Hand rail and post design for metal stairs.
Hand rail and post design for metal stairs.
(OP)
I am working on designing a post for a steel stairs and was wondering if I could use plastic analysis instead of elastic analysis. If so I have been trying to find a reference in the AISC or any other manual for provisions to do so. If you guys could help me out, it will be highly appreciated.
Thank you
Thank you






RE: Hand rail and post design for metal stairs.
RE: Hand rail and post design for metal stairs.
AISC does not consider stairs to be "structural steel" and therefore does not address the design. Applicable building codes contemplate normal design procedures using ASD or LRFD, but not plastic design.
Check the NAAMM Stair Manual for guidance.
RE: Hand rail and post design for metal stairs.
Thank you.
RE: Hand rail and post design for metal stairs.
RE: Hand rail and post design for metal stairs.
Dik
RE: Hand rail and post design for metal stairs.
To Dik: Same here I use elastic section modulus for designs but in one of my old collected sample calculation I found out that the other person designed his post using the plastic section modulus which gives him more room for allowed strength. So I was wondering if we could do that and if so are there any provision written anywhere if someone questions why did we used it.
RE: Hand rail and post design for metal stairs.
RE: Hand rail and post design for metal stairs.
If d/t ratio is less than 0.45E/fy then
Mn = Mp =FyZx. (for round HSS)
Using this equation (Zx) gives me more room for strength for the post. Please clarify if this is applicable .
RE: Hand rail and post design for metal stairs.
Actual "Plastic Design", as nutte, pointed out, is something entirely different. It's a way to take advantage of reserve capacity in compact, laterally braced members after the first hinges firm. I'm sure there you can find information on it if you do a google search.
RE: Hand rail and post design for metal stairs.
I have always found that the attachment of the post to the stinger is impossible to verify unless you use a stinger that has a large enough flange to weld the post to. We have looked at using other methods for attachment, none of which we have been successful with. Stair fabricators are just not used to the shapes required to make sure everything works properly.
RE: Hand rail and post design for metal stairs.
Previously IBC allowed an increase in allowable bending stress. With the current plastic design allowables in AISC, the stress increase is no longer allowed in IBC. But, the results are the same.
www.FerrellEngineering.com
Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.
RE: Hand rail and post design for metal stairs.
The allowable stress increase is recognized in the NAAMM standard. I would not use both the stress increase and Zx.
www.FerrellEngineering.com
Providing fabrication and erection efficient structural design of connections. Consulting services for structural welding and bolting.
RE: Hand rail and post design for metal stairs.
RE: Hand rail and post design for metal stairs.
http://www.modernsteel.com/uploads/issues/february...
I have reviewed a number of shop drawings that show an all-around fillet weld of a 1.5" diameter post on a channel with a 1.5" flange. You can never get the calcs to work out without an all around fillet, unless you do a CJP weld.
See WillisV's post regarding MC12x14.3 stringers in this thread thread507-237196: Stair handrail loading
RE: Hand rail and post design for metal stairs.
Dik