How do I calculate bending moment on a simply supported beam?

For a simply supported beam of span L with a uniformly distributed load w (kN/m), the maximum bending moment is M = wL²/8 at midspan. For a single concentrated load P at midspan, M = PL/4. For a concentrated load P at distance a from one support (where b = L-a), M = Pab/L. For multiple loads, sum the contributions. The maximum shear is at supports: V = wL/2 for uniform load, V = P/2 for central point load. In CalcSteel, you don't need to compute this manually — the FEM solver produces the full bending moment and shear diagrams when you run an analysis. Just model the beam, define the support conditions (pin + roller), apply the load, and click Calculate.