Mass and Stiffness Proportional Damping Form

Access the Mass and Stiffness Proportional Damping form as follows:

Click the Define menu > Analysis Cases command to display the Analysis Cases form.
Click the Add New Case button or highlight a previously defined analysis case and click the Add Copy of Case or the Modify/Show Case button to display the Analysis Case Data form.
Do one of the following:

Select Time History from the Analysis Case Type drop-down list and Linear for Analysis Type and Direct Integration for Time History Type to display the Analysis Case Data - Linear Direct Integration History form
Select Time History from the Analysis Case Type drop-down list and Nonlinear for Analysis Type and Direct Integration for Time History Type to display the Analysis Case - Nonlinear Direct Integration History form.

Click the Damping Modify/Show button on the Analysis Case - Linear Direct Integration History form or the Analysis Case - Nonlinear Direct Integration History form.

Three types of entry are available. The input required on the form depends on which of the three types is selected.

Direct Specification option. When this option is selected, directly enter values in the Mass Proportional Coefficient and the Stiffness Proportional Coefficient edit boxes.
Specify Damping by Period option. When this option is selected, enter values in the First and Second Periods and associated Damping edit boxes. Note that as values are entered in those edit boxes, SAP2000 calculates and displays the Mass Proportional Coefficient and the Stiffness Proportional Coefficient in their respective display boxes.
Specify Damping by Frequency option. When this option is selected, enter values in the Frequency and Damping edit boxes. Note that as values are entered in those edit boxes, SAP2000 calculates and displays the Mass Proportional Coefficient and the Stiffness Proportional Coefficient in their respective display boxes.
Recalculate Coefficients button. If after entering values in the Damping edit boxes, the Mass Proportional Coefficient and the Stiffness Proportional Coefficient do not change, click the Recalculate Coefficients button.