【作者】 胡卫华；

【导师】 任伟新；

【作者基本信息】 福州大学 ， 结构工程， 2005， 硕士

【摘要】 索的动刚度描述动态过程中索的荷载与变形之间的关系，可以准确的反映索结构的动力行为。从模态分析的角度探讨索的动刚度，其定义为响应与激励的比值，即索的频响函数，是索本身所固有特性的反映。通过实验模态分析，可以估计出索的频响函数，辅以曲线拟合，就可以通过模态分析的方法实现索模态参数的识别，用于研究索的动力特性。本文的主要工作包括： 1．考虑阻尼的影响，假设索的静态索形为抛物线，从索的振动微分方程出发，推导了索的动刚度一般解析表达式。将索的动刚度退化为静刚度，验证动刚度的正确性，并深入讨论了索动刚度各项的物理含义。 2．对索动刚度进行数值分析，研究了不同简化模型对索模态参数的影响，在此基础上提出了用于索模态参数识别的索动刚度简化模型，以便于索的模态参数识别。 3．用模态实验的方法测得了索的频响函数，详细讨论了索模态试验中各种试验参数的影响，如采用频率、锤头硬度、锤击位置、传感器布置、频率分辨率，窗函数和平均技术，得到了索频响函数的正确估计。 4．采用最小二乘拟合的方法，应用理论频响函数(动刚度)和试验频响函数，识别出了索的各阶频率和阻尼，从而建立了一个斜拉索模态参数识别的新方法。更多还原

【Abstract】 The dynamic stiffness of cables describes the load-deformation behavior of cables subjected to dynamic loading, which can represent the dynamic properties of cable structures accurately. The dynamic stiffness is basically defined as a ratio of response to excitation. From the viewpoint of modal analysis, this definition is identical to the frequency response function (FRF) that reflects the intrinsic characteristics of cables. The FRF can be synthesized using the measured excitation and response signals from cable modal tests. By fitting both cable dynamic stiffness and measured FRF, then, the FRF is cured fit to identify the modal parameters of cables. The main work of this thesis includes1. Assuming that the cable static equilibrium configuration is a parabolic profile and considering the damping, a closed-form expression of dynamic stiffness is derived based on the cable vibration differential equation. The derived cable dynamic stiffness has been compared with the cable static stiffness and the physical meaning of each item in the cable dynamic stiffness is clarified.2. Comprehensive numerical studies have been carried out on the closed-form expression of dynamic stiffness. Several simplified cable dynamic stiffness models are discussed and compared. Based on the numerical study results, a simplified dynamic stiffness model is presented for the purpose of cable modal parameter identification with a good accuracy.3. A series of cable modal tests have been conducted in the laboratory with different cable tension levels and corresponding FRFs are obtained. A number of issues related to the cable modal tests have been discussed such as sampling frequency, hammer toughness, excitation placement, accelerometer arrangement, frequency resolution, windowing and average technique. As a result, the FRFs are estimated with a relative accuracy form measured excitation and responses.4. Based on the proposed simplified cable dynamic stiffness and measured FRPs, the cable modal parameters (frequencies and damping ratio) have been successfully identified by using a least square curve fitting technique. Subsequently, a new method to estimate the cable modal parameters is established.更多还原