超高层建筑非定常非线性气动力模型及风致非线性振动和分岔研究

The high-rise buildings with section varying along the height are taken as object to deeply investigate the unsteady aerodynamic and nonlinear self-excited force model, and then the wind-induced nonlinear vibration and bifurcation behavior by combining theoretical and experimental means. The characteristics of power spectra, coherence functions and phase angles of unsteady aerodynamic of along-wind, across-wind and torsion are studied according to rigid model synchronous multi-pressure measurement wind tunnel test, and their new function expressions with appropriate physical meaning are then presented. The time histories of displacement responses, acceleration responses etc. are obtained by aeroelastic model wind tunnel test. The wavelet ridge is extracted by the wavelet transform method, and then the time-variant aerodynamic damping ratio and aerodynamic stiffness are identified. Subsequently, the nonlinear self-excited force model is set up based on the regression analysis. The wind-induced nonlinear responses of high-rise building are calculated by the precise integration method according to the nonlinear theory, which are compared with the results by linear vibration theory and the results directly by aeroelastic model test to analyze the difference and the contribution of the nonlinear force. Moreover, the bifurcation behavior of wind-induced nonlinear vibration is studied according to the phase diagram and the poinearémapping diagram. This project has a good theoretical and practical value, which can further improve the wind-resistant theory of ultra-high-rise buildings and provides a reference for engineering applications.

本项目以截面沿高度变化的超高层建筑为研究对象，用理论与风洞试验相结合的手段对其非定常气动力、非线性自激力模型进行深入的研究，然后进一步分析其风致非线性振动和分岔行为。通过刚性模型同步测压风洞试验研究各测点层顺风向、横风向和扭转方向非定常气动力的功率谱、相干函数和相位角特征，并由此给出其具有适当物理意义的新函数表达式；通过气动弹性模型风洞实验获得位移、加速度等响应时程，利用小波变换方法提取小波脊线，从而识别出时变的气动阻尼比和气动刚度,再由回归分析法建立非线性自激气动力数学模型；根据非线性理论用精细积分法计算超高层建筑的风致非线性响应，与根据线性振动理论的计算结果、气弹模型实验的直接测量结果进行比较，分析它们的差异性以及非线性力的贡献，并根据相图和庞加莱映射图进行风致非线性振动的分岔行为研究。本项目的研究可以进一步完善超高层建筑的抗风理论并为工程应用提供参考，具有很好的理论和实用价值。

随着人类审美观点、建造技术的进步，现代超高层建筑的体型不再是仅限于沿高度不变的标准方形或矩形截面，因此，建筑风力的非定常特征和漩涡脱落现象更加明显；随着建造技术和建筑材料的进步，超高层建筑正在向着更高、更柔、更纤细的方向发展，这必然导致其对风的敏感性增加，非线性自激力更突出，气动弹性效应增强，其对结构风致效应的贡献将不容忽视。因此，本项目以截面沿高度变化的超高层建筑为研究对象，用理论与风洞试验相结合的手段对其非定常气动力、非线性自激力模型进行深入的研究，然后进一步分析风致非线性气动力对结构振动的贡献和非线性“涡激共振”的幅值。主要内容如下：（1）通过刚性模型同步测压风洞试验研究各测点层顺风向、横风向和扭转方向非定常气动力的功率谱、相干函数特征，结果发现顺风向的气动力主要由紊流力组成，其功率谱和相干函数与风速接近，而横风向和扭转方向的气动力则由紊流力和涡激力共同组成，其功率谱和相干函数则会存在漩涡脱落峰，由此给出其具有适当物理意义的新函数表达式；（2）通过气动弹性模型风洞实验获得位移、加速度等响应时程，利用小波变换方法提取小波脊线，从而识别出时变的气动阻尼比和气动刚度，再由回归分析法建立非线性抖振自激气动力数学模型，同时，建立新的非线性“涡激共振”模型，结合非线性最小二乘法，识别其气动参数，结果表明，本项目给出的方法是有效的；（3）根据非线性理论用精细积分法计算超高层建筑的风致非线性响应，与根据线性振动理论的计算结果、气弹模型实验的直接测量结果进行比较，分析发现横风向和扭转方向的结果存在一些差异，当阻尼比较小时，非线性力的贡献不可忽视，特别是发生“涡激共振”的时候，其振动幅值显著增大。本项目的研究可以进一步完善超高层建筑的抗风理论并为工程应用提供参考，具有很好的理论和实用价值。