Time Domain Buffeting Response Analysis Of Suspension Bridge UnderNon-stationaryTyphoon

Abstract:With the deeper understanding of the non-stationarity of the extreme wind, e.g., typhoon, downburst and etc., and lighter and more flexible structure of the bridge, the aerodynamic behavior of flexible bridge in the typhoon prone regions under such non-stationary wind are increasingly concerned. To propose a method to investigate the buffeting response analysis of bridge in time domain induced by non-stationary typhoon wind will promote the accuracy of buffeting response analysis of bridge.This research mainly focuses on proposing a method to carry out buffeting response analysis induced by non-stationary typhoon wind in time domain based on the collected wind time series. This method involves in time-frequency analysis method、non-stationary wind simulation method and FEM(Finite Element Method). The dissertation has accomplished several achievements, in particularly:1、Provide the wind simulation program based on Fortran90and wave superstition method and make it more efficient by utilizing the FFT method.2、Investigate the non-stationarity of the collected wind data during typhoon via the Hilbert-Huang method, and the result shows that there are obvious time-varying transient frequency properties in the typhoon wind.3、Estimate the EPSP (Evolutionary Power Spectrum) by utilizing the STFT (Short Time Flourier Transform) method, while the fitting EPSP has been estimated by deterministic modulating function of time-varying average characters of the real typhoon wind. By comparing the result of fitting EPSP derived by several regular spectrums, the Von-Karman spectrum is chosen. And the fitting EPSP greatly meets the EPSP estimated by STFT.4、The one-dimensional, multivariate, non-stationary wind time series simulation program is proposed to simulate the non-stationary wind based on fitting EPSP and wave superstition method. The program is further applied to provide45non-stationary wind time series along the span of the Shideng Suspending Bridge. By comparing the analyzing result of the simulated stationary and non-stationary wind time series via Hilbert-Huang method, the significance of buffeting response analysis induced by the simulated non-stationary time series is guaranteed due to its more obvious time-varying transient frequency.5、The3D finite element model of Shideng suspension bridge has been established and the original status of the bridge has been identified by controlling the displacement of center of the span and adjusting the original strain of the main cable. This model further has been utilized to investigate its dynamic characteristics of the bridge in completion state based on mode analysis method.6、The numeral method has been used to carry out the buffeting response analysis of suspension bridge under stationary and non-stationary wind based on FEM software ANSYS in time domain. And the response of the bridge induced by non-stationary wind is obviously larger than that induced by stationary wind due to the larger root mean square of the displacement of point along the span of bridge.