On the Nonlinearity Index for Aeroelastic Vibration of a Bridge Deck Sectional Model
桥梁节段模型气弹振动的非线性判别方法研究

Error indices were proposed within the framework of ERA (eigensystem realization algorithm) method to evaluate the quality of flutter derivatives identified via wind tunnel experiment of a bridge deck sectional model. By decomposing signal energy into subspaces, the energy ratios among the total signal energy and the effectively identified signal energy and the un-identified signal energy were calculated, respectively, two error indices were defined during the system identification process. Error indices were constructed based on above results. By comparing two sets of error indices obtained from the free attenuation vibration experiment and the wake turbulence-induced ambient vibration experiment performed under identical experimental conditions, respectively, the effect of nonlinearity on the identified flutter derivatives was evaluated based on the proposed error index. Results suggest that within two sectional models used in above mentioned two experiments, the partially streamlined box girder model shows a stronger index for nonlinearity, while the other bluff model with openings presents weaker nonlinearity.