基于R.H.Scanlan提出的自由振动法求解桥梁颤振导数实验量很大，且在提取交叉导数的过程中，一方面要求模型的竖向运动和扭转运动在所有的风速下都具有相同的频率比和阻尼比是很难达到的，另一方面非耦合导数的识别误差将带到耦合导数中。基于Modified Ibrahim Timedomain Method(MITD)时域的改进方法，应用变尺度优化算法进行提取桥梁断面的全部颤振导数。研究结果表明，应用此方法具有解决非线性参数辨识问题的可行性。

The experimental task was very large for solving fremitus derivative of bridge by free vibration method proposed by R.H.Scanlan.And in the process of extracting cross derivative, it was difficult that the frequency ratio and damping ratio under vertical motion and torsional motion were kept the same in all wind speed.Besides, the discriminating error of uncoupled derivative would be coupled in derivative.Considering these, an improved method based on Modified Ibrahim Timedomain Method was proposed.With the application, it was found that this method was better than least square method.

国家自然科学基金资助(50778185);重庆市大学“211工程”三期创新人才培养计划建设项目(S09105)