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Operating Failure Contributors
Published in Maurice L. Adams, Power Plant Centrifugal Pumps, 2017
In a number of troubleshooting experiences, the elusive root cause of plant rotating machinery vibration problems has been determined to be the neglect at the design stage that the support structure is not immoveable. Specifically, suppose a machine is to be mounted to the floor of a large plant and the vibration design analysis of the machine assumes the floor to be perfectly rigid. The vibration analysis will likely be seriously flawed. Common sense dictates that one does not devise an FEA model of the entire plant building just to couple it to the vibration model for the pump alone. Usually it is the vertical floor motion under the machine that is the important feature that needs to be incorporated into the overall vibration analysis model. The approach for characterizing any linear electrical circuit’s impedance as a simple LCR circuit is by imposing a controlled harmonic voltage and measuring the resulting harmonic current output over the applicable frequency range. By varying the frequency of the imposed voltage, equivalent LCR coefficients can be solved as functions of frequency. For the vibration counterpart, a controlled harmonic vertical force is imposed upon the floor and the resulting floor vibration simultaneously measured. Figure 3.22 shows a schematic of this and Equation 3.6 is the system equation of motion (Adams 2010):
Vibration performance of cross-laminated timber (CLT) floor under multi-person load
Published in Airong Chen, Xin Ruan, Dan M. Frangopol, Life-Cycle Civil Engineering: Innovation, Theory and Practice, 2021
Haoyu Huang, Chang Wang, Xiaoqi Lin, Wen-Shao Chang
Through the time-history analysis of the finite element results of OPENSEES, it can be seen that the number of people moving on the floor will inevitably affect the floor vibration response. VDV of CLT floor under multi-human load is always greater than that of single person, which indicates it is significant to consider the CLT floor vibration performance un-der multi-person load in design process. Another finding is that the VDV calculated by OPENSEES is consistent with that from experimental tests.
Continuous Models for Vibration
Published in Haym Benaroya, Mark Nagurka, Seon Han, Mechanical Vibration, 2017
Haym Benaroya, Mark Nagurka, Seon Han
In most cases, the perception of floor vibration is related to the response acceleration at different natural frequencies of the floor. Humans are most sensitive to vibrations at frequencies between 4 to 8 Hz. Larger accelerations can be tolerated at higher and lower frequencies.
Occupational falls: interventions for fall detection, prevention and safety promotion
Published in Theoretical Issues in Ergonomics Science, 2021
Sachini N. K. Kodithuwakku Arachchige, Harish Chander, Adam C. Knight, Reuben F. Burch V, Daniel W. Carruth
Floor-vibration sensors (smart floors/intelligent floors) and floor position sensors that can detect positions on the floor are commonly used to detect falls in fall-prone areas in the workplace. This is an alternative economical method for high technology methods. Floor vibration sensors detect the change of vibration patterns and floor sensors detect position via electrical capacity (Steinhage and Lauterbach 2008). The major difference between these two types is that the floor-vibration sensors can directly detect falls while floor sensors detect altered posture (long term inactivity, longer lying period) (Steinhage and Lauterbach 2008). However, due to limited applicability over a large workplace and the requirement of specific floor types, its use is restricted (Haffner et al. 2018).
Vibrational performance of wood floors in traditional residential timber structures in southwest China
Published in Architectural Engineering and Design Management, 2023
Jiajia Ou, Zhao Chen, Weiguo Long, Di Chen, Yi Zhang
For time domain vibration data, indicators such as the average amplitude and root-mean-square peak acceleration are used to evaluate the impact of floor vibration on human comfort. The average amplitude is calculated as follows: where T is the sampling time, and x(t) is the vibrational amplitude at time t.