Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
(OP)
Can anyone direct me to a design example for the design of bent longitudinal reinforcment to be used as shear reinforcement?
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Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
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RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
Historically, old structures that used this bent up bar system didn't really depend on this bar all that much for shear. Either side of the diagonal portion of the bar the Vs goes to zero unless there are additionally spaced stirrups.
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
I am in the US and was stating the historical case based on the fact that here these types of bent bars are not specified much (if at all) anymore. Much to much labor intensive.
It's interesting to know that in Europe its still utilized. Am I right, though, in stating that only the small length of beam located in the range of the diagonal portion is helped in shear? And that either side of the diagonal portion is not helped by these bars?
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
As posted by xxpegasus11; "Stirrups would still be required throughout as there is a limit for inclined bars to provide up to half of the shear resistance required."
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
Guess its a matter of economy and whats practical. You wouldnt normally find inclined bars in simple rc beams but still there on deeper beams, heavy shear etc.
The maximum effect would be taken over a greater length than just the diagonal portion though. The bars are assumed to act as tension members of a lattice girder, with concrete providing the compression struts. So, in the simplest case say, of one inclined bar at 45deg, the top "bend" would be 0.41d from support,plus 1.41d being the distance of the imaginary V formed by the bar and the concrete , so in effect the total length for shear resistance provided would be 1.82d
Sorry, if it sounds confusing - hard to describe without a sketch.
Brian,
The excess shear over the concrete shear resistance can be provided with stirrups or a combination of stirrups and inclined bars. Your code I expect has a limit on how much can be taken by inclined bars. In the UK it would be 50% if thats any help.
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)
RE: Bent longintudinal shear reinforcement , (ACI 11.5.4.2)