Footbridge system identification using wireless inertial measurement units for force and response measurements
Footbridge system identification using wireless inertial measurement units for force and response measurements
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DOI：
10.1016/j.jsv.2016.08.008
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发表时间：
2016-12
影响因子：
4.7
通讯作者：
J. Brownjohn;M. Bocian;D. Hester;A. Quattrone;W. Hudson;Daniel Moore;Sushma Goh;M. S. Lim
中科院分区：
文献类型：
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作者：
J. Brownjohn;M. Bocian;D. Hester;A. Quattrone;W. Hudson;Daniel Moore;Sushma Goh;M. S. Lim
由于主要关注的是安全性，结构的振动适用性设计往往被忽视或管理不善，导致一些高姿态的结构在行走，跑步或跳跃引起的人类动态载荷下无法充分发挥作用。一个标准的工具，以通知更好的设计，证明适合的目的之前，进入服务和设计改造是模态测试，一个程序，通常涉及加速度测量使用一系列有线传感器和力生成使用机械振动器。一个关键但经常被忽视的方面是使用输入（力）与输出（响应）关系来估计模态质量，这是直接控制使用中振动水平的关键参数。本文介绍了无线惯性测量单元（伊穆斯）的使用，该单元专为生物力学运动捕获应用而设计，用于109 m人行桥的模态测试。伊穆斯首先用于仅输出的振动测量，以识别模态频率、形状和阻尼比，然后用于同时测量跳跃的人体受试者的身体加速度，以激发特定的振动模式，并在跳跃位置建立桥面加速度。使用模态振型和垂直加速度数据从一个合适的身体地标缩放的身体质量，从而提供跳跃力数据，它是可能的，以创建频率响应函数和估计模态mass.The模态质量估计这座桥进行了检查，对使用仪器锤和已知的质量分布获得的估计，显示实验估计之间的一致性。最后，该方法被用于一个应用研究应用程序中的短跨度人行桥的高度便携式和易于使用的伊穆斯提供的物流和操作简单的好处证明是非常有用的振动服务能力的有效评估，包括估计模态质量。
With the main focus on safety, design of structures for vibration serviceability is often overlooked or mismanaged, resulting in some high profile structures failing publicly to perform adequately under human dynamic loading due to walking, running or jumping. A standard tool to inform better design, prove fitness for purpose before entering service and design retrofits is modal testing, a procedure that typically involves acceleration measurements using an array of wired sensors and force generation using a mechanical shaker. A critical but often overlooked aspect is using input (force) to output (response) relationships to enable estimation of modal mass, which is a key parameter directly controlling vibration levels in service.This paper describes the use of wireless inertial measurement units (IMUs), designed for biomechanics motion capture applications, for the modal testing of a 109 m footbridge. IMUs were first used for an output-only vibration survey to identify mode frequencies, shapes and damping ratios, then for simultaneous measurement of body accelerations of a human subject jumping to excite specific vibrations modes and build up bridge deck accelerations at the jumping location. Using the mode shapes and the vertical acceleration data from a suitable body landmark scaled by body mass, thus providing jumping force data, it was possible to create frequency response functions and estimate modal masses.The modal mass estimates for this bridge were checked against estimates obtained using an instrumented hammer and known mass distributions, showing consistency among the experimental estimates. Finally, the method was used in an applied research application on a short span footbridge where the benefits of logistical and operational simplicity afforded by the highly portable and easy to use IMUs proved extremely useful for an efficient evaluation of vibration serviceability, including estimation of modal masses.