expansion joints in large wood buildings

[Skicat]

We have a very large 4 and 5 story wood building we are designing and were wondering if anbody has experience with expansion joints in large wood structures. We can't find anything in either text books or the code about them. Has anybody used EJ's in large wood buildings, and if so, what criteria did you use for laying them out? Thank you.

 

[RARWOOD]

I not familair with the use of expansion joints in large wood buildings to accommodate horizontal expansion or contraction of the building.

A major concern for a 4 to 5 story building is the vertical shrinkage of the wood structure. And, if you are using brick veneer, the vertical expansion of the brick.

The shrinkage of wood in the longitudinal direction is so small that normally, it is neglected. The major shrinkage in wood occurs in the direction of the width and thickness.

 

[SlideRuleEra]

An addtional reason expansion joints are not needed in "All Wood" buildings has to do with lumber -it is short, compared to steel or concrete. You get what amount to "construction" joints on a regular basis (say every 10' to 20') whether you want them or not.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[csd72]

Finishes for timber buildings are usually less sensitive to thermal movement, with the obvious exception of masonry veneer.

 

[MiketheEngineer]

Make sure you aren't mixing steel beams with it

 

[dm3415]

I think one of your primary concerns that no one has touched on yet are the hold-downs that continue floor to floor. When the inevitable longitudinal wood shrinkage occurs, the hold-downs go into compression and can distress the members they are attached too and create strain issues that can prevent them from doing their job when that time comes. Our friends at Simpson of course have a product for that that you might look at.

The other issue I've seen is with the other trades. The wood shrinkage tends to "push up" all the conduit and pipe that doesn't shrink causing havoc with electricity, gas, and water connections and the finish work around them.