Stair Handrail Load

[BadgerPE]

I am designing a set of steel stairs for mezzanine access at a production facility. One side of the stairs runs along a wall so there will only be a railing on that side. The other side is exposed and will have a guardrail and handrail. Occupant load is less than 50 and the facility is an Occupancy F building so I am using the reduced load of 20 plf per IBC 1607.7.1 for distributed loading. I am also checking a 200# concentrated load at multiple locations non-concurrently with the distributed load. My question is, should the 20 plf load be applied to the entire length of the guardrail, or should it only be applied to a portion of the guardrail at a time. The reason I ask, is while I have sufficient strength, deflection under service load is quite high (approximately 1.2" of horizontal deflection in guardrail vertical end member). My verticals are 2x2x1/4" and the horizontals are the same size. It seems as though the deflection is high, but the likelihood of a full 20 plf load over the length of a 15' guardrail is fairly low. However, I want to justify the deflection before I send this to drafting.

 

[spats]

Yes, the distributed load must be applied over the entire length. What is your post spacing? I would think in your case the 200 lb. load would control, particularly for an end post.

 

[connectegr]

The 20 plf is applied over the entire length. Note that there is a graph in NAAMM that provides the increased strength on having multiple posts. If you are modeling the rail a similar interaction is already considered.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[connectegr]

spats is correct... 200# concentrated load should control. It should be applied at top of post for design of post and at center of rail spanning between posts.

I cannot think of a case where there is any benefit in reducing the uniform load from 50 plf to 20 plf, if the concentrated load remains 200#.

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[Ron]

50 plf lateral is typical. If post spacing is greater than 4', the 50 plf will control. If less than 4', the 200 lb lateral load will control. Free end of the stair rail will have high deflection...otherwise not so much.

This is a life safety issue, so be careful with reductions!

 

[dik]

and make sure to check the weld for the size of post.

Dik

 

[RareBugTX]

20 plf? only, that does not sound good to me. I use 150 plf along top full rail, PLUS 200 lb at a critical point.

 

[connectegr]

RareBugRA
150 plf That is a serious handrail! You will need a post ever few inches.

Did you mean 50 plf?

http://www.FerrellEngineering.com

Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.

 

[BadgerPE]

I found the issue with my end post deflection and you guys were right that the 200# point load governed. However, just to clarify, I used the 20plf load along the entire length of the rail only to evaluate the overall stability and serviceability of the structure. Strength is a non-issue due to the size/span of the members. The stairs extend to a mezzanine with a small workshop only so I feel comfortable reducing to the 20plf for serviceability. Thanks for all the help and sorry I didn't respond quicker as I was thrown into something else.