TR.18 Inactive/Delete Specification
This set of commands may be used to temporarily
inactivate or permanently delete specified
JOINT
s or
MEMBER
s.
General Format
INACTIVE { MEMBERS member-list | ELEMENTS element-list }
DELETE { MEMBERS member-list | JOINTS joint-list }
Description
These commands can be used to specify that certain joints
or members be deactivated or completely deleted from a structure. The
INACTIVE
command makes the members and elements
temporarily inactive; the user must re-activate them during the later part of
the input for further processing. The
DELETE
command will completely delete the
members/elements from the structure; you cannot re-activate them. The Delete
Joint command must be immediately after the Joint Coordinates. The
DELETE
commands must be provided immediately after all
member/element incidences are provided and before any
INACTIVE
commands.
Notes
-
The
DELETE MEMBER
command will automatically delete all joints associated with deleted members, provided the joints are not connected by any other active members or elements. -
This command will also delete all the joints, which were not connected to the structure in the first place. For example, such joints may have been generated for ease of input of joint coordinates and were intended to be deleted. Hence, if a
DELETE MEMBER
command is used, aDELETE JOINT
command should not be used. -
The
DELETE MEMBER
command is applicable for deletion of members as well as elements. If the list of members to be deleted extends beyond one line, it should be continued on to the next line by providing a blank space followed by a hyphen (-) at the end of the current line. -
If inactivating members causes joints to become unconnected in space (i.e., orphaned), a warning stating that those joints are not connected by any members or elements will be displayed in the output file. These warnings can normally be ignored.
-
The inactivated members may be restored for further processes (such as an analysis or design for a 2nd set of load cases) by using the
CHANGE
command. See TR.37 Analysis Specification and Example EX. US-4 Inactive Members in a Braced Frame for more information. -
The
DELETE MEMBER
command should be used to delete elements too. Specify the command asDELETE MEMBER j
, where j is the element number of the element you wish to delete. In the example shown below, 29 to 34 and 43 are element numbers. -
Loads that have been defined on members declared as
INACTIVE
members will not be considered in the analysis. This applies toSELFWEIGHT
,MEMBER LOADS
,PRESTRESS
, andPOSTSTRESS LOADS
,TEMPERATURE LOAD
s, etc.For those joints that become orphaned (see note d above), loads applied to such joints, either explicitly through the
JOINT LOAD
command, or generated by some means as in moving, wind or seismic load generation, will be "lost", meaning, they will not get considered for the analysis for those load cases for which the associated member is inactivated. -
The
DELETE JOINT
command must be specified before all incidence commands such asMEMBER INCIDENCE
,ELEMENT INCIDENCE
, etc.
Example
INACTIVE MEMBERS 5 7 TO 10
DELETE MEMBERS 29 TO 34 43