{Curve} Interaction Surface Definition for {Property Name} Form

Use the {Curve} Interaction Surface Definition for {Property Name} form to define, review and modify the interaction surface (P-M2-M3) or curve (P-M2, P-M3, M-2M3). The options available on the form depend on the type of interactive hinge. The options are common to all hinge types unless noted otherwise.

Interaction Curve is Symmetric check box - for P-M2, P-M3, M2-M3 type hinges. When this check box is checked, the interaction curve is symmetric.
User Interaction Surface Options - for P-M2-M3 type hinges only. Choose the symmetry for the interaction surface: circular symmetry, doubly symmetric about M2 and M3, or with no symmetry. Doubly Symmetric about M2 and M3 is the default.
- For the Doubly Symmetric About M2 and M3, the interaction surface is input in the (+ M2, +M3) quadrant for all values of P (i.e., both positive and negative). Thus only 90 degrees of the full 360-degree interaction surface is input. Symmetry is then used by the program to define the interaction surface in the (- M2, +M3), (- M2, -M3), and (+ M2, -M3) quadrants.
- For the Circular option, input is needed for all 360 degrees of the interaction surface.

Note the tips in the Interaction Surface Requirements area in the lower left corner of the form. These tips explain the requirements for the various interaction surface options to assist in understanding the input on this form.

Number of Curves edit box. Enter the number of curves for the interaction curve. For the P-M2-M3 hinge type, this is the number of equally spaced P-M curves that will be used to define the interaction surface.
Number of Points on Each Curve edit box. Enter the number of points on each curve of the interaction surface/curve. Eleven is the default.
Scale Factors (Same for All Curves), P, M2, and M3 edit boxes.
Enter a scale factor in the P edit box of the Scaling area. The default for this value is 1. This scale factor multiplies all values in the P column in the Spreadsheet on the right side of the form.
Enter a scale factor in the M edit boxes of the Scaling area. The default for this value is 1. This scale factor multiplies all values in all the M columns in the Spreadsheet on the right side of the form. Typically the interaction surface in the spreadsheet is normalized so that the maximum moment at Angle 90 is 1, and the scale factor is set to the actual value of maximum moment at Angle 90 (+M3). Alternatively, you may set the scale factor to 1 and input actual moment values in the spreadsheet, or use any other scaling.
Include Scale Factors in Plots check box - for P-M2-M3 type hinges only. When this check box is checked, SAP2000 will modify the plot shown in the lower right corner of the form to reflect the selected scale factors.
Units drop-down list. Use this drop-down list to change the units on the form.
First and Last Points (Same for All Curves) area, P, M2 and M3 edit boxes. Specify axial values for the first point and the last point of the interaction surface curve. If the edit boxes are available (depending on the selections made elsewhere on the form), also specify moment values.
Interaction Curve Data
- Current Curve drop-down list and scroll buttons. Use the drop-down list to select a curve; the data for that curve will display in the spreadsheet. The scroll (i.e. arrow) buttons to the right of the Current Curve drop-down list also can be used to move from one curve to another.
- Spreadsheet
- - Use the defaults or enter values in the spreadsheet to indicate the various P-M interaction curves, which in the case of a P-M2-M3 hinge together define the interaction surface. The spreadsheet will display M column data for each of the curves specified in the Number of Curves edit box. Move through the data using the Current Curve scroll buttons.

Important Notes:
	For the axial load values, tension should always be input as positive and compression should always be input as negative. This is opposite the design convention for concrete but is consistent with the analysis convention and the steel-design convention.
	The angle associated with each M column is indicated in the Interaction Surface Requirements area in the lower left corner of the form. Angle 0 corresponds to the +M2 axis (usually the minor moment), Angle 90 corresponds to +M3 (usually the major moment), and so on. The moment values in each M column should always be input as positive values.

When entering values in the P column of the spreadsheet, the plot at the right-hand side of the form shows the P versus M Curve 1 diagram. When entering values in an M column, the plot at the right of the form shows P versus the M Curve associated with the cursor location.

1. - Check Full Curve button. If the hinge type is P-M2, P-M3, or M2-M3, use this button to check the acceptability of the curve after changes have been made in the spreadsheet
  - For P-M2-M3 hinge types only:
  - - 3D Plot, Plan, Elevation, and Aperture arrow buttons and 3D, MM, PM3 and PM2 buttons. Use these buttons to adjust the graphical display of the interaction surface in the lower right corner of the form. Angle values can also be typed directly into the edit boxes.
    - Show All Lines check box. Check this check box to display all lines on the graphical display to the right of the check box.
    - Hide P Direction Lines check box. Check this check box to hide the P Direction Lines on the graphical display to the right of the check box.
    - Hide M2-M3 Lines check box. Check this check box to hide the M2-M3 Lines on the graphical display to the right of the check box.
    - Insert Curve button. Click this button to insert another curve in the plot.
    - Delete Curve button. Click this button to delete a curve.
    - Check Surface button. After making changes to the spreadsheet, click this button to have SAP2000 verify the acceptability of the interaction surface. SAP2000 will display a message box confirming acceptability or identifying the condition that makes the surface unacceptable.
  - Highlight Current Curve check box. Check this check box to display the current curve on the graphical display to the right of the check box. The "current curve" is the curve selected in the Current Curve drop-down list near the top of the form.