Lateral design for high plane aspect ratio 1

[tjhubo]

I am working on the lateral design of a 4-stroy residential construction, which has the first story built with CMU, and upper stories with wood frame. Since located in city, the house has a plane size of 18’x70’. Furthermore, the owner wants to make a big opening at the front 18’ wall for commercial.

Since IRC is not applicable, are there any empirical or conventional design methods for this kind of building? Any information and/or suggestion on lateral support system will be greatly appreciated.

BTW: The site has a basic wind speed of 90 mph, and a seismic design category of B.

 

[JAE]

Under the IBC (which I suppose you are under) you can use what's called "Light Framed Construction" as an empirical design method but only with certain design restrictions (of which I really don't think your building would fall under).

For the front wall, you'd have to use some sort of open, moment frame system with two or three columns and a cross beam at the top of the first floor. This creates a soft lower story which puts you into an irregular building per seismic criteria, but with a B - it may not be a big deal.

 

[DaveAtkins]

I agree with JAE, unless you can use some interior walls as shear walls. But I suspect these 18' long interior walls, with openings through them, may not be very effective.

DaveAtkins

 

[tjhubo]

Thank JAE and DaveAtkins for your helpful reply.

I am wondering if I could use some CMU buttress to take the lateral load for this case?

 

[JAE]

Yes, as long as they are engineered properly, and as long as you have a place to put these buttresses.