Glulam Beam & Column Design Software

1. Canadian Stress Grades

You won’t find US “24F-V4” grades here. Our calculator includes the standard Canadian stress grades per CSA O86 Table 6.3:

• 24f-E (Douglas Fir-Larch): The most common high-strength grade. Excellent for long spans and heavy loads.
• 20f-E (Spruce-Pine-Fir / SPF): A cost-effective option for standard framing and shorter spans.
• 20f-EX (Hem-Fir): Often used in specific regional markets.
• Custom Grades: Ability to input custom properties for proprietary products (e.g., Nordic Lam, Element5).

2. The Volume Effect ($K_Z$)

In CSA O86, the strength of Glulam is dependent on its volume. A massive girder is statistically likely to have more defects than a small header.

The calculator applies the size effect formula:

$$K_Z = \left(\frac{130}{b \cdot L}\right)^{1/5.95}$$

(Note: This logic is specific to CSA O86 and differs from the US “Depth Effect” or European “Height Effect”).

3. Lateral Stability ($K_L$)

For deep, narrow beams, the calculator checks the Slenderness Ratio ($C_B$) to prevent lateral torsional buckling.

It automatically calculates the $K_L$ reduction factor based on your restraint conditions (e.g., “Compression edge held in line by decking”).

Factored Resistance ($\phi$):

We apply the standard material resistance factors:

• $\phi = 0.9$ for Bending and Shear (standard for Glulam).
• $\phi = 0.8$ for Compression Parallel (Columns).

Modification Factors:

• $K_D$ (Duration of Load): Adjusts for Short Term (1.15) vs. Standard (1.0) vs. Permanent (0.65).
• $K_S$ (Service Condition): Typically 1.0 for Dry Service, but usually reduces to ~0.8 for Wet Service (exposed).
• $K_H$ (System Factor): Defaults to 1.0, but can be increased to 1.04 if the beam is part of a load-sharing system (Case 1).

Deflection & Creep:

Total deflection is calculated as:

$$\Delta_{Total} = \Delta_{Short} + K_{creep} \cdot \Delta_{Long}$$

• We use the specific $K_{creep}$ factors for Glulam adhesives (typically lower than sawn timber), ensuring you don’t overestimate long-term sag.