Beam Designer

Solves any single-span beam (cantilever, simply supported, propped, fixed, overhanging) under arbitrary loads by the direct stiffness method, then performs the BS 5950-1:2000 member checks for PFC channels, SHS (hot-finished or cold-formed), RHS (hot-finished), UB universal beams, or UC universal columns. Blue Book section data is built in; every value is editable.

Analysis: 2-node Euler Bernoulli beam elements (direct stiffness); reactions exact, shear/moment by statics, deflection at nodes exact. Section data: SCI P363 Blue Book. This is a design aid only — the developer takes no responsibility for the results, and all calculations must be checked by a competent structural engineer.

Design code
Switching code changes the cross-section/member-resistance formulas (classification, shear, moment, LTB, buckling). The beam analysis, loads, and combinations are shared.
Section & grade
Drawing orientation only — section properties and resistances are identical. The shear centre, self-weight eccentricity, and plate sides follow the mirrored orientation; per-load e is always measured from the shear centre as drawn.
Design strength auto-set from grade & flange/wall thickness — BS EN 10025-2 (P362 Table 5.1: S275 → 275/265, S355 → 355/345 for t≤16 / 16<t≤40) for EC3; Table 9 for BS 5950. Override if required.
Leave blank to use gross area (no bolt holes).
Welded bottom plate
Thickness, mm
Outstand left, mm
Outstand right, mm
Continuous plate along the full length, welded to the flange edges (or section edges for SHS/RHS). Outstands are measured beyond each flange tip; 0 = stops at the flange edge. It carries eccentric supported loads (e.g. a wall outside the flange) — enter those loads with their e in Loads. The plate is not designed; it only adds self-weight, included automatically as Dead (G).
Geometry & supports
Pinned = vertical restraint only. Fixed = vertical + rotational. Position measured from the left end (0 m).
Loads
Forces positive downward (kN, kN/m). Moment positive anticlockwise (kN m). Enter characteristic (unfactored) values and tag each load's case the partial factors come from the Load Combinations below, not from the load itself. Section self-weight is added automatically as Dead (G) from the selected section mass/m.
When activated, each load row gains its own shear-centre offset e (mm). In EC3 unrestrained mode each transverse load also gets its own zg load height above the shear centre. Applied moments act through the shear centre. Automatic self-weight acts through the centroid: e = 0 for doubly symmetric sections, but e = esc for PFC channels.
Load Combinations
Switch on every combination you want considered in the design. For each ULS combination switched on, the solver finds Shear/Moment everywhere along the member; the worst case from any switched-on combination governs each check (envelope), and the report states which combination governs which check. At least one ULS and one SLS (deflection) combination must be on.
Axial & lateral-torsional buckling
Fully restrained: the compression flange is held in position along its length (e.g. by a slab or decking), so lateral–torsional buckling cannot occur and the design follows the SCI restrained-beam procedure to EN 1993-1-1 (classification → shear → shear buckling → moment → deflection). Applies to the EC3 code path.
Positive = compression, negative = tension. Entered directly as the governing ULS design value it is not run through the Load Combinations below. Leave 0 for a pure beam.
Coincident ULS design moment about the minor (z–z) axis, entered directly (this solver bends in one plane). Forms the full EC3 biaxial interaction (My/MN,y)α + (Mz/MN,z)β ≤ 1 (cl 6.2.9.1). Leave 0 for uniaxial bending.
For PFC, this sets both the LTB effective length (Table 13/14) and the strut effective length. For SHS, LTB does not apply (cl 4.3.6.1), so this sets only the strut effective length (Table 22).
C1 (moment-gradient factor for LTB) is computed from the official end-moment-gradient table where that case applies. For transverse-load or combined cases, the safe default C1=1.0 is used unless you override it with a verified value (e.g. from LTBeam or other software).
Deflection & advanced
Defaults: E = 205 000 for BS 5950 and 210 000 for EC3. Ke = 1.2 / 1.1 / 1.0 for S275 / S355 / S460. Robertson constant (Table 23/24) auto-selects per axis: SHS hot-finished a=2.0/2.0, cold-formed a=5.5/5.5 (both axes, by symmetry); UB rolled I-section a=2.0/3.5 (curve a/b) for flange =40 mm, a=3.5/5.5 (curve b/c) over 40 mm; UC rolled H-section a=3.5/5.5 (curve b/c) for flange =40 mm, a=5.5/8.0 (curve c/d) over 40 mm one curve lower than UB at the same thickness; PFC defaults to a=5.5/5.5 channels properly sit under Table 25, not these generic curves, so override if you have a precise value.