Concrete01

Concrete with zero tensile strength: a parabolic rise to the peak, a linear descent to a crushing plateau, and nothing at all in tension.

🔧 Grasshopper component

Concrete01 (Alpaca4d) — Alpaca4d ▸ MomentCurvature_βeta, nickname Concrete

Inputs

Defaults are C25/30.

MatNameMaterial NameTextC25/30Label for the material.

fcoNumber-25000Compressive strength, in kN/m².

Negative.

fcuNumber-20000Crushing strength at EpsilonCu — what is left past the peak.

Negative, and no larger in magnitude than fco.

EpsilonCoNumber-0.002Strain at fco. Negative, dimensionless.

EpsilonCuNumber-0.0035Strain at fcu. Negative, dimensionless.

MinMaxBooleanfalseWrap the material so a fibre fails once its strain leaves the range between EpsilonCu and zero.

Outputs

MaterialMaterialUniaxial material, for a Patch, Layer or Fiber Point.

Warning

Every stress and strain here is negative. Compression negative is the OpenSees convention for Concrete01, and entering 25000 instead of -25000 gives a section that behaves backwards without any error.

📈 When to use it

Use it when

• You are modelling the concrete part of a reinforced-concrete section.
• You want the cracking and the crushing to come out of the analysis rather than be assumed.

Do not use it when

• You need tensile strength — Concrete01 has none, which is conservative for flexure but wrong for anything relying on tension stiffening.
• You need confinement modelled explicitly. You can approximate it by giving the core patch a higher fcu and a larger EpsilonCu than the cover.

💡 MinMax

With MinMax on, a fibre that strains past EpsilonCu stops carrying stress permanently, which is what physically happens when concrete crushes. Off, the material follows its curve indefinitely and the moment–curvature curve keeps a residual capacity it should not have.

Turn it on for anything you intend to read a failure point off.

🔗 Relation to OpenSees

uniaxialMaterial Concrete01 $matTag $fpc $epsc0 $fpcu $epscU
uniaxialMaterial MinMax     $wrapTag $matTag -min $minStrain -max $maxStrain

The MinMax wrapper is written only when the MinMax input is true, and the fibres then reference the wrapper's tag.