Tool
Basic Beam Deflection Check
Simply supported beam under a uniformly distributed load: δ = 5 w L⁴ / (384 E I). Enter unfactored (SLS) loading. Common limits: L/360 (general), L/500 (below brittle finishes), L/250 (total including permanent).
Output
Enter inputs and press Calculate to see results.
Calculation record
Produce a formatted Bebbington Engineering Studio calculation sheet showing the inputs, working, results and engineering basis. These fields are optional and are printed on the document only.
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Tool version 1.0 · Last reviewed Not yet recorded — pending engineering validation
Method and assumptions
- · Simply supported beam carrying a uniformly distributed load: δ = 5 w L⁴ / (384 E I).
- · Loading entered is unfactored (serviceability limit state).
- · Elastic behaviour, uncracked prismatic section, no allowance for creep, shrinkage, pre-camber or construction sequence.
- · Allowable deflection is taken as L divided by the selected limit (L/250, L/360 or L/500).
Worked example
- Span L = 6.0 m, SLS UDL w = 10 kN/m, I = 21 500 cm⁴, E = 210 000 N/mm², limit L/360.
- δ = 5 × 10 × 6000⁴ / (384 × 210 000 × 21 500 × 10⁴) ≈ 3.7 mm.
- Allowable = 6000 / 360 = 16.7 mm — the check passes.
Engineering basis & limitations — Beam Deflection Checkv1.0 · reviewed Not yet recorded — pending engineering validation
Design standard
- · Elastic beam theory; serviceability limits consistent with BS EN 1993-1-1 and UK practice.
Analysis and design method
- · Simply supported single span under a uniformly distributed load: δ = 5wL⁴ / (384EI).
- · Deflection compared with the selected span/deflection limit.
Load combination basis
- · Serviceability only — the user enters the SLS load directly. No ULS check is performed.
Material assumptions
- · Elastic modulus entered or assumed by the user; linear elastic behaviour throughout.
Serviceability criteria
- · Limits of L/250, L/360 and L/500 are offered. The appropriate limit depends on the supported construction and finishes and remains a design decision.
Not checked by this tool
- · Strength checks of any kind — bending, shear, buckling and stability are not assessed.
- · Support settlement, pre-camber, creep and shrinkage of supported construction.
- · Connections, bearings, fixings and their detailing.
- · Fire resistance, corrosion protection and durability requirements.
- · Overall structural stability, robustness and disproportionate collapse.
- · Vibration, dynamic response and fatigue.
- · Temporary works, construction sequence and buildability.
Where this tool does not apply
- · Any arrangement other than a simply supported span with a uniformly distributed load.
- · Composite, cracked-section or non-linear behaviour.
Preliminary / informational calculation — not a BES project-specific structural design. Within the checks and assumptions listed above, only the stated utilisations have been assessed; a satisfactory utilisation does not confirm overall structural adequacy.
Disclaimer
Indicative result only. The calculation depends on the assumptions and information entered and does not constitute structural design or professional advice. Do not use the result for construction, procurement, Building Regulations submissions or safety-critical decisions. All results must be independently verified by a suitably qualified structural engineer before being used for design, construction or regulatory purposes. Bebbington Engineering Studio Ltd accepts no responsibility for reliance placed on unverified results.