CES Bridge Building Rules & Tips 2010


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Technical Guidelines and Tips on Popsicle Bridge Building Contest hosted by DLSU Civil Engineering Society (CES).

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CES Bridge Building Rules & Tips 2010

  1. 1. DLSU-CES BRIDGE Building Contest SY 2009-2010 Technical Guidelines
  2. 2. Truss Bridge Competition
  3. 3. Bridge Specifications <ul><li>Design a truss bridge that will be laid on two smooth supports with a span length (S) of 560 mm . </li></ul><ul><li>The bridge must satisfy the following specifications. (Refer to the figures) </li></ul><ul><ul><li>560 mm ≤ Length (L) ≤ 770 mm </li></ul></ul><ul><ul><li>Width (B) ≤ 140 mm </li></ul></ul><ul><ul><li>Height of Truss (H) ≤ 100 mm from the flat surface of the deck to the top </li></ul></ul><ul><ul><li>Depth (D) ≤ 50 mm from the support surface to the flat surface of the bridge deck </li></ul></ul><ul><ul><li>H + D ≤ 150 mm </li></ul></ul><ul><ul><li>Weight (W) ≤ 1.50 kg </li></ul></ul>
  4. 4. TRUSS Bridge Specs Weight, W ≤ 1.50 kg H+D ≤150mm Length, L ≤ 770 mm Height H ≤ 100 mm Span Length, between UTM supports S = 560 mm UTM Support Provide a 60 mm minimum flat bearing surface at the supported points (see sample bridges) Bridge Deck Width B ≤ 140 mm Top of UTM Depth D ≤ 50 mm
  5. 5. Sample Bridge Design A H L S D
  6. 6. Sample Bridge Design A H+D ≤ 150 mm
  7. 7. Sample Bridge Design B H L S D
  8. 8. Sample Bridge Design B H+D ≤ 15 0 mm D ≤ 50 mm H ≤ 100 mm
  9. 9. Other Requirements <ul><li>No portion of the bridge structure shall extend below the support surfaces. </li></ul><ul><li>The bridge structure shall be symmetrical about its longitudinal and transverse centerlines. </li></ul><ul><li>The bridge must have a smooth surface for the bridge deck where a toy vehicle must be able to move. </li></ul>
  10. 10. Materials and Construction <ul><li>The bridge must be constructed using plain popsicle sticks only . </li></ul><ul><li>The popsicle sticks may be cut or sanded in any manner. </li></ul><ul><li>Only all purpose glue (white) must be used to connect the popsicle sticks. </li></ul><ul><li>No other materials must be used. </li></ul><ul><li>Do not paint, coat or stain the bridge with any foreign substance. </li></ul>
  11. 11. Sample Bridge L = 700 mm, H = 200 mm, B = 130 mm, W = 1.26 kg
  12. 12. Pre-Qualification Screening <ul><ul><li>REASONS FOR DISQUALIFICATION </li></ul></ul><ul><ul><li>Not a Truss Bridge </li></ul></ul><ul><ul><li>No flat surface on bridge deck where a toy car may pass </li></ul></ul><ul><ul><li>Does not satisfy minimum required bridge span length (S) </li></ul></ul><ul><ul><li>Exceeds the maximum total length (L) </li></ul></ul><ul><ul><li>Exceeds the maximum height (H) </li></ul></ul><ul><ul><li>Exceeds the maximum width (B) </li></ul></ul><ul><ul><li>Exceeds the maximum depth (D) </li></ul></ul><ul><ul><li>Exceeds H+D limit of 150 mm </li></ul></ul><ul><ul><li>Exceeds the maximum weight (W) </li></ul></ul><ul><ul><li>Other materials (paint, coating, etc) aside from popsicle sticks and glue used </li></ul></ul><ul><ul><li>Portions of the bridge extend below the supports </li></ul></ul>
  13. 13. Weight , W <= 1500 g
  14. 14. Bridge Design Category (One Winner) <ul><li>Only bridges which pass the prequalification screening will be qualified. </li></ul><ul><ul><li>Creativity & innovation in form and design – 30% </li></ul></ul><ul><ul><li>Application of bridge design principles – 30% </li></ul></ul><ul><ul><li>Practicality and Implementability – 20% </li></ul></ul><ul><ul><li>Neat and well-polished bridge -20% </li></ul></ul>
  15. 15. Best Bridge Design Winnner: 2008-2009 (DHVCAT)
  16. 16. Bridge Testing <ul><li>A Universal Testing Machine (UTM) will be used to test the bridge. </li></ul><ul><li>Two 14 mm rebars spaced at a specified distance, will be placed on the bridge deck at midspan. </li></ul><ul><li>A hollow “cage” will be placed on the rebars, on which the load from the UTM will be transferred. </li></ul><ul><li>A displacement transducer will be attached to the UTM to measure the bridge displacement (  ) in mm. </li></ul><ul><li>The load P (kg) when the load dial of the UTM stops indicates bridge failure. </li></ul>
  17. 17. <ul><li>The Three Bridges with the </li></ul><ul><li>Highest Strength Rating (S) </li></ul><ul><li>S = 1000 (P/  ) </li></ul><ul><li>W </li></ul><ul><li>where P in kg,  in mm, and W = bridge weight in kg </li></ul><ul><li>The strength rating S is the bridge stiffness (kg/m) per unit weight (kg). </li></ul>Strength Design Category (Top 3 Winners) P 
  18. 18. Bridge Testing Testing Results P = 30 kg,  = 5 mm, W = 1.26 kg S = 30 x 1000/(5 x 1.26) = 4761.90 (kg/m)/kg
  19. 21. TOP 4 STRENGTH CATEGORY 5 th Bridge Building Contest 2008-2009
  20. 22. W=0.492 kg, P=27 kg, D=8.7 mm, S=6308
  21. 23. W=0.541 kg, P=25 kg, D=8.6 mm, S=5375
  22. 24. W=1.205 kg, P=65 kg, D=13.4 mm, S=4025
  23. 25. Popsicle Stick Bridge Building <ul><li>TIPS </li></ul>
  24. 26. TIP 1 : if you want to efficiently use the strength of popsicle sticks, design your bridge such that tensile forces not compressive forces are developed in most of the members. “ Popsicle sticks are stronger in tension than compression because of buckling.”
  25. 27. You can analyze the truss using A structural analysis software.
  26. 28. TIP 2 : If you want to increase the capacity of the members against buckling, then provide braces.
  27. 29. Before Loading After Loading: No Horizontal Braces at the top. Buckling occurred.
  28. 30. TIP 3 : A deep hollow box girder is relatively light and has a larger flexural capacity.
  29. 31. TIP 4 : Don’t make your bridge to heavy!
  30. 35. tHank yOu! Happy Bridge Building!