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For cable-stayed bridge with wide box girder and single cable plane, because the single cable plane does not work on the main beam torsion, the torsional stiffness of structure is therefore small, especially for the bridge under construction, the final structural system has not yet completed, structural stiffness, especially torsional stiffness is lower, structural nonlinearity and stability will be more apparent. In this thesis, taking the Lushan Bridge in Fu yang as example, structural nonlinearity and stability of the bridge during the whole construction process has been numerically investigated.Based on the structural analysis software MIDAS/CIVIL, a plane structural finite element model is firstly establish, and the reasonable state of cable-stayed bridge in completion is determined by using the unknown load factor method. On the computed final state of the bridge, the reasonable state of the bridge under construction is determined by using the reverse-forward iteration method. Secondly, the theory and methoad of structural nonlinear and stability analysis are presented. Finally, by using the computer software Midas/Civil and Ansys, the static performance and structural stability of the bridge under the biggest double, single cantilever, and the closure construction stages is analyzed, and effects of the nonlinear factors on the static performance and structural stability of the bridge are discussed.The results show that:(1) The cable sag effect is the main factor influencing structural static performance, and then the large displacement effect, the smallest is the coupled beam-column effect of bending moment and axial force. For the cable-stayed bridge with wide box girder and single cable plane, these factors should be considered together in the static analysis.(2) The linear stability factor is much larger than nonlinear stability factor, and therefore in structural stability analysis, the nonlinear analytical method should be employed.
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