strapping in a wood building 1

[imagine18]

Hi all,

I saw a project recently that was a single story wood building. On all the top plate corners around the building, the engineer of record had installed horizontal straps to be wrapped around the corner. I hadn't seen this before and wasn't sure why the engineer had called it out. Is it a CBC specification? Any help is appreciated.

 

[charliealphabravo]

I would be curious to know the reason as well.

I use a detail that requires the top plates to be staggered at the corners so that the nails at the connection are in direct shear for internal pressure loads. Another detail requires at least 3 studs at wall corners for the same reason. I think these kinds of details (including yours) are used to provide redundancy and ensure minimal structural stability/integrity, since the calculated loads go through the diaphragms and then through the sidewall and endwall roof and base connections.

In what area will the structure be located?

 

[focuseng]

I'll sometimes design a "tension ring" at the top of a the walls with a small uniform hip roof structure. Usually more complicated then just a tie strap as it involves the hip rafter heel connections too. Trick I picked up designing steel grain tank roofs. Otherwise ... donno.

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MAP

 

[dhengr]

The straps at any joints along the wall and at the corners are to tie the top plates together. You can’t make an effective butt joint btwn. two plates over a single stud. After all that is the top chord of the lateral load resisting system. Was what you were looking at a single top plate? This is normally taken care of by a double top plate with staggering splices along the length of the wall and lapping the two plates (a half lap) at the corners or intersections when a double top plate is used. Then they are also nailed together along the full length of the wall. The single top plate in light framing is part of the save framing lumber (Green?) thinking/movement. But, it pretty much requires that you stack framing right over the studs, because a single plate will not span from stud to stud under a roof truss or many floor joists.

 

[imagine18]

Thank you all for the input. This project is a single story wood fast food restaraunt in Idaho. Just a rectangular box...the top plate consists of 2 plates that over lap, so yeah, I am a little confused. The strapping could be for redundancy, not sure. Thanks for the input everyone.

 

[jdgengineer]

If you were looking at a building with a single top plate the Exception to Section 2308.9.2.1 of the 2009 IBC requires that the corners be tied with a strap.

In complicated wood buildings, my office will sometimes use steel straps at the corners. It's not required by the code (as far as I know except for single top plates), but we feel that it can add some redundancy to the structure and straps are relatively cheap.

 

[TDIengineer]

If this had a double top plate I would assume it was added for redundancy. The corners always get beat up.