Prestressed Concrete Beam

• Response Combinations

• Output Stations

• Prestressing

1. Click the File menu > New Model command to display the New Model form.

2. Click the drop-down box to set the units to .

3. Click the Beam button to display the Beam form. In that form:

• Type 1 in the Number of Spans edit box.

• Type 30 in the Span Length edit box.

• Click the OK button.

4. Click the “X” in the top right-hand corner of the 3-D View window to close it.

5. Click the Define menu > Materials command to display the Define Materials form.

6. Click on CONC in the Materials area to highlight it (select it), and then click the Modify/Show Material button to display the Material Property Data form. In that form:

• Verify 0.15 is entered in the Weight per Unit Volume edit box.

• Click the OK buttons on the Material Property Data and Define Materials forms to close all forms.

7. Click the drop-down box in the status bar to change the units to.

8. Click the Define menu > Materials command to display the Define Materials form.

9. Click on CONC in the Materials area to highlight it (select it), and then click the Modify/Show Material button to display the Material Property Data form. In that form:

• Type 4400 in the Modulus of Elasticity edit box.

• Verify .2 is entered in the Poisson’s Ratio edit box.

• Type 6 in the Specified Conc Comp Strength, f′c edit box.

• Verify 60 is entered in the Bending Reinf Yield Stress, fy edit box.

• Type 60 in the Shear Reinf. Yield Stress, fys edit box.

• Accept the other default values.

• Click the OK buttons on the Material Property Data and Define Materials forms to close all forms.

10. Click the Define menu > Frame Sections command to display the Frame Properties form. In that form:

• Click the drop-down box that reads Add I/Wide Flange and then click on the Add Rectangular item.

• Click the Add New Property button to display the Rectangular Section form. In that form:

  • Type CONBEAM in the Section Name edit box.

  • Select CONC from the Material drop-down box.

  • Type 30 in the Depth (t3) edit box.

  • Type 18 in the Width (t2) edit box.

  • Click the OK buttons on the Rectangular Section and Frame Properties forms to close all forms.

11. Click the Define menu > Load Cases command to display the Define Loads form. In that form:

    • Type LIVE in the Load Name edit box.

    • Select LIVE from the Type drop-down box.

    • Click the Add New Load button.

    • Type PRESTRES in the Load Name edit box.

    • Select OTHER from the Type drop-down box.

    • Click the Add New Load button.

    • Click the OK button.

12. Select the line (frame) object by clicking on it.

13. Click the Assign menu > Frame/Cable/Tendon > Frame Sections command to display the Frame Properties form. In that form:

    • Click on CONBEAM in the Properties list box to highlight it.

    • Click the OK button.

14. Click the Draw menu > Frame/Cable/Tendons command to display the Properties of Object form. In that form,

• Click the Line Object Type drop-down list and select the Tendon option.

• Click on the joint at one end of the beam and then click on the joint at the other end of the beam to draw the tendon. The Tendon Data for Line Object 3 form will display when you release the mouse button.

15. With the Tendon Data for Line Object 3 form displayed, click the Parabolic Calculator button to display the Define Parabolic Tendon Layout for Line Object 3 form. In that form,

    • Select 1 from the Quick Start drop-down list in the lower left corner of the form.

    • Click the Quick Start button to update the Tendon Layout Data spreadsheet. An additional row of data will be added to the spreadsheet. In the spreadsheet area,

    • Type 8 in Coord 2 cell of the first row of data.

    • Ensure that -12 is in the Coord 2 cell in the second row of data.

    • Type 3 in the Coord 2 cell in the third row of data.

    • Click the Refresh button to update the spreadsheet area and the graphical display area.

    • Ensure that the Use Calculated Results for This Tendon check box is checked.

    • Click the Done button to close the Define Parabolic Tendon Layout for Line Object 3 form and redisplay the Tendon Data for Line Object 3 form.

16. With the Tendon Data for Line Object 3 form redisplayed, click the Add button in the Tendon Loads area of the form to display the Tendon Load form. In that form,

    • Select the PRESTRES load case from the Load Case Name drop-down list.

    • Type 200 in the Force edit box.

