# structure geogrid property command

Syntax

structure geogrid property keyword ... <range>

Primary keywords:

Assigns a property to elements in the range. The element can have isotropic, orthotropic, or anisotropic elastic material properties. The following properties are available:

density f

density (needed if dynamic mode or gravity is active)

thickness f

geogrid thickness

thermal-expansion f

thermal expansion coefficient

anisotropic-membrane f1 f2 f3 f4 f5 f6

anisotropic membrane material properties {$$c^{\prime}_{11}, c^{\prime}_{12}, c^{\prime}_{13}, c^{\prime}_{22}, c^{\prime}_{23}, c^{\prime}_{33}$$} $$[F/L^2]$$, which define membrane material-stiffness matrices $$[Eʹ_m]$$ and $$[Eʹ_b]$$, respectively, in the material directions $$x'$$, $$y'$$, $$z'$$.

anisotropic-bending f1 f2 f3 f4 f5 f6

anisotropic bending material properties {$$c^{\prime}_{11}, c^{\prime}_{12}, c^{\prime}_{13}, c^{\prime}_{22}, c^{\prime}_{23}, c^{\prime}_{33}$$} $$[F/L^2]$$, which define bending material-stiffness matrices $$[Eʹ_m]$$ and $$[Eʹ_b]$$, respectively, in the material directions $$x'$$, $$y'$$, $$z'$$.

material-x v

specify the vector v whose projection onto the geogrid surface defines the $$x'$$-axis of the material coordinate system. The material directions correspond with the principal directions of orthotropy (for more information, see below).

isotropic f1 f2

isotropic material properties: $$E$$ and $$v$$ where $$E$$ is Young’s modulus $$[F/L^2]$$ and $$v$$ is Poisson’s ratio

orthotropic-membrane f1 f2 f3 f4

orthotropic membrane material properties {$$c^{\prime}_{11}, c^{\prime}_{12}, c^{\prime}_{22}, c^{\prime}_{33}$$} $$[F/L^2]$$, which define membrane material-stiffness matrices $$[Eʹ_m]$$ and $$[Eʹ_b]$$, respectively, in the material directions $$x'$$, $$y'$$, $$z'$$.

orthotropic-bending f1 f2 f3 f4

orthotropic bending material properties {$$c^{\prime}_{11}, c^{\prime}_{12}, c^{\prime}_{22}, c^{\prime}_{33}$$} $$[F/L^2]$$, which define bending material-stiffness matrices $$[Eʹ_m]$$ and $$[Eʹ_b]$$, respectively, in the material directions $$x'$$, $$y'$$, $$z'$$.

coupling-cohesion f

coupling spring cohesion (stress units)

coupling-friction f

coupling spring friction angle (degrees)

coupling-stiffness f

coupling spring stiffness per unit area

slide b

large-strain sliding flag

slide-tolerance f

large-strain sliding tolerance

Further information on the material-x keyword

The material coordinate system, $$xʹ$$, $$yʹ$$, $$zʹ$$, defines the orthotropic and anisotropic properties and satisfies the following conditions: 1) $$xʹ$$ is the projection of the given vector onto the surface; 2) $$zʹ$$ is normal to the surface and aligned with the z-axis of the shell-type element coordinate system; and 3) $$yʹ$$ = $$zʹ$$ × $$xʹ$$. The material coordinate system moves with the shell surface during large-strain updates, which means that the relative orientations of this system and the element local system do not change (the angle $$β$$ in this figure does not change). If the material-x vector is not specified, then the $$xʹ$$-axis will be aligned with the $$x$$-axis of the structural element local coordinate system.

The material coordinate system can be queried with the command structure geogrid list property material-x and the FISH function struct.shell.beta. It can be visualized with the Structural Geometry plot item by choosing the corresponding System attribute.