Static Stability Analysis And Time Domain Wind-Induced Buffeting Analysis Of The Long-Tan River Long-Span Bridge

With the improvement of the calculation technique, development of the construction technique and employment of new type material, the bridge structures gradually develop towards the long span and light weight aspects, the problem about stability and wind-induced response of the great bridge increasingly represent prominent. Therefore, it is very necessary to conduct the comprehensive and systemic investigation on the bridge stability and wind-induced response. In this paper, combined with the a long-span continuous rigid frame bridge with thin-wall high piers-Long-Tan River Long-Span bridge which is a part of the Shanghai-Chengdu express way in the west Hubei province (from Yichang to Enshi), the static stability and time domain analysis of wind-induced buffeting response is studied, including the following four aspects.On the static stability. First on all, the local stability analysis solution about the thin-wall component is obtained in order to determine the limit value of the minimum width-thin ratio under the different constrained conditions. By utilizing the great current finite element program ANSYS, two types of finite element models in different stage, i.e., beam model and shell model are established for Long-Tan River great bridge, respectively. The first kand of stability analyses are conducted for the some cases in the construction and completed bridge stage. In addition, the second kind of stability analyses are made by adopting the Modified Newton-Rahpson iterative method, the initial deflection induced by the unilateral sunlight and the geometrical nonlinearity effect are considered. Finally, the stability safety capability estimation is conducted for the Long-Tan River great bridge.On the wind tunnel tests. The aerodynamic force coefficients of both the girder and the pier sections of the Long-tan river bridge are measured by performing sectional model tests. The aero-elastic models of the main bridge structure are modeled in worse-case state during erection stage and only-pier state. For variating wind attack angles and yaw angles, with or without the neighborhood background girders, the galloping stability, vortex-excited resonant, and buffeting responses of the bridge are investigated respectively by performing corresponding wind tunnel tests.On the wind field simulation. The fluctuating velocities of wind fields is depicted by the statistical characteristics, like power spectral density functions, mean velocities, etc. These are firstly given here. As far as the weighted amplitude wave superposition (WAWS) method for simulation of the wind fields is concerned, its formula are derived. The simulated wind fields will be unbiased and ergodic, that is, the estimated first and second order moments are equal to the corresponding targets not only in the ensemble sense, but also in the temporal sense. The computation efficiency can be improved by the FFT technique. Flow chart of the simulation procedure is given, as well as the numerical methods to obtain statistics from the simulated results. The FORTRAN language is employed to program the formulas of the WAWS method, so that fluctuating velocities of the wind field around the Long-tan river bridge are simulated.On the time domain buffeting analysis. Practical formulas for evaluating the static and buffeting aerodynamic loading on the bridge decks are derived, on the basis of the quasi-steady aerodynamic theories. The loading time histories, both during the construction stage and the full stage, are then calculated from the simulated wind fields. Using the ANSYS software, FE (finite element) models of the bridge is established and loaded. Then, the wind-induced time domain buffeting responses of the bridge during the two stages are predicted, by conducting the time history dynamic analysis.Finally, the work in this paper is summarized and some conclusions about the study are drawn, besides, the further research problems are indicated.