Frame building long and narrow

[rittz]

My client wants a frame building 40 ft wide 100 ft long 18ft stud walls, wood pre-engineered trusses at 2 ft oc. He wants two 16 ft wide x 16 ft high doors in the end wall. That leaves just 8 ft that could be employed as a shear wall. I’m not sure that will do it. He does not want interior shear walls (40ft wide). Knee braces would be a last resort. Any ideas are welcome. Foundation is a concrete wall on a footing to frost depth

 

[SlideRuleEra]

How about a design based on a pole building?

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[DaveAtkins]

I did a similar building several years ago--believe it or not, we ended up with a structural steel rigid frame in the middle of the building. Some of the lateral load went to the end walls, but most went to the moment frame.

DaveAtkins

 

[BAretired]

Two 16' doors in a 40' end wall leaves very little to resist wind forces as a shearwall, but it could be done with a three legged steel frame incorporated in the wall. The roof diaphragm would need special detailing to span 100'.

Steel frames at 25' centers seems more reasonable with pre-engineered parallel chord wood trusses or steel purlins spanning between frames.

BA

 

[OHIOMatt]

I agree with SlideRuleEra. For lateral resistance, consider cantelever column action. I do not always like to design them this way, but if consideration is given to load paths and deflections, it will likely work and meet all code requirements. If you would happen to be in an exteremely high wind area, it will be tricky.

There are thousands of buildings constructed in this manner every year.

 

[ToadJones]

You might consider Simpson style moment frames in the end walls with bottom chord bracing making up your diaphragm.
You would essentially be making up a 40' deep horizontal truss in the plane of the bottom chord for a diaphragm taking the loads to the end-wall moment frames.

 

[azcats]

How about masonry on the end walls? With a parapet or gable you might have enough height to make masonry lintels work and be able to keep fixity at the top of the piers. Although this would likely require 12" (or bigger) block and you may still have trouble with out of plane loads in the middle pier. Masonry would also give you an easy way to make a diaphragm connection with a wood ledger & anchor bolts.

 

[msquared48]

Depending on your wind load, you could be seeing 4 to 5 kips per endwall (just based on 20 psf).

I would forget the frame unless a SW would not work. If you extend the concrete stem wall high enough to limit the wood SW height to 12 feet, then the wood portion of a 4' wide SW would fall within the allowable aspect ratio of 3.5 to 1.

I would use spacings of 4'-0", 16'-4", 1'-4", 16'-4", and 2'0" across the endwall, with the 4'0" dimension being the shearwall portion. You should be able to do it with one layer of plywood each side, but the holddowns will probably be very large - HD 10A or better. May have to use a header beam over the first door to span out, and lower, the holdown force to the foundation.

You will probably also need a concrete grade at the endwall to span out the uplift loads.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[msquared48]

On second thought - you may have to forget the shearwall as the forces are probably doubled from what I said - more like 9 to 10 kips per endwall based on 20 psf. If you are more in the 10 psf range - the minimum - it would work.

May have to do what Dave Atkins suggested.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[rscassar]

If posts are designed to cantilever 18', how is it proposed to stand a post of that height in a footing while the concrete hardens?

If the lateral forces are high, I would consider using cantilevered steel posts and then fixing the wood frame to the steel posts.

When you sketch it to scale there is not much to work with in the end walls to obtain lateral stability.