Live Load vs. Max. # of People
Live Load vs. Max. # of People
(OP)
I provide Structural Engineering for a local manufacturer that provided approximately 101 balconies for a new assisted living facility in Florida. Most balconies were designed for a 60 psf live load (1.5x40psf, per ASCE-7-2010), and used for individual resident balconies. We also engineered a large (29'-0"x6'-0") public balcony off a "community room". This large balcony was designed for a 100 psf live load.
Prior to occupancy, the Owner is requesting a "maximum allowed persons" (or similar term) for the public balcony so it can be posted. I have never been asked this before, and am having reservations about how to respond.
How should I go about "rating" this large balcony which was designed for 100 psf, as it pertains to a facilities standpoint (presuming the person asking/using this information is not an engineer). I have responded previously by simply saying it was designed for a 100 psf live load, but this question keeps coming back to me in a "maximum persons" number. I am a little more at ease that this is for an assisted living facility than a college dorm, as the likelihood of residents jumping/partying is slightly less.
Thank you in advance.
Prior to occupancy, the Owner is requesting a "maximum allowed persons" (or similar term) for the public balcony so it can be posted. I have never been asked this before, and am having reservations about how to respond.
How should I go about "rating" this large balcony which was designed for 100 psf, as it pertains to a facilities standpoint (presuming the person asking/using this information is not an engineer). I have responded previously by simply saying it was designed for a 100 psf live load, but this question keeps coming back to me in a "maximum persons" number. I am a little more at ease that this is for an assisted living facility than a college dorm, as the likelihood of residents jumping/partying is slightly less.
Thank you in advance.






RE: Live Load vs. Max. # of People
This number may have to be revised downward. What answer did the above calc give?
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RE: Live Load vs. Max. # of People
RE: Live Load vs. Max. # of People
I just tell them it's designed for assembly and give a number (i.e. maybe a 240 # person for every X ft^2) that I still tell them not to hold me to it.
RE: Live Load vs. Max. # of People
Thank you for your response. I agree that the requested information goes beyond a structural response. I have deferred back to the Architect of Record for the project, and simply stated that the balcony was designed for a 100 psf live load. Not having been apart of the building design, I try to defer such questions. Thank you for your time.
RE: Live Load vs. Max. # of People
RE: Live Load vs. Max. # of People
If you assume an individual human can take up a 1 ft. x 1.5 ft. area and weighs 160 lbs., you can place an outer row of people at the outer 1 ft. strip of your cantilever.
That puts 19 individuals along the outer width (29 ft. x 1 ft area) and it creates a moment at the support.
Do the same for row 2, 3, etc. and you find that the maximum number of rows of individuals would be 4 rows - totaling about 1677 ft-lbs (i.e. less than 1800)
Total number of people = 76
Or you can turn the people sideways so you have 29 people along the outer edge of balcony - with that we get max. 3 rows totaling about 1800 ft-lbs.
Total number of people = 67
So you could perhaps play around with a spreadsheet, the weight/person and area/person - calculating these numbers and perhaps go with maximum 60 or 65.
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RE: Live Load vs. Max. # of People
RE: Live Load vs. Max. # of People
Regarding the amount of space each person takes up, and weighs:
Are there any studies that verify these numbers? I know that everyone seems to have their favorite number; are these actually based
on research?
-CF
RE: Live Load vs. Max. # of People
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RE: Live Load vs. Max. # of People
RE: Live Load vs. Max. # of People
I'd use an average of 200 lb per person, figure how many people that is for your footprint, then round way, way down. If your balcony is 8 ft. x 12 ft., that would be 29 people. Say five rows of three would be fifteen. Seems like fifteen is plenty.
RE: Live Load vs. Max. # of People
RE: Live Load vs. Max. # of People
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RE: Live Load vs. Max. # of People
Average weight per passenger in the US appears to be circa 185 lbs.
Document in link quotes a Europe wide study and recommends 88 kg ( 193 lb) for a 70: 30 mix male / female. https://www.easa.europa.eu/system/files/dfu/Weight...
So a 200 lb average per person is justifiable and traceable.
The problem with baloneys is that the actual loading is not uniform. Tends to be concentrated at the edges (resting or leaning on the balcony posts) or standing in small groups.
So if max people for the area on a uniform basis is 87 ( 29 x 6 x 100 / 200) then 50% of that would seem to be a good number to start with - 44. I would revert with the answer you would not recommend more than 45 to 50 people.
At even 50 this is 3.5 ft^2 per person. Apparently an accepted value for maximum density of people in an elevator is 5 per m2 or 2.1 ft^2 each. But a balcony isn't an elevator and most people would find that too crowded for a balcony.
So 50 it is.
IMHO.
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