Lap Splice From Footing to CMU Wall Filled Solid 6

[cap4000]

IBC 2000 has an equation #21-22 on pg.499 and eq.#21-25 on pg.506 for lap splices in masonry. Is this actually the same for a rebar dowel from a concrete footing to a cmu wall filled solid with concrete?? What ever happen to the typical 48 bar diameters??

 

[SacreBleu]

It looks like the 10-significant digit accuracy people that wrote ACI 530 considered every possible variable, short of the gravitational pull of the moon, to come up with the masonry lap splice calculation.
The old 48 bar diameters a la UBC just was an approximation, and won't fly any more.

 

[WillisV]

The IBC equation gives fairly similar results to the tried and true 48db up through number 5 bars. It severely punishes you for using bars larger than no. 5s and it is therefore advisable to use smaller bars and closer spacing to avoid this problem. Utilizing typical assumptions (8in wall - rebar in center - 1500psi compressive strength block) the following laps can be found:

Rebar Size IBC Eqn 48db
3 19 18
4 25 24
5 31 30
6 57 36
7 79 42
8 112 48
9 146 54