older concrete beam, bent bars
older concrete beam, bent bars
(OP)
i'm working on a portion of an existing concrete building from 1962. i have access to the original drawings. a concrete beam reinforcing schedule has columns for: top bars, bottom bars, bent bars, stirrup marks, and ties.
we're adding some load to a specific concrete beam. the beam is listed to have 2-#10 top bars, 4-#10 bottom bars, 3-#10 bent bars, "3104" stirrup mark, and ties are #2 @ 12" o.c.
my question is: at the mid-span of the beam, do i have 4-#10 bottom reinforcing bars, or 7-#10 bottom reinforcing bars (from adding the 3 bent bars to the 4 bottom bars)?
any other information i can provide? thanks for reading and your anticipated replies!
we're adding some load to a specific concrete beam. the beam is listed to have 2-#10 top bars, 4-#10 bottom bars, 3-#10 bent bars, "3104" stirrup mark, and ties are #2 @ 12" o.c.
my question is: at the mid-span of the beam, do i have 4-#10 bottom reinforcing bars, or 7-#10 bottom reinforcing bars (from adding the 3 bent bars to the 4 bottom bars)?
any other information i can provide? thanks for reading and your anticipated replies!






RE: older concrete beam, bent bars
RE: older concrete beam, bent bars
RE: older concrete beam, bent bars
RE: older concrete beam, bent bars
RE: older concrete beam, bent bars
The unusual part of the specification, in my view is the #2@12 ties. I don't remember ever using ties and stirrups in the same beam. Some people called stirrups ties, but they were never as small as #2. Are the stirrup spacings given on the drawings?
BA
RE: older concrete beam, bent bars
the #2 @ 12" ties is just stated in the schedule; there is no beam elevation to show these pieces.
RE: older concrete beam, bent bars
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: older concrete beam, bent bars
To analyze the beam, you must also know the amount of negative steel over the columns and the spacing of the stirrups.
BA
RE: older concrete beam, bent bars
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: older concrete beam, bent bars
RE: older concrete beam, bent bars
I suspect that "3104" represents a #3 bar bent to a configuration represented in a chart somewhere on the drawings as "104", at least that is the way I have seen it on shop drawings in the past. I believe the stirrups are #3 bars, but I do not know why #2@12 ties have been added.
#2 are plain (undeformed) bars. I doubt that they would be much use as stirrups in a beam which required so much reinforcement as 7-#10.
BA
RE: older concrete beam, bent bars
RE: older concrete beam, bent bars
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: older concrete beam, bent bars
Bent bars were considered very efficient because they saved the development length for the top bars and the bottom bars and, as you noted, acted as shear reinforcement too. Material savings were offset by higher labor costs in placing the bent bars.
BA