Wind-induced Vibration And Its Control During The Period Of Construction Of Multi-pylon Cable-stayed Bridge With High Piers

Now as technology of cable-stayed bridge construction grown, cable-stayed bridge is developing toward thin, lightweight, larger and multi-pylon. Its sensitivity to wind continually increases. For multi-span cable-stayed bridges with high piers, its piers are very high and its stiffness is very small. So the large buffeting responses during construction stages will appear, and the large buffeting responses can cause many problems such as fatigue of bridges, affect construction quality and crisis of the safety of construction machinery and personnel and so on, and even cause accident of ridge destroyed. Therefore, it is very necessary to study buffeting response and the effective measures to control it of multi-span cable-stayed bridges with high piers. Based on on the engineering background of the Chi Shi cable-stayed bridge under construction in the domestic, this paper mainly studies the buffeting response analysis of the construction of cable-stayed bridge with high piers and the measures to control buffeting response of it. The main contents of this paper are as follows:(1) A brief introduction of the development history of cable-stayed bridge at home and abroad were given. The research status of multiple pylons cable-stayed bridge and the buffeting theory and the wind-induced vibration control measures of the construction of bridges were reviewed.(2) Weighted amplitude wave superposition (WAWS) method was used to develop the fluctuating wind field simulation program based MATLAB software.The fluctuating wind speeds of the nodes of pylon and the main deck of the Chi Shi cable-stayed bridge were simulated with the program developed in present thesis, The wind spectrum of the fluctuating wind speeds were agree well with the wind spectrum given by the specification code, and the effectiveness of the fluctuating wind field simulation program in this paper was verified.(3) The dynamic characteristics of the maximum double cantilever structure of the Chi Shi cable-stayed bridge was calculated with ANSYS software. Based on the Davenport quasi-steady buffeting theory, the time-domain buffeting analysis method of the large span bridge was established using ANSYS software. The wind-induced buffeting responses of the original maximum double cantilever structure of Chi Shi bridge was calculated. Finally, the assessment of the safety of bridge structure caused by wind-induced buffeting responses at design wind speed were conducted. (4) Based the comprehensive review of the wind-induced vibrations control measures of large span cable-stayed bridges during construction stages, the wind-induced vibrations control measure of "tied-down cables and tuned mass dampers (TMD)" was given according to the characteristics of the Chi Shi cable-stayed bridge.. The buffeting responses analysis of the maximum double cantilever state for bridge structure with the wind-resistant control measures were calculated. And the buffeting responses of the bridge structure with and without wind-induced vibration control measures were compared to verify the effectiveness of the wind-induced vibration control measures.(5) A aeroelastic full bridge model with the geometrical scale ratio of1/200and the wind-induced vibration control measures were designed and made separately. The wind tunnel experiments of the maximum double cantilever structure of the Chi Shi cable-stayed bridge with and without wind-induced vibration control measures were conducted separately.The experimental results were compared with the numerical results in present thesis to verify the reliability of the method and the vibration control effect of wind-resistance measure in this paper.