Mass and Stiffness Proportional Damping 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, the program 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, the program 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.

Access the Mass and Stiffness Proportional Damping form as follows:

1. Click the Define menu > Load Cases command to display the Load Cases form.

2. Click the Add New Case button or highlight a previously defined load case and click the Add Copy of Case or the Modify/Show Case button to display the Load Case Data form.

3. Do one of the following:

   • Select Time History for the Load Case Type and Linear Direct Integration for the Subtype to display the Load Case Data form for a  Linear Direct Integration history case

   • Select Time History for the Load Case Type and Nonlinear Direct Integration for the Subtype to display the Load Case Data form for a Nonlinear Direct Integration history case.

4. Click the Proportional Damping Modify/Show button.