Development Length & Lap Splice
Rectangular section to AS3600:2018 + Amdt 2. Free, no login.
Preliminary tool, not certified engineering advice. Verify results against AS3600:2018 and obtain independent review before relying on any output. Certley accepts no liability for use of this calculator.
How it works
This calculator implements AS3600:2018 Section 13 for development length and lap splice design of deformed reinforcing bars. Select between Development Length (the embedment needed to fully anchor a bar) and Lap Splice (the overlap needed to transfer force between two bars). Both modes support tension and compression reinforcement.
What it calculates
Tension development computes the basic development length Lsy.tb using the bar-geometry factor k2, cover and spacing factor k3, and √f'c (capped at √65). The optional refined calculation applies transverse-reinforcement factor k4, transverse-pressure factor k5, and the combined floor k3·k4·k5 ≥ 0.7 per Cl 13.1.2.3.
Tension lap splice adds the narrow-element rule (Lsy.t + 1.5sb) and the k7 factor for staggering. Non-contact splices with clear bar spacing sb greater than 3db are handled automatically.
Compression uses the simpler Cl 13.1.5 formula with the k6 confinement factor and gives both the compression development length Lsy.c and compression lap (max of Lsy.c, 40db, and 300 mm).
Verify with a registered engineer
Development lengths depend on as-built cover, bar positions, and transverse reinforcement that may differ from design assumptions. Have a registered structural engineer review your detailing. Need it certified? Get a quote from a Certley engineer.