Moment connection between two wood joists
Moment connection between two wood joists
(OP)
I have an existing condition where we are taking out an existing chase and infilling the opening. The chase was next to an existing masonry wall.
The existing 2x12 roof rafters which are bearing on the chase now need to be sistered to others to extend and bear on the wall. The required additional span is 4' with overall span of 23'. I am trying to design a moment connection between the two parts using thru bolts but with a 4.5 k-ft moment, it appears that I'll need a lot of thru blots to connect the two parts. Is there some kind of Simpson device or anything else to create a moment connection in wood members?
The existing 2x12 roof rafters which are bearing on the chase now need to be sistered to others to extend and bear on the wall. The required additional span is 4' with overall span of 23'. I am trying to design a moment connection between the two parts using thru bolts but with a 4.5 k-ft moment, it appears that I'll need a lot of thru blots to connect the two parts. Is there some kind of Simpson device or anything else to create a moment connection in wood members?






RE: Moment connection between two wood joists
RE: Moment connection between two wood joists
The problem is similar in theory to a group of bolts in a steel connection in rotation, you have to calc the center of the bolt group and distribute shears amongst the bolts..
If I read that right you want to extend a 19' span to 23'? My gut feeling without any calcs is that if you conservatively take a 12' long 2x12 and stagger nail with 16d that you could cantilever out 4' no problem with regular 20/20 psf type roof loading... Shame there isn't a table somewhere for this situation. Have them build up a mock on site with (2) 2x12s and then drive one of their trucks over it, see "if that'll hold her!"...
Guess you also have the options of full length LVLs to span the entire length.
RE: Moment connection between two wood joists
RE: Moment connection between two wood joists
Try spacing your bolts way out - you will get some help that way..
Don't know your "overlap" length - but you might consider some new joists or sister joists.
And NO - no one makes a moment connecting device. The closest would be a truss plate but you would need a 20,000 lb machine to install them.
RE: Moment connection between two wood joists
RE: Moment connection between two wood joists
RE: Moment connection between two wood joists
RE: Moment connection between two wood joists
EIT
RE: Moment connection between two wood joists
Just sister the joist and call it good. Assuming there are few elecytrical;, mechanical and plumbing lines to temporarily dismantle, it's the simplest, cheapest, quickest, and most reliable fix.
Mike McCann
MMC Engineering
RE: Moment connection between two wood joists
Find out what the strongest bolted connection is for shear capacity in the given configuration.
Then calculate how far apart they will need to be to take the required shear and moment. i.e V/2 + M/spacing<bolt shear capacity.