Your building is 32 ft wide, which is right in between the 28 and 36 foot columns of the chart. It sounds like the girders under the joists will be an "interior bearing wall" span supporting "one floor only." They have charts for girders and headers in the ICC. Hopefully Don_P will be along sometime soon and see if I have messed up or not. Perhaps you need some engineered wood, or steel. That still FAILS the fiberstress in bending test. Using three columns across the length reduces the span for each to approximately 120" (10 ft) The calculator tells me that 4 layers of 2x12 (actual beam width of 6" and depth of 11.25" will FAIL the Fiberstress in bending test and the deflection test. (the calc is fixed to use a value of L/360 on floors)īut let's see what happens when we use. Using Don_P's simple beam calculator and the following data for SYP. Half of that will rest on the center beam and a quarter on each side wall.Ģ4750 / 2 = 12375 on the center beam for each segment. If we call the LL to be 40 PSF, let's call the DL out at 15 PSF. Let's call that a 32 x 42 building that = 1344 sq ft.ĭivide that into three parts = 448 sq ft per section I always though it was better to stagger the joints to minimize a hinge effect over the column, but he says his way is correct. My contractor (NOT an engineer) says a beam built up out of 3 or 4 2X12's will be 'plenty', but of course, the inspector has to believe that, too.Īs an aside, my contractor builds such beams with all of the joints over the column. Materials available locally are #2 southern yellow pine- strong stuff. Design load should be 40 psf minimum live load, and I want a L/480 stiffness. I don't have enough room to put them on top of the carrier beam, so they will be attached with hangers. They will be hung from ledgers at the edges, and the carrier beam in the middle. Specs- The floor joists will be 2X12's on 16" centers. The lumber yard said I would need an LVL, but what did they do before those were around? I show two evenly spaced support posts, but could go with three if it would help. I'm attaching a drawing with the dimensions. I use this chart: A 15' long 2x12 will span the two 7 1/2' spans and support a 362#/LF total load at a L/360 deflection limit, so this will do.I'm wondering if there's a way to prescriptively calculate the carrier beam I need for my main floor. This cuts the span in half so you can use a smaller beam. I would lag it into every stud, but I also like to support it at both ends and in the middle, with a stud laid flat against the wall and lagged into a stud. The ledger along the wall needs design as well. Support with a 4x4 post or 3 2x4's as columns in the walls. Using a readily available 1.9E LVL, a double 11 1/4" deep LVL beam will support a LL of 284#/LF and a total load of 416#/LF, so this is more than adequate. The beam has a contributing area of 6SF x 50#/SF total load, for a total load of 300#/LF. The actual span is 9'-6", so this will work. Using that, and a 10#/SF dead load, Spruce-Pine-Fir for material and a deflection limit of L/360, 2圆's will span 9'-5". This should be adequate for what you describe. I use this calculator for sizing joists:Ī 40#/SF live load is typical for residential floors.
Joists I like to space at a maximum of 16" on center, to support the floor sheathing properly.
Run perpendicular to the joists and provide solid blocking under all seams. I like 3/4" T&G plywood, glued and screwed and staggered for the decking.
0 kommentar(er)
