Truss Repair Question
Truss Repair Question
(OP)
I've been asked to look at a residential truss repair. The truss spans about 20 ft. The contractor has replaced the damaged members of the truss and is proposing using 12"x12" OSB gusset plates where the members connect. At one connection where the web connects to the bottom chord, the bottom chord has been spliced. See the attached jpeg. Right now there is only a Simpson tie plate holding the chord together.
I don't like the splice being under the web members (at the joint), but at this point I don't think moving it is an option. My thought was to replace the tie plate with a couple of Simpson straps - e.g. an MSTC along the side (where the tie plate currently is), and maybe an MSTA strap along the bottom edge. And then tie the whole joint together with the OSB gusset.
I haven't calculated the loads yet, but I would appreciate anyone's initial thoughts or opinions about how I'm thinking on tying this together.
Thanks!
I don't like the splice being under the web members (at the joint), but at this point I don't think moving it is an option. My thought was to replace the tie plate with a couple of Simpson straps - e.g. an MSTC along the side (where the tie plate currently is), and maybe an MSTA strap along the bottom edge. And then tie the whole joint together with the OSB gusset.
I haven't calculated the loads yet, but I would appreciate anyone's initial thoughts or opinions about how I'm thinking on tying this together.
Thanks!






RE: Truss Repair Question
RE: Truss Repair Question
That needs to be remedied with plywood scab plate(s) of suficient size to avoid splitting the members. Do the numbers and figure it out. I do not think that just straps will suffice here.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
Mike - I do plan on using a plywood gusset plate (on both sides). Since the bottom chord is in tension, my thought was to use the straps to help transfer the tension load across the splice.
RE: Truss Repair Question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
RE: Truss Repair Question
You couls also use a longer section of a CMST coiled strap and do the same thing.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
RE: Truss Repair Question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
RE: Truss Repair Question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
BA
RE: Truss Repair Question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
On the 24x24 size - is that what you typically use for this type of gusset? Is there some rule of thumb that you're going by? I was trying to figure out what I should use for the effective width.
RE: Truss Repair Question
BA
RE: Truss Repair Question
RE: Truss Repair Question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
RE: Truss Repair Question
RE: Truss Repair Question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
RE: Truss Repair Question
Assuming the grain is straight in the member, you do not want adjoining nails in the same grain line for that will encourage splitting. Hence the staggering vertically.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Truss Repair Question
RE: Truss Repair Question
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RE: Truss Repair Question
RE: Truss Repair Question
Another option is to support the member for actual loading, and against deflection, remove the bad plates and replate with larger plates. They make portable presses which work quite nicely. The local truss manufacturer should be able to provide that repair in place.
RE: Truss Repair Question
Also, when using clinched nails at the plywood or OSB face I use a decease value (usually 66% for the clinched side) for the connection. This is due to the damage I have seen done to the plywood and OSB when the nails are clinched.
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: Truss Repair Question
RE: Truss Repair Question