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RE: 75 PSF Equipment on 50 PSF Floor

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Subject: 75 PSF Equipment on 50 PSF Floor

Dear Chris,

Analysis: (from: G Vishwanath,Bangalore, India)

1)area of equipment= 2.5 ft x 6.167 ft = 15.417 sq ft (Given)

1a) w/ extra 6" all around 3.5 x 7.167 = 25.08 sf

2)Load = 1200 pounds (Given)

3)Load intensity = 1200 / 15.417 = 77.8 psf

3a) 1200/ 25.08sf = 47.85 psf

4)Design load originally considered = 50 psf  (Given)

4a) Where is the 20 psf for movable partitions? Do they actually exists where the unit will be installed?

4b) Based on the existing  structure recalculate the actual dead loads. Is there an extra 5 psf

    of miscellaneous or is the MEP overstated compared to the actual installed system?

Solution: (from: Rick Burch, Columbia, SC)

"OK by inspection" appears to be acceptable after the numbers are slightly massage. I have performed  this

type of analysis and justification plenty of times for hospitals and data center installation. From the info

provided It appears that you could install the equipment without doing much reinforcement. I have added a 1/4" thick plate on

floors just for a bonus.



Mitchell J. Sklar, P.E., MBA
Senior Structural Engineer

215-997-0931 p
413-383-1615 f

-----Original Message-----
From: Chris Banbury [mailto:cbanbury(--nospam--at)]
Sent: Thursday, March 20, 2003 4:22 PM
To: seaint(--nospam--at)
Subject: 75 PSF Equipment on 50 PSF Floor

I've been asked to determine if a 1200 lb medical intrument can be placed on the third floor of a hospital office building.  The instrument is 30"D x 74"W.  The building was constructed in 1989 and I've obtained the original plans from county records.  The design live loads listed on the plans include 50 psf for office and higher loads for corridors etc.  However, the entire third floor was originally designed, permitted, and constructed as an empty shell with no corridors, partitions, or offices so it seems I'm forced to use the lowest uniform load given.  Non-bearing walls, hallways, offices, laboratories, etc. were added later as the hospital found doctors who wanted custom rental space.  Since the equipment exceeds the minimum uniform live load I am considering the following:
1. frame a platform to span several floor beams
2. place a steel bearing plate to distribute load over a larger area
3. paint or demarcate an area on the floor around the instrument where no additional equipment can be located such that the painted area satisfies the allowable superimposed live load
4. modify the floor beams in order to increase the load rating of the floor
5. calculate the actual allowable superimposed live load of the concrete slab and steel beams from the structural drawings.  Since the corridor locations were unknown at design stage, it is possible that 100 psf was used for the entire floor.
Obviously there are concerns with all these solutions.  I would appreciate any additional thoughts or advice on this problem.
Christopher A. Banbury, PE
Vice President
Nicholson Engineering Associates, Inc.
PO Box 12230, Brooksville, FL 34603
7468 Horse Lake RD, Brooksville, FL 34601
(352) 799-0170 (o)
(352) 754-9167 (f)