Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
(OP)
I am trying to find an explanation to the ACI-02 (99 also) 7.6.6.2 that reads "Bundled bars shall be enclosed within stirrups or ties." Is this a compression provision to prevent the bars from buckling or a flexural provision to confine the concrete? I am designing a 7'0" deep pile cap with bundled bars and am trying to figure out the background for this to try to find the best solution for a pile cap.
Thanks
Thanks






RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
Please see FAQ731-376 for great suggestions on how to make the best use of Eng-Tips Fora.
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
RE: Bundled Bars ACI-02 7.6.6.2 Requirement to Enclose within stirrups
7.6.6.2 Bundled bars shall be enclosed within stirrups or ties.
R7.6.6 ---Bundled bars
Sentence 2. Bundled bars shall be tied, wired, or otherwise fastened together to ensure remaining in position whether vertical or horizontal.
It looks like there are two requirements. Both to tie the individual bundle tightly to act as a unit and maintain the geometry you intend. And also to enclose the bundled steel as you would typical long beam bars with stirrups or with ties as in a column.
As to the effect this tying may produce....
Look how the bridge columns failed in the Loma Prieta earthquake. The ties act like a cage to contain the concrete after failure to maintain a semblence of integrity after failure allowing for safety. The bars in compression act like independent columns. The ties then act to limit the unbraced length of the steel rebar columns. Even though the calculations don't reflect this, that is another intent. Beam bars in compression are similar. Only, the requirement is specific for bundled bars. The bundled bars have their advantages, but a disadvantage may be their greater tendency to buckle compared to individual concrete encased bars.