Beam Size Calculator — IS 13920: Ductile Detailing Guidance
Quick recommendation for overall beam depth and width per the rule-of-thumb in your brief: D = L/12 to L/10, b ≈ D/1.5, and b ≥ 200 mm. This tool expands that with checks, effective depth estimate and practical notes an experienced engineer would expect.
Use 20–25 mm for beams in normal exposure; increase for severe exposure or larger bar sizes.
Per your note: do not design width less than this. Typical practical widths: 230/300/350/450 mm depending on formwork & slab-beam interactions.
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Cross-section preview
Not to scale for structural verification — illustrative only.
Engineer notes (expert guidance)
- IS 13920:2016 deals with ductile detailing of reinforced concrete structures — ties, hooks, anchorage, laps and confinement are important for seismic design. This tool gives geometric guidance only.
- Overall depth D from span/ratio is a rule-of-thumb. Final design must check: flexural reinforcement (required Ast), shear (check Vc and provide stirrups), serviceability (deflection), and torsion if applicable.
- Effective depth d = D - (clear cover + stirrup_dia + 0.5*main_bar_dia). Use this for section design (moment capacity & shear). The tool computes d for convenience.
- Width b chosen by D/1.5 is a guideline. Keep b ≥ minimum (here set by you). If beam is cast monolithically with slab, consider flushed flange, shear keys and practical width to accommodate reinforcement and formwork.
- For seismic regions: provide minimum longitudinal reinforcement, links with required spacing, adequate anchorage length, and transverse confinement near plastic hinge zones per IS 13920 & IS 456.
- Always run a full structural design per IS 456:2000 / IS 13920:2016 and expert judgement; this tool helps choose a practical starting geometry for detailed checks.
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