鉴于现有时域-频域混合的线性气动自激力模型所存在的局限性，本课题通过开发一套采用节段模型自由振动方法测试桥梁断面气动自激力的风洞试验技术，提出气动自激力的自由振动风洞试验测试方法。基于节段模型气动自激力的风洞试验结果对主梁断面气动自激力的非定常特性和非线性特性进行研究。在此基础上探索建立适用有效的桥梁断面非线性气动自激力数学模型，采用非耦合和耦合自由振动测试的气动自激力对该数学模型的参数进行识别，并通过典型桥梁主梁断面在颤振前和颤振发生后大攻角振动状态测试的气动自激力试验结果对该非线性时域数学模型的可靠性和适用性进行验证。结合所提出的桥梁断面气动自激力非线性时域数学模型，进一步发展大跨度桥梁结构三维非线性颤振分析的实用理论和分析方法，本课题对大跨度桥梁抗风理论的发展具有重要的理论和实用意义。

In view of the limitation of the existing linear model of the self-excited forces in the time-frequency domain, wind tunnel testing to measure the self-excited forces of bridge decks is proposed based on the free-vibration technique of sectional model. The nonlinear and non-steady characteristics of the aerodynamic forces of the bridge deck are investigated based on the testing result of the forces in the wind tunnel. Furthermore, a proper and effective nonlinear model of the self-excited forces of the bridge decks is proposed and the aerodynamic coefficients of the nonlinear model are extracted from the result of the forces with the non-coupling and coupling free-vibration wind tunnel test. The reliability and applicability of the nonlinear model is proved based on the forces measured from the free-vibration testing with large torsional amplitudes at the stable state and at the flutter state. Moreover, the nonlinear analysis of coupled flutter of long-span bridges is developed based on the proposed nonlinear time-domain model of the self-excited forces of the bridge decks and the research of the proposed project has hence important theoretical and practical significances.