Universal response spectrum procedure for predicting walking-induced floor vibration
Universal response spectrum procedure for predicting walking-induced floor vibration
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DOI：
10.1016/j.ymssp.2015.09.010
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发表时间：
2016-03
影响因子：
8.4
通讯作者：
J. Brownjohn;V. Racic;Jun Chen
中科院分区：
文献类型：
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作者：
J. Brownjohn;V. Racic;Jun Chen
人的行走引起的地板振动是一个重要的使用性问题，无论是对人类居住者还是对振动敏感的设备。目前用于预测行人荷载引起的振动响应的设计方法是复杂的，并且受到低频和高频地板划分的影响。为了简化设计过程并避免地板分类问题，本文提出了一种预测行人脚步声引起的振动响应指标的方法，该方法适用于固有频率在1-20 Hz范围内的任何类型的地板。采用反应谱方法，使用60多名在仪器跑步机上行走的人记录的852个体重归一化垂直地面反作用力（GRF）时间历史数据库来计算反应指标。选择的指标是1 s的峰值、峰值均方根加速度（RMS）和峰值包络速度（1 / 3倍频程）。通过对grf进行权重归一化并将其应用于固有频率在1-20 Hz范围内、阻尼比在0.5-5%范围内的单位质量单自由度振荡器来评估这些特性。此外，为了考虑模态振型和跨越时间（即动荷载持续时间）的影响，记录的GRFs应用于三种最典型的模态振型和5至40米的楼面跨度。所得到的峰值作为频率的函数，即频谱，被浓缩为在广泛应用范围内被超过的选定概率的统计表示。RMS（加速度）谱显示出起搏速率的一阶谐波对应的强峰值，随后在约3.5 Hz处出现明显的最小值，第二个小得多的峰值对应于二阶谐波，并且从5 Hz左右开始随着频率的增加而稳步下降。三倍频谱随频率、跨度和阻尼的变化呈渐近趋势。在振动适用性评估的实验活动中，对具有代表性的地板样品进行了模态特性识别和行走响应研究，并对加速度RMS谱进行了全面的验证。由于统计方法的精确验证是不可能的，因此测量的峰值均方根值与等效理想结构的分布相匹配。在绝大多数情况下，用于表示最坏情况的测量值拟合相应模拟光谱的上十分位数，表明与所提出的方法一致。
Floor vibrations caused by people walking are an important serviceability problem both for human occupants and vibration-sensitive equipment. Present design methodologies available for prediction of vibration response due to footfall loading are complex and suffer from division between low and high frequency floors. In order to simplify the design process and to avoid the problem of floor classification, this paper presents a methodology for predicting vibration response metrics due to pedestrian footfalls for any floor type having natural frequency in the range 1–20 Hz.Using a response spectrum approach, a database of 852 weight-normalised vertical ground reaction force (GRF) time histories recorded for more than 60 individuals walking on an instrumented treadmill was used to calculate response metrics. Chosen metrics were peak values of 1 s peak root-mean-square (RMS) acceleration and peak envelope one-third octave velocities. These were evaluated by weight-normalising the GRFs and applying to unit-mass single degree of freedom oscillators having natural frequencies in the range 1–20 Hz and damping ratios in the range 0.5–5%. Moreover, to account for effect of mode shape and duration of crossing (i.e. duration of dynamic loading), the recorded GRFs were applied for three most typical mode shapes and floor spans from 5 m to 40 m.The resulting peak values as functions of frequency i.e. spectra are condensed to statistical representations for chosen probability of being exceeded over a wide range of applications. RMS (acceleration) spectra show strong peaks corresponding to the first harmonic of pacing rate followed by clear minima at approximately 3.5 Hz, a second much smaller peak corresponding to the second harmonic and a steady decline with increasing frequency beginning around 5 Hz. One-third octave spectra show asymptotic trends with frequency, span and damping.A comprehensive validation exercise focusing on the acceleration RMS spectra was based on a representative range of floor samples for which modal properties had been identified and walking response studied during experimental campaigns of vibration serviceability evaluation. Due to the statistical approach an exact validation would not be possible, hence measured peak RMS values were matched to distributions for the equivalent idealised structure. In the vast majority of cases the measured values, intended to represent worst-case conditions, fitted the upper decile of the corresponding simulated spectra indicating consistency with the proposed approach.