Lap Splice Lengths(1) and Hooked Bar Embedments (inches)
(1) Min. lap for spliced bars, in., assumes fy = 60 ksi, per ACI 318-14, Equation (25.4.2.3a).
(2) 40 bar diameters for fy = 40 ksi and 48 diameters for fy = 60 ksi
(3) Min. lap is development length x 1.3, assuming Class B splice. Cannot be reduced for stress level.
(4) Assumes standard hook and not reduced by ratio As (required) / As (provided).
Note that IBC 2018 Section 2107.2, offers an alternative to TMS 402-16, Section 2.1.7.7.1.1. If the alternative is used, it replaces the following development length equation in TMS 402:
g = 1.0 for #3, #4, #5 bars, 1.4 for #6, #7, and 1.5 for #8
K = Smallest of (minimum masonry cover, the clear spacing between adjacent reinforcement splices, and 9 db
This requirement resulted in much longer lap lengths and has met with considerable objection.