.22%, whereas the variation at the lower edge is 1.02% in the stages. Thus, the effect of material time variation on stress is small. The maximum displacement is 12.3 mm, whereas the current step displacement is 5.1 mm in the maximum cantilever stage. Thus, the displacement is deeply influenced by the material time-dependent performance.