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Structural Wood Design Problem 1 - Design a Wood Floor Joist:
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Floor joists spaced every 16 in carry a floor over a simple span of 16 ft.
Assume that the top of the joist is laterally supported by the plywood sheathing.
The ASD loading on the joist is 80 plf. Moisture is less than 19% and it is at room temperature.
Use a Southern Pine 2"x10", (actual dimensions 1.5" x 9.25"), No. 2. Check the moment, shear and deflection.
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1. From the steel beams submenu,open the shears and moments submenu then open the simple beam - uniform load calculation, 1SBUDL.aspx.
Input the "Title" of the calculation, the "Designer/Checker" information, enter the variables and click on the "Calculate" button and read the results.
The maximum shear is 640 lbs and the maximum moment load is 2560 lb-ft.
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2. Next, from the structural wood submenu open the wood beam section properties calculation, BeamSectionProperties.aspx.
Input the "Title" of the calculation, the "Designer/Checker" information, enter the variables, click on the "Calculate" button and read the results.
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3. From the structural wood submenu open the southern pine reference tables, Wood_Reference_Design_Values_Pine.pdf.
Derive all of the factors for Southern Pine No. 2, under the given conditions.
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4. From the structural wood submenu open the wood flexure strength calculation, WoodFlexure.aspx.
Input the "Title" of the calculation, the "Designer/Checker" information, enter the variables, click on the "Calculate" button and read the results.
The allowable moment is 36,899 in-lb, or 3074.9 lb-ft > 2560 lb-ft, so moment strength is adequate.
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5. From the structural wood submenu open the wood shear strength calculation, WoodShear.aspx.
Input the "Title" of the calculation, the "Designer/Checker" information, enter the variables, click on the "Calculate" button and read the results.
The allowable shear is 1,618.75 lb > 640 lb, so shear strength is adequate.
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6. From the structural wood submenu open the wood beam deflection calculation, WoodBeamDefl.aspx.
Input the "Title" of the calculation, the "Designer/Checker" information, enter the variables, click on the "Calculate" button and read the results.
The deflection of the joist under the loading is 0.745 inches.
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7. Summary
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The allowable moment is 36,899 in-lb, or 3074.9 lb-ft > 2560 lb-ft, so moment strength is adequate.
The allowable shear is 1,618.75 lb > 640 lb, so shear strength is adequate.
The 2"x10" Southern Pine, No. 2, floor joist is adequate and will result in minimal deflection of 3/4".
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