ConfinedConcrete01 Material

This command is used to construct a ConfinedConcrete01 concrete material object.

uniaxialMaterial ConfinedConcrete01 $tag $secType $fpc $Ec (<-epscu $epscu> OR <-gamma $gamma>) (<-nu $nu> OR <-varub> OR <-varnoub>) $2L ($a) ($b) $phis $S $fyh $Es0 $haRatio $mu $phiLon <-internal $phisi $Si $fyhi $Es0i $haRatioi $mui> <-wrap $cover $Am $Sw $fuil $Es0w> <-gravel> <-silica> <-tol $tol> <-maxNumIter $maxNumIter> <-epscuLimit $epscuLimit> <-stRatio $stRatio>

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$tag	integer tag identifying material
$secType	tag for the transverse reinforcement configurations. See NOTES 1.
$fpc	nconfined cylindrical strength of concrete specimen.
$Ec	initial elastic modulus of unconfined concrete.
$epscu	confined concrete ultimate strain. See NOTES 2.
$gamma	value betwwen 0 and 1.0. See NOTES 2.
$nu	Poissons Ratio.
$2L	concrete core dimension of square section or diameter of concrete core section measured respect to the hoop center line.
$a	dimensions of multiple hoops for S4a section type measured respect to hoop center line.
$b	dimensions of multiple hoops for S4a and S4b section types measured respect to hoop center line.

NOTES:

1) The following section types are available:

S1	square section with S1 type of transverse reinforcement with or without external FRP wrapping;
S2	square section with S2 type of transverse reinforcement with or without external FRP wrapping;
S3	square section with S3 type of transverse reinforcement with or without external FRP wrapping;
S4a	square section with S4a type of transverse reinforcement with or without external FRP wrapping;
S4b	square section with S4b type of transverse reinforcement with or without external FRP wrapping;
S5	square section with S5 type of transverse reinforcement with or without external FRP wrapping;
C	circular section with or without external FRP wrapping;
R	rectangular section with or without external FRP wrapping.

2) The confined concrete ultimate strain is defined using -epscu or -gamma. If -gamma option, $gamma specified is the ratio of the strength corresponding to ultimate strain to the peak strength of the confined concrete stress-strain curve. If $gamma cannot be achieved in the range [0, $epscuLimit] then $epscuLimit (optional, default: 0.05) will be assumed as ultimate strain.

3) Poissons Ratio is specified by one of 3 methods: a)providing $nu using the -nu option. b)using the -varUB option in which Poisson’s ratio is defined as a function of axial strain by means of the expression proposed by Braga et al. (2006) with the upper bond equal to 0.5; or c) using the -varNoUB option in which case Poisson’s ratio is defined as a function of axial strain by means of the expression proposed by Braga et al. (2006) without any upper bond.

REFEERENCES:

1. Attard, M. M., Setunge, S., 1996. “Stress-strain relationship of confined and unconfined concrete”. Material Journal ACI, 93(5), 432-444
2. Braga, F., Gigliotti, R., Laterza, M., 2006. “Analytical stress-strain relationship for concrete confined by steel stirrups and/or FRP jackets”. Journal of Structural Engineering ASCE, 132(9), 1402-1416.
3. D’Amato M., February 2009. “Analytical models for non linear analysis of RC structures: confined concrete and bond-slips of longitudinal bars”. Doctoral Thesis. University of Basilicata, Potenza, Italy.
4. Karsan, I. D., Jirsa, J. O., 1969. “Behavior of concrete under compressive loadings”, Journal of Structural Division ASCE, 95(12), 2543-2563.

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Code Developed by: Michele D'Amato, University of Basilicata, Italy