Local Coordinate System
By default, all nodes have a coordinate system equal to the global coordinate system. However, you can define a local coordinate system for each node.
When to Use
A local coordinate system is useful when:
- A support is on an inclined plane
- You want to define loads in a rotated direction
- Response forces should be calculated in a specific direction
Defining the Local Axis
The local x-axis can be defined by entering an angle in degrees. This angle is measured from the global x-axis, counter-clockwise positive.
When a local coordinate system is defined:
- Support restraints act in the local directions
- Node loads are applied in the local coordinate system
- Response forces are calculated in the local system
Example
For a roller support on a 30-degree slope, set the local x-axis to 30 degrees. Then restrain the local z-direction to create a roller that allows movement along the slope.