Reorientating Steelwork Elements
- Last UpdatedFeb 19, 2025
- 3 minute read
Keywords
ROTATE BY ABOUT THROUGH AND
Description
The method of rotating a Section about its Neutral Axis by setting its Beta Angle (BANG) attribute was described in Orientation Angle. This section explains the use of the ROTATE command to achieve a greater range of re-orientating effects on Sections and on other steelwork elements.
The command allows the user to specify the rotation required in any of the following ways:
-
As a specified angle of rotation about a default axis (similar in effect to setting the BANG attribute). This default axis is the Neutral Axis for Sections, Joints and Fittings, and the Z axis for other elements.
-
As a specified angle of rotation about a given axis, the latter defined by its direction and/or through point. If the direction and/or through point are omitted, the default direction is that of the Neutral Axis or Z axis; the default through point is the Origin or Start Position (depending on the type of element involved).
-
By reference to the component’s axes or p-lines.
Examples
ROTATE BY -45
Rotates by 45° about the element’s Neutral Axis or Z axis (anticlockwise when looking from Start to End or in the +Z direction, since the rotation is specified as a negative angle).
ROTATE BY 45 ABOUT E
Rotates by 45° about the E-W axis (clockwise when looking E).
ROTATE ABOUT E BY 45
The same as the preceding example.
ROT THRO POSE ABOUT S BY -25
Rotates a Section about an axis which passes in the N-S direction through its End position. The rotation is 25° anticlockwise when looking S along this axis.
ROT ABOUT PPLIN TOS BY 45
Rotates by 45° about the Top-of-Steel p-line (clockwise when looking in the Start to End direction).
ROT AND PPLIN BOS IS E45N
Rotates element about its Neutral Axis until the Bottom-of-Steel p-line points as closely as possible to the E45N direction.
ROTATE AND Y IS N45W25D
Rotates element until the Y axis points as closely as possible to the YN45W25D direction.
ROT AND PPLIN TOS IS PPLIN
BOS OF /SCTN1 LEAV DIR
WRT /STRU1Rotates element until its TOS p-line points in the direction of the BOS p-line of / SCTN1 in the specified coordinate system.
Command Syntax:
Rotation about a given axis:
>- ROTate ABOut -+- <plin> -.
| |
‘- <bdir> -+- THRough - <bpos> -+- BY -+- <uval> -------------------.
| | | |
| | ‘- <bdir> TOwards <bdir> ---|
| | |
| ‘- AND -+- <plin> -. |
| | | |
| ‘- <bdir> -+- IS <bdir> ----|
| |
|- BY - +- <uval> --------------------. |
| | | |
| ‘- <bdir> - TOwards - <bdir> -+ |
| | |
‘- AND -+- <plin> -. | |
| | | |
‘- <bdir> -+- IS - <bdir> ----+- THRough <bpos> -|
| |
‘------------------+-->
Rotation to pass through a given point:
>- ROTate THRough - <bpos> -+- ABOut -+- <plin> -.
| | |
| ‘- <bdir> -+- BY -+- <uval> -----------------------.
| | | |
| | ‘- <bdir> - TOwards - <bdir> ----|
| | |
| ‘- AND -+- <plin> -. |
| | | |
| ‘- <bdir> -+- IS - <bdir> ------|
| |
|- BY -+- <uval> --------------------. |
| | | |
| ‘- <bdir> - TOwards - <bdir> -+- ABOut -+- <plin> -. |
| | | | |
| | ‘- <bdir>- +--|
| | |
| ‘-----------------------|
| |
‘- AND -+- <plin> -. |
| | |
‘- <bdir> -+- IS - <bdir> -+- ABOut -+- <plin> -. |
| | | |
| ‘- <bdir>- +----|
| |
‘-------------------------+->
Rotation by a specified amount:
>- ROTate BY - -+- <uval> --------------------.
| |
‘- <bdir> - TOwards - <bdir> -+- ABOut -+- <plin> -.
| | |
| ‘- <bdir> -+- THRough - <bpos> ---.
| | |
| ‘----------------------|
| |
|- THRough - <bpos> -+- ABOut -+- <plin> -. |
| | | | |
| | ‘- <bdir> -+-|
| | |
| ‘----------------------|
| |
‘-------------------------------------------+->
Rotation to give a specified orientation
>- ROTate AND -+- <plin> -.
| |
‘- <bdir> -+- IS - <bdir> -+- ABOut -+- <plin> -.
| | |
| ‘- <bdir> -+- THRough - <bpos> ----.
| | |
| ‘-----------------------|
| |
|- THRough - <bpos> -+- ABOut -+- <plin> -. |
| | | | |
| | ‘- <bdir> -+--|
| | |
| ‘-----------------------|
| |
‘--------------------------------------------+-->
Note:
In each of the preceding diagrams <plin> identifies a specific p-line.