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Rafal.Gaweda
Posts: 4,991
Registered: ‎04-26-2010

Re: Crack width calculation for reinforced concrete

12-22-2011 06:46 AM in reply to: gn

gn wrote:

I have ran the reinforcement design in robot, but would like to extract the design data from robot and use it to produce a detailed crack width calculation, I will complete this on a excel sheet we use in the office.

 

My intension is to use the various functions in the Robot addon, spreadsheet calculator (SC) to take the relavent data from my robot model and use it in this spread sheet.

 

I recommend ordinary Excell + Robot API

 

 

What I was looking at doing was trying to extract things like reinforcemnt diameters, fyk for steel etc directly from the robot model and into my crack width spreadsheet so that when the design was completed on Robot it could be cross checked and a detailed design calc could be produced also. Do you have a copy of the SDK for robot so make it easier for us to extract the relavent data.

 

SDK installation on your DVD. If not, SDK in unpacked version here:

 

http://www.megaupload.com/?d=XM699PPN

 

 

I note there has been a request for a "RC slab deflections in Robot according to BS 8110" but according to EC 2 could you provide that as I wish to update our system here to EC 2 and that would help in the transition.  

 

In different way: code paragraphs, formulas, tables not implemented in RC EC2 design:

 

2.5 Design assisted by testing

2.7 Requirements for fastenings

3.1.5 Stress-strain relation for non-linear structural analysis

3.1.9 Confined concrete

3.2.6 Fatigue

3.3 Prestressing steel

3.4 Prestressing devices

5.6 Plastic analysis

5.7 Non-linear analysis

5.8.3 Simplified criteria for second order effects

5.8.6 General method

5.9 Lateral instability of slender beams

5.10 Prestressed members and structures

6.2.5 Shear at the interface between concretes cast at different times

6.3.3 Warping torsion

6.5 Design with strut and tie models

6.7 Partially loaded areas

8.7.3 Lap length

8.7.4 Transverse reinforcement in the lap zone

8.9 Bundled bars

8.10 Prestressing tendons

9.6 Walls

9.7 Deep beams

9.8.1 Pile caps

9.9 Regions with discontinuity in geometry or action

9.10 Tying systems

10. Additional rules for precast concrete elements and structures

11. Lightweight aggregated concrete structures

12. Plain and lightly reinforced concrete structures

Annexes:

F (Informative) Reinforcement expressions for in-plane stress conditions

G.2 (Informative) Soil structure interaction

H (Informative) Global second order effects in structures

I (Informative) Analysis of flat slabs and shear walls
J (Informative) Examples of regions with discontinuity in geometry or action

 

Limitations:

- theoretical RC calculations :
  calculation model of concrete - no choice, always a rectangle
  calculation model of steel - no choice, always perfectly elastic-plastic (flat plastic branch)
 provided reinforcement for slabs
  Punching - forces applied within the penetration zone not considered, except for concentrated forces aplied on the same node as the support (by analogy to other standards)
  Punching - only for the dimensioning of ULS (by analogy to other standards)
  Punching - dimensioning is carried out for only one combination, this occurs for which the largest axial force, although in the calculation comes to interaction with the bending moments (similarly to other standards)
  Punching - dimensioning slabs or columns with heads - lack of double bar-critical circuits (by analogy to other standards)
  [9.10] Systems binding and wreaths

         -  



Rafal Gaweda
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Distinguished Contributor
mirko.jurcevic
Posts: 198
Registered: ‎01-12-2013

Re: Crack width calculation for reinforced concrete

04-30-2013 06:25 AM in reply to: Rafal.Gaweda

I have few questions:

 

IN CALCULATION NOTE FOR RC BEAM, WHAT IS WHAT:

2.5.5 Deflection and cracking

wt(QP) Total due to quasi-permanent combination - LONGTERM DEFLECTION IN  t=∞ ?
Dwt(QP) Deflection increment from the quasi-permanent load combination after erecting a structure. INSTANT DEFLECTION IN t=0 ?

wk - width of perpendicular cracks - WHICH CRACKS, LONGTERM (t=∞) OR SHORTTERM (t=0)?

 

Which code combination does it uses for crack width calculation? SLS -  QP?

INTELIKA

Mirko Jurcevic M.Eng.
INTELIKA d.o.o.
www.intelika.hr
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Product Support
Rafal.Gaweda
Posts: 4,991
Registered: ‎04-26-2010

Re: Crack width calculation for reinforced concrete

05-06-2013 01:19 AM in reply to: mirko.jurcevic

Ad1 Yes,„Long term deflection (t=inf) due to quasi-permanent combination”

 

Ad2 Deflection as described :

EN 1992-1-1:2004 7.4.1

(5) Deflections that could damage adjacent parts of the structure should be limited. For the

deflection after construction, span/500 is normally an appropriate limit for quasi-permanent

loads. Other limits may be considered, depending on the sensitivity of adjacent parts.

