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TR.16.1 Listing of Entities by Specifying Groups

This command allows you to specify a group of entities (e.g., members, joints, elements, etc.) and save the information using a 'group-name'. The 'group-name' may be subsequently used in the input file instead of a member/joint list to specify other attributes. This very useful feature allows avoiding of multiple specifications of the same member/joint list. Following is the general format required for the GROUP command.

General Format

START GROUP DEFINITION

followed by

(GEOMETRY)
_(group-name ) member/element/solid-list 

or

JOINT
_(group-name ) joint-list 
MEMBER
_(group-name ) member-list 
ELEMENT
_(group-name ) element-list 
SOLID
_(group-name ) solid-list 
FLOOR
_(group-name ) member-list 

followed by

END GROUP DEFINITION

Where:

  • group-name = an alphanumeric name specified to identify the group. The group-name must start with the '_' (underscore) character and is limited to 24 characters.
  • joint-list = the list of joints belonging to the group. TO, BY, and ALL are permitted.
  • member-list = the list of members/joints belonging to the group TO, BY, ALL, BEAM, PLATE, and SOLID are permitted.
  • ALL means all members, plates, and solids; BEAM means all beams; PLATE all plates; and SOLID all solids.

Notes

  1. The GROUP definition must start with the START GROUP DEFINITION command and end with the END command.

  2. More than one GROUP name may be specified within the same definition specification.

  3. The words JOINT, MEMBER, ELEMENT, FLOOR, or SOLID may be provided if the you wish to identify the group name and lists with those specific items. However, if the group name and list is merely a means of grouping together more than one type of structural component under a single heading, the word GEOMETRY may be provided. In the absence of any of those words (GEOMETRY, JOINT, MEMBER, ELEMENT, FLOOR, or SOLID), the list is assumed to be that for GEOMETRY

  4. The same joint or member/element number may be included in up to four groups. Multiple definitions are useful for output but can be ambiguous for input data such as constants, section property, release, etc.

  5. If two or more consecutively entered groups have the same name, then they will be merged. If not consecutive, the second entry of the same name will be ignored.

  6. A member group may be used in lieu of a member-list with virtually any command which requires member lists, such as MEMBER LOADS, steel and concrete parameters, etc. There is one place however where a MEMBER GROUP will not suffice, and that is for defining panels during a FLOOR LOAD assignment.

    In Applying FLOOR LOAD onto a Floor Group, a panel has to be specified using a FLOOR GROUP, not a MEMBER GROUP. A FLOOR GROUP is not accepted in lieu of a member-list for any other command.

  7. The maximum number of group allowed in an input file is equal to the total number of member, plates, solid, and nodes times the number of duplicate entities allowed to be in different group, which is by default 10 (may be changed using the SET GROUP DUPLICATE i command as described in TR.5 Set Command Specification).

    For example, if a model has 10 members, 3 plates and 2 solids, and 100 nodes. The maximum number of groups could be 10 · (10 + 3 + 2 + 100) = 1150.

  8. Group definitions must follow the joint coordinates, member/plate incidiences, and any renumber (i.e., SUBSTITUTE commands). Likewas, group definitions must come before any load, reference loads, or load definition commands.

Example 1

START GROUP DEFINITION
_TRUSS 1 TO 20 25 35
_BEAM 40 TO 50
END
MEMBER PROPERTIES
_TRUSS TA LD L40304
_BEAM TA ST W12X26

Example 2

START GROUP DEFINITION
JOINT
_TAGA 1 TO 10
MEMBER
_TAGB 40 TO 50
GEOMETRY
_TAGC 101 TO 135
END
 
MEMBER PROPERTIES
_TAGB TA LD L40304
_TAGC TA ST W12X26