Joints in wood buildings 2

[strucguy]

We are considering to include temporary expansion joints as outlined in the article below for an upcoming three story wood project. The building is about 80 ft wide and 300 feet long. Do these joints serve any real purpose? We have designed wood structures of a smaller scale without incorporating these and never had any issues whatsoever. But, as the proposed building is a little longer than what we have done before, we are little skeptical to ignore these joints altogether. Your feedback is greatly appreciated. Thanks.

http://www.norbord.com/na/cms/wp-content/uploads/U425.pdf

 

[MiketheEngineer]

Don't think I have ever seen it done - wood is quite pliable versus steel and concrete. BUT I may be wrong!!

 

[msquared48]

I do not know about expansion/contraction joints for wood, but I would definitely consider one or two seismic joints, that would function as expansion/contraction joints too.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[strucguy]

msquared48...the building will be located in an area where seismic loads are not that important. That said would it be a good idea to leave it to the contractor to figure out if he wants to provide these joints? I can modify my specification and general notes pointing to this article and have the contractor make the final call. Atleast that way I will have my back covered. What do you guys think of that approach?

 

[msquared48]

No, no, no!

As the structural engineer of record, it is up to you to make that call. Never leave any engineering design to a contractor as they are not licensed to do that ... unless they too are a structural engineer... Like that happens a lot!

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[strucguy]

I guess I will go ahead and include an expansion joint right in the middle. Having a joint at every 80 ft seems to like an overkill. Thanks a lot for your input!

 

[strucguy]

please bear with my typos. I guess I need to proof read my posts before submitting.

 

[MiketheEngineer]

Also - what is your temperature swing? In SOCAL - it is about 40F - here in StL it can be well over 100f

And as the EOR - it is your call - as noted.

 

[strucguy]

The project in in Midwest. So, the temperature swing is pretty close to 100 F.

 

[woodman88]

Luckily here in Arizona, we do not have the moisture/humidity the article is talking about. I see no problems structurally of providing the joints, if you are in an area with high moisture/humidity.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[RFreund]

Interesting. This report really is not that new but I have not come across this. I'd be interested to see any case studies. Usually the floor shrinks pretty good once it is 'closed in'.

EIT

http://www.HowToEngineer.com

 

[msquared48]

When I was in the service, there were a lot of joints in the wood buildings.

They were not always structural.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com