Analysis And Research On Windproof Of Continuous Rigid-frame Bridge

With the development of industry of building bridges in our country, more and more continuous rigid frame bridges have been used in highway construction with its unique superiority. However, for the continuous rigid-frame bridges with double thin-walled flexible piers, the influence of wind load is very obvious when they are in the cantilever erection stages. In the maximum double cantilever stage, wind load must be considered in the designs. Therefore, wind-resistant analysis of the long-span continuous rigid frame is very necessary. Based on the engineering example of Meishan Bridge, have analyzed the wind including response by using finite element analysis software ANSYS and FLUENT to provide necessary data for design. The research of this paper is significant in theory and practicality. The main results of this paper are as follows:(1) This paper firstly introduced the existing theory on bridge wind engineering, the author analyzed the advantages and disadvantages of each method, and enumerated the background of the development of the theory and the theory of evolution trend. The wind speed time-history curves have been generated by using the harmonic wave method. Compared the goal spectrum and analog spectrum, both above fitting good.(2) Based on the MeiShan Bridge, the dynamic characteristics of the bridge which in the maximum double cantilever stag and in the operation stage are analyzed. By drawing the top 10 vibrating modes, we know the influence of wind load is very large when the bridge is in the cantilever erection stages. From vibration mode can be seen the anti-pushing rigidity of the bridge is very small, It can reduce the internal force which caused by the changes of temperature or the shrinkage and creep of concrete.(3) Wind resistance are analyzed in three of the most unfavorable load working conditions when Meishan Bridge is in the maximum double cantilever stag, then extracting its control Internal force. We can find the control internal force of the bottom of the pier is bigger than cantilever root, and the results leans to safety. Indicate that using this method to guide design is feasible in the preliminary design stage.(4) Calculated three component coefficient by using FLUENT software. Drawn the pressure distribution chart and wind vector diagrams in the action of different wind Angle attacks, and got three component coefficient surveillance maps, etc. We can judge whether convergence through the three component coefficient surveillance maps. Finally calculated the values of the three component coefficients in the -6°～ 6°wind angle of attack. Obtained the relations between the three component coefficient and the wind angle of attack. Provides the necessary parameters for the chattering analysis.(5) Change the chattering force to time-histories by using the curves of wind speed process. Then taking Meishan Bridge as an example, analyzed the buffeting in Time-history by using the finite element analysis software ANSYS. Finally, the displacement and internal force schedule curves were obtained. The results show that the results in the analysis of the buffeting responses are smaller than which in the analysis of the static gust response. As a result, using the theory of static gust response to analyze the bridge wind resistance is security.