curved load bearing masonry walls

[nuche1973]

I am looking at plans for new construction of a residential facility with a large waiting room. The exterior walls are load bearing masonry with a radius of 22 feet. The issue is there is a 9 foot window in the center of the wall. The Arch’s detail show a bond beam at the top of the opening. I believe that the window will be radial to match the wall radius. My question is: can a curved lintel be constructed using bond beams? I thought about using a curved steel beam, but am unsure of the cost. As always any thoughts would be appreciated. Thanks.

 

[kslee1000]

I think a reinforced concrete beam would be more suitable for this situation - beam rotation (torsion) & deflection (bending) occur simultaneously. The beam (lintel) over the curved window needs long back spans to provide stability & strength.

 

[hokie66]

Depends on how much block your have over the opening, the more the better, but if you build the whole wall as fully grouted and reinforced 8" blockwork, I think you could make it work. I wouldn't try to use a loose lintel, whether steel or concrete, as the wall needs to act monolithically.

 

[concretemasonry]

The lintel could also be made using a 16" high unit(8" length) or two courses of 8" high consisting of a traditional bond beam and another course of block grouted together.

The radius is not that tight, but the challenge is to determine what the real loads are on the beam and masonry wall of unknown height are. If you have enough masonry above, it is not a big problem because of arch action.

Once you try to make "simplifying" assumptions, you make the analysis more conservative and easier, but open to many different problems, but that is just the nature of structural engineering.

The architect could have a say on the length of the units (8" or 16") depending on the ultimate wall finish. I would assume he is comfortable with 16" long segments and not 8" segments. The 8" segment length is usually acceptable for most exposed masonry walls.

 

[nuche1973]

Thanks for the information.

 

[jike]

If the loads (and thus the torsion) get too great, another option is steel columns at either side of the window with a curved steel lintel beam. Of course, the connection of the lintel to the column has to resist the torsion.