Pitched roof as diaphragm
Pitched roof as diaphragm
(OP)
Can a pitched roof with wood trusses, such as a roof on a house, be used as a diaphragm to transfer lateral loads to shears walls? If so, do the bottom chords of the trusses have to be designed to resist compression?






RE: Pitched roof as diaphragm
RE: Pitched roof as diaphragm
Carl Bauer
www.bauerconsultbotswana.com
RE: Pitched roof as diaphragm
RE: Pitched roof as diaphragm
Cheers
RE: Pitched roof as diaphragm
RE: Pitched roof as diaphragm
RE: Pitched roof as diaphragm
Wood Truss handbook, available from the Wood Truss council of America (www.woodtruss.com)
ANSI TPI 1-1995 Design Specification...Wood Trusses
WTCA also has quality criteria that you can better evaluate your trusses by. I don't think a 1" bow is really that bad, however, joint gaps in compression members can be serious.
A truss may be outta plumb by 1/50 of the depth up to 2".
RE: Pitched roof as diaphragm
I think in general the biggest problem is making sure the structure is detailed so you can transfer the shear into the diaphragm chords and boundary elements.
I have also used trusses as drag struts with mixed results. I've tried specifing the load that the trusses must carry to the shear walls with very poor result. When I did this the truss plant providing the trusses did not have educated enough staff members to properly do the design.
Another thing I have done is require the truss supplier to set a truss directly over the shear wall below. Then I had them apply plywood to both sides of the tyruss.
RE: Pitched roof as diaphragm
Thanks
RE: Pitched roof as diaphragm
And another stab at answering your question would be to point you towards "Wind Loads on Structures" by Claës Dyrbye and Svend Ole Hansen Consulting Engineers. It's a decidely european text, but I have found it handy to have around.
RE: Pitched roof as diaphragm
I am looking for some theory on drag collector truss design, shear wall design for truss based structures etc. Anyone know of any good reading material for this?
Thanks