Link/Support Directional Properties Form

Use the Link/Support Directional Properties form to specify effective stiffness and damping and where appropriate, the location of shear deformation relative to the distance from End J. The effective stiffness is a spring stiffness. The effective damping specifies dashpot-type damping; it is not a specification of percent critical damping.

The appearance of the Link/Support Directional Properties form changes depending on the Link Type selected in the Link/Support Type drop-down list on the Link/Support Property Data form and if the Nonlinear check box is checked on that form.

Note: To use the nonlinear dynamic link properties, the software must be the nonlinear version of SAP2000.

Linear link type. When the Link Type on the Link/Support Property Data form is Linear and the Modify/Show button is clicked, the Link/Support Directional Properties form has the following areas:
- Link/Support Name display box. This is the name assigned to the property definition on the Link/Support Property Data form.
- Directional Control area. Check the appropriate Direction check boxes in this area to specify the direction(s) for which stiffness and damping is to be specified on this form. If the Fixed check box is checked, the associated degree of freedom is fixed or rigid.
- Stiffness Values Used for All Load Cases
- - Stiffness Is Uncoupled option or Stiffness Is Coupled option. Choose to specify uncoupled or coupled stiffness and then enter the necessary values in the available edit boxes.
- Damping Values Used for All Load Cases
- - Damping is Uncoupled option or Damping is Coupled option. Choose to specify uncoupled or coupled damping and then enter the necessary values in the available edit boxes.
- Shear Direction from End J area and U2 and U3 edit boxes. Use these edit boxes to specify the location of shear deformation relative to the distance from End J.
- Units drop-down list. Use the values shown in the Units drop-down list or select new units from the list.
When other link types, except Multi-Linear Plastic (i.e., Multi-Linear Elastic, Damper, Gap, Hook, Plastic {Wen}, Rubber or Friction Isolator, T/C Friction) are selected and the Modify/Show button is clicked, the appearance of and options available on the Link/Support Directional Properties form depend on the link type and if the definition is linear or nonlinear as specified on the Link/Support Property Data form.
- Property Name display box. When the property definition is linear, this is the name assigned to the property definition on the Link/Support Property Data form.
- Direction display box. Displays the direction for the link definition.
- Type display box. The type of link selected in the Link/Support Type drop-down box on the Link/Support Property Data form.
- Nonlinear display box. Identifies if the property definition is linear or nonlinear.
- Properties Used For Linear Load Cases
- - Effective Stiffness edit box. Enter a value to specify the stiffness for linear load cases.
  - Effective Damping edit box. Enter a value to specify the effective damping for linear load cases.
- Properties Used For Nonlinear Load Cases. The parameters vary for the different Link/Support types (Damper, Gap, Hook, Plastic [Wen], Rubber Isolator, Friction Isolator, T/C Friction Isolator). The options are assumed to be self explanatory. Use the suggested default values or type new ones into the edit boxes.
- Multi-Linear Force Deformation Definition area. When the Link/Support Type is Multi-Linear Elastic or Plastic, the Nonlinear check box has been checked and the Modify/Show button is clicked on the Link/Support Property Data form, use the small spreadsheet near the bottom of the Link/Support Directional Properties form to specify a force-deformation definition. Enter values for Displ (displacement) and Force in the appropriate cells.
- Click the Order Rows button to arrange the rows of data in ascending order.
- Click the Delete Row {Number} button to delete the select row of the spreadsheet.
- - Click the Add Row {Number} to add a row at the bottom of the spreadsheet.
Multi-Linear Plastic link type. When the Link Type is Multi-Linear Plastic, the Nonlinear check box has been checked and the Modify/Show button is clicked on the Link/Support Property Data form, the Link/Support Directional Properties form includes a drop-down list of hysteresis types, as well as the options above; use the drop-down list to select the appropriate hysteresis type for the curve, and enter the associated parameters as required. See Hysteresis Types for more information. The Hysteresis Definition Sketch in the lower right of the form is provided for informational purposes only and cannot be edited, nor will it update when changes are made on the form.

The Edit menu commands on the forms can be used to cut, copy, paste, or delete editable data on the form. The menu also has commands to add another row, delete a row, and order rows in the spreadsheet area on the form.

References

Kinematic model: L.E. Malvern, 1969. Introduction to the Mechanics of a Continuous Medium. Prentice-Hall.

Takeda model: T. Takeda, M.A. Sozen, N.N. Nielsen, "Reinforced Concrete Response to Simulated Earthquakes," J. Struct. Engrg. Div., ASCE, V. 96, No. 12, 1970, pp. 2257-2573

Pivot model: R.K. Dowell, F. Seible, E.L. Wilson, "Pivot Hysteresis Model for Reinforced Concrete Members," ACI Struct. J., ACI, V. 95, No. 5, 1998, pp. 607-617

Access the Link/Support Directional Properties form as follows:

Click the Define menu > Section Properties > Link/Support Properties command or select a link object and click the Assign menu > Link/Support > Link/Support Properties command to display the Link/Support Property form. The Link/Support Property Data form also can be accessed by clicking the + (plus) symbol that may appear next to a drop-down list of available link properties, such as the Link Property drop-down lists on the Assign Springs Along Line Object form.
Click the Add New Property button or highlight a previously defined link/support definition in the Properties area of the form and click the Modify/Show Property button to display the Link/Support Property Data form.
Check one of the Direction check boxes (e.g., U1, U2, U3 and so on) and click the Modify/Show for All button (or the Modify/Show for {Direction} button if a nonlinear type is selected in the Link/Support Type drop-down list on the Link/Support Property Data form) to display the Link/Support Directional Properties form.