Tapered Wood Beam Calculator, NDS 2018

What it checks

The module designs a symmetric double-tapered glulam beam with a constant width and a depth that varies linearly from the supports to the midspan. It applies the NDS 2018 §3.3.3 method for double-tapered glulam beams under a uniform distributed load and a center point load. The engine numerically locates the critical section where the bending stress is maximum, accounting for the changing section modulus along the taper.

Inputs

Geometry - Span length (ft), constant width (ft), depth at supports (ft), and depth at midspan (ft).
Loading - Uniform distributed load (klf) and center point load (kips).
Material - Adjusted allowable bending stress (psi), where the user applies factors such as CD, CM, Ct, CV, and CL.

What it reports

Critical Section Location - The position along the span where the bending stress reaches its maximum value.
Maximum Bending Stress - The calculated bending stress (psi) at the critical section, compared against the adjusted allowable stress.
Section Modulus - The elastic section modulus (in³) at the critical section, derived from the local depth and constant width.
Bending Moment - The internal bending moment (kip-ft) at the critical section, calculated from the applied loads.
Depth Profile - The linear variation of beam depth from the support to the apex, used to determine the local section properties.

Code references

The engine cites NDS 2018 §3.3.3 for the design of double-tapered glulam beams. This section governs the calculation of bending stresses in members with linearly varying depth, specifically for symmetric double-taper configurations under combined uniform and point loading.

Limits

The module assumes a symmetric double-tapered beam with a constant width and linear depth variation. It is configured for glulam roof beams and does not account for shear, deflection, or other load combinations beyond the specified uniform distributed load and center point load. Results are engineering aids; the engineer of record is responsible for the design.

This module ships in the desktop app

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