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Re: Lateral Load Due to Foot-Traffic

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        There may be something in one of your codes specifying this but someone else will have to provide this information for you.
        As a scientific method of estimating this force I would consider the "people" as equivalent to fluid in a pipe elbow.  The scientific formula would be a variation of Newton's second law.
Instead of
F = M*a,
F = M*(dv/dt)
we would have
F = v*(dM/dt)
F = v*Q
F = force of people coming (decelerating) AND going (accelerating).
v = speed people are moving.
Q = Mass of people per second passing any given point.
        What numbers to use for v and Q are anybody's guess.  My guess would be five feet per second (about 3.3 miles per hour) and thirty psf times the five feet used previously for v, or 5*30 = 150 pounds per foot of corridor width.  (I chose 30 psf because I don't think people could be packed in at 100 psf and walking 5 ft/sec both at the same time.)  This would give
F = 5*150/32.2 = 23.3 pounds per foot of corridor width
F = 23.3*6 = 140 pounds in each direction. <=====
        I think I'd factor this up if it were me.  1,000 pounds seems about right!
        Perhaps Scott Maxwell will be so kind as to review and comment on my math.
H. Daryl Richardson
----- Original Message -----
Sent: Tuesday, November 08, 2005 4:12 PM
Subject: Lateral Load Due to Foot-Traffic

I have a 6-ft wide wood-framed exterior one-story stairway/exiting-corridor, no roof.  At about mid-height is a landing supported on 4x4 posts where the stairway makes a 90 degree turn.  I have the feeling that lateral loads due to wind and seismic loading will be relatively insignificant compared during emergency exiting with people turning the corner.  Any ideas on how to estimate or calculate the appropriate lateral load?   


Nels Roselund, SE

South San Gabriel, CA