Tall Parapet 1

[Ben29]

Seeking advice on best option for framing a tall parapet above storefront opening. Option 1 shows the block continuing to top of parapet. Option 2 shows block stopping 1 course above joist bearing elevation and metal stud framing above.

My hangup with option #2 is that I am concerned that a horizontal crack will form in the brick facade at the height where the block stops and the metal stud begins.

Any input is appreciated.

 

[DaveAtkins]

I think either option works. The stud framing will be very stiff the way you have it braced.

DaveAtkins

 

[Brad805]

I agree with Dave. Is the arch ok with the brace below the joists? It seems that might be visible or clash with a ceiling. Unless someone is set on these options I would look at options to avoid the roof penetrations.

 

[Ben29]

Brad: The angle brace occurs above the ceiling line (ceiling line not shown in the detail). I am showing the angle brace to align with the tie rod that supports the canopy.

 

[gte447f]

I also think either way is fine. I don't think I would be worried about the possibility of a horizontal crack in the brick veneer at the transition from CMU to metal stud. In fact, at the location where the kickers brace the parapet, I would probably have more confidence in metal stud-to-metal stud connection than metal stud-to-CMU connection , so I might lean toward option #2.

 

[StrEng007]

Option #2, but I would be tempted to provide structural steel each side of the glazing to act as a wind column, then run a horizontal tube at the top of parapet. This would do two things, provide a decent support for the lateral loads at the storefront, and provide a structural support for your kickers.

As for the kickers, I would use a round or square HSS (diagonal with a 12" vertical section) and space them farther apart. Using 16" o.c. is going to create obstacles for any re-roofing in the future as you're confining the roof space below your current #2 option.

Take it with a grain of salt, I'm used to 175MPH wind speeds.

 

[EZBuilding]

Similar to StrEng007's comments - I would consider a reinforced concrete tie column on either side of glazing that would continue up and cantilever beyond the roof level. Similar idea to the steel tube, but then you don't have the joint between the masonry and steel column...

 

[structSU10]

My only issue is what those braces do to the joist. there is now a hard spot and as the joists are loaded they will want to push out at the header and pull the top of parapet in.

I would try to find a way to cantilever the parapet and eliminate all kickers if possible.

 

[cliff234]

I would frame it a little differently. Perhaps this is a reflection of preferred construction practices where I work (northeastern US). I would frame the area in question as follows:
•Provide HSS columns on each side of the window openings and extend to top of parapet. Design columns to be strong enough and stiff enough to eliminate all diagonal braces. (Provide additional HSS columns in corners so that projecting façade is framed with steel and does not rely on CMU for support of gravity loads.)
•Provide horizontal HSS girts at top of parapet
•Eliminate all CMU and replace with CFS framing behind the brick. (CFS is braced by both the roof framing and girts.
•Provide W Shape roof beams (instead of joists) at HSS columns at roof (to brace the HSS columns).
-Provide HSS beams at heads of windows to support eccentric brick load

Advantages:
•No concentrated loads on joists (requiring special joists).
•No need for joist reinforcing at concentrated loads.
•No finicky diagonal brace connections to joists, beams over openings, and CMU
•Fewer pieces = faster construction and less expensive.
•No awkward sequencing of construction requiring block walls to be built before completion of steel erection.
-No grouting of block walls

 

[Ben29]

Cliff... I too had a feeling that this was the way to go. I designed this 2 years ago and it sat on a shelf. Now they want to issue for permit and I'm having second thoughts about the whole design.

I am married to using the steel bar joist roof, however.

 

[gte447f]

Ben29, I agree with cliff234, and your revised sections and elevations are much better in my opinion, and more in line with what I am used to seeing in my area. Based on your OP, I had assumed the front elevation must have been mostly CMU, but if it is basically steel framed and you can eliminate all CMU entirely, then that is the way to go in my opinion.

 

[cliff234]

Ben29 – I agree that the roof joists should stay. My suggestion to use W shapes on the roof was only for the members bracing the HSS columns. (There will be a significant axial loads in those members, so it would be better to use W shapes versus joists.) Another reason to frame W shapes to the columns is that your roof spandrels are offset from the columns. Framing W shapes to the columns gives the offset spandrels something to connect to.

 

[XR250]

This will get "value engineered" to an all metal stud system. I mean enough 12ga studs will do most anything.
At least that is how it was when I was doing light gage.