(Long term deflection increase depends on QPR loads after building errection)

 

 

Ad3 long term cracks:  

EN 1992-1-1:2004 7.3.1

(5) A limiting calculated crack width, wmax

(…)

it may be assumed that limiting the calculated

crack widths to the values of wmax given in Table 7.1N, under the quasi-permanent combination of loads,



Rafal Gaweda
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Distinguished Contributor
mirko.jurcevic
Posts: 198
Registered: ‎01-12-2013

Re: Crack width calculation for reinforced concrete

05-06-2013 03:08 AM in reply to: Rafal.Gaweda

Thank you Rafal. I just wanted to be sure.


Still, it's to bad that we cannot control what's Robot doing, it would be nice that we can check what value Robot uses in each variable, either that or good verification manual so we don't have to ask this kind of questions. This way, we have to 'trust' Robot uses right values and right formulaes.
I have manually calculated an example of T-beam, and results are different from those Robot gives me:
ROBOT:
{
  wt(QP)=23,70mm
  Dwt(QP)=15,33mm
  wk=0,25mm
}
Manual:
{
  wt(QP)=27,9mm
  Dwt(QP)=19,0mm
  wk=0,22mm
}
As you can see, differences are from 13% to 24%.

 

I already wrote on other forum thread that I can't find verification manual for v2014.

INTELIKA

Mirko Jurcevic M.Eng.
INTELIKA d.o.o.
www.intelika.hr
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Product Support
Rafal.Gaweda
Posts: 4,991
Registered: ‎04-26-2010

Re: Crack width calculation for reinforced concrete

05-06-2013 03:10 AM in reply to: mirko.jurcevic

File please + scan of your manual calcs please.



Rafal Gaweda
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Distinguished Contributor
mirko.jurcevic
Posts: 198
Registered: ‎01-12-2013

Re: Crack width calculation for reinforced concrete

05-06-2013 03:48 AM in reply to: Rafal.Gaweda

I've sent you private message.

INTELIKA

Mirko Jurcevic M.Eng.
INTELIKA d.o.o.
www.intelika.hr
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Product Support
Rafal.Gaweda
Posts: 4,991
Registered: ‎04-26-2010

Re: Crack width calculation for reinforced concrete

05-21-2013 07:06 AM in reply to: mirko.jurcevic

Mirko,

 

First part of answer - cracks (basing on model and documents you sent me):

 

In fact rebars are loacated 2mm beloww the level you assumed:

 

posz.jpg

 

but it does not give significant difference.

 

According to your book example explanations, our understanding of Slovenian language + googletranslate...

 

we see this

 

srmax.jpg

 

we understood that c is calulated as     d  -   1/2*rebar_diam    -   transversal_rebar_diam

so it is cover to transversal rebar

 

But according to EC2 7.11

 

srmaxec2.jpg

 

so this difference gives srmax 209mm instead of 190mm and thus 0.25mm cracks instead of 0.22mm.



Rafal Gaweda
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Active Contributor
kariz1384
Posts: 26
Registered: ‎05-03-2013

Re: Crack width calculation for reinforced concrete

05-21-2013 11:29 AM in reply to: gn

hi,

Which version of MS Office do you guys use? I have tried with 2007, but without any luck. Do I have to enable or disable something to get spread sheet working.

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Distinguished Contributor
mirko.jurcevic
Posts: 198
Registered: ‎01-12-2013

Re: Crack width calculation for reinforced concrete

05-21-2013 11:24 PM in reply to: Rafal.Gaweda

..it's Croatian language, not Slovenian. They are similar but very different. :smileywink:

 

we understood that c is calulated as     d  -   1/2*rebar_diam    -   transversal_rebar_diam

so it is cover to transversal rebar

That's correct.

 

But according to EC2 7.11....


Yes, I've cheked in my Croatian version of EC2, that correct too. I didn't pay attention to it before.

Usually, when we calculate reinforced concrete, and someone says cover "c", we all assume that's distance from face of concrete to the first reinforcement bar.

This may be an error. I will check this with the author of the book.

 

Thank you very much Rafal !

Hope to see the rest of it soon.

 

 

INTELIKA

Mirko Jurcevic M.Eng.
INTELIKA d.o.o.
www.intelika.hr
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Distinguished Contributor
mirko.jurcevic
Posts: 198
Registered: ‎01-12-2013

Re: Crack width calculation for reinforced concrete

05-21-2013 11:28 PM in reply to: kariz1384

If you are referring to Robot extension Spreadsheet caculator then it is assumed that you must enable macros to make it work.

Look here:

http://grok.lsu.edu/article.aspx?articleid=6144

 

I didn't use those spreadsheets much, though.

INTELIKA

Mirko Jurcevic M.Eng.
INTELIKA d.o.o.
www.intelika.hr
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