Enter your Beam Type, Load Type, and structural properties — Length (L), Elastic Modulus (E), Moment of Inertia (I), and either a Point Load (P) with Position (a) or a Distributed Load (q) — and the Beam Deflection Calculator gives you Maximum Deflection, Deflection Ratio, and a pass/fail assessment.
Maximum Deflection
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Deflection Ratio
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Allowable Deflection (L/250)
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Design Check
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Beam deflection is the vertical displacement of a beam when subjected to loads. It's critical for structural design as excessive deflection can cause aesthetic issues, damage finishes, affect functionality, and compromise structural integrity.
The general beam deflection formula is δ = (load factor × L³)/(E × I), where δ is deflection, L is beam length, E is elastic modulus, and I is moment of inertia. The load factor varies based on support conditions and load type.
Beam deflection is caused by applied loads creating bending moments that deform the beam. Factors affecting deflection include load magnitude and type, beam span, material properties (E), and cross-sectional properties (I).
Common deflection limits are L/250 for floors with plaster ceilings, L/300 for floors without plaster, and L/180 for roof beams. These limits ensure structural serviceability and prevent damage to finishes.
Moment of inertia depends on the beam's cross-sectional shape. For a rectangular beam: I = bh³/12. For I-beams and other standard sections, use published tables or section property calculators.
Simply supported beams are supported at both ends, resulting in lower deflections. Cantilever beams are fixed at one end and free at the other, producing much larger deflections for the same load and span.
Yes, the principle of superposition allows you to calculate deflection for each load separately and sum the results. This is valid for elastic behavior and small deflections typical in structural design.