Wood & Steel mix construction issues?
Wood & Steel mix construction issues?
(OP)
I am designing a 3 story residential house, with a combination of steel columns, steel beams to support floors, with a combination of wood bearing walls and other wood wall components.
Is there any issues I should be concerned, such as when I will specify 40 ft tall single columns...which will need lateral bracing at each floor level...any suggestions on how to do that with wood elements?
Should shrinkage differential between the two materials be a concern?
Any comments appreciated. Thanks.
Is there any issues I should be concerned, such as when I will specify 40 ft tall single columns...which will need lateral bracing at each floor level...any suggestions on how to do that with wood elements?
Should shrinkage differential between the two materials be a concern?
Any comments appreciated. Thanks.





RE: Wood & Steel mix construction issues?
http://www.awc.org/Standards/wsdd.html
It works, this is how many of the famous wooden roller coasters at amusement parks are constructed.
www.SlideRuleEra.net
RE: Wood & Steel mix construction issues?
It is not clear to me how you would construct a 40' long column out standard dimension lumber. Chapter 3 in "Wood Structural Design Data" only appears to address space columns and mechanically laminated columns. My understanding is the use of either space columns or mechanically laminated columns would require the use of full length pieces.
The method you are describing sounds like the 40' columns are made up by overlapping shorter lengths of lumber.
I have seen a discussions in an older design book that seem to imply that short pieces could be joined together with butt joints to create a longer column. This method seems to rely on the use of overlapping lengths on the outside of the compression area to assure the column acts as one unit. The book doesn't present enough information, so I am not clear on what they actually were describing.
RE: Wood & Steel mix construction issues?
For longer mechanically laminated columns with spliced laminations, the Forest Products Lab has done a fair amount work. Here are a few references:
"Bending Properties of Reinforced and Unreinforced Spliced Nail-Laminated Posts"
ht
"Bending Properties of Four-Layer Nail-Laminated Posts"
ht
"Modeling Vertically Mechanically Laminated Lumber"
http
An authority on this subject (and author of the above documents) is Dr. David Bohnhoff at the University of Wisconsin. His website shows other publications
http://bse.wisc.edu/profiles/faculty/bohnhoff.html
Although I have not seen it, the American Society of Agricultural and Biological Engineers offers a document titled "Design Requirements and Bending Properties for Mechanically Laminated Columns". From the on-line summary it seems to cover columns where there is a maximum of one end joint per lamination
http:
www.SlideRuleEra.net
RE: Wood & Steel mix construction issues?
http://bse.wisc.edu/bohnhoff/publications.htm
www.SlideRuleEra.net
RE: Wood & Steel mix construction issues?
I had forgot about the work done in the area of pole building. Good information!!!!
RE: Wood & Steel mix construction issues?
RE: Wood & Steel mix construction issues?
The steel will not shrink or grow at all - unless you have wide temperature variations.
New wood will definitely shrink the first year or two and then going from winter to summer and back - you will see movement - esp in something 40' tall.
Can you "stack" wood columns and use your floor diaphragms
to provide lateral support??
RE: Wood & Steel mix construction issues?
RE: Wood & Steel mix construction issues?
RE: Wood & Steel mix construction issues?
walls from second floor to roof are not on the wall below. According to the Canadian COde, partitions can be offset
600mm from the walls below. If almost all the walls except
only a stretches of 4 and 5 ft in either direction go continuous because these are the stair well and architect have no choice. Please tell me how can i support the walls from second floor to roof and how is the lateral system for wind works if the walls are not on each other.
RE: Wood & Steel mix construction issues?
"3 1/2" wood pipe"? I assume you mean a steel pipe column. If I need a nailer, I use a tube section with Nelson Sill plate anchors. Works well for me.
I do not like mixing steel with wood in residences, but with higher end homes, it is unavoidable. Stay away from dimension lumber wherever possible and go with TJI's, glulams, parallams, micropams and the like. Most (90%) of the shrinkage occurs across the depth of dimension limber, as with joists and plates. The use of TJI's for the joists will minimize that.
Mike McCann
McCann Engineering
RE: Wood & Steel mix construction issues?