Form: Assign Springs Along Frame Object
Line springs can be assigned in any of the local axes directions of a frame object. CSiBridge distributes the springs associated with the frame object to all of the nodes associated with the internal-to-CSiBridge (analysis model) representation of the line object. Note that internally CSiBridge may mesh (break up) a line object into several elements with associated points between each element.
Assign line springs to frame objects as follows:
Select the frame object to which the spring assignment is to be made.
Click the Advanced > Assign > Frames > Line Springs command to display the Assign Springs Along Frame Object form:
Spring Type.
Simple. When this option is selected, use the default value for the stiffness per unit length or enter another value in the Spring Stiffness per Unit Length edit box. Also specify if the spring has both Tension and Compression, or only Tension or only Compression by selecting the appropriate option from the Simple Spring Resists drop-down list.
Link Property. When this option is selected, the spring is a based on a link property. The option will be available if link properties have already been defined in the model; in that case, select the property from the drop-down list. If no link property has been defined, clicking the + (plus) symbol beside the drop-down list will access the Link/Support Properties form, which can be used to define the necessary link property. Then select that property in the drop-down list.
Link Local 2-Axis Angle from Default Orientation edit box. This edit box becomes available when the spring is being defined using a link property definition. Use the edit box to specify an orientation angle for the link local axis measured counterclockwise from its default orientation.
Spring Tension Direction. Specify the direction of the spring tension or, when the Spring Type is Link Property, the direction of the positive, local 1-axis:
Parallel to Line Object Local Axis option and drop-down list. With this option, use the drop-down list to choose the local axis direction of the line object to which the spring is being assigned. The direction of the spring tension will be parallel to the selected local axis direction.
In Line Object 2-3 Plane option and Counterclockwise Angle from Line +2-Axis edit box. With this option, the spring tension direction will be in the 2-3 plane of the line object to which the spring is assigned. Use the Counterclockwise Angle from Line +2-Axis edit box to specify an angle to adjust the orientation of the tension direction. As the name implies, the angle is measured counterclockwise from the +2 axis of the line object to which the spring is assigned.
User Specified Direction Vector option and Coordinate System drop-down list and Global X, Y and Z Component edit boxes. Use this option to specify the spring tension direction along a specified vector. Select the Coordinate System for the vector from the drop-down list. The possible options include the Global axis, any user-defined coordinate systems, and the local axes of the line object to which the spring is assigned.
Options Specify how the springs will be applied.
Add to existing springs: Adds this assignment to the existing spring assignments.
Replace existing springs: Replaces the existing assignment with this assignment. If no assignment exists, the new assignment is still made. This is the default option.
Delete existing springs: Deletes all spring assignments made to the selected line object(s).
Note that the default option is Replace and that the program defaults to this every time the form is opened.
Units drop-down list. Use the Units shown in the drop-down list or select other units from the drop-down list for use on this form.
Note: If a beam on elastic foundation is to be modeled using line springs, the Advanced > Assign > Frames > Automatic Frame Mesh command can be used to ensure that sufficient numbers of springs are used in the model. CSiBridge will automatically determine the required stiffness for each spring. This feature saves a considerable amount of time.
See Also