DAI Jie, QU Jun, QIAO Jiangang, QIN Fengjiang
According to the structural characteristics of the cable-stayed bridge with hybrid girder, an active set method is proposed to determine the reasonable completion state for the cable-stayed bridge with hybrid girder. A quadratic programming model is built, with the total bending and axial energy of the girder and the pylon as the objective function, and the vertical displacement of the steel box girder, the horizontal displacement of the pylon, the normal stress in the concrete girder and pylon, the cable force and their distributional uniformity as the constraint conditions. The active set method is employed to optimize the completion state of the cablestayed bridge with hybrid girder. The optimization and comparison results show that under the condition of the completion state obtained through the method proposed in this paper, a smooth shape of the whole structure is obtained, with the vertical displacement of the main girder in the range of -22-8 mm, with the top of the pylon having a horizontal pre-deviation of 20 mm to the main span, and with the internal force and the normal stress in the whole structure all similar with what obtained from the unconstraint minimum bending energy method. The normal stresses in the steel girder and the steel pylon are in the range of -84.43-16.38 MPa, and the normal stresses in the concrete girder and the concrete pylon are in the range of -16.31-0.003 MPa, and the cable force is in the range of 2061-2457 kN, which are in a more uniform distribution than that obtained from the unconstraint minimum bending energy method, with the side piers having a more pressure reservation. Thus, the results show the great effectiveness and superiority of the method.
