3.1.10.40. Tri31 Element

This command constructs a constant-strain triangular element using three nodes and one integration point. The command name in OpenSees is Tri31 or tri31. Use with -ndm 2 -ndf 2.

element Tri31 $eleTag $iNode $jNode $kNode $thick $type $matTag <$pressure $rho $b1 $b2>

Argument	Type	Description
$eleTag	integer	unique element tag
$iNode $jNode $kNode	integer	three nodes in counter-clockwise order
$thick	float	element thickness
$type	string	material formulation: PlaneStrain or PlaneStress
$matTag	integer	tag of an nD material
$pressure	float	surface pressure (optional; default 0.0)
$rho	float	element mass density per unit volume (optional; default 0.0)
$b1 $b2	float	constant body forces in the domain (optional; default 0.0)

Note

1. If all optional arguments are supplied, all four must be provided.

2. Consistent nodal loads are computed from pressure and body forces.

3. Valid Element Recorder queries include forces, stresses, and material $matNum ....

Example

1. Tcl Code

element Tri31 1 1 2 3 1.0 PlaneStress 1

2. Python Code

element('Tri31', 1, 1, 2, 3, 1.0, 'PlaneStress', 1)

Code developed by: Roozbeh G. Mikola, N. Sitar