Required reinforcement module

[sanjuan100]

Hello,

I'm using RSA for designing a relatively simple RC structure. It's a two storey building, 20x12m aprox. in plan. RC columns and RC downstand beams. The model has seismic loads that have been defined using modal analysis and spectral case for the site where it's located.

After running the analysis and doing the verification of checking forces and deflections seem sensible in the "Results" window I have continue onto finding the required reinfoicement for beams and columns.

This is where I have the issue. I do not understand how Robot calculates required reinforcement for elements. Would it be possible to know how this module works?

One aspect in particular I find especially surprising below:

* Selecting the combinations for designing the elements (I'm using code comb.) it seems the reinforcement provided by the programme is a lot bigger when you select the three of them (ULS, SLS, ALS) than when you select each one independently (or ULS or SLS or ALS) i.e. I was expecting finding an envelope when selecting the three of them but not getting a different and more onerous results.

I have the model uploaded in dropbox but need to send an email to share it. Can anyone let me know what's the best way (or just one) to share it (it's 5-6 Mb)?

I'll appreciate any help.

Thank you.

[Rafal.Gaweda]

Example results for beam 29

[sanjuan100]

Hello Rafal,

Thanks for you reply.

Please see attached what I get looking at column reinforcement. What I don't understand that much more reinforcement selecting all types of combinations (?)

Regards,

sanjuan100

[sanjuan100]

... last attachment with all combinations.

[Rafal.Gaweda]

In general for each calcaulations ULS state should  be used.

SLS and ALS design enlarges already calculated reinforcement in ULS calculations

We are checking why ALS (due to seismic) and SLS (?) add so much reinforcement.

I will update you asap.

[sanjuan100]

Hello Rafal,

Is there any development on this question re required reinforcement? Any ideas why Robot gives higher values (perhaps unexpected) of required reinforcement when selecting the three combinations (ULS, SLS, ACC)?

Apologies if I'm insisting on this, I'm new to the forum and not sure how quickly doubts get resolved or whether they do at all in some cases.

On a different question but related to this, what are the differences between the "required reinforcement" tool and "provided reinforcement" tool?

Kind regards,

Alvaro

[Rafal.Gaweda]

Alvaro

Is there any development on this question re required reinforcement? Any ideas why Robot gives higher values (perhaps unexpected) of required reinforcement when selecting the three combinations (ULS, SLS, ACC)?

Apologies if I'm insisting on this, I'm new to the forum and not sure how quickly doubts get resolved or whether they do at all in some cases.

We are checking why ALS (due to seismic) and SLS (?) add so much reinforcement.

I will update you asap.

On a different question but related to this, what are the differences between the "required reinforcement" tool and "provided reinforcement" tool?

In short : theroretical reinforcement gives you as  results required area of steel (values) ; provided  - generates real bars also.

[sanjuan100]

Rafal,

It's been almost two weeks since I last posted in this forum. Could you please let me know if there is any progress on this matter?

One question that still puzzles me is why reinforcement requeriments enhance when you select all types of combs? (i.e. in the pictures of my earlier post reinforcement req along b ULS 2f20, SLS 2f20 & ALS 3f20, but when you select all three ULS, SLS & ALS together rft req is 9f20)

In this case, I was expecting a result of 3f20 (the biggest of all three independently) not 9f20.

I would really appreciate if you could clarify the question above as well as more information of how the required reinforcement module for RC elements (columns in particular) works.

Thanks in advance for your help.

Regards,

sanjuan100

[Artur.Kosakowski]

This situation is under the investigation by the development team but my assumption is that the reinforcement distribution algorithm used in this module may not be optimal for columns which are under load cases that generate almost uniform bending with smaller values of bending moments (ULS) together with bi-directional bending with large values of bending (ACC) resulting in not optimal distribution of reinforcement (bars grouped along two opposite sides that are not effective for bending in the perpendicular direction). Please note that I may be wrong in my assumption and we need to wait for the development team fidings.

For now I would suggest that you use the RC Column Provided reinforcement module instead.

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