1 (edited by jpv 2016-12-14 12:17:09)

Topic: Automatic generation of concrete parameters

Hi,

The ATENA theory manual gives a table with formulas used for automatic generation of concrete constitutive model parameters for the SBETA model. In my case, I am using the Cementicious2 model in GiD (CC3DNonLinCementitious2). Are these formulas still applicable? In particular, I am looking at the formulas for Initial Elastic Modulus and Fracture Energy. When using the formulas specified, I am not getting the same values as the automatically generated ones. Can you please clarify? Also, what is the Initial Elastic modulus formula based on?

I am using GiD 11.0.8 and ATENA 5.3.2 Build 12360

Thanks

Re: Automatic generation of concrete parameters

Dear jpv,
first of all, we recommend updating to the current ATENA versiopn, 5.3.4j (you can get the installer through the ATENA Update Check utility or download it directly from our web).

You should be able to find at least some of the generation formulas used for the NLCem2 material model family in the ATENA Input File Format manual. Please note there are 2 ways of generating the concrete parameters in ATENA-GiD - based on the cube or cylinder compressive strength and based on the EC2 concrete class.

Regards.

Re: Automatic generation of concrete parameters

Thanks for your reply.

I generate the values based on cube/cylinder compressive strength. I found the formulas in the Input File Format manual and the formulas for Initial Elastic Modulus and Fracture Energy are the same as those given in the theory manual:

E = (6000-15.5 fcu) sqrt(fcu)
Gf = 0.000025 ft

However, when I generate the values for NLCem2 model, the generated values do not seem to correspond to these formulas. For example, if I specify a mean cubic strength of 32MPa and generate values according to a mean safety format, I get:

E = 30447 MPa
ft = 2.24 MPa
fc = -28.4 MPa
Gf = 133 N/m

Incidentally, the formulas given in the manual for ft and fc also do not seem to correspond to these values, but I use measured values for these.

Am I misinterpreting something?

Thanks

Re: Automatic generation of concrete parameters

A reference to the EC2 formulas:

http://books.google.gr/books?id=Dl36ncD … mp;f=false [^]

Re: Automatic generation of concrete parameters

Many thanks. The equation given in fib bulletin 1 for E agrees with the generated parameters, but not the one given for fracture energy. The theory manual gives a reference to VOS (1983), however I do not get the same values as the automatically generated ones. Can you please confirm which formula is used for fracture energy and a reference for it?

Thanks

Re: Automatic generation of concrete parameters

According to Zdenek Janda, who has implemented the corresponding dialogs in ATENA GiD, the formula for generating the mean fracture energy comes from the Fib Model Code 2010 (MC2010)

Gf = 73.0*fcm^0.18

where the mean cylinder strength is

fcm = fck+8

Re: Automatic generation of concrete parameters

Excellent, many thanks for your help