Home / Calculators / IS 456 flexure 🇮🇳 IN
IS 456:2000 Annex G — Rectangular Beam Flexure
Neutral axis depth xu · xu/d ductility check against xu,max/d · required tension reinforcement Ast
⚠ Notation notes:
1. IS 456 grade M25 means fck = 25 N/mm² on a 150mm cube — like GB and SP, unlike ACI's cylinder f'c or Eurocode's dual cylinder/cube C25/30 notation.
2. IS 456 folds the steel partial factor into a single 0.87·fy multiplier (0.87 = 1/1.15) rather than computing a separate design strength fyd — same idea as Eurocode's fyd = fyk/γs, different notation.
1. IS 456 grade M25 means fck = 25 N/mm² on a 150mm cube — like GB and SP, unlike ACI's cylinder f'c or Eurocode's dual cylinder/cube C25/30 notation.
2. IS 456 folds the steel partial factor into a single 0.87·fy multiplier (0.87 = 1/1.15) rather than computing a separate design strength fyd — same idea as Eurocode's fyd = fyk/γs, different notation.
Input data
From IS 456 §18.2.3.1 / IS 1893 §6.3.1 combinations
Results
Neutral axis xu (mm)—
xu/d—
xu,max/d Annex G—
Ast (mm²)—
Mur (kN·m)—
DCR = Mu/Mur—
⚠ Not verified: —
REFERENCES
Annex G, G-1.1C = 0.36·fck·b·xu; Mur = 0.36·fck·b·xu·(d − 0.42·xu)
Annex G, Table G-1.1bxu,max/d by rebar grade
§26.5.1.1Ast,min ≈ 0.85·b·d/fy
© CopyrightIS codes are copyright BIS. Only clause numbers cited; no text reproduced.
Engine: in-codes.js · IN-IS456-2000.v1-beta ·
Step-by-step
Shear design — not provided
IS 456 Table 19 gives the design shear strength τc as a function of concrete grade AND tension steel percentage pt in a fine-grained tabular form. The full table could not be verified — this pack refuses rather than approximating a safety-critical table from memory.
Preliminary calculation tool. Final design requires the full official text of IS 456:2000, IS 1893 (Part 1):2016 and IS 875, and review by a licensed structural engineer.