Partial Tensile Lap
Partial Tensile Lap
(OP)
A building has been constructed with less than the full required development length of exposed (set) dowel between a foundation wall and a structural slab. My past experience has been that the required tensile lap can be determined per ACI 12.2 and then the fraction of the normal design strength which is provided by the partial development can be determined: e.g. if a #5 bar requires 21.2" of development in 5ksi mix, than a #5 with 19" of development has [19/21.2= 89%] strength.
I have been trying to find a source for this, and have combed the forums to the extent possible, all to no avail. I have seen some instances of people saying exactly what I think to be the case, but never a source... Can anyone point me in the right direction?
Thanks!
I have been trying to find a source for this, and have combed the forums to the extent possible, all to no avail. I have seen some instances of people saying exactly what I think to be the case, but never a source... Can anyone point me in the right direction?
Thanks!





RE: Partial Tensile Lap
Thus, if you have more steel area than required by analysis then you can reduce the development length (from which your lap is calculated).
However, you cannot reduce it lower than 12" as a minimum.
A tension lap is either Class A (1.0 x dev. length) or Class B (1.3 times dev. length).
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RE: Partial Tensile Lap
RE: Partial Tensile Lap
@wannabeSE: yes, I was.
RE: Partial Tensile Lap
Below, I've sketched two versions of how this ought to be done. The first is the conventional way that most designers approach this. The second is the way that I think it ought to be. For what it's worth, most designers that I know will model this joint as pinned and only provide top steel for crack control. The reason is primarily quality control. Wet set = kinda bad; field bending = kinda bad; dowels getting run over by forklifts = kinda bad. All tolled... bad.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Partial Tensile Lap
Thanks for the response :)
RE: Partial Tensile Lap
RE: Partial Tensile Lap
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Partial Tensile Lap
@txstructural: that's also interesting, but the slab shouldn't see much lateral force aside from thermal which it should resist fully with a tiny fraction of the steel. i think that the real answer is the As/As req. they can then gracefully turn to their calculations check the design for allowable tensile reduction.
thanks again for the replies. it's always interesting hear the amazingly varied directions other engineers' minds move in. :)