2x6 Load Capacity Theory
Understanding the structural behavior and load-bearing capacity of 2x6 lumber requires consideration of multiple engineering principles.
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Structural Properties
- Section Modulus: 7.56 cubic inches
- Moment of Inertia: 20.8 inches⁴
- Cross-sectional Area: 8.25 square inches
- Fiber Stress Capacity: Varies by species and grade
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Load Types and Calculations
- Uniform Load (w) = Total Load ÷ Span Length
- Maximum Moment (M) = wL²/8 for simple spans
- Deflection (Δ) = 5wL⁴/(384EI)
- Shear Force (V) = wL/2 at supports
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Design Factors
- Load Duration Factor (CD): 1.0 for permanent loads
- Temperature Factor (Ct): 1.0 for normal conditions
- Size Factor (CF): Based on actual dimensions
- Wet Service Factor (CM): 1.0 for dry conditions
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Performance Criteria
- Strength Limit: Fb × S ≥ Maximum Moment
- Deflection Limit: L/360 for floors
- Bearing Length: Minimum 1.5 inches
- Lateral Support: Required every 16-24 inches
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Species-Specific Values
- Douglas Fir: Fb = 1500 psi (No.1)
- Southern Pine: Fb = 1250 psi (No.1)
- Hem-Fir: Fb = 1200 psi (No.1)
- SPF: Fb = 1100 psi (No.1)
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Application Adjustments
- Repetitive Member Factor: 1.15 for floor joists
- Bearing Enhancement Factor: 1.75 maximum
- System Factor: Based on assembly type
- Load Sharing in Floor Systems