基础激励测试结构动力特性精度研究

结构动力特性决定结构在动力荷载作用下的动力响应,对结构的动力破坏与安全具有重要意义.精确测试结构动力特性参数是其研究的一个重要方面.采用基础激励的方法测试结构动力特性是一种行之有效的方法.通过实验的方法研究了基础激励测试结构动力特性的精度.实验结果表明,结构动力特性参数在实验范围内不受激励幅值大小的影响；基础激励频段范围对结构的振型影响不大,但对频率与阻尼比的影响很大；只要基础激励的频段包含所要测试的结构固有频率,就能精确测试出结构此阶的频率与阻尼比；如基础激励频段不包含所要测试的结构固有频率,则不能精确测试出结构此阶的频率与阻尼比.因此在使用基础激励方法测试结构动力特性时,应使基础激励的频段包含所要测试的结构固有频率.

On the Precision of Structural Dynamic Properties in Base Excitation Testing

Dynamic properties of structure determine the dynamic response induced by dynamic loading, so are important to dynamic failure and safety of structure. Accurate measurement of structure dynamic characteristic parameters is an important aspect of dynamic response. It is an effective method to measure the structure dynamic properties by using base excitation. The measurement precision of structure dynamic properties was experimentally studied based on base excitation. Experimental results show that dynamic properties of structure are not affected by amplitude of base excitation, and base excitation frequency range has only little effect on the vibration type of structure; but affects the ratio of frequency and damping remarkably. So long as the frequency range of base excitation includes the natural frequency of tested structure, the ratio of frequency and damping of structure can be measured accurately. If the frequency range of base excitation does not include the nature frequency of tested structure, the dynamic properties of the structure can not be measured effectively by base excitation method. So, when structure dynamic properties are measured by using base excitation, the frequency range of base excitation should include the natural frequency of tested structure.