Structural Wood Beam Calculator Cornell

Cornell Structural Wood Beam Equation:

\[ M = \frac{w \times L^2}{8} \] \[ f_b = \frac{M}{S} \leq F_b \]

Uniform Load (w):

plf

Span Length (L):

Section Modulus (S):

in³

Allowable Bending Stress (F_b):

psi

Moment (M):

Bending Stress (f_b):

Is Section Adequate?:

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1. What is the Cornell Structural Wood Beam Equation?

The Cornell structural wood beam equation calculates the maximum moment and bending stress in a simply supported beam under uniform load. It helps determine if a wood beam can safely support a given load.

2. How Does the Calculator Work?

The calculator uses the following equations:

\[ M = \frac{w \times L^2}{8} \] \[ f_b = \frac{M}{S} \leq F_b \]

Where:

\( M \) — Maximum moment (ft-lb)
\( w \) — Uniform load (pounds per linear foot)
\( L \) — Span length (feet)
\( f_b \) — Actual bending stress (psi)
\( S \) — Section modulus (in³)
\( F_b \) — Allowable bending stress (psi)

Explanation: The equation calculates the maximum moment in a simply supported beam, then determines the resulting bending stress which must be less than the material's allowable stress.

3. Importance of Beam Calculations

Details: Proper beam calculations ensure structural safety by verifying that bending stresses don't exceed the wood's capacity, preventing excessive deflection or failure.

4. Using the Calculator

Tips: Enter uniform load in plf, span length in feet, section modulus in in³, and allowable bending stress in psi. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is section modulus (S)?
A: Section modulus is a geometric property that measures a beam's resistance to bending, calculated based on the cross-section shape and dimensions.

Q2: Where can I find F_b values for different wood species?
A: F_b values are published in wood design manuals like NDS Supplement or AWC Design Values publications.

Q3: Does this account for beam deflection?
A: No, this only checks bending stress. Deflection should be checked separately using deflection equations.

Q4: What safety factors are included?
A: The allowable stress (F_b) already incorporates appropriate safety factors per building codes.

Q5: Can this be used for other materials?
A: The moment equation applies to any material, but the allowable stresses would differ for steel, concrete, etc.