5 story wood building
5 story wood building
(OP)
We just got a new project, and it happens to be a 4 & 5 story wood apartment building. We've never designed a 5 story building and I've been tasked with researching the topic. Particularly, the lateral stability aspects of a 5 story wood structure. Can you point me somewhere? Thanks.






RE: 5 story wood building
http://structuremag.org/
http://gostructural.com/archive.asp?id=402
One of them did an article a few months ago on shrinkage compensating tie downs for multistorey shear walls. I think there are also a number of other related articles also.
RE: 5 story wood building
Mike McCann
McCann Engineering
RE: 5 story wood building
RE: 5 story wood building
RE: 5 story wood building
The "2006 IBC Structural/Seismic Design Manual, volume 2", which is published by the SEAOC has a detailed example of a 3-story, light framed hotel structure. In fact, there are two example designs; one for a wood framed building and one for a cold formed steel structure.
The book cost about $70.
RE: 5 story wood building
RE: 5 story wood building
Need to make sure the species you're using can handle 5 stories. I dont think the typical SPF will work in most cases. Note plate crushing too especially around areas where you have stacking elevator lobbies, etc where you get larger loads.
RE: 5 story wood building
But, even if the Code allows it, is it a good idea?
DaveAtkins
RE: 5 story wood building
Can you tell me where the IBC Code allows a 5 story wood building. Typically its 3 stories max.
RE: 5 story wood building
Check out this nice link for your answer.
http://ww
RE: 5 story wood building
RE: 5 story wood building
I did not research the IBC regarding how many stories a wood framed structure can be. Maybe it is only 4 stories--I don't know.
But your link references the IRC, not the IBC.
DaveAtkins
RE: 5 story wood building
DaveAtkins
RE: 5 story wood building
RE: 5 story wood building
* point loads on your top plates get more important and these need to be specifically checked. You may need triple top plates in some cases.
*a change of stud spacing can also effect the top plates.
* ensure that all point loads are followed down to ground.
* transfer of axial loads through floor plates needs to be carefully looked at.
* axial effects from wind overturning can be significant.
csd
RE: 5 story wood building
In the IBC it is found in footnote m of Table 720.1(2). You should check whether this reduction applies to your project.
RE: 5 story wood building
RE: 5 story wood building
Mike McCann
McCann Engineering
RE: 5 story wood building
Studs on the lower two floors will be 4x or 3x's depending on the wall layout, height. Regardless the shearwalls will require a wider nailing to work with the tighter nail spacing.
We try to utilize kiln dry plates, or engineered lumber to minimize shrinkage. Typically the majority of the shrinkage over the floors comes from the plates, two top plates and a sill per level at 1/8" per plate (approx) adds up to 3/8" per floor times five levels fairly significant.
If you are putting this on top of a concrete podium it is important to use line loads in lieu of a estimated projected surface load. We have reviewed projects were a non-conservative psf load was use and deflections were a big issues.
Recently heard that lumber is at a 20 year low due to the surplus due to the downturn in the residential market. So good time to go to wood.
Regards,
RE: 5 story wood building
In Minnesota prior to 1990 there were probably over a dozen 4 story wood frame apartment buildings built in the Minneapolis area and at least one five story building.
For the last 13-14 years I have not been dealing with the code requirements for heights and area so I don't know what the current limits are.
There are several things you can do when designing this type of building. One is to run your floor joist parallel with the outside walls. This puts less weight on your bearing walls and more dead load on the shear walls pependicular to the outside walls. Most contractors do not want to do this instead they want to run long span floor trusses and dump all the load into the corridor and outside walls.
When roof and floor trusses are used at 24" o.c. place a stud at every truss location. 16" o.c. spacing can be used adding an extra stud every 4' of wall at the truss that doesn't line up with the 16" o.c. spacing.
To properly detail the building you must accurately calculate the wood shrinkage and if you are using brick veener you must also calculate the brick expansion.
Plate crushing often is a problem because in many areas of the US they use SPF studs for top plates. In the past when I have designed multstory wood framed buildings I specified that the bearing stress under the roof trusses was to be less than 425 psi. If you don't do that the truss designer will base his bearing on the bearing stress of his bottom chord which will probably be 625 psi or higher.