Bending Moment Design

Sizer compares the factored allowable bending stress F_b' to the bending stress f_b due to the internal moment M at the point on the beam with the critical f_b / F_b' ratio. Sizer checks this ratio at the point of highest moment M in the interior of each span, and at the ends of the span.

For_. multi-span and cantilevered beams, both positive and negative bending moments are checked.

If there is an interior notch, the bending moment resistance at the beam support uses the reduced section size to calculate F_b'

For rotated beams (oblique angle), the a moment resistance calculated for each axis using the section modulus in each direction. For SCL and glulam members separate f_bx and f_by resistances are used. The resistance calculated for each direction is then compared to the component of of the bending moment in that direction. Results for both directions are output. I-joists and CLT cannot be rotated.

Refer to NDS 3.3 - Bending Members - Flexure for a complete account of moment design equations and procedures.