Study On The Wind-induced Vibration Responses And Vibration-reduction Design Method By TMD Of Long-span Cable-stayed Bridges Deck

With the development of Science & Technology and the society, more and more long-span bridges have been built and will be built in our country. For the slender long-span bridges, wind-induced vibrations are very important to their design and construction. Based on the summary of the various wind-induced vibrations, by taking a bay bridge as an example, the long-span cable-stayed bridge deck's vertical buffeting responses are studied. Then the passive TMD wind-resistant and vibration-reduced control methods are studied. Several problems have been studied in this paper as follows:1. Firstly, the vibration-reduction mechanism and conformations of the TMD have been discussed. Based on the random vibration theory, the laws of the TMD system's basic parameters including mass ratio, frequency ratio, damping ratio to the effect of vibration-reduced have been studied, also the TMD and the main structure's phase-frequency response have been analyzed. The results proved that the TMD vibration-reduced method is effective.2. Taking a bay long-span cable-stayed bridge as an example, the reasonable finite element model has been established and the bridge dynamical characteristics have been analyzed. Based on the mechanics principle of the cable-stayed bridges, the cable-stayed bridge deck has been simplified to a five-span continuous bridge with multiple spring supports, and the approximate formula of the first vertical vibration frequency can be calculated from the energy relationship between the cable-stayed bridge deck and its spring supports.3. Choosing the deck's flexural vibration mode function is important to calculate the deck's wind-induced vibration responses. But Wind-resistant Design Specification for Highway Bridges advises the mode function (sine function) not exact. So a calculating method of mode function, which can satisfy the complexity of boundary conditions of the cable-stayed bridge deck and express its flexural vibration shape exactly, is proposed in this paper using the cubic spline function. The comparisons with FEA results prove the method accurate, and the mode function above can be easy to the study of the wind-induced vibration.