Large-span precast prestressed concrete box girders have been widely used in bridge construction near or across the sea. However, this would easily lead to a hydration heat problem, including large initial tensile stress and concrete cracks during the stage of concrete pouring. A 5 m long segment of the prestressed concrete box girder for the Hangzhou Bay Cross-Sea Railway Bridge was continuously monitored to investigate the hydration heat effect on the long-span concrete box girder during the pouring stage of construction. The initial temperature variation and stress distribution of the concrete in the segment were analyzed through finite element analysis based on the experimental data and temperature monitoring results. A suitable concrete pouring and maintenance plan for the box girder was proposed after the comparison of several construction schemes. The results indicate that the primary cause of initial tensile stress is the temperature difference between the inner and outer surfaces of the long-span precast concrete box girder. By adding some ventilation inside the box girder with suitable maintenance measures, the initial tensile stress in the concrete can be effectively reduced, thus mitigating the risk of early cracking.
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