huangyhg

reinforce wood beam
hi everyone,
i'm a mechanical engineer (machine design) and i would like to remove a supporting column in my basement. i will eventually figure out what is the load psf (plus adding a few feet of snow). i've attached a drawing to make things clear (see link below)
the 6" x 9" wood beam is actually supported at both ends by the foundation. additionally, there are 2 columns. i would like to leave one in place and remove the other one. the span would go from 12 feet up to 20 feet.
my first idea was to add either 1 wood beam on each side or 1 c channel on each side. the new beams would not be supported at each ends. i can't add anything underneath because the head clearance is already small.
my questions are: what type of connection can be used and what is the best approach to calculate the stress and deformation of the new assembly?
thanks to all!
just as i wouldn't attempt to perform surgery on myself or design a generator, i wouldn't advise you to do structural engineering. hire a structural engineer and get it designed right. you don't want to miss something and have your house fall down.
there is no reason you can't do what you want to do. but re
it looks like you're adding a wall. can you make this wall load-bearing?
be very careful as to where discontinuities in the existing beam occur. even with supplemental steel/wood bolted to either side, if there's a "break" in the older material you don't have full moment capacity of the section.
i would just shore your floor system, remove the old beam on the left side of the floor plan, and place a new one that spans to that new wall you're building.
i tend to agree with jedclampett. retain an engineer to do a proper job. i don't know what your building authority requires, but if it were here, you would be required to submit a drawing sealed by a structural engineer.
ba
i assume that your 6x9 beam is that size partly because of dimensional constraints (head clearance). given that, it would be difficult to go from a 12-foot span to a 20-foot span without excessive stress increases and deflection, even with nominal reinforcement. further, as vandede427 noted, discontinuities in the existing beam are more prominent when you go to such spans. bottom line....get a structural engineer involved...this is not something you want solved in a few lines of text in a forum. then engineer needs to see the conditions and design accordingly.
agree with the se suggestion here.
regarding the beam, the shear will be almost doubled, the stress tripled and the deflection more than quadrupled. you still need to check the footing(s), column size, and connections.
mike mccann
mmc engineering
your sheetrock in your house will crack (alot) and you will have a trampoline for a floor and a sagging floor if you stay 9" with a 20' span.
best to hire a structural engineer.
regards,
mdj

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