Generator pad design

[nishantnjoshi]

What approach should be used for generator pad design?

The generator dimension are 16.526' x 8' x 8'. Weight is 36000 lbs.

To calculate the depth of pad can I use (Weight of generator/ density of concrete * length of pad * width of pad).

The generator is in a enclosed area. So do I have to only check soil bearing capacity?

And for reinforcement, minimum reinforcement will govern. So 0.0018BH amount of reinforcement will be required?

Thank you for your help in advance.

 

[Sawbux]

Are you in a seismic area? Will need to calculate for that, if so. If it contains a fuel tank, calculate with tank empty & full - different centers of gravity.

For dynamics of the operating generator, I typically use a foundation weighing at least 2X the weight of the machine. Usually a minimum 12" of pad depth and a foot or so extra pad surface aroung the perimeter gives sufficient concrete weight.

Place on good soil, with 6" or so of compacted crushed rock or whatever the geotech recommends.

For reinforcing, reinforce top & bottom to resist any + or - moments. Short direction .0018 is OK, but never less than #4@12". Put std hooks on top mat to reinforce corners. Long direction, I usually up the reinforcing to eliminate chances of cracking, maybe .004.

Hope this helps.

 

[Lomarandil]

Outside the structural concerns, consider what the spill prevention measures are going to include -- you may want to size and detail your foundation to capture any fuel or oil leaks (plus some volume for rain)

 

[racookpe1978]

Your generator SHOULD have very specific pad and foundation requirements specified, though (smaller) pad-mounted stand-alone generators with their own frame are more forgiving than very long, pedestal-supported generator trains with separate turbine/mover and generator assemblies.

REQUIRE your generator sales team to give you THEIR recommended minimum pad dimensions and its reinforcement (final stiffness) criteria that THEY want to support THEIR generator. If you make assumptions for how stiff and how heavy a pad you think the generator frame needs to sit upon, when there are vibration problems or alignment problems, the generator sales team will not be ready to accept responsibility for the rework and repair costs.

 

[bridgebuster]

We did one similar a few years ago. 41k generator. Our pad was 1'-6" thick; reinforced with #5@12 E/W, T/B; it weighed about 3x the generator. Our generator was within an enclosure supported on the same pad, so we had to address wind and snow loads.

 

[nishantnjoshi]

It is not a seismic zone.

Thank you everybody. The information provided was useful.