RC beam-column joint

[mojtaba]

hi,
RC beam-column joint contribution to interstory drift and total energy dissipated of the structural system?
as you know, a great amount of energy can be dissipated in hysteretic action of beam-column joints in MCE level of excitation?
how can we account this in our modeling?
tnx

[huffte]

Well, I would suggest a literature search if you don't trust the implicit hysteretic energy dissipation incorporated into a fiber-element-modeling scheme as that used with inelastic elements in SeismoStruct.

But it would seem to me that SeismoStruct analysis of RC frames with inelastic elements is a proven solution.

Have you investigated to Verification Manual, pages 91-95 (Verification Problem file Ch4-RC-03.spf) and pages 137-143 (specifically devoted to RC beam-column joints)? There is even a section for steel joints following that if you are interested.

If you have a unique situation and the discussions in the Verification Manual do not meet your needs, you may be able to combine elastic elements with inelastic links. Once again, a literature search on the modeling of RC beam-column joints might reveal which, if any, of the SeismoStruct inelastic links might be appropriate for hysteretic behavior of RC beam-column joints.

Best of luck mojtaba.

[mojtaba]

hi,
very tnx for your response,
as I know, if we want to model and then analyze a structure in which subjected to high inelastic range of response such as MCE level, we must consider the inelastic dissipated energy of beams, columns, and beam-columns joint, in a high inelastic range of structure response both beams and beam-column joint have nearly the same contributions to total energy dissipation of whole structural system. in this case, when we want to model a structure in a seismostruct framework, we don't model the nonlinear beam-column joint behavior, and subsequently we discard this source of energy dissipation mechanism beside the ability of it to the interstory drift contribution.
I've read your mentioned examples, but some tips exist in these examples, the 3D RC model is nearly in a linear range!
and the next case which is about how to model beam-column joint, is very energy taker task for modeling in such a macro modeling approach!
I've read in a PEER report that, Rayleigh damping ratio could be raised up to 12% when we wanna consider MCE level of earthquake instead of design level earthquake!
my opinion is this, IF we could raise up the amount of Rayleigh damping ratio instead of modeling the behavior of nonlinear dissipation mechanism of beam-column joints?
my English is not good, I apologize for it.
tnx a lot for your regards,

[huffte]

It is a very good question you pose, mojtaba. I think that your approach of increasing the effective damping to account for un-modeled hysteretic energy dissipation holds promise for sure. The question will be "How much additional damping can I count on for various levels of loading?"

This is a question which will likely require some research. There are various rules for evaluating effective damping from hysteretic behavior. If you can get your hands on any of these, it might be of help:

"Equivalent Damping in Support of Direct Displacement-Based Design", H. M. Dwairi; M. J. Kowalsky; J. M. Nau, Journal of Earthquake Engineering.

"Best-fit models for nonlinear seismic response of reinforced concrete frames", Lepage, Hoppera, Delgado, Dragovich, Engineering Structures, 2010.

"VISCOUS DAMPING IN SEISMIC DESIGN AND ANALYSIS", Priestley and Grant, Journal of Earthquake Engineering, Imperial College Press.

[mojtaba]

tnx a lot for your response, you have a very nice and positive personality.
I have not access to these papers, because our university does not access to these mentioned journals!
tnx for your helps, I'll try to find them.

[zsaeed]

i have modeled a circular column (fixed at base and cantilever at top)the column is subjected to constant gravitational load and Incremental lateral displacement..I am studying the Energy Dissipation. When i compared the results with experimental data , the energy dissipation at lower drift level is matching the experimental data but when at higher drift level my model is seismostruct shows very high dissipation of energy ..??
What could be the reason and how can i correct my model soo that i get close values of energy dissipation at higher drift levels as well ???

[ruipinho]

zsaeed,

Your query is not really related to this discussion topic (which is on beam-column joints), and I would thus suggest you to start a new discussion, if you wish to pursue this matter further.

I may nonetheless note that there could be several factors causing the numerical vs. experimental discrepancies that you observe, such as e.g. the fact that in your model you probably did not include shear deformations, bond slippage, rebar buckling, etc.

In addition, modelling choices on the cyclic parameters of the rebar steel model and on the number of beam element integration points, may also have an important impact.

I suggest you to carry out a careful literature search on numerical modelling of experimental results for further guidance (also because your question is not really related to SeismoStruct per se, but is rather of a more general earthquake engineering nature).

Rui

[Ralazem]

Was there a solution found for the original question of beam-column joint modelling?

[seismosoft]

Hello Ralazem,
You may find detailed examples of modeling joints in the Verification Report, pages 123-134. An automatic calculation of the energy dissipated is not carried out by the program, however you may calculate it as the area below the force-displacement curve.
Seismosoft Support

[1MS18CSE25]

Hai sir i am student working on RC beam column joint. I need to find hysteresis curve of RC beam column joint subjected to cyclic loading and also need to find energy dissipated you mentioned those page numbers related to energy dissipation where I can find those. Can you please send me link.