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 Property Data form and if the Nonlinear check box is checked on that form.
Linear - Please refer to the Linear Link/Support Directional Properties form topic.
Damper, Gap, Hook, Multi-Linear Elastic, Plastic {Wen}, Rubber or Friction Isolator, T/C Friction, Triple Pendulum Isolator - When the Link Type is any of these, the options available depend on if the definition is linear or nonlinear, and include the following:
Property Name display box. The name assigned to the property definition .
Direction display box. The direction for the link definition.
Type display box. Identifies the Link Type as specified on the Link Property Data form.
Nonlinear - Yes / No display box. Identifies if the property definition is linear or nonlinear.
Linear Properties
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.
Nonlinear Properties. The parameters vary for the different Link/Support types (Damper, Gap, Friction Isolator, T/C Friction Isolator, Triple Pendulum Isolator). The options are assumed to be self explanatory. Use the suggested default values or type new ones into the edit boxes.
Shear Deformation Location - Distance from End J edit box. Use this edit box to specify the location of shear deformation relative to the distance from End J.
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.
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.
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.