Tread Riser Support

[McMichael05]

Does anyone know of any resources for allowable spans for a 1/4" bent plate tread riser support? These stairs have a clear span of 5'-3". I am looking at the AMP load and deflection tables for treads and riser but they only have up to 10ga thickness for the treads. Dead load is around 30psf and Live load is 100psf.

 

[dik]

You should be able to design it by calculating the section modulus for the shape... 1/4" seems to be pretty chunky and you might want to increase your dead load to 35psf

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[McMichael05]

I agree and i did end up doing that and obviously found that its far more than adequate for the loads. The thing that isnt shown in the detail i attached is that on one side, the tread cantilevers out about 8" and every 4' there is a handrail attached to it which is why i think they went with a 1/4" plate. Still going to recommend adding in a reinforcing plate at the handrails.

 

[dik]

Can you put a thicker 'end' plate at the guardrail locations that you can attach to? I would think that even 1/8" material would be adequate. I wouldn't think that an 8" cantilever would be an issue...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[kwinner]

What is critical when designing these feature stair elements is communicating clearly with the architect and owner on what their desires and expectations are. If this is an artistic feature, and vibrations/stiffness are not of concern, then you can push code limits and help provide the desired structure. If stiffness and lack of vibrations are a concern, then you get to help find ways to "elegantly" provide the proper amount of strength/stiffness.

 

[McMichael05]

Yeah youre right, i ran the numbers and a stiffener is overkill. The plate itself is adequate even for the cantilever with the handrail attached. That being said, my boss just wants that extra security at the handrail locations.