takeda

[felipehunggar]

How can i model a rc member with takeda modelling rules?, i use the links options but nothing happen.

[seismosoft]

Sorry, but we cannot really understand your question. Please read the Help System carefully and thoroughly, for instructions on how to use link elements, as well as their range of applications (e.g. in SeismoStruct, link elements have not really been devised to model RC members).

SeismoSoft Support

[rashid]

Hi All,

In Seismostruct, the two parameters for stiffness degradation in the Takeda model are outer and inner loop stiffness degradation (both for unloading stiffness ?). Standard literature, like the book Displacement-Based Seismic Design of Structures refers to controlling parameters of alpha and beta for the unloading and reloading stiffness; plus different values of alpha and beta for beams and columns. E.g., for columns alpha = 0.5 and beta = 0, for beams 0.3 & 0.6.

The explanation by Z.Gronti in a previous post Hysteretic Beahvior of Bridge Pier describes that both parameters in Seismostruct are for unloading stiffness.

Any recommendations for as how to account for the different behavior of beams and columns (in line with the book reference above) using the Takeda model definition in Seismostruct?

Regards,
Rashid

[seismosoft]

Hello rashid,

The help of the program contains exact definitions of the two parameters beta 0 and beta 1, and how these affect the stiffness degradation.
However, you are right that it has an error:
(i) beta 0 is for loading the on primary curve, whereas
(ii) beta 1 is for unloading and reloading in the inner cycles

Further, may also have a look at the following references that are mentioned in the bibliography of SeismoStruct's help:
Otani S. [1981] "Hysteresis Models of Reinforced Concrete for earthquake Response Analysis," Journal of Faculty of Engineering, University of Tokyo, Vol XXXVI, No2, 1981 pp 407-441
Takeda T., Sozen M.A., Nielsen N.N. [1970] "Reinforced concrete response to simulated earthquakes," Journal of Structural Division, ASCE, Vol. 96, No. ST12, pp. 2557-2573

Thanks for spotting that.
Seismosoft Support

[rashid]

Hi Seismosoft team,

Yes, I did see the help section. The explanation of Bo and B1 in the help section is the same as in the manual.

By saying that it has an error, do you mean that there is an error in the formulation/coding of the takeda model (error in Bo and B1 parameters) in Seismostruct or just a textual error in the manual and the help section ?

if Bo and B1 are already working as you explained in your message, then the implementation of the takeda model in Seismostruct is consistent with literature (and different values of Betas can be used for beams and columns as given in literature), and the error is just in the description of betas in the help/manual.

Thank you
Rashid

[z.gronti]

Dear Rashid,

The error is just in the explanation in the User Manual and Help System and not within the program.