1

I am reading a textbook on fundamentals of vibrations and it has a very brief introduction to shock spectra. It mentions that

For comparison purposes, it is customary to use the response of an undamped single degree of freedom system to obtain the shock spectrum.

So is it that we always find the maximum response of an undamped single DOF system to get the shock spectrum? If yes, then how does it help us, because can't the response of the structure which I am analysing (say a building) be widly different from that of a single DOF system? For example, consider two shocks. The shock which seems "stronger" (higher maximum response in general) when using a single DOF system may actually be weaker when using my structure.

Also, just saying an undamped single DOF system seems vague because response to the same shock may differ for different single DOF systems. Is there a specific single DOF system that is used here (like the mass-spring system)?

ModCon
  • 113
  • 2

1 Answers1

1

Not necessarily, many shock response spectra are created for systems under the impulse of a shock with damping.

However many codes allowing seismic design using the response spectra with an estimated 100-year or whatever design earthquake require the assumption of the three spectra $ S_d, \ S_v, \, and \ S_a $

related as:

$ S_v= \omega S_d\\ S_a= \omega^2 S_d$

And this is valid only for a single degree of freedom system with no damping.

kamran
  • 23,517
  • 2
  • 22
  • 42