3.1.9.15. Quadrilateral Element

This command is used to construct a FourNodeQuad element object which uses a bilinear isoparametric formulation.

Command

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

Argument	Type	Description
$eleTag	integer	unique element object tag
$iNode $jNode $kNode $lNode	integer four nodes defining element boundaries	input in counter-clockwise order around the element.
$thick	float	element thickness
$type	string	string representing material behavior. The type parameter can be either “PlaneStrain” or “PlaneStress.”
$matTag	integer	tag of nDMaterial
$pressure	float	surface pressure (optional: default = 0.0)
$rho	float	element mass density (per unit volume) from which a lumped element mass matrix is computed (optional: default=0.0)
$b1 $b2	float	constant body forces defined in the isoparametric domain (optional: default=0.0)

Fig. 3.1.9.16 Quad Element Node Numbering

Note

The optional arguments must either be all specified or none specified.

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

The valid queries to a Quad 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 isoparametric domain.

Example

The following example constructs a quad element for use in a plane stress problem with tag 1 between nodes 1, 2, 3, 4 with an nDMaterial of tag 1.

1. Tcl Code

element quad 1 1 2 3 4 "PlaneStress" 1

2. Python Code

element('quad',1,1,2,3,4, 'PlaneStress', 1, b1, b2, b3)

Code Developed by: Michael H. Scott