Wood truss repair methodology
Wood truss repair methodology
(OP)
Hi guys,
I would like to get your feedback on the appropriate procedure...for example a typical plywood gusset repair for a damaged plate or web. I would usually calculate the T/C loads in the members and then follow something like the article by Fox in Structure Magazine which has been referenced in this forum several times.
On two occasions now I have had supervisors and colleagues question me on this method and ask why I don't just specify something like "5/8" plywood gussets glued and screwed" and abbreviate or bypass the load analysis. I don't want to complicate the matter unnecessarily but the answer seems self evident to me and I'd like to have a reasoned and diplomatic response since I have had this put to me twice now.
Thanks in advance.
I would like to get your feedback on the appropriate procedure...for example a typical plywood gusset repair for a damaged plate or web. I would usually calculate the T/C loads in the members and then follow something like the article by Fox in Structure Magazine which has been referenced in this forum several times.
On two occasions now I have had supervisors and colleagues question me on this method and ask why I don't just specify something like "5/8" plywood gussets glued and screwed" and abbreviate or bypass the load analysis. I don't want to complicate the matter unnecessarily but the answer seems self evident to me and I'd like to have a reasoned and diplomatic response since I have had this put to me twice now.
Thanks in advance.






RE: Wood truss repair methodology
I don't know how you can decide on the number of nails to use without identifying the load conditions, member grades, number of plywood plies, and knowing the forces.
It is true that experience is helpful, but this is not Betty Crocker here... It's supposed to be engineering.
I'll step down now.
By the way, just was asked by a framer if 2X6 @ 16 are ok to span 16 feet for floor load. Now, I will give you that the answer to that is "by inspection".
Mike McCann
MMC Engineering
RE: Wood truss repair methodology
I follow the same path, as does my supervisor.
RE: Wood truss repair methodology
Never forget that every piece of engineering work you do is open to the scrutiny of other engineers, lawyers and the public. Do it right and you don't have to worry about it. Do it wrong or don't consider it at all (hiding behind the blanket of "engineering judgment" based on nothing) and you'll potentially pay the price for it.
Hey Mike....but what about those of us who tend to look like the Pillsbury Dough Boy?
RE: Wood truss repair methodology
They are sagging about 3" over 24 ft.
RE: Wood truss repair methodology
Not saying it can't be done, only that our experience was that anything other than replacing metal truss plates with larger plates using a field press, or installing large, bolted plywood gussets, was not practical.
Excel: oh, my.
I examined some mobile homes in the wake of Hurricane Charley and found thin lauan plywood gussets glued on 2x2s... many with wallpaper on them. Most of the gussets held, but the 2x2s shattered.
RE: Wood truss repair methodology
My answer is that I like doing the numbers. It is why I became an Engineer.
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.
RE: Wood truss repair methodology
Wallpaper - NICE!