×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

bi-axial shear in concrete

bi-axial shear in concrete

bi-axial shear in concrete

(OP)
I would like to know when I have to consider bi-axial shear; is it when Vux > 0,2Vuy (20%) ?. And is it correct to use: sqrt ((Vux)^2+(Vuy)^2)  <  2.65*sqrt(f'c) for shear provided by the concrete.

Thanks

RE: bi-axial shear in concrete


Dear Hyper

Where abouts are you currently situated

I am From Christchurch New Zealand

There is no such thing as an international code but I may be able to help

Let me know details

Regards

Mark

RE: bi-axial shear in concrete

(OP)
Hi Mark
the ideas comes from a book that considers an analogy with torsion to solve biaxial shear; where instead of using axial shear and 0.53*sqrt(f'c) uses 2.65*sqrt(f'c). but using the two shear forces. If we have Vux=3, Vuy=4 then Vu=5; if the concrete resists 4.5 then we cannot do an axial design; therefore the shear resistance of the concrete should not be the same at some percentage of the two (Vux and Vuy).
Regards.

RE: bi-axial shear in concrete

Hyper,

Concrete theory is not one of my strong suits, but for a practical solution, this is what I would do:

I assume you are designing a concrete column or isolated beam loaded on both axes, and that the shear you are refering to is "diagonal tension" as opposed to "pure shear."   In either case a good design would include longitudinal bars and ties.

The shear resistance of a concrete member is provided by the contribution of the concrete (Vc) and the contribution of the ties (Vs).  

How the concrete contribute to the biaxial shear is not clear.   I have looked for some reference to biaxial shear with no success.    If we take the resultant of both shear as squareroot of (Vux^2 + Vuy^2), this resultant would be acting at an angle to the main axes of the section, and that would complicate the analysis.     I would use, instead, a reduced concrete strength for each shear (Vcx and Vcy), such that Vcx = Vc*Vux/(Vux+Vuy),  and  Vcy = Vc*Vuy/(Vux+Vuy).      Notice that this would make Vcx + Vcy = Vc.     

I would design and detail the ties independently for each shear (Vux and Vuy).   If there is only one tie around the section, each tie could resists both shears, since only the two sides of the loop parallel to the load are stressed.

This approach would produce a slightly conservative design.


Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources