Design for sensitive equipment.
Floor system frequency of vibration calculation.
Unlike the sdof system which has a single natural frequency and corresponding mode of vibration a continuous system theoretically has an infinite number of natural frequencies and associated modes.
The natural frequency of the system assuming a single degree of freedom can be calculated by.
This calculator gives the fundamental vibration frequency of a floor joist girder and the combined floor system.
Floor systems and footbridges for vibration serviceability due to human activities.
The simple spandeflection ag of the floor girder may be calculated in the same manner as a.
6 floor vibration continuous systems a beam has a mass stiffness and boundary conditions at the supports that define its behaviour.
False floor l spread of energy throughout the whole structure.
Require the calculation of the first natural frequency of the floor system and the maximum amplitude of acceleration.
P o is 65 lb for office.
Observe the behavior when the excitation frequency coincides with the natural frequency of the system.
Supporting the floor system also af fects the natural frequency of the floor system.
Try this test for each type of excitation.
The system has a fundamental frequency which corresponds to the first lowest mode of vibration.
In this mode the vibration reaches maximum amplitude in one position an antinode at mid span of the beam.
Is the natural frequency of the floor system βis the modal damping in the floor system and w is the effective weight that moves because of the excitation.
People are often annoyed by and are very sensitive to vibrations in the 8 10 hz range.
Where f is the natural frequency of the considered mode k mod is the modal stiffness m.
Modal mass m mod each mode of a system with several degrees of freedom can be represented by a system with generalised mass a single degree of freedom.
Watch what the system is doing.
Damping by furniture and finishing e g.
Both human comfort and the need to.
At first glance the criteria might look a bit formidable it certainly is different than the older criteria.
In reality only f n and w require calculations.
Hz 1 3 13 2 1 2 1 2 1 g w kg.
The additional benefit of making it easy to calculate the system natural frequency.
For best results the frequency should be 15 hz or higher.
If more flexibility is needed air springs are used.
The natural frequency of the floor system may then be estimated by the following formula 2 3 f 0 18i g aj ag 3 for concrete floor systems sup ported on walls 4gmay.
If the forcing frequency is close to the natural frequency of the system and the system is lightly damped huge vibration amplitudes may occur.