    • Ensure that all of the Friction and Anchorage Losses and Other Loss Parameters are zero. If necessary, type zero in the Curvature Coefficient, Wobble Coefficient, Anchorage Set Slip, Elastic Shortening Stress, Creep Stress, Shrinkage Stress and Steel Relaxation Stress edit boxes.

    • Click the OK buttons on the Tendon Load form and the Tendon Data for Line Object 3 form to close those forms.

17. Click the drop-down box in the status bar to change the units to .

18. Click the Define menu > Combinations command to display the Define Response Combinations form. In that form:

    • Click the Add New Combo button to display the Response Combination Data form. In that form:

      • Accept the default Response Combination Name, COMB1

      • Accept the default Combination Type, Linear Add.

      • Verify the DEAD Case is selected in the Case Name drop-down box.

      • Verify that 1 is entered in the Scale Factor edit box.

      • Click the Add button.

      • Select LIVE Case from the Case Name drop-down box.

      • Click the Add button.

      • Select PRESTRES Case from the Case Name drop-down box.

      • Click the Add button.

      • Click the OK buttons on the Response Combination Data and Define Response Combinations forms to close all forms.

19. Select the line (frame) object.

20. Click the Assign menu > Frame/Cable/Tendon Loads > Distributed command to display the Frame Distributed Loads form. In that form:

    • Verify that the Load Case Name is DEAD.

    • In the Load Type and Direction area, verify that the Forces option is selected and that the Gravity direction is selected.

    • In the Uniform Load area, type 2.2.

    • Click the OK button.

21. Select the line (frame) object.

22. Click the Assign menu > Frame/Cable/Tendon Loads > Distributed command to display the Frame Distributed Loads form. In that form:

• Select LIVE from the Load Case Name drop-down box.

• In the Uniform Load area type 1.6.

• Click the OK button.

23. Select the line (frame) object.

24. Click the Assign menu > Frame/Cable/Tendon > Output Stations command to display the Assign Output Station Spacing form. In that form:

• Type 4 in the Min Number Stations edit box.

• Click the OK button.

25. Click the Show Undeformed Shape button to remove the displayed frame output station assignments.

26. Click the Analyze menu > Set Analysis Options command to display the Analysis Options form.

• In that form click the Plane Frame XZ Plane button to set the available degrees of freedom.

• Click the OK button.

27. 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.

• Verify that the LIVE analysis case is set to Run in the Action list.

• Verify that the PRESTRES analysis case is set to Run in the Action list.

• Click the Run Now button to run the analysis.

28. 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.

29. Click the Display menu > Show Forces/Stresses > Frames/Cables/Tendons command to display the Member Force Diagram for Frames form. In that form:

• Select COMB1 from the Case/Combo Name drop-down box.

• Select the Moment 3-3 option in the Component area.

• Uncheck the Fill Diagram check box.

• Check the Show Values on Diagram check box.

• Click the OK button to display the moment diagram.

Note: You may want to print this moment diagram for comparison with the one obtained when 20 output stations are specified. To print the moment diagram, click the File menu > Print Graphics command.

Note: For response combinations, when force diagrams are plotted, exact values are only calculated at the ends of each output station. Those exact values are plotted and then they are connected with straight lines.

30. Click the Lock/Unlock Model button to unlock the model. Click the OK button when asked if it is ok to delete.

31. Select the line (frame) object.

32. Click the Assign menu > Frame/Cable/Tendon > Output Stations command to display the Assign Output Station Spacing form. In that form:

• Type 20 in the Min Number Stations edit box.

• Click the OK button.

33. Click the Show Undeformed Shape button to remove the displayed frame output station assignments.

34. Click the Run Analysis button to display the Set Analysis Cases to Run form. In that form, click the Run Now button to run the analysis.

35. 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

36. Click the Display menu > Show Forces/Stresses > Frames/Cables/Tendons command to display the Member Force Diagram for Frames form. In that form:

• Verify that the COMB1 is selected in the Case/Combo Name drop-down box.

• Verify that the Moment 3-3 option is selected in the Component area.

• Verify that the Show Values on Diagram check box is checked.

• Click the OK button to display the moment diagram.

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