Design Glulam elements to Eurocode 5. Analyze bending, shear, and stability for GL24, GL28, and GL30 grades in seconds.
Glue Laminated Timber (Glulam) allows for spans and geometries that solid timber simply cannot match. By laminating stress-graded timber stock, Glulam offers higher strength, consistency, and architectural beauty.
The SPEC Toolbox Glulam Calculator removes the complexity of Eurocode 5 (EN 1995-1-1) verification. Whether you are designing a simple roof ridge beam or a heavy-duty column, this tool automates the interaction checks, stability factors, and material properties for all standard European Glulam grades (EN 14080).
This tool performs a complete structural analysis of Glulam beams and columns under gravity and wind loads. It verifies:
1. Size Effect ($k_h$)
Unlike steel, timber is stronger in smaller volumes. Eurocode 5 accounts for this with the Size Effect Factor ($k_h$).
For depths less than 600mm, the characteristic bending and tensile strength is increased.
$$k_h = \min \left( \left(\frac{600}{h}\right)^{0.1}, 1.1 \right)$$
Our calculator automatically updates this factor as you adjust the beam depth, ensuring you get the full benefit of the material’s efficiency.
2. Lateral Torsional Buckling (LTB)
Deep, slender Glulam beams are prone to buckling sideways under load.
The calculator determines the Relative Slenderness ($\lambda_{rel,m}$) and applies the reduction factor ($k_{crit}$).
3. Material Hierarchy (EN 14080)
We support the full range of harmonized European Glulam grades:
Combined Axial & Bending:
For columns or beams with axial loads, the interaction formula is critical:
$$\left(\frac{\sigma_{c,0,d}}{k_c \cdot f_{c,0,d}}\right) + \left(\frac{\sigma_{m,y,d}}{f_{m,y,d}}\right) \le 1.0$$
The tool checks both “Squared” and “Linear” interaction limits as required by Clause 6.3.2.
Shear Verification ($k_{cr}$):
Eurocode 5 requires a reduction in shear width to account for fissures (cracks) in the timber.
Service Classes:
This module is for Prismatic (Straight) members. For tapered, curved, or pitched-cambered beams, please use our advanced Complex Beam Module (coming soon), as these require specialized stress checks for tension perpendicular to grain ($k_{vol}$).
Yes. The calculator verifies the Compression Perpendicular to Grain ($f_{c,90,d}$) at the supports. You can adjust the bearing length ($l_b$) to ensure the beam doesn’t crush the wall plate.
This module covers “Cold” design. For fire verification (R30, R60), use the Beam Fire Calculator to determine the effective reduced cross-section ($d_{eff}$) after charring.
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