Modifying Lengths of Sections

Model Reference Manual

Once positioned, a Section may have its ends repositioned independently by using the EXTEND command. This effectively lengthens or shortens the Section by a specified amount and resets its POSS and/or POSE attributes accordingly. (The user could, of course, set POSS and/or POSE directly, as described in Start and End Positions, but this would need prior calculation of the new positions needed to achieve the required length change.)

The increase or decrease in length may be specified as a direct measurement or as a proportion of the current length of the Section.

The <plane> allows the user to define the amount of extension required by intersecting the neutral axis with a defined plane. The section is extended (or shortened) to meet the plane.

The RECALCULATE option causes the positions of elements which are members of the modified Section to be recalculated so that they remain in the same positions after the change. For example, the ZDIST defining the position of a Secondary Node would be recalculated if the POSS (from which ZDIST is measured) were moved by the EXTEND command, so that the SNOD remained unmoved.


Examples:
EXTEND END BY E1000	Move POSE by 1000mm Eastward.
EXTEND BY E1000	As above (defaults to END).
EXTEND START BY W1000 RECALC	Move POSS by 1000mm Westward and recalculate the positions of all member SNODs, FITTs etc. so that they remain unmoved.
EXTEND START BY U500 E2000 S500	Move POSS by the given amounts.
EXTEND END 1750	Move POSE so as to increase the Section’s length by 1750mm (default units).
EXTEND -1750	Move POSE (defaults to END) so as to decrease the Section’s length by 1750mm (default units).
EXTEND START PROP 0.25	Move POSS so as to increase the Section’s current length by 25%.
EXTEND PROP -0.2	Moves POSE (defaults to END) so as to decrease the Section’s length by 20%.
EXTEND END PLANE E30N DIST 0.0	Moves POSE to meet the defined plane.

Command Syntax:

>-- EXTend --+- STart -.
             |         |
             |-- ENd* -|
             |         |
             ‘---------+- PROPortional - value -.
                       |                       |
                       |- BY --- <axpos> ------|
                       |                       |
                       |                       |
                       |- <plane> -------------|
                       |                       |
                       ‘- <uval> --------------+- RECALCulate --.
                                               |                |
                                               ‘----------------+->