Tutorial

Mesh Area Objects
“Trick” Problem

Click the File menu > New Model command to display the New Model form.
Click the drop-down box to set the units to .
Click on the Grid Only button to display the New Coord/Grid System form. In that form:

Select the Cartesian Tab.
In the Number of Grid Lines area, type 3 in the X direction edit box.
In the Number of Grid Lines area, type 3 in the Y direction edit box.
In the Number of Grid Lines area, type 1 in the Z direction edit box.

In the Grid Spacing area, type 4 the X direction edit box.

In the Grid Spacing area, type 6 the Y direction edit box.

Click the OK button.

Click the “X” in the top right-hand corner of the 3-D View window to close it.
Click the drop-down box in the status bar to change the units to .
Click the Define menu > Materials command to display the Define Materials form.
Highlight the CONC material and click the Modify/Show Material button to display the Material Property Data form. In that form:

Verify that the Modulus of Elasticity is 3600.
Verify that the Poisson’s Ratio is 0.2.
Click the OK buttons on the Material Property Data and Define Materials forms to close the forms.

Click the Define menu > Area Sections command to display the Area Sections form. In that form:
- Click the Modify/Show Section button to display the Area Section Data form. In that form:
  - Verify that the selected Material Name is CONC.
  - Verify that the Shell option is selected in the Area Type area.
  - Verify that both the Membrane and the Bending thicknesses are 12.
  - Verify that the Shell option is selected in the Type area.
  - Click the OK buttons on the Area Section Data and Area Sections forms to close all forms.

Verify that the Snap to Points and Grid Intersections button on the side toolbar is depressed.
Click the Draw Rectangular Area button on the side toolbar or the Draw menu > Draw Rectangular Area command to display the Properties of Object form. In that form:

Verify that the selected Property is ASEC1.

Click on upper left-hand corner grid intersection (Point “B” in the problem statement) and then click on the lower right-hand grid intersection (Point “A”) to draw an area object over the entire structure.
Click the Set Select Mode button to exit the Draw mode and enter Select mode.
Click on the area object to select it.
Click the Edit menu > Mesh Areas command to display the Mesh Selected Shells form.
Fill in this form as shown in the adjacent figure and click the OK button.
Select the joints that are labeled “A,” “B” and “C” in the problem statement.
Click the Assign menu > Joint > Restraints command to display the Joint Restraints form. In that form:

Uncheck the Translation 1 and
Translation 2 check boxes.
Verify that the Translation 3 check box is checked.
Verify that the Rotation about 1, 2 and 3 check boxes are not checked.
Click the OK button.

Click the Show Undeformed Shape button to remove the display of joint restraints and reset the window display (and title).
Click the drop-down box in the status bar to change the units to .
Click the Set Display Options button (or the View menu > Set Display Options command) to display the Display Options for Active Window form. In that form:

Check the Labels box in the Joints area.
Click the OK button.

Select joint 106 (coordinates 7, 12, 0) by clicking on it.
Click the Assign menu > Joint Loads > Forces command to display the Joint Forces form. In that form:

Type -814 in the Force Global Z edit box in the Loads area.
Click the OK button.

Select joint 16 (coordinates 1, 6, 0) by clicking on it.
Click the Assign menu > Joint Loads > Forces command to display the Joint Forces form. In that form:

Type -698 in the Force Global Z edit box in the Loads area.
Click the OK button.

Select joint 32 (coordinates 2, 3, 0) by clicking on it.
Click the Assign menu > Joint Loads > Forces command to display the Joint Forces form. In that form:

Type -901 in the Force Global Z edit box in the Loads area.
Click the OK button.

Click the Show Undeformed Shape button to reset the window display.
Click the Set Display Options button (or the View menu > Set Display Options command) to display the Display Options for Active Window form. In that form:

Uncheck the Labels box in the Joints area.
Click the OK button.

Click the Analyze menu > Set Analysis Options command to display the Analysis Options form. In that form:

Click the Plane Grid XY Plane button to set the available degrees of freedom.
Click the OK button.

Click the Set Default 3D View button to switch to a 3-D View.
Click the Run Analysis button to display the Set Analysis Cases to Run form. In that form:

Highlight (select) MODAL in the Case Name list and click the Run/Do Not Run Case button.
Verify that the DEAD analysis case is set to Run in the Action list.
Click the Run Now button to run the analysis.

When the analysis is complete check the messages in the SAP Analysis Monitor window (there should be no warnings or errors) and then click the OK button to close the window.
Click the Display menu > Show Forces/Stresses > Joints command to display the Joint Reaction Forces form. In that form:

Verify that the Reactions option is selected in the Type area.
Click the OK button and view the support reactions.

Note: The reaction at the joint labeled “C” in the problem statement is virtually zero (0). The reason for this apparently odd result is that the resultant of all the applied loads lies on a line connecting the support points labeled “A” and “B,” and thus by simple statics, the reaction at support point “C” must be zero. Note that you could move the support point labeled “C” anywhere on the structure (except on the line connecting support points “A” and “B” because this would result in an unstable structure) and the resulting reactions would not change.