Probability-based prediction of multi-mode vibration response to walking excitation
Probability-based prediction of multi-mode vibration response to walking excitation
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DOI：
10.1016/j.engstruct.2006.07.004
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发表时间：
2007-06
影响因子：
5.5
通讯作者：
S. Z̆ivanović;A. Pavic;P. Reynolds
中科院分区：
文献类型：
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作者：
S. Z̆ivanović;A. Pavic;P. Reynolds
在人行桥的振动正常使用性检查中，由单个人行走引起的力通常被建模为具有与人行桥固有频率之一匹配的频率的谐波力。该方法假设，在构成行走力的无限多个谐波中，只有一个谐波对于振动正常使用性检查是重要的。另一个常见的假设是，人行桥可以模拟为单自由度系统，这意味着只有在一个单一的模式振动是感兴趣的。此外，由于这种方法的确定性，它不能考虑到跨学科和学科内的步行力的变化，现在在文献中有很好的记录。考虑到这些变化，本文提出了一种新的概率方法进行振动正常使用性检查。考虑了步行频率的概率分布、步行力的步长和最低五次谐波和次谐波幅值等因素。使用步行力的时间历程测量跑步机上，力的频率内容进行了研究，从而在制定的多谐力模型。该模型可用于人行天桥的多模态响应分析。这一点已在一座已建成的悬链线人行桥结构上得到成功验证。虽然本文只分析了人行桥的振动响应，但所提出的力模型也有可能在多模态响应更频繁发生的楼板振动估计中实施。该模型易于编程，因此可以提供一个强大的工具，用于有效地估计由于单人行走引起的各种级别的振动响应的概率。因此，建议的概率为基础的方法有可能彻底改变目前的实践规范的哲学处理下的人致振动结构的振动适用性。
In vibration serviceability checks of footbridges, a force induced by a single person walking is usually modelled as a harmonic force having a frequency that matches one of the footbridge natural frequencies. This approach assumes that, among the infinite number of harmonics a walking force is composed of, only a single harmonic is important for a vibration serviceability check. Another usual assumption is that the footbridge can be modelled as an SDOF system, implying that only vibration in a single mode is of interest. In addition, due to the deterministic nature of this approach, it cannot take into account inter- and intra-subject variabilities in the walking force that are now well documented in the literature. To account for these variabilities, a novel probabilistic approach to carry out a vibration serviceability check is developed in this paper. Factors such as the probability distribution of walking frequencies, step lengths and amplitude of walking force for its five lowest harmonics and subharmonics are taken into account. Using walking force time histories measured on a treadmill, the frequency content of the force was investigated, resulting in the formulation of a multi-harmonic force model. This model can be used to estimate the multi-mode response in footbridges. This was verified successfully on an as-built catenary footbridge structure. Although only the vibration response of footbridges was analysed in this paper, the force model proposed has the potential to be implemented in the estimation of floor vibration as well, where multi-mode response occurs more frequently. The model is easily programmable and as such could present a powerful tool for estimating efficiently the probability of various levels of vibration response due to single person walking. Therefore, the proposed probability-based methodology has the potential to revolutionise the philosophy of the current codes of practice dealing with vibration serviceability of structures under human-induced vibration.