topic Re: Immediate and long term deflection as per ACI code On Robot in Robot Structural Analysis Forum

Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:29:08 GMT

Hi All,

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:28:37 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Rafal.Gaweda — Wed, 24 May 2017 08:57:54 GMT

Hi @mustafahesenow

Regarding the Beam Parameter from member type definition

There is an issue in program code in this module. Need to be corrected by us.

Regarding Beam provided reinforcement :

Regarding 2 : send us model and your hand calcs

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:28:49 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Artur.Kosakowski — Mon, 29 May 2017 12:57:50 GMT

Hi @mustafahesenow

Could you explain how you exactly calculated the value indicated below?

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:27:17 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Artur.Kosakowski — Wed, 31 May 2017 09:59:43 GMT

Hi Mustafa,

I'm sorry for not being able to give you detailed reply faster but my knowledge of ACI is limited and I needed to reach out for assistance

1. My understanding is that you imported simple load cases but you used manually defined combinations in your hand calculations

2. My understanding is that you defined your own combination 1.0D + 0.5LL and you assumed is as long term (ACI: dead + sustained live load)

In Robot this is not possible to assign which combination is of which type.

3. In RSA sustained load is defined by its ratio to the entire load and it is only possible in the stand alone mode of RC Beam design. If imported from a model all live loads are treated as long term.

4. There is difference in the formulas for fr between RSA and your hand calculations

5. RSA calculates Ie from the middle of the beam rather than as the cleavage value which as far as I can read is 'considered satisfactory'.

6. For calculating cracked deflection Robot uses linear scaling u*E’I’/EI where E’I’ is the stiffness calculated with ACI formulas whwrwas you replaced EI with this value in the model and calculated the deflection running its static analysis. This may be difficult to be done for a large models and poses a question shall the change be done for the actually designed beam of all elements of a structure?

I hope this helps.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

P.S. I'll be travelling for the next 3 weeks so I have to postpone the analysis of your DAM topic till I'm back

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:26:56 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Rafal.Gaweda — Fri, 09 Jun 2017 10:14:56 GMT

Hi @mustafahesenow

Thank you for your reply

Answer for question 6

A lot of engineering books says that deflection could be calculated in this way:

u = alpha*M*L^2/EI

where: alpha coefficient depends to loads and supports, M – moment, L - span length, EI – stiffness of element.

It's mean that if we change only EI to E’I’ the finial deflection could be calculated as:

u’ = u*EI/E’I’

Our calculation based on this assumption. We take u and EI from static analysis and calculate new E’I’ based on code requirements. At the end, we multiply original deflection u by ratio EI/E'I'.

Calculation based on this assumption are enough accurate but not identical with static analysis with new E'I'.

The rest of your points are qualified by dev team as needed improvements or software issue.

I will inform you separately.

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:26:42 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Artur.Kosakowski — Wed, 21 Jun 2017 10:17:19 GMT

Hi @mustafahesenow

It is E*I with creep and cracks taken into account.

I hope this helps.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:26:27 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Artur.Kosakowski — Tue, 19 Dec 2017 13:54:22 GMT

Hi @mustafahesenow

It is in the hands of the RSA development team. I do understand that you would like to an update but all I can promise is that I will post it the moment i have any new information.

Re: Immediate and long term deflection as per ACI code On Robot

mustafahesenow — Wed, 18 Oct 2023 13:26:04 GMT

Re: Immediate and long term deflection as per ACI code On Robot

Anonymous — Mon, 09 Apr 2018 13:56:56 GMT

Hello @mustafahesenow, I tried to compare a same rc beam section in rsa with another program and I have the same problem because RSA is giving a much higher long deflections. Did you find out what is the problem ?

Thank You.

Re: Immediate and long term deflection as per ACI code On Robot

Anonymous — Sun, 15 Apr 2018 19:37:02 GMT

.. ...

Re: Immediate and long term deflection as per ACI code On Robot

saclovitzky — Mon, 16 Apr 2018 09:53:26 GMT

It is really a pain using "any" structural analysis/design package in designing reinforced concrete members.

It is always the issues of reinforcement areas and long term deflections.

Most of the time, I designed using other packages(specifically for designing rc members) for peace of mind.

Re: Immediate and long term deflection as per ACI code On Robot

Anonymous — Wed, 12 Feb 2020 01:44:28 GMT

Hi @mustafahesenow

Have you tested the version 2020 of robot towards these issues? Is there any update regarding the topic or the issues still stand unsolved? and I think If the design is performed using the BS-8110 same issues still appear, Is that correct?

Re: Immediate and long term deflection as per ACI code On Robot

Anonymous — Wed, 12 Feb 2020 02:15:04 GMT

Hi Mr. @Artur.Kosakowski

Kindly, Are the issues regarding this topic included in the hotfix for 2019 (see picture attached) or 2020 versions? Is there any update on the issues?

Re: Immediate and long term deflection as per ACI code On Robot

saclovitzky — Fri, 04 Feb 2022 13:36:34 GMT

Is this sorted already in RSAP 2022?