Field Measurement And Buffeting Analysis For A Long Span Cable-Stayed Bridge During Erection Stage

The research of buffeting problem became more important because the main span of cable-stayed bridge was getting longer. This dissertation reviewed actuality and problems of long span bridges buffeting analysis. And the aerodynamic admittance research was a very important aerodynamic parameter in bridge buffeting analysis. This dissertation fully researched buffeting response of the single longest cantilevered building state of Su-tong Bridge. The main research was shown as follow:1. The dissertation reviewed the development course and actuality of field measurement of civil engineering structures.2. The dissertation introduced the buffeting aerodynamic force and aerodynamic admittance function, and proposed the frequency analysis method of long span bridge buffeting response basing on field measured aerodynamic admittance function.3. The turbulence wind field of Su-tong Bridge was field measured to get the accurate turbulence wind field characteristics, and give accurate datum to the latter wind tunnel test research and actual identification. Two types of turbulence wind field were passively simulated in wind tunnel. And then the turbulence wind field characteristics were got to analyse the characteristics. The comparison of characteristics between simulated wind field and actual wind field proved the shortage of the passive simulation equipment.4. Using the particularly designed self-developed 60 channels synchronization pulse pressure measurement system, the aerodynamic force of Su-tong bridge deck was field measured to get the time history and frequency curve of average press distribution characteristics, fluctuating press distribution characteristics, static force coefficient and dynamic loads. And the results were compared with those of wind tunnel test.5. The aerodynamic admittance function of Su-tong Bridge deck section was identified in actual site and wind tunnel with the particularly designed self-developed 60 channels synchronization pulse pressure measurement system. The difference of aerodynamic admittance function was discussed between two types of turbulence wind field and actual condition. And the aerodynamic admittance functions were compared with Sears function. Then the aerodynamic admittance function of Su-tong Bridge deck was not between the traditional 1 and Sears function. Moreover, the aerodynamic admittance function of spire turbulence wind field was more closed to that of actual wind field. Lastly, several possible reasons were analyzed.6. Comparing buffeting response calculated by actually tested aerodynamic admittance function with GPS displacement measure results and wind tunnel test results, the actually tested aerodynamic admittance function was proved to be much better in analyzing the buffeting response of Su-tong bridge. And the reliability of research was discussed about the buffet response and wind tunnel test.