Anchoring Steel Platforms into arapet walls

[Antnyt23]

I have been tasked with providing some steel rooftop platforms that anchor into existing parapet walls. I'm trying to do a bit of review on possible ways that this is done and ways to reinforce different types of roof parapets.

My initial thoughts are the addition of a platform spanning from two parapet walls (say in the corner of a building) when coupled with the wind load that the parapets are already exposed to will cause a moment that is greater than the parapets initial design strength. My thought would be to reinforce it with some vertical steel members to help strengthen the parapet against the reactions caused by the platform.

Once I find out the reactions of the platform I assume I can analyze the building parapet like a cantilever from the rooftop to make sure it can resist the new forces in addition to the wind loading on it. In the case where they do not have the strength to resist the forces I can add reinforcing to the parapets to provide the appropriate strength. My thoughts were through bolting channels or angles on the parapets to strengthen them however that may not be the best or most aesthetically appealing method.

I was curious if anyone has dealt with similar situations and had some input on this subject or knows of some good reference material in concerns to this subject.

 

[wannabeSE]

I have added equipment platforms attached to cast in place a concrete parapet. The parapets capacity depends on the parapet construction.
If it is concrete, use the concrete code. If the parapet is masonry, use the masonry code. If the parapet is wood . . .

 

[frogit22]

You may be able to attach the platform just above the roof covering (above the flashing). This lower attachment point may be simpler and provide lower lateral forces imposed on the parapet.

 

[TDIengineer]

I would recommend using those pilasters as vertical carrying members, concentrically loaded, not to the inside face.

I would then add some lateral braces from your elevated platform to your roof members where that load can be taken... possibly at a column beam intersection. I think you should dump your lateral loads directly into your diaphragm. I would not recommend using an existing parapet to the load transfer unless the loads are very small, and the parapet was overdesigned (maybe short with great vertical reinforcing).