flitch plate design
flitch plate design
(OP)
Installing Flitchs on existing exposed basement beam to remove one lally column. Resulting beam will span 13'6" c to c from another lally to outside concrete wall (3" deep pocket available in foundation). Existing beam is triple 2x8s, but outer ones terminate over lally to be removed so are useless. I am calculating 2- 1/2"x 7" plates to carry uniform floor load only (no wall above) of 600 plf, counting three 2x8s (one of three existing plus one each side of flitchs). Questions are:
1. Planning to put 3/4" bolts 24" o.c. staggered t&b (so bolts along top are 48" apart, ditto on bottom, but staggered). Also putting two bolts each end. I want to double check this pattern, spacing and bolt size. any references you can direct me to for a double-check?
2. To put the flitch and outside 2x8s into the 3" deep foundation pocket, I cannot get bolts closer than 5" from that end, and only 2" from max shear point (edge of concrete pocket). Is this too far from the end or too close to shear point?
3. End bolts over lally on other end will be over center line of lally...ok?
4. Because there are already 3 2x8s, the flitches will be over the very edge (slightly overhanging) the top lally plate, but will have the three center 2x8s bearing fully on plate. Outside 2x8s will not be over plate at all. ok?
I am very grateful for any help with these details. The devil is ALWAYS in the details. Thanks.
1. Planning to put 3/4" bolts 24" o.c. staggered t&b (so bolts along top are 48" apart, ditto on bottom, but staggered). Also putting two bolts each end. I want to double check this pattern, spacing and bolt size. any references you can direct me to for a double-check?
2. To put the flitch and outside 2x8s into the 3" deep foundation pocket, I cannot get bolts closer than 5" from that end, and only 2" from max shear point (edge of concrete pocket). Is this too far from the end or too close to shear point?
3. End bolts over lally on other end will be over center line of lally...ok?
4. Because there are already 3 2x8s, the flitches will be over the very edge (slightly overhanging) the top lally plate, but will have the three center 2x8s bearing fully on plate. Outside 2x8s will not be over plate at all. ok?
I am very grateful for any help with these details. The devil is ALWAYS in the details. Thanks.





RE: flitch plate design
Design Guides for Flitch Plate Beams and Lally Columns
(.pdf) 1,959 KB.
it prints out at 76 pages, but worth it
http://www.destefanoassociates.com/tech/tech.htm#sidocs
Ray
RE: flitch plate design
Thanks.
RE: flitch plate design
I had 2 on file. That last post is a good one, try this other one.
I located this one on toolbase.org via a search of fplates.
http://www.toolbase.org/docs/MainNav/WoodFrameConstruction/2947_flitchplate.pdf
It is a fine detail breakdown of other wood types.
Hope it helps.
Ray