Dear all,
I am teaching a course on manual limit analyses (yield line theories and Hillerborg's strip method) for reinforced concrete structures. I am not sure whether they are being used in practice (by design engineers) as nonlinear FEA seems to prevail.
Bests,
Phu
Concrete is not my area of work.
Yes. the concept of limit analysis in design still used in practice. In fact design and some FEA analysis of my field (Pressure vessel design and analysis according to ASME code) is done using limit analysis theory. ASME BPVC code as well as AISC steel construction manual code still uses limit load theory for design.
Yes they are still in use but give much less information than a step by step analysis with nonlinear FEM.
Hi Nikhil and Prof Schrefler,
Thanks for your replies.
Best regards,
Phu
I do not think that limit analysis ( for example , yield line theory) have much use in design offices these days. Every body uses softwares such as ETABs for reinforced concrete design. Yield line theory was actually one of my favorite topics when I took advanced concrete design in McGill university 24 years ago!
Gvozdev (1960 ) developed the modern concept of limit analysis as it applied to reinforced concrete structures; while K.W.Johansen(1930) used the upper bound techniques of limit analysis, and developed the Yield Line Theory for Slab Design for engineering practice.
This approach is now being extended and expanded to the design of concrete structures by Muttonietal.(1997) in a very practical manner.
Muttoni,A., Schwartz,J., Thurlimann,B., 1997. Design of Concrete Structures with Stress Fields. Birkhauser,Berlin.
Article Plasticity, limit analysis and structural design
Thanks a lot for your reply. The article of Chen was very nice.
Bests,
Phu
Hi Phu,
If required design information is the bearing capacity of structures, then you can use both limit analysis (LA) and nonlinear FEM but LA is more direct and efficient. This is why LA is used broadly for determination of bearing capacity of soil foundation.
For RC structure, LA is also useful for predicting the collapse pattern (yield lines in slabs), which is important to structural design. You can see M. Gilbert, L. He, C.C. Smith, C.V. Le. Automatic yield-line analysis of slabs using discontinuity layout optimization. Proceedings of the Royal Society A: Mathematical, Physical & Engineering Sciences, 470, 20140071, 2014 for more details.
Bests,
Canh
With my personal experience, like Canh's comments, I do feel LA is generally simpler which does not require a lot of input parameters like nonlinear FEM, on the other hand, commonly with more assumptions behind.
Limit analysis is a powerful design tool, however the application to RC structures, in particular to framed structures subject to seismic loads, requires a careful design of the section ductility to avoid damage.
Good question.. Please share me the best answer might you trust...
Regards…
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