The load and deflection calculator now reports service-load effects instead of a “Beam Adequate” verdict. The old nominal capacities and span-scaling rule were not a traceable resistance calculation and have been removed.
Enter loads in the right units
Dead and imposed loads are entered in kN/m². Multiplying their sum by tributary width in metres gives kN/m along the beam. The tool then adds the selected section’s self-weight once. These uniform loads must be established for your project; the defaults are demonstration inputs.
With the default 0.75 kN/m² dead load, 1.5 kN/m² imposed load and 2 m width, the external line load is 4.5 kN/m. A 203×133×25 adds 25.1 × 9.81 / 1000 = 0.246231 kN/m. At a 4 m support-centre span, the total 4.746231 kN/m gives approximately 9.49 kN at each support and 9.49 kNm maximum moment.
Read the output without treating it as approval
The tool reports elastic stress from moment divided by section modulus and calculates deflection. It does not compare stress with a factored design resistance. The deflection target is your selected L/ratio; being within it is not a strength or buckling check.
The same inputs give approximately 3.22 mm deflection, compared with 11.11 mm for an illustrative L/360 target. The methodology page records formulas, unit conversions and the British Steel source.
When this model is unsuitable
Do not enter a concentrated column reaction as though it were a uniform load. Cantilevers, continuous beams, composite sections and partially restrained supports require different analysis. Load combinations, buckling, shear, bearings, masonry, connections and fire resistance remain project-specific design work.
Structural work requires a chartered structural engineer and the applicable Building Control approval. This educational article has not received an independent engineering review.