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Rebar Development Length Calculator

Calculate basic straight-bar anchorage length from bar diameter, design steel stress and design bond strength.

Rebar Development Length Calculator

FREE ONLINE TOOL

Formula and assumptions

lb,rqd (mm) = db (mm) × σsd (MPa) / [4 × fbd (MPa)]; lb,rqd/db = σsd/(4fbd).

Basic force-equilibrium calculation for a straight bar. Supply design bond strength and steel stress from your applicable design rules; defaults are illustrative. This is not a complete ACI or Eurocode development-length check. Cover, confinement, casting position, coating, hooks, minimum lengths and lap splices require separate checks.

STEP BY STEP

How to use rebar development length calculator

  1. Check the input units and assumptions.
  2. Review the result and example.

IN PRACTICE

Example

db = 16 mm; σsd = 435 MPa; fbd = 2.7 MPa → lb,rqd = 644.44 mm = 40.28db.

GOOD TO KNOW

Which formula is used?

lb,rqd (mm) = db (mm) × σsd (MPa) / [4 × fbd (MPa)]; lb,rqd/db = σsd/(4fbd). Basic force-equilibrium calculation for a straight bar. Supply design bond strength and steel stress from your applicable design rules; defaults are illustrative. This is not a complete ACI or Eurocode development-length check. Cover, confinement, casting position, coating, hooks, minimum lengths and lap splices require separate checks.

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