Nonlinear evolution analysis of buffeting response of suspension bridge with span

In the report， 11 suspension bridge models with different spans were designed. The wind tunnel tests were performed to obtain the aerodynamic three-component force coefficient of the main girder section. the Matlab toolbox was used to generate the time history of fluctuating wind speed the of the B-type wind field and the buffeting forces were obtained. Based on the data， the structural dynamic characteristics were analyzed， and the buffeting responses of 11 models considering geometric linearity and nonlinearity were calculated. The results showed that with the increase of the span， the structural natural frequency decreases gradually， and the root mean square value of the buffeting displacement increases gradually. For the vertical and torsional responses， with the increase of span， the differences between the linear and nonlinear results increase. For the lateral response， the differences change slightly， which suggested that the geometric nonlinearity mainly affects the responses in the vertical and torsional directions. In order to explore the evolution of the buffeting response with the main span length， the spectrum analysis was performed to obtain the contributions of the resonance and the background components of each main mode. Then， the variation of the two contributions was analyzed. Finally， a formula describing the evolution of buffeting responses with the span length was obtained via data fitting. A bridge was used as a numerical example， the buffeting responses were calculated， and the results are compared with that by the fitted formula， which verifies the practicability of the proposed formula， and can be used as a fast evaluation tool for buffeting responses of suspension bridges immersed in B-type wind fields.