The tension sequence of prestressing steel strands for curved box girder bridges

Tension modeling of ramp D of the Shiyezhou interchange of the Runyang Yangze River Highway Bridge was carried out by using the finite element method. Several tension plans were designed. Through analysis of stress variation of the box girder under different tension plans, proper tension sequence was confirmed based on the principle that the concrete should bear no tensile stress at all or the lowest possible tensile stress if necessary. Based on the computational results and the theoretical analysis of the effects of the tension sequence on the stress and deformation of the box girder, the transversal tension sequence principle of 'outer first, then inner, symmetrical and balanced' was put forward. Through construction monitoring and long-term monitoring of the bridge, the results were proved useful and could be applied to similar projects.