Specifying a maximum floor load for industrial equipment
Specifying a maximum floor load for industrial equipment
(OP)
Hi all. I am trying to develop a procurement specification for large CT systems, and am stumped in how to specify the requirements for floor loading. Because the CT systems are going into a variety of different facilities and floor types, I would like to specify a maximum floor load, such that not only can the facility be prepared accordingly, but more importantly to ensure interchangeability among a number of pre-qualified CT systems (i.e. if one goes down, we can replace with a similar pre-qualified one from another manufacturer). My question is: what basic parameters should I be using to specify maximum floor loads?
I do know the weight of all the commercial CT systems being evaluated (range 5000 to 20000 lbs), but I hardly think specifying a maximum CT system weight is enough. I can also guess on a maximum pressure load (3500 psi?), since most facilities are concrete slab, but that is attacking the problem from the facility side, which I probably cannot characterize adequately (i.e. some facility installations may be raised flooring). If most limiting case is a raised floor, should I specify a maximum point load per raised panel (2 ft x 2 ft)?
In any case, for floor static bearing pressure only, are there any structural engineers out there that can suggest an approach? Thanks
I do know the weight of all the commercial CT systems being evaluated (range 5000 to 20000 lbs), but I hardly think specifying a maximum CT system weight is enough. I can also guess on a maximum pressure load (3500 psi?), since most facilities are concrete slab, but that is attacking the problem from the facility side, which I probably cannot characterize adequately (i.e. some facility installations may be raised flooring). If most limiting case is a raised floor, should I specify a maximum point load per raised panel (2 ft x 2 ft)?
In any case, for floor static bearing pressure only, are there any structural engineers out there that can suggest an approach? Thanks





RE: Specifying a maximum floor load for industrial equipment
I would think 3500 psi is very very high, as a lot of concrete mixes would not take that kind of pressure.
You could try specifying a maximum load in lbs per square foot, such as 250 psf.
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Specifying a maximum floor load for industrial equipment
Also I would suspect you could specify that the floor must support a "kazillion pound load distributed over and area of X square feet with Y inches maximum deflection measured from Z". This would probably give Facilities Managers and Structural Engineering contractors nightmares for weeks.
TygerDawg
Blue Technik LLC
Virtuoso Robotics Engineering
www.bluetechnik.com
RE: Specifying a maximum floor load for industrial equipment
latinoguy,
Large heavy equipment often (on offshore platforms) can be skid mounted on heavy WF beams to spread out the loads. Another possible option.
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Specifying a maximum floor load for industrial equipment
Your distinction between compressive stress and bearing strength seems critical. Also, a maximum deflection capability seems critical as well. I understand that bearing plates, skids and other means can always be used to distribute equipment loads to bring them into more reasonable limits, but I'm still left with determining a practical upper load limit for equipment.
It sounds like I should approach this from the facility side, and take a reasonable guess on what the facility limits would be. Yet some of the equipment is quoted as being as high as 500 psf. Is this a reasonable limit for concrete slabs typically found in "light" industrial facilities? I've surveyed a few raised floor providers too, and even they have products with max "uniform" load of 650 psf (over 2ft x 2ft), and 2500 lbs max "concentrated" load (over 1 square inch) that yields a max deflection of .040 inches. Is there a good reference that suggests typical maximum values found in facilities such as warehouses and laboratories?
Thanks again!
RE: Specifying a maximum floor load for industrial equipment
Most "light" buildings would be designed for a live load of only about 100 to 150 psf. 150 is getting relatively heavy (and costly) for light construction.
Industrial buildings might be in the range of 100 to 200 psf in storage areas. I would class 500 psf as quite a heavy loading.
I'm curious. Can you post a general arrangement dwg and a load footprint for these things? (I was a structural engineer in a past life.)
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Specifying a maximum floor load for industrial equipment
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RE: Specifying a maximum floor load for industrial equipment
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Specifying a maximum floor load for industrial equipment
http://www.wbdg.org/ccb/DOD/UFC/ufc_3_310_01.pdf
As you suggested, this also recommends (based on IBC 2006) a MINIMUM uniformly distributed live load of 125 psf for general "light" storage warehouses. A MINIMUM concentrated live load of 2000 lbs is recommended for "light" manufacturing. I suppose I could use the higher of the minimums for "heavy" loads (i.e. 250 psf and 3000 lbs), but I still wonder if this is relevant for determining design limits on equipment, since all this depends on a particular building? Do you think the following equipment design requirement below is adequate?
"The imaging system shall have provisions for allowing installation within manufacturing, warehouse or other light industrial facility with a maximum uniformly distributed live load rating of 250 psf, and a maximum concentrated live load rating of 3,000 lbs. Bearing plates, skids, framing or other means may be used to achieve this load rating, but must then be considered part of imaging system configuration."
RE: Specifying a maximum floor load for industrial equipment
I think your best bet is to spec a continuous railed skid, 4 ft between rails and no bearing plates (load concentrations), remembering that roughly 5/8 of a center point load will effectively bear down on the central 1/9th area (like on a 3x3 matrix) of any "uniform thickness plate-type" design.
**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Specifying a maximum floor load for industrial equipment
I purchased a high-speed CNC machine sever years ago and I was in the process of having my shop built at the same time. I contacted the CNC manufacturer about the shop floor requirements and not only did they reply with drawings but they also provided me with the requirements of the concrete. They gave me the psi rating and either the formula or the actual thickness for the concrete flooring immediately under the CNC machine. They also provided a special mounting procedure to keep the machine from moving under any vibrations due to load or rpm or combination.
So, I would suggest contacting the manufacturer of your CT for their requirements and recommendations. They will probably even furnish a project engineer to ensure this is done properly.
Larry