桅杆风振试验研究

基于风洞模型试验的方法,对桅杆的风振响应进行了试验研究。研究表明:① 桅杆的自振频率相当密集,其风振响应亦具有明显的宽带特征;② 桅杆风振响应频谱随风速的增大由多频离散谱向连续谱转变,在大风条件下位移谱上的频率成份大量增多,振动显现出混沌特征,此时基于振型叠加法的分析结果误差较大;③ 桅杆动位移响应在风速较大时不宜采用零均值假设,但在可靠性分析中仍可采用按动位移均值平移后的Gauss分布假设;④ 桅杆横风振动主要源于顺、横风向振动间能量的转移,应通过在前两阶自振频率处增设VED或TSD装置加以控制。

EXPERIMENTAL STUDY OF THE DYNAMIC BEHAVIOR OF GUYED MASTS IN WIND TUNNEL

In this paper, the dynamic behavior of guyed masts is investigated through model tests in a wind tunnel. It is found that: ① A guyed mast has very close natural frequencies and its dynamic responses have the property of broad band; ② As wind speed increases, PSD of responses alter from discrete form to continuous style and large amounts of frequency component emerge. Responses show some chaotic characteristics. Superposition methods are inaccurate in this case and numerical analysis is recommended; ③It is improper for fluctuating displacements to take zero-average assumption under high wind speed conditions. However, on probabilistic problems the Gaussian assumption may still be made provided average is considered; ④ Lateral responses are mainly derived from energy transfer between longitudinal and lateral vibrations. Installations of VED or TSD devices tuned at the 1st and 2nd natural frequencies are suggested.