Wood Truss Connection Failure
Wood Truss Connection Failure
(OP)
I did an investigation into a wood truss failure and am providing a fix (see attached photo for failure). It's an entire section of the roof system that failed at the same connection point...probably about (35) trusses total. The request has been made to remove the deflection in the trusses such that they are at approximately the original state before failure. The deflection cause interior partition expandable doors to be inoperable due to the deflections in the trusses.
Apparently, the doors stopped being use about 12 years ago, and someone recently went into the roof system to see what was going on.
Anyone have any guides or recommendations on an approach to remove the deflection? The roof has a Spanish clay tile roof so it's pretty heavy. Maybe it would be easier to not remove the deflection and readjust the partition doors?
Thanks,
Apparently, the doors stopped being use about 12 years ago, and someone recently went into the roof system to see what was going on.
Anyone have any guides or recommendations on an approach to remove the deflection? The roof has a Spanish clay tile roof so it's pretty heavy. Maybe it would be easier to not remove the deflection and readjust the partition doors?
Thanks,






RE: Wood Truss Connection Failure
RE: Wood Truss Connection Failure
RE: Wood Truss Connection Failure
Any thoughts on how quickly to jack the truss back into place? I'm concerned if I go too fast it may cause 2nd and 3rd order effects to connections. I was thinking like 1/8" every week or something like that.
RE: Wood Truss Connection Failure
Dik
RE: Wood Truss Connection Failure
I originally thought about bracing locations at each intersection of webs/bottom chord on the bottom chord would be the best option for jacking it back up.
RE: Wood Truss Connection Failure
one question, although you've likely already confirmed it because you seem to be in contact with truss supplier and contractor.... question: was Spanish tile the original roofing? If yes, so be it. If no, trusses may have additional problems.
second, if you're in contact with 'supplier', assuming truss supplier, they could/should/almost-certainly-would supply you with efficient fix. .. ?
third, looks like 2x4 web and at least 2x8 chord and, like everyone says, a too small plate. It seems to be the heaviest loaded tension web in the system. is the web member adequate, ok?
forth, or fourth or.... whatever.... assuming only the panel point connector is the thing: It also appears difficult to access in your photo. I'd prefer a metal plate connector as it will be stronger in a smaller 'footprint' than a plywood plate. I've had truss yards with mobile hydraulic truss plate press machines rent their equipment to a contractor to field 'press' plates. I'd anticipate the possibility of removing the web completely as the top end is a bit shredded, and field plating both ends.
fifthish, regarding shoring/jacking.... i'd be looking at shores/jacks at bottom chord panel points as follows: 3,4,5, assuming left wall is panel point 1. special emphasis on 4 and 5.
RE: Wood Truss Connection Failure
Dik
RE: Wood Truss Connection Failure
you're web pulled out about an inch or so it appears from the photo, and, your door isn't working, and that makes sense.
I'm guessing you're not in snow country?
RE: Wood Truss Connection Failure
RE: Wood Truss Connection Failure
As for jacking location, I would place the jack at the panel point just to the right of where you have deflection noted on your sketch. You can also place a jack at each panel point and do them sequentially. That will minimize your risk of overstressing any single point and will spread the upward load on the truss a bit better.
RE: Wood Truss Connection Failure
RE: Wood Truss Connection Failure
oldestguy: Great idea on the ring shanks. I will look into that as well.
RE: Wood Truss Connection Failure
RE: Wood Truss Connection Failure
Added: You should also review the other plated connections to see if any have failed. Plates should be in neat contact with the wood members. If you can slip a business card between the plate and the member, you should consider that joint to have failed also.
Dik
RE: Wood Truss Connection Failure
RE: Wood Truss Connection Failure
some eccentricity is introduced into the panel point that adds secondary moment to the chord etc, true, but since your chord and other web axial forces are rather small at this panel point..... just saying . Your main issue is getting the tension forces of your web back into the truss,
RE: Wood Truss Connection Failure