Splicing of Top Bars in a grade beam

[Mark R]

I recently started using a new rebar detailing package and I just had a case where it did something I consider strange. I had a great beam that rested on 3 Piers one at each end and one near the middle. Per ACI the top Bars are placed at 130% of the bottom Bars. All Bars are #6 Bars, bottom splices 36" so top splices would be 47" (I actually used 48"as input to the program).

One span is 16'8" and the other is 15'0". The program gave me top Bars of 26'2" and 15'0". When I question the program designer about this he said that in beams that only contacts 3 Piers you don't want a slice between 2 of them and that's why the shorter bar extends to the center Pier? Thus I have a splice of 7'6" on the top Bars. Considering there are multiples of this great beam it ends up being a significant amount of additional rebar. I'm actually going to go back and just use continuous Bars 31'8" on the top but I'm sure I will have other cases that the program does the same thing.

My thinking through this incorrectly or is what the program is doing incorrect? Note, I simplified some of the information to make understanding simpler for everyone who reviews this question.

Please note I'm a mechanical engineer by training and just end up doing civil/structural on occasion so I'm not well versed in the field.

 

[dik]

Can you provide a sketch with the beam and pier sizes and the rebar proposed?

Dik