Dynamic Loads

[begstr]

Designing a floor for a piece of equipment that vibrates. I'm given the choked weight (22,000 kg). The dynamic loads are: Horizontal (4.8 Hz) = +/- 1320 N and Vertical (4.8 Hz) = +/- 3760 N.

The floor with be W shaped beams with grating.

People will be working around the machine while in operation, so I'd obviously like to keep the floor vibrations low.

Any advice on how to proceed would be helpful.

Thanks!!

 

[kslee1000]

I think the equipment shall equipped with vibration/shock absorbers.

 

[Elindio1]

Please refer to Mason Industries website. They have example of selection of vibration absorbers for unbalanced load equipment.

 

[civilperson]

Two separate structural systems, one for the platform and one for the machine. Take as far back as possible, (separate foundations or at the least separate columns).

 

[begstr]

I'm looking more for how to design the beams themselves to take the dynamic loads.

 

[271828]

Unless you have some really weird situation, you wouldn't do anything special in the beam design to account for dynamic loads. The vibe isolators will make the loads small.

 

[begstr]

We've been in plants where the beams were acceptably designed for the choked weight of the cleaner, but the floor still moved up and down and was almost uncomfortable to be on.

Other plants with the same cleaner and very overdesigned beams (as far as the choked weight) have little movement. It seems as though they just used a factor of 3 or so to increase the load. This seems arbitrary, and I was hoping to find some equations or basis.

Thanks

 

[ChipB]

A rule of thumb for vibrating equipment is 3x the mass in concrete to dampen the movement. So you'd need 30k of concrete to dampen it. We usually plate between the bottom flanges of the support beams, and fill the void with concrete.

 

[kslee1000]

Similar to mill crane runway design, the load factor runs as high as 4 using ASD. Durability, fatigue and serviceability are the main concerns. Be conservative when dealing with structures subject to significant vibratory/repeative/cyclical loadins, especially with frequent human activities around.