Structure on a stiff foundation
Structure on a stiff foundation
(OP)
My structure has the first natural frequency at approx.15 Hz. The structure is mounted on a foundation with stiffness approx. 30 Hz. The manufacturer of the foundation claims he can measure the 15 Hz. frequency at the foundation. I would assume that if you have the 15 Hz at the structure and the 30 Hz at the foundation, the separation should be enough to not see any significant accelerations at 15 Hz at the foundation. So where could the 15 Hz. come from? Do I need more separation between the structure and the foundation?





RE: Structure on a stiff foundation
Tobalcane
"If you avoid failure, you also avoid success."
RE: Structure on a stiff foundation
Cheers
Greg Locock
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RE: Structure on a stiff foundation
RE: Structure on a stiff foundation
Twoballcane: The 30 Hz. frequency is with the mass of the structure.
Greg: I agree it will see the spring force, but not as a dynamic load. If they are decoupled as we want to achieve, it will be like a static force, and no dynamic amplification. But the foundation manufacturer measures a clear amplification.
RE: Structure on a stiff foundation
Tobalcane
"If you avoid failure, you also avoid success."
RE: Structure on a stiff foundation
Regards,
Ibrahim Demir
RE: Structure on a stiff foundation
RE: Structure on a stiff foundation
"I am just guessing thet the clear multiple of 2 between the forcing frequency and the natural frequency may be effecting the foundation."
Reagrds,
Ibrahim Demir
RE: Structure on a stiff foundation
"The structure is mounted on a foundation with stiffness approx. 30 Hz" or "The 30 Hz. frequency is with the mass of the structure."...The foundation is at 30hz with or without the structure?
Tobalcane
"If you avoid failure, you also avoid success."