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Re: Residential garage floor live load >>> Code

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Since the deck is continuous, wouldn't it be better to calculate the equivalent loading that way, i.e., negative moments at the supports and positive moments at the midspans? For a 3 span condition, the coefficients to wL^2 drop some.

ken ng wrote:

The garage area is 21'x21'.

I plan to use concrete over metal deck with steel beam support at 21'/4spaces = 5.25' spacing.

If I used 3K concentrated load, then I might have a little problem.

Maximum moment from point load:

M=P*L/4 = (3k*5.25ʼ)/4 =3.9k-ft

Equivalent uniform load:

W=(m*8)/L^2 = (3.9*8)/5.25^2 =1143 psf

I donʼt know if any concrete metal deck will support this 3k or 1143 psf?

*From:* "Rhkratzse(--nospam--at)" <Rhkratzse(--nospam--at)>
*To:* erik_g(--nospam--at); seaint(--nospam--at)
*Sent:* Sunday, November 2, 2008 1:01:48 PM
*Subject:* Re: Residential garage floor live load >>> Code

What?! You're suggesting that we actually follow the Code???
What a bizarre concept!  :)


In a message dated 11/2/08 1:28:05 PM, erik_g(--nospam--at) writes:
ASCE 7-05, table 4-1 footnote a):

Floors in garages or portions of a building used for the storage of motor vehicles shall be designed for the uniformly distributed live loads of Table 4-1 or the following concentrated load: (1) for garages restricted to passenger vehicles accommodating not more than nine passengers, 3,000 lb (13.35 kN) acting on an area of 4.5 in. by 4.5 in. (114 mm by 114 mm) footprint of a jack; and (2) for mechanical parking structures without slab or deck that are used for storing
passenger car only, 2,250 lb (10 kN) per wheel.

-----Original Message-----
From: Jeff Smith [mailto:jeffsmith7(--nospam--at)]
Sent: Sunday, November 02, 2008 11:31 AM
To: seaint(--nospam--at)
Subject: RE: Residential garage floor live load

Not at the office, but I beleive ACSE has language about a point load based on a jack. Theoretically someone could use a floor jack that could transfer more than half of the car load. Land Rovers and say an F150 are over 6000 pounds.


From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)]
Sent: Sunday, November 02, 2008 11:12 AM
To: seaint(--nospam--at)
Subject: Re: Residential garage floor live load

I used to design them for the wheel load of a Ford Excursion. I don't know how many of those are selling now adays, but I would be very conservative in your design if I were you.


On Sun, Nov 2, 2008 at 8:16 AM, ken ng <zy7up(--nospam--at)> wrote:

I never have any project which the 2 cars garage slab is located above the bedrooms. I used live load = 50 psf. Does 50 psf live load is under estimate? Should I include 1,500# concentrate wheel load?

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