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## Robot Structural Analysis

Active Member
Posts: 7
Registered: ‎12-07-2011

# Crack width calculation for reinforced concrete

1506 Views, 25 Replies
12-21-2011 02:38 AM

Guy's

I am trying to get detailed calculations for crack widths in RSA, although I input limiting crack widths in the reinforcement calculations, I wondered if there was a detailed output given by robot without going into the spreadsheet calculator extension.

Further I have veiwed the 2 youtube tutorials on the spreadsheet calculator, and was wondering if there are any further tutorials or learning material for it.

Thanks again.

Gavin

Product Support
Posts: 4,188
Registered: ‎04-26-2010

# Re: Crack width calculation for reinforced concrete

12-21-2011 03:07 AM in reply to: gn

Which module we are talking about?

Which code?

Rafal Gaweda
Active Member
Posts: 7
Registered: ‎12-07-2011

# Re: Crack width calculation for reinforced concrete

12-21-2011 03:22 AM in reply to: Rafal.Gaweda

I shall  explain a bit better,

I am using robot structural analysis 2011 and trying to complete SLS calculation for a concrete structure, in this case I have a test model in which I have designed the reinforcement asigned a limiting crack width of 0.2mm but would like to see the crack width calculations from robot.

The code we are using is BS 8110 but ussually our carck width calculations conform to BS 5400.

Best Regards

Gavin

Product Support
Posts: 4,188
Registered: ‎04-26-2010

# Re: Crack width calculation for reinforced concrete

12-21-2011 03:32 AM in reply to: gn

RC slab deflections in Robot according to BS 8110.

Concrete creeping coefficient (creep coefficient) fi - specified by the
user or calculated automatically (taking into account effective section
thickness) according to Figure 7.1 in BS 8110
coefficient (Figure 7.1 in BS 8110) and modulus of elasticity of
the concrete (part 7.2 of BS 8110)
Relative environment humidity - used in calculations of creep
coefficient (Figure 7.1 in BS 8110)
Part of loads: variable long-term - starting from v.14.5 it means what part of live load can
be treated as long-term load (the rest is treated as short-term). This
coefficient equal to 1 means that all dead and live loads are long-term
Up to v.14.0 above coefficient related not only to live loads but to all

Deflections are calculated using point 3.6 of code and Figure 3.1. Moreover some methods
described in Chapter 5 of the following handbook are used: F.K.Kong, R.H.Evans,"Reinforced
and Prestressed Concrete", 3rd edition, Van Nostrand Reinhold (UK) Co. Ltd. 1987

For short-term loads the short-term modulus of elasticity of the
concrete Ec is used when calculating deflections (in practice Ec28).
For long-term loads the effective modulus of elasticity of the concrete
Eff=Ec/(1+fi) is used when calculating deflections.
Total deflection is calculated as the sum of above ones.

Parts 7.4 of BS 8110 is not taken into account.

Rafal Gaweda
Active Member
Posts: 7
Registered: ‎12-07-2011

# Re: Crack width calculation for reinforced concrete

12-21-2011 03:44 AM in reply to: Rafal.Gaweda

Thank you for this information Rafal thats great, does robot output detailed calcs of crack width, and if so how is this done?

Product Support
Posts: 4,188
Registered: ‎04-26-2010

# Re: Crack width calculation for reinforced concrete

12-21-2011 05:22 AM in reply to: gn

No, there is no detail calcs  in notes of rc modules.

There are all final results there

Rafal Gaweda
Mentor
Posts: 183
Registered: ‎12-06-2011

# Re: Crack width calculation for reinforced concrete

12-22-2011 12:09 AM in reply to: Rafal.Gaweda

RC slab deflections in Robot according to BS 8110.

Concrete creeping coefficient (creep coefficient) fi - specified by the
user or calculated automatically (taking into account effective section
thickness) according to Figure 7.1 in BS 8110
coefficient (Figure 7.1 in BS 8110) and modulus of elasticity of
the concrete (part 7.2 of BS 8110)
Relative environment humidity - used in calculations of creep
coefficient (Figure 7.1 in BS 8110)
Part of loads: variable long-term - starting from v.14.5 it means what part of live load can
be treated as long-term load (the rest is treated as short-term). This
coefficient equal to 1 means that all dead and live loads are long-term
Up to v.14.0 above coefficient related not only to live loads but to all

Deflections are calculated using point 3.6 of code and Figure 3.1. Moreover some methods
described in Chapter 5 of the following handbook are used: F.K.Kong, R.H.Evans,"Reinforced
and Prestressed Concrete", 3rd edition, Van Nostrand Reinhold (UK) Co. Ltd. 1987

For short-term loads the short-term modulus of elasticity of the
concrete Ec is used when calculating deflections (in practice Ec28).
For long-term loads the effective modulus of elasticity of the concrete
Eff=Ec/(1+fi) is used when calculating deflections.
Total deflection is calculated as the sum of above ones.

Parts 7.4 of BS 8110 is not taken into account.

I like this ... Can you give me the same breakdown for EC2?

Active Member
Posts: 7
Registered: ‎12-07-2011

# Re: Crack width calculation for reinforced concrete

12-22-2011 01:16 AM in reply to: gn

Thank you Rafal for your help,

I will use the spread sheet calculator to bring out the results, have you any additional tutorial material on the spreadsheet calculator?

If so could you point me in the right direction.

Best Regards

Gavin

Product Support
Posts: 4,188
Registered: ‎04-26-2010

# Re: Crack width calculation for reinforced concrete

12-22-2011 01:42 AM in reply to: gn

I will use the spread sheet calculator to bring out the results, have you any additional tutorial material on the spreadsheet calculator?

spread sheet calculator to bring out the results? What do you mean by that ?

Rafal Gaweda
Active Member
Posts: 7
Registered: ‎12-07-2011

# Re: Crack width calculation for reinforced concrete

12-22-2011 03:26 AM in reply to: Rafal.Gaweda

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.

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.

We have a copy Kong and Evans, which I have now researched and will use this as the basis fo my detailed calculation in SC.

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.

Once again thank you for all the assistance it is a great help.

Best regards

Gavin