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Member : Definition

The member wizard can be activated from the Members Table view using the wizard button or from a Graphic view by selecting a member and then Edit member from the right-click menu.

Definition​

Name​

An optional identifier for the member.

Type​

Members are assigned a type. This embraces one dimensional (1D), two dimensional (2D), and three dimensional (3D) members:

1D – 1D generic, beam, column, 1D void cutter

2D – 2D generic, slab, wall, 2D void cutter

3D - 3D generic

The void cutter member types can be used to create voids in intersecting or coplanar 2D members. For 1D void cutters, the member's section shape will be cut through 2D members when the angle between the 2D member's normal and the 1D member's x axis is less than 60 degrees.

Property​

These are the properties that define the type, shape and dimensions of the section or 2D properties. Either choose a property from the list or type in a property number.

Group​

This defines the group to which the member belongs. No further information is required to define a group.

Topology​

The geometry of the member is defined through the topology. The syntax for member topology depends on the member type:

1D members​

  • An ordered list of nodes

    • a straight beam member between nodes 21 and 22 would have topology ’21 22’

  • Node number preceded by A for arc through node

    * an arc member between node 21 and 22, passing through node 23 would have topology ’21 A23 22’.

    * a 1D arc member can have only 3 nodes

    Note: For 1D arc members from earlier versions of GSA, defined with a radius, the member is transformed to one with a third node defining the arc.

2D members​

  • An ordered list of nodes
    • A simple slab defined by nodes 41, 42, 43 and 44 the topology is ’41 42 43 44’
  • Node number preceded by A for an arc through a node
    • The slab above with an arc through node 43, the topology is ’41 42 A43 44’
  • V (node list) for a void
    • The slab above, with a void defined by nodes 45 to 48 the topology is '41 42 43 44 V(45 46 47 48)’
  • P (node list) for points to be included
    • To include fixed points in the mesh at node 50 and 55: ’41 42 43 44 P(50 55)’
  • L (node list) for lines to be included
    • To include a fixed polyline segment in the mesh between nodes 71, 72 and 73: ’41 42 43 44 L(71 72 73)’
  • A (node list) for additional solid areas to be included
    • To include an additional area (must be coplanar with the first): ’41 42 43 44 A(45 46 47 48)’

3D members​

3D members are defined by a closed boundary mesh of triangles and/or triangle strips.

  • To create a 3D cube, where the base is a clockwise loop of nodes 1-4 and the top is a clockwise loop of nodes 5-8 the topology is: ‘1 2 4 3; 5 6 8 7; 1 5 2 6 3 7 4 8 1 5’ (where the first triangle strip is the base, second the top and third the sides of the cube).

See Creating 3D members for more information.

Orientation node and angle​

The orientation of 1D members is controlled by an orientation angle and an orientation node. The orientation node along with the end nodes defines the xy plane of the member.

For 1D members the orientation angle defines the rotation of the members about its axis from the default orientation, so for example setting an I beam to work as an H beam. For 2D members the orientation angle relates to a rotation about an out-of-plane axis from the local x direction defined by the properties. The angle is measured in degrees.

Meshing​

When creating elements from members (Model > Coordination tools > Create elements from members) GSA needs to know how to create element meshes. Typically the meshing will take into account other members, however, these can be meshed independently or excluded altogether. The resulting mesh will be influenced by the analysis type, meshing mode, and target mesh size for the resulting elements.

1D analysis type​

The 1D analysis type determines what type of 1D element is created in the analysis layer.

2D analysis type​

The 1D analysis type determines whether a linear element, quadratic element, rigid diaphragm or load panel is created in the analysis layer.

2D meshing mode​

The 2D meshing mode determines if the mesh that is created is a quad dominant, quad only or tri only. This option is only available if the 2D analysis type is linear element or quadratic element.

Element size​

This parameter determines the target mesh size or the analysis element. This option is not available if the 2D analysis type is rigid diaphragm or load panel.

Releases​

The releases are used when mapping members to elements to provide appropriate element releases in the analysis model.

This option is only available for 1D members

Tapered 1D member​

An 1D member can be tapered from one end to the next if the member refers to a section that includes two different size sections. See section definition on how to define section for tapered members.

Member end conditions and effective length...​

This specifies the member conditions that apply at the ends of a 1D member. See the design properties for more information.