Tri31

This command is used to construct a constant strain triangular element (Tri31) which uses three nodes and one integration points. 

element tri31 $eleTag $iNode $jNode $kNode $thick $type
        $matTag <$pressure $rho $b1 $b2>
eleTag

unique element object tag

iNode jNode kNode

three nodes defining element boundaries, input in counter-clockwise order around the element.

thick

element thickness

type

string representing material behavior. The type parameter can be either “PlaneStrain” or “PlaneStress.”

matTag

tag of nDMaterial

pressure

surface pressure (optional, default = 0.0)

rho

element mass density (per unit volume) from which a lumped element mass matrix is computed (optional, default=0.0; if rho=0.0, then materials are queried for mass density)

b1 b2

constant body forces defined in the domain (optional, default=0.0)

NOTE:

  1. Consistent nodal loads are computed from the pressure and body forces.
  2. The valid queries to a Tri31 element when creating an ElementRecorder object are ‘forces’, ‘stresses,’ and ‘material $matNum matArg1 matArg2 …’ Where $matNum refers to the material object at the integration point corresponding to the node numbers in the domain.

Code Developed by: Roozbeh G. Mikola, UC Berkeley and N. Sitar, UC Berkeley