Study On Aerodynamic Parameter Identification And Wind-Induced Responses Of Long-Span Arch Bridges

In this paper, with the application of physical wind tunnel testing and theoretical model analysis, the study on wind-induced vibration of Long-span arch bridges has been completed for typical bridge projects, including Shanghai Lupu Bridge, Guangzhou Xinguang Bridge, Hunan Maocaojie Bridge, Zhejiang Sanmenkou Bridge and Yinbin Minjiang Second Bridge. The main work of this study covers identification of aerodynamic coefficients, analysis of aerostatic stability, analysis of buffeting in time domain, aeroelastic stability calculation, aerodynamics stability analysis including galloping, flutter and vortex-shedding vibration. The main research work and findings can be concluded:1. The steady-state aerodynamic coefficients of rectangle arch rib, tetragonal prism arch rib and arch rib shaped like a top were measured by force balance testing. The drag coefficients change little with wind angles of attack. Reynolds number have effects on the steady state aerodynamic coefficient results of multiple cylindrical arch rib in wind tunnel reduced-scale model testing. Consequently, the steady state aerodynamic coefficient of multiple cylindrical arch rib must be modified.2. The equivalent aerodynamic admittance of rectangle arch rib, tetragonal prism arch rib and arch rib shaped like a top were identified by cross-spectrum method. The identification results of different aerodynamic bodies show some difference, but in general, the trends of equivalent aerodynamic admittance are reduced with the increase of reduced frequency. Under the conditions of the attack of angle 0°, the identification results of the drag equivalent aerodynamic admittances on three types of arch rib models are all less than unit, the identification results of the lift equivalent aerodynamic admittance are more than one within low discount frequency , the identification results of the moment equivalent aerodynamic admittances on rectangle arch rib and arch rib shaped like a top are more than one within low reduced frequency.3. Eighteen flutter derivatives of three arch rib section models in smooth flow are extracted using stochastic search algorithm. Buffeting response of three long-span arch bridges were calculated in time domain. The influences of self-excited force and aerodynamic admittances on buffeting response were discussed. The buffeting displacement results based on aerodynamic admittances with measured values, Sears function and one are different one to another. The self-excited forces basically reduce buffeting displacement, but with small portion. The impacts of the self-excited forces can be neglected on the conservative side.4. The nonlinear aerostatic stability of Guangzhou Xinguang Bridgeand Zhejiang Sanmenkou Bridge were analyzed by the plastic hinge method and the low relaxation method. The critical wind speed of instability using the low relaxation method was smaller than using the plastic hinge method, thus, the low relaxation method results in conservative results. In addition, because the low relaxation method needn't confirm plastic hinge by manual operation, the low relaxation method is sampler and more practical than the plastic hinge method.5. The research of the potential wind-induced vibration forms of long-span arch bridges show that the possibility of flutter and galloping is little, vortex-shedding vibration occurs in bluff arch rib section, for example, Shanghai Lupu Bridge, and the phenomenon of arch buffeting is quite common.