Study on dynamic stability of structure is a hot subject in the fields of engineering mechanics, but its basic theory and analytical method still need to be further improved. This paper improved the current method for dynamic stability analysis called “dynamic eigenvalue method”, and the method for nonlinear dynamic stability analysis based on ANSYS platform is proposed. A long column under harmonic loads is taken as the research objective, dynamic eigenvalues affected by the load frequency, load amplitude and damping ratio are studied. Results show that, the increasing of load frequency or dynamic load amplitude will lead to the increase of maximum dynamic eigenvalue and decrease of minimum dynamic eigenvalue, which is not beneficial to dynamic stability of structure. The increasing of damping ratio will lead to the decrease of maximum dynamic eigenvalue and increase of minimum dynamic eigenvalue, this make the dynamic eigenvalue more stable. Therefore, the high damping is beneficial to dynamic stability of structure.

In order to assess the service states of the permanent prestress of transverse prestressing bundle for the Xiangjiang Yinpenling Bridge (XYB), the permanent prestress values are measured. Appearance census of the diseases of transverse prestressing bundles for the cable-stayed part, the east and west incremental launching girder parts of the XYB are carried out. Three transverse prestressing bundles of the most serious corrosion are investigated by windowing damage inspection. The measured results and the analysis of the permanent prestress for the XYB show that the average permanent prestress of the three transverse prestressing bundles is about 300MPa to 550MPa, which do not meet the requirements of the design tension stress. It suggests that the appropriate treatment measures should be taken.

This paper studied the main cracking reasons for small and medium-span continuous girder bridge with secondary concreting based on ANSYS. Some prevention measures to concrete crack caused by the inelastic subsidence were also proposed. In considering the global deformation of scaffold-beam, the inelastic deformation of scaffold, the hydration heat of cement, and the characteristics of early-age concrete, influence of inelastic subsidence of support foundation on concrete cracking were analyzed by time-varying transient analysis. It can be concluded that the value of inelastic deformation is the decisive factor for the concrete cracking. Field measurement results of several bridges validate the conclusion.