The document outlines the technical guidelines for a truss bridge competition held at DLSU-CES for the academic year 2009-2010, specifying various design requirements such as dimensions, weight limits, and material restrictions. Bridges must adhere to strict specifications, including using only popsicle sticks and all-purpose glue, and must have a smooth deck for a toy vehicle. A universal testing machine will evaluate the bridges based on strength and displacement, with awards given for creativity, design principles, and practicality.

1. DLSU-CES BRIDGE Building Contest SY 2009-2010 Technical Guidelines

2. Truss Bridge Competition

3. Bridge Specifications Design a truss bridge that will be laid on two smooth supports with a span length (S) of 560 mm . The bridge must satisfy the following specifications. (Refer to the figures) 560 mm ≤ Length (L) ≤ 770 mm Width (B) ≤ 140 mm Height of Truss (H) ≤ 100 mm from the flat surface of the deck to the top Depth (D) ≤ 50 mm from the support surface to the flat surface of the bridge deck H + D ≤ 150 mm Weight (W) ≤ 1.50 kg

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. Sample Bridge Design A H L S D

6. Sample Bridge Design A H+D ≤ 150 mm

7. Sample Bridge Design B H L S D

8. Sample Bridge Design B H+D ≤ 15 0 mm D ≤ 50 mm H ≤ 100 mm

9. Other Requirements No portion of the bridge structure shall extend below the support surfaces. The bridge structure shall be symmetrical about its longitudinal and transverse centerlines. The bridge must have a smooth surface for the bridge deck where a toy vehicle must be able to move.

10. Materials and Construction The bridge must be constructed using plain popsicle sticks only . The popsicle sticks may be cut or sanded in any manner. Only all purpose glue (white) must be used to connect the popsicle sticks. No other materials must be used. Do not paint, coat or stain the bridge with any foreign substance.

11. Sample Bridge L = 700 mm, H = 200 mm, B = 130 mm, W = 1.26 kg

12. Pre-Qualification Screening REASONS FOR DISQUALIFICATION Not a Truss Bridge No flat surface on bridge deck where a toy car may pass Does not satisfy minimum required bridge span length (S) Exceeds the maximum total length (L) Exceeds the maximum height (H) Exceeds the maximum width (B) Exceeds the maximum depth (D) Exceeds H+D limit of 150 mm Exceeds the maximum weight (W) Other materials (paint, coating, etc) aside from popsicle sticks and glue used Portions of the bridge extend below the supports

13. Weight , W <= 1500 g

14. Bridge Design Category (One Winner) Only bridges which pass the prequalification screening will be qualified. Creativity & innovation in form and design – 30% Application of bridge design principles – 30% Practicality and Implementability – 20% Neat and well-polished bridge -20%

15. Best Bridge Design Winnner: 2008-2009 (DHVCAT)

16. Bridge Testing A Universal Testing Machine (UTM) will be used to test the bridge. Two 14 mm rebars spaced at a specified distance, will be placed on the bridge deck at midspan. A hollow “cage” will be placed on the rebars, on which the load from the UTM will be transferred. A displacement transducer will be attached to the UTM to measure the bridge displacement (  ) in mm. The load P (kg) when the load dial of the UTM stops indicates bridge failure.

17. The Three Bridges with the Highest Strength Rating (S) S = 1000 (P/  ) W where P in kg,  in mm, and W = bridge weight in kg The strength rating S is the bridge stiffness (kg/m) per unit weight (kg). Strength Design Category (Top 3 Winners) P 

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

21. TOP 4 STRENGTH CATEGORY 5 th Bridge Building Contest 2008-2009

22. W=0.492 kg, P=27 kg, D=8.7 mm, S=6308

23. W=0.541 kg, P=25 kg, D=8.6 mm, S=5375

24. W=1.205 kg, P=65 kg, D=13.4 mm, S=4025

25. Popsicle Stick Bridge Building TIPS

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.”

27. You can analyze the truss using A structural analysis software.

28. TIP 2 : If you want to increase the capacity of the members against buckling, then provide braces.

29. Before Loading After Loading: No Horizontal Braces at the top. Buckling occurred.

30. TIP 3 : A deep hollow box girder is relatively light and has a larger flexural capacity.

31. TIP 4 : Don’t make your bridge to heavy!

35. tHank yOu! Happy Bridge Building!