Long-Term Mechanical Performance Of The Multi-Span Extradosed Bridge

As a time-related material, the shrinkage and creep of concrete play a decisive role on the long-term displacements of structure. Besides this impact vary from different structural patterns and different operation period. For this reason, it is necessary to research the effects of shrinkage and creep on extradosed cable-stayed bridge. Meanwhile, there are some differences between the static and dynamic response which come from the initial finite element model and the practical value due to the simplification and hypothesis at the time when we build the initial finite element model. So the updating of the finite element model set to minimize the response margin between the initial finite element model and practical value is another worthwhile subject. As discussed above, this paper focused on following aspects based on the project of Balihu Bridge:(1) Various simulation models of shrinkage and creep were applied to process analysis of theoretical calculation of Balihu Bridge. The main beam and main tower displacement and cable force caused by shrinkage and creep were computed to compare the differencees between simulation models. Finally come to the conclusion that the development of shrinkage and creep of ACI 209 prediction model is mainly concentrated in early stage. The predictive value of CEB-FIP (1978) is conservative. The forecast values of both JTG D62-2004 and CEB-FIP (1990) are between the two that were discussed above.(2)By processing temperature amendment, a more precise result of influence of shrinkage and creep on bridge deflection can be drawn and with this result an optimal simulation model of shrinkage and creep can be determined by comparison of calculated results. The calculated values of the JTG D62-2004 forecast model are in accord with the measured values. The calculated values of CEB-FIP (1978) are the biggest deviations from the observed values.(3) Based on data gathered from static-dynamic experiment, this paper amended the updating of the finite element model of Balihu Bridge. By applying sensitivity analysis on parameters of amendment a target function was built and optimized by Particle Swarm Optimiation and thus the finite element model of Balihu Bridge can be updated. After finite element model updation, Although the error of partial response value is increased, both the static displacement and the dynamic frequency are in good agreement with the measured values of the model modified by the model.