Draw a Bridge in RISA

Do you need to design a structure that inherently follows building codes? If so, RISA is for you. RISA is the most prolific modeling software in the field of structural engineering and can be used to model almost any kind of structure. It already contains all the building codes for almost every material in the field, so you will rest assured that your structure follows the necessary building codes. This instruction will equip you with the tool set of RISA by building a simple, truss bridge.

Steps

Open RISA

  1. Click the RISA icon.
  2. When you open RISA you will encounter the following screen with the “Starting a Model” dialogue box as demonstrated in the picture.
  3. Close the dialogue by clicking "Close".
    • The dialogue box functions to help the user to get started, however it overlooks the most important aspect of the design: Drawing the Grid. So we will begin by closing the dialogue box and drawing the grid.

Draw Grid

  1. Click on the icon pictured in the black box or Go to Modify --> Grid.
  2. Enter (5@3, 3@1) into the “Define Drawing Grid” dialogue box as shown in Figure 3.
    • 5@3 means 5 columns that are {{safesubst:#invoke:convert|convert}} wide
    • 3@1 means 3 rows that are {{safesubst:#invoke:convert|convert}} deep/long
  3. Save Grid by clicking “Save” under the “Save and Recall Grid Settings”.
    • This allows you to retrieve the same grid later on. It's especially useful if you always use the same grid.
  4. Label the grid, “Drawing Grid 2” when this dialogue box appears.
  5. Click “Ok”.

Label Sections

  1. Go to Spreadsheets --> Sections or simultaneously press the keys Ctrl+Alt+S.
    • This leads to a dialogue box appearing. It is pictured in the following step.
  2. Label the sections by typing the following section names into the "Label" column.
    • TopChords
    • BotChords
    • Webbing
    • Columns
    • Lateral Bracing

Draw Members

  1. Begin Drawing the Top Chord.
  2. Click on the icon pictured in the black box or Go to Insert --> Members...
  3. Choose TOPCHORDS to be the Member Section Set as pictured.
  4. Set Release Codes to be “Pinned at Both Ends (Torsion Fixed)”.
  5. Click “Ok” to advance.
  6. Draw the first member from N1 to N2 as pictured
    • Note that the nodes N1 and N2 will not show up until you click on them.
  7. Draw the second member from N2 to N3 as pictured.
  8. Draw the third member from N3 to N4 as pictured.
  9. Draw the fourth member from N4 to N5 as pictured.
  10. Draw the the fifth member from N5 to N6 as pictured.
  11. Click "Esc" on your keyboard to continue.
    • DO NOT CLICK "Esc" TWICE! If you happen to do so, go to the Troubleshooting Section (Part 6) to get it figured out.
  12. Begin Drawing the Bottom Chord.
  13. Repeat Steps 1-10 to draw the bottom chord, except in step 2 use BOTCHORDS instead of TOPCHORDS. The image demonstrates the bottom chord.
  14. Begin Drawing the Columns.
  15. Repeat Steps 1-4 to begin drawing the Columns, except in Step 2 use COLUMNS instead of TOPCHORDS.
  16. Draw a member from N1 to N13.
  17. Draw a member from N6 to N14.
  18. Begin Drawing the Webbing.
  19. Repeat Steps 1-4 to begin drawing the Webbing, except in Step 2 use WEBBING instead of TOPCHORDS.
  20. Draw a member from N1 to N8.
  21. Draw a member from N8 to N3.
  22. Draw a member from N3 to N10.
  23. Draw a member from N10 to N5.
  24. Draw a member from N5 to N12.

Define Fixity

  1. Click on the icon pictured here or go to Modify --> Boundaries.
  2. This dialogue box will appear.
  3. Click the “Fixed” button in the following window.
  4. Click "Apply" to continue.
  5. Click on the nodes N13 and N14 to fix the bottom of the columns.
    • This tells RISA that the bridge is attached to the ground here and will not be able to move or rotate in any direction.
  6. It should look like this.
  7. Click Esc on your keyboard to continue.

Troubleshooting

  1. This is the picture of your screen when you accidentally press "Esc" twice.
  2. Go to Window --> Single View to return to your model.

Tips

  • Make sure you print out these directions if you want to use them. It will make it easier to follow the instructions, especially if you don't have a dual monitor setup.

Warnings

  • Only registered versions of RISA receive updates to the current building codes.
  • Unless you use the registered version of RISA, you will not be able to receive tech support. RISA's tech support is considered a vital asset when modeling complicated structures.
  • Be aware that older versions that may be available to torrent for free do not receive the updated codes.
Retrieved from "https://kipkis.com/index.php?title=Draw_a_Bridge_in_RISA&oldid=300441"