Analysis And Research On Aerostatic Instability Of Long-Span Suspention Bridge Under Nonuniformly-Distributed Wind

As the Western-Development gets deeper, more and more long-span bridges stretching across valleys appear. Wind resistance performance is one of the most important safety performances of long-span bridges, as a vital part of it, the research on aerostatic stability of long-span bridge is of great value. Due to complex topography features of valley, wind speed doesn’t distribute evenly along the span, thus it is significant of us to do research on the aerostatic stability of bridges in unevenly-distributed wind.The geometric nonlinearity and wind load nonlinearity are considered in the thesis. Using the result of numerical simulation of wind in the valley, An ANSYS program based on the iteration of time and wind load is written to analyze the aerostatic stability of long-span suspension bridges. By using the written program, the aerostatic stability of one bridge is analyzed, revealing the regulation of the structural deformation variation under different wind velocities. Difference of deformation and critical wind speed of the bridge under evenly and unevenly distributed wind is found. Furthermore, by changing the shape of wind speed curve, a research of aerostatic stability under different condition of wind distribution is done. By altering the initial wind attack angle and adjusting the three component coefficient (number or curve slope), parametric influence of nonlinear aerostatic stability for the bridge has been studied.According to the results, first, because of the complex topography features of valley and the wind direction, the wind speed around the span is always amplified or deflated, then the possibility of losing aerostatic stability changes accordingly. Second,larger displacement area changes from the center of the span to the edge when the wind does not distribute evenly.Third,different shapes of wind speed curves leads to different position of high-level local buckling area, also changes the average wind speed it needs to unstabilize the bridge. At last, initial wind attack angle affects the aerostatic stability by changing the critical wind speed and so on.