Concrete Design Twisting Moments (Wood - Armer)
Concrete Design Twisting Moments (Wood - Armer)
(OP)
Just a quick survey:
1) Do you, in your typical concrete design, consider twisting moments?
2) Have you ever considered twisting moments?
3) If you do consider twisting moments, what method do you use for design (Wood-Armer?)?
4) What region are you in (USA, NZ, Europe...)?
I think that the inclusion of twisting moments in design is not universal, and varies greatly by region, but it would be interesting to see everyone's experience with this.
1) Do you, in your typical concrete design, consider twisting moments?
2) Have you ever considered twisting moments?
3) If you do consider twisting moments, what method do you use for design (Wood-Armer?)?
4) What region are you in (USA, NZ, Europe...)?
I think that the inclusion of twisting moments in design is not universal, and varies greatly by region, but it would be interesting to see everyone's experience with this.






RE: Concrete Design Twisting Moments (Wood - Armer)
2) Yes.
3) Wood-Armer
4) Canada
It sort of depends on what you mean by "consider". In an elastic, two way FEM analysis, twisting moments will almost always be generated. To disregard those moments altogether is to produce a flawed design, without question. It doesn't make sense to reinforce for the twisting moment explicitly however. You tend to wind up with light amounts of reinforcing in places where reinforcing looks odd. Dealing with the twisting by converting it to conventional flexure somehow (Wood-Armer) is better.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Concrete Design Twisting Moments (Wood - Armer)
This question gets asked alot. Mxy in FEM analysis needs to be accounted for in design.
Nobody should be using Mxx and Myy as there orthogonal strip design actions and ignoring Mxy.
RE: Concrete Design Twisting Moments (Wood - Armer)
http://www.structural-safety.org/media/364894/cros...
Regards Jake
RE: Concrete Design Twisting Moments (Wood - Armer)
2) Yes.
3) Wood-Armer
4) USA
Maine EIT, Civil/Structural.
RE: Concrete Design Twisting Moments (Wood - Armer)
2) Yes
3) Wood-Armer
4) USA
I agree that the twisting moments are an integral part of achieving equilibrium and that they should be included in design. It's not the standard practice at my current company though. Designs are primarily for crack control with ACI 350, and that adds quite a bit of conservatism. The majority of engineers in my office have actually never heard of Wood-Armer.
RE: Concrete Design Twisting Moments (Wood - Armer)
RE: Concrete Design Twisting Moments (Wood - Armer)
Maine EIT, Civil/Structural.
RE: Concrete Design Twisting Moments (Wood - Armer)
And Advance Design America software does it for you
RE: Concrete Design Twisting Moments (Wood - Armer)
But I add that A23.3-2004 Concrete code REQUIRED to consider twisting moment using Wood-Amer Method for elastic plate method (FEM). See Clause 13.6.4
RE: Concrete Design Twisting Moments (Wood - Armer)
US Design software tends to ignore it. European always allows for it. e.g. RAM Concept ignores it by default but they added an option for the user to include it in design a few years ago. Sofistik, Oasys, Cedrus and Orion from Europe all allow for it automatically.
Some design codes specifically say to include it (Canadian, NZ), while other does not see the need to define it specifically and instead insist that the design satisfy equilibrium. To satisfy equilibrium, you must include all actions from the analysis and Mxy must therefore be included in design.
I did an interesting comparison with a square grid once between RAPT (2D frame) and Orion (FEM) and the total panel moments were exactly the same as long as Orion included the effects of the Mxy moments in the design moments (which it does automatically).
The actual effect will vary depending on the coarseness of the mesh and the symmetry of the structure and the location in the structure.
RE: Concrete Design Twisting Moments (Wood - Armer)
RE: Concrete Design Twisting Moments (Wood - Armer)
2. Yes
3. Wood-Armer (turned on in Ram Concept Strip design preferences)
4. U.S.A/India