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Re: Dapped Bearing - Prestressed Double Tee

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            Glen,

                        The dapped end design procedure is only partly based on statics. It is mainly based on testing. So the design is what works, not what can be analyzed.

Crack number 3 in PCI 5th Ed. Fig. 4.6.3 (which I assume you have since you reference PCI section 4.6.3) which emanates from the reentrant corner will develop occasionally even with full Ash steel and just selfweight. Since it is essentially a shear crack at the end of the beam, I would not recommend taking credit for any concrete shear.

That said, there is a fully tested alternate dap design which I have never been able to fully understand despite coaching from the guy that developed it, which does take credit for Vc. However, the embedded hardware is completely different, so if you have existing double tees, it will do you no good. Part of the reason I do not fully follow the design method is it was developed by a precast manufacturer and they designed it one way, but PCI had it tested by a professor and he designed it another way. There are probably millions of double tee stems reinforced this way and working just fine despite my apprehension about it. If you want the PCI testing, I could probably copy it to pdf, but it’s well over 100 pages.

            Jim Getaz

            Precast Concrete Engineer