1. Project 2: Straw Bridge Situation: We should across the river safely.
Design brief: To design and make a straw bridge model for practicing purpose
Group : 3 or 4 members
Duration: 3 cycles

2. Project 2: Straw Bridge
Material provided: plastic straws – 40 (200mm long)
Colourless Self Adhesive Tape
Requirement :
1) You are free to design the structure. The product must be made of plastic straw and is fastened by colourless self-adhesive tape.

3. Project 2: Straw Bridge
2) The bridge model should be 100mm wide and over 500mm long.
>500mm
100mm
This is a sample only. Don’t copy!

4. Project 2: Straw Bridge
180mm
500mm
Testing platform
175mm

5. