New punched openings in existing cmu.

[joemarch]

I'm dealing with puting some new opens in both bearing and non-bearing cmu walls. The opens range from 6'-0" to 12'-0". Its obvious I need to provide a steel lintel and columns for the larger openings. My question is for the smaller opens. How much of the cmu wall next to the open can I use for the design in order to take the wind reaction from the new lintel. I do not know what the reinforcing is in the new wall. What are your thoughts?

 

[Lutfi]

Most codes require that you have vertical bars in each jamb (each side of the opening) that extend from footing to the tie/bond beam that may be at floor or roof level.

I strongly recommend that you comply with this provision unless your local code does not require it.

Good luck

 

[joemarch]

Thanks for response Lutfi.

I should have been a little clearer about the cmu wall. It is an existing cmu wall and I don't know if the wall has any reforcing in it.

So, say I put a 3'-6" opening in the existing wall with a new lintel. How much of the existing wall (treated as unreinforced) adjacent to the opening can I use to take my wind reaction from the lintel? Wondering what people have done before?

Thanks for your help

 

[Lutfi]

I have used details where added vertical bars on both sides of a new masonry opening. It can be done. It is not cheap. I also have a detail to install a steel lintel to span over the new opening as well.

I do not understand the question about wind load reaction from the lintel. Can you elaborate more?

Regards,
Lutfi


Lutfi

http://www.cdeco.com

 

[joemarch]

Lutfi,

Would it be possible to get those details from you? I'm sure adding vertical bars must be cheaper than adding vertical steel members. Does the reinforcing then get tied into the existing bond beam at bar joist bearing?

I guess what I was going to try to do for some smaller opens was use like a double angle lintel. I was going to put a point load on the non-rein. wall (wind reaction from lintel) and treat a portion of the wall as a non-reinforced beam spanning from the floor slab to the bond beam at joist bearing. I guess I was wondering how much of the wall I could use as the beam? I haven't run any numbers so I'm not sure if this design will even work.

Thanks alot Lutfi.

 

[jheidt2543]

For the larger openings in a masonry wall, particularly in an industrial building, I prefer to use channel jambs for the opening. The channels provide some additional support for the lintel, but more importanly the project the masonry opening jambs from damage due to traffic through the opening. I've also found them cheaper than trying to add rebar and grout to the masonry units.

It's just another thought!