Form: Element Stress Contours for Planes
Use the Display menu > Show Forces/Stresses > Planes command to display stresses for planes on the active window.
Define a load case (or use the default DEAD or MODAL cases) and run an analysis of a model containing Plane objects.
Click the Display menu > Show Forces/Stresses > Planes command to display the Element Stress Contours for Planes form. Use the form to specify the parameters for the display.
Case/Combo Name drop-down list. Choose the load case or combination whose plane element stresses are to be displayed.
Multivalued Options. For multi-step cases, choose the step number, time step, or frequency step; or choose Envelope to view the maximum or minimum results over all steps.
Component options. Specify which component of stress is to be displayed. Click here for information about the possible components for plane internal stresses
Contour Range: The plane element internal stresses are displayed as colored contours. Specify two values:
Min: Any element with a stress less than the value shown here is displayed in the color associated with Min in the Contours area of the Assign Output Colors form. Note that the color associated with Min is the top color in the form.
Max: Any element with stress greater than or equal to the value shown here is displayed in the color associated with Max in the Contours area of the Assign Output Colors form. Note that the color associated with Max is the bottom color in the form.
The program spaces the intermediate range values equally between the specified Min and Max values. If the Min and Max values are set to zero, SAP2000 will automatically create a contour range that includes all values. This is the default.
Stress Averaging: Specify if stress averaging is to be used when displaying the stresses. Consider the four elements labeled A, B, C and D shown in the sketch at right. These four elements all have a common point, labeled 1, in the sketch. Each of the elements has an associated internal force or stress at joint 1. Typically the forces or stresses at common points in different elements are different. The finer the mesh the closer the values become.
The options available for stress averaging are None for no stress averaging, At All Joints for stress averaging at all joints or over Objects & Groups for stress averaging at points selected just before plotting the plane stresses, or for stress averaging of groups selected using the Set Groups button.
If the None option is used so that the stress contours are plotted with no stress averaging at the common points, the changes in stress from element to element typically will appear abrupt. Large stress variations between elements may indicate that the model is not properly meshed and may need to be refined to properly capture the variation in stress. Therefore, use this option to determine if the model is meshed properly.
Stress averaging using the At All Joints or over Objects & Groups option tends to eliminate abrupt changes in the plot and smoothes the contours. Thus, after the meshing of the model has been shown to be acceptable using the None option, the At All Joints option will give better results of the stress in the elements by averaging the stress between elements and reducing the error because of the stress on each individual element. The over Objects & Groups option should be used if a discontinuity, such as two planes meeting at an angle, is included in the model. In that case, each plane should be averaged independently using the over Objects & Groups option. This will avoid the problem of averaging across the two planes, which would give incorrect result. The results would be incorrect because the stress along the two planes is not continuous relative to the elements' local axes.
Show Deformed Shape check box. When this check box is checked, the plane stresses will be displayed on the deformed shape.