Maximum Post Spacing for Decorative Railing

[snowmachine88]

I have a decorative rail along a stair case bolted to concrete posts at the top and bottom. The length along the rail between posts is up to 14.7 feet. I am using a 1.25" x 2.5" kick bar to meet AASHTO loading requirements for pedestrian rails. This seems like a heavy bar to use, but the top member is a 6" pipe. Is a 14.7 ft post spacing excessive? Should I place an additional post at mid height along the stairs?

 

[FlashSet]

Mu = 50 plf *14.7^2 * 12 / 8 = 16.21 k-in

Zx = 1.25 * 2.5^2 /4 = 1.95 in^3
M_allow = 36/1.67 * 1.95 = 42 k-in > 16.21 k - in

Looks like you are okay!!!!

But I am confused, is the 6" pipe your handrail or your guardrail? It is too big to be a handrail. I have never used the term "Kick bar" before, but I am assuming that is similar to a toe board?

 

[Tmoose]

I'd also be contemplating that the base of the posts must also resist the moment created by a fat mema stumbling and hitting that rugged handrail for a well alanced design.

http://cdn.lolbrary.com/2013/12/6/lolbrary.com_41319_1386352934.jpg

 

[snowmachine88]

The 6" pipe is just decorative. I believe the architect called the bottom bar a kick bar. I looked at the loading on the bar in the other direction such that Zx = 2.5*1.25^2/4=0.98 and it still works. I guess I was looking or more of a rule of thumb for maximum post spacings. I can up size the bar to make it work, but then the rail will just look really heavy, and may not be economical.

 

[Tmoose]

I know what I think when I or someone else bump a railing etc and it begins to shake very visibly at some bending mode.

 

[racookpe1978]

1. You have a single load limit (200 lbs sideways at the top of the rail.) AND a second, 50 lbs per foot limit for the rail overall. (Usually, posts are 4 ft apart, so the two are "about" equal.)

So, the 200 lbs requirement looks OK, but 15 ft x 50 lbs/ft = 750 sideways at the top (42 inch high for a guardrail, right?) on the post.

2. Don't confuse a "handrail" grip requirement at +36 (+/-2 inch) measured from the toe of each step on a stair, with the guard rail requirement for height. If the guard rail (only on commercial applications!) is horizontal, I do not see a "grip" requirement coming up for rail diameters.

 

[Duwe6]

concur on 'grip' not being part of a handrail requirement.

Toeplate = toeboard = kick plate when it comes to handrails.

One further note; [morons] at OSHA have specified 42" - period. What they did is to codify the old 3½-ft nominal rail height. Americans are now significantly taller than they were in 1901, and 42" is a little too low to be safe for anyone over about 5'-10" tall; their center of gravity is above the top of the OSHA-mandated rail. Most mezz handrails [all?] in malls have their handrails at about 44" to 48" tall. Much safer structure for the slightly above-average person.