Engineering Calculating Footfall Induced Vibration: Troubleshooting and Tips

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The discussion focuses on troubleshooting footfall induced vibration calculations, specifically comparing results from a user's calculations to those in a design guide. The user reports a significant discrepancy in their results, obtaining 0.000726 instead of the expected 5.79E-0.4. Clarification is sought on calculating the parameter ##\mu##, which is crucial for accurate results. Another participant notes a potential error in the damping ratio, suggesting it should be 1.5% instead of 0.9%, but this alone does not account for the large difference in results. The conversation emphasizes the need for precise calculations and understanding of the parameters involved in footfall analysis.
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Homework Statement
Find real responde mode 1
Relevant Equations
How to find the same results as in the book
Hey guys. Im about to learn about footfall induced vibration. However i want to reach the same results as in the pdf page 44 ''design guide for footfall analysis''

i get 0.000726 while they get 5,79E-0,4.

Can anyone help me figure out what im going wrong and where i have made a mistake?

 

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I'm not sure I get how to calculate the ##\mu##. Otherwise, the only error I can find in your calculation is that ##\zeta_m## should be 1.5%, not 0.9%, but this is not sufficient to explain the discrepancy.
 
Thread 'Why wasn’t gravity included in the potential energy for this problem?'

Thread 'Why wasn’t gravity included in the potential energy for this problem?'

I’m looking at the attached vibration problem. The solution in the manual includes the spring potential energy but does NOT include the gravitational potential energy of the hanging mass. Can someone explain why gravitational potential energy is not included when deriving the equation of motion? I tried asking ChatGPT but kept going in circles and couldn't figure out. Thanks!
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