Example Usage:

To calculate the example provided on the Omni Calculator’s Wood Beam Span page:

Beam Specifications:

• Wood Species: Select structural Douglas Fir Larch
• Size: 2″ x 10″ (actual dimensions 1.5″ x 9.5″)
• Span: 8 feet (96 inches)
• Load: 240 pounds per foot (20 pounds per inch)

Deflection Calculation:

• Modulus of Elasticity (E): 1,900,000 psi
• Area Moment of Inertia (I): (1.5 x 9.5³) / 12 = 107.17 in⁴
• Deflection (δ): (5 × 20 × 96⁴) / (384 × 1900000 × 107.17) = 0.10862 in

Bending Stress Calculation:

• Moment (M): (20 × 96²) / 8 = 23040 lbf-in
• Section Modulus (S): (1.5 × 9.5²) / 6 = 22.563 in³
• Actual Bending Stress (f_b): 23040 / 22.563 = 1021.2 psi
• Adjusted Allowable Bending Stress (F_b‘): 1500 × 0.711 = 1066.4 psi

Shear Stress Calculation:

• Actual Shear Stress (f_v): (20 × 96) / (2 × 1.5 × 9.5) = 67.37 psi
• Adjusted Allowable Shear Stress (F_v‘): 180 × 0.97 × 0.8 = 139.68 psi