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Appendix B - Development and Lap Lengths

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Lap Splice Lengths(1) and Hooked Bar Embedments (inches)

 

AppendixB-2

 

 

(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:

 

 AppendixB-1

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.

 

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