Strut-and-Tie Models
Strut-and-Tie Models
(OP)
I studied the strut-and-tie model recently this semester using it for deep beams and corbel/bracket design as well as seismic design of joints in special moment frames after a method in a book by Paulay and Priestly (spelling?). The method seems pretty logical but also takes quite a bit of work to really do a good job and do it right. How many of you out there use strut-and-tie models in practice? Do you find you get better designs, i.e. more economical use of materials over more tradional methods? What are your opinions on the design code itself? Do you have any advice for those of us who would like to become more proficient at this, such as pitfalls or areas that aren't very clear ro codified well? At my company we don't encounter situations much that would require us to use strut-and-tie methods so I have no practical experience or even opinions on their use and how well they perform outside of academia. I appreciate any responses,





RE: Strut-and-Tie Models
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RE: Strut-and-Tie Models
Anyone? Bueller? Bueller?
RE: Strut-and-Tie Models
I'm trying to design a deep beam and the only real option given in the code is Strut-and-Tie. I couldn't find a good example that was easy to impliment in the time I have to work on this, so it's now become a "in my spare time" project to learn STM.
I ended up using the method given by Park and Pauley (ACI reference 10.22) since it was the method most fimiliar to one of the members of my firm. Nobody hear uses STM or even knows were to start.
RE: Strut-and-Tie Models
If your bound and determined to do strut and tie, try the PCA "Notes on 318-02..", chapter 17.
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Dan
www.dtware.com
RE: Strut-and-Tie Models
ACI does have a really great publication SP208, Strut and Tie models which is nothing but practical examples. If you want to see examples and how they are worked, this is the book.
I do not agree that it seems cumbersome at first. BUt if you see practical examples and work them a little bit, they do get easier. It will be a learning curve for all structural engineers.
RE: Strut-and-Tie Models
I designed a lot of heavily-loaded and complicated concrete, all buildings, before I came back to school. Our firm (a pretty large and very reputable one) never, ever, ever used STM for anything.
Last semester, I had advanced concrete and we spent a good while on STM and I found it to be just about worthless from my perspective. I think it's really handy and useful for big-time bridge people, but I doubt that many building designers use it.
Structural engineer is a tremendously wide and deep discipline with many other more useful topics to study, in my opinion. Examples would be computer programming, technical writing, publishing a paper, basket weaving, etc.
DBD
RE: Strut-and-Tie Models
There's nothing difficult about it other than, perhaps, that it's a new concept to many of you.
RE: Strut-and-Tie Models
Does ACI 318-05 elaborate any more on the topic than 02 does?
RE: Strut-and-Tie Models
RE: Strut-and-Tie Models
Commentary states that for a B region, to follw traditional shear design procedures from 11.1 through 11.5. However, if the entire beam is such that No B regions exist, the entire element is a D region, how does one handle shear design? Is consideration of shear inherent in the design of struts and ties?
I'll take any responses at boydzander@aol.com if anyone is interested in responding that way.
Thanks
Boyd
RE: Strut-and-Tie Models
i find the discussion on this topic very interesting. i have no idea what the codes referenced are or of the design procedures you refer to - but i do use the 'strut & tie' method fairly regularly in concrete pile cap design (we/i call it the 'truss analogy' by the way)... before i waffle on, i'd like to make sure we're talking about the same things so will someone please answer the following before i write further on this topic as i might be completely mistaken:
are your (American) designs (of pile caps and deep beams) primarily driven by seismic requirements? Because mine isn't. We did a bit of earthquake stuff at college but generally there is no requirement to cater for such scenarios (with the exception of some more sensitive structures) in Britain. (Yet!)
if the forces you design for are primarily gravity induced, then maybe we can expand a little on this topic and share some trans-atlantic knowledge?!?!?!?!?! :+)
RE: Strut-and-Tie Models
I started this thread primarily to evaluate different opinions using the S&T method, or truss analogy, versus other code prescribed methods. I was looking for input from those who have used either or both methods just for ease of use, is it really better, is S&T more difficult/time consuming, and so on. I myself have very little real world experience with strut-and-tie modeling.
Please feel free to discuss S&T models, and other concrete deep-beam design models with which you are familiar, and compare and contrast them.