The Buffeting Response And Control Study Of Long-span Cable-stayed Bridge At The Longest Cantilever Construction Stage

With the development of modern materials and construction techniques, the wind effects on bridges become more prominent as the structures grow with longer span and more flexibility. And cantilever construction method is usually adopted in the long-span cable-stayed bridge construction. Turbulence wind often induces the bridges to the buffeting response at the longest cantilever construction stage and the great buffetings are bound to affect the construction safety, therefore, how to ensure the dynamical stabilities of the bridge construction and use economical and effective measures to reduce the wind-induced finite vibration become one of the primary problems of bridge researchers.Based on existing research findings in wind-induced vibration control, this paper investigates the static wind loads subjected to average wind speed and dynamic wind loads under turbulence components, and expatiates the wind load specifications of some countries. In addition, taking the Hongshan Bridge and the Sutong Yangtse River Bridge for example, the buffeting response of the beam at the longest double cantilever construction stage, are studied in the paper. Emphasis is put on the following two aspects. First, the parameters which affect the buffeting response at the longest cantilever construction stage are analyzed in detail. Second, the proportion of the buffeting background part to the total buffeting response is investigated carefully. The results indicate that the variations of wind velocity, damping and structural frequency play a major role on affecting the buffeting response of the beam at three directions. And especially, the buffeting response will decrease obviously when the structural frequency increases. Hence, during the construction stage of the cable stayed bridges, it is an effective approach to reduce the wind response by increasing the structural frequency. The above mentioned results are tested and verified by the scaled full model of Changsha Hongshan Bridge in a scale of 1:30, namely, by using different temporary supports to reduce buffeting response and improve wind resistance characteristics during the construction stage. And the buffeting response of the Hongshan Bridge at the longest cantilever construction stage and setting temporary piers, are calculated, therefore the applicability in engineering is proved.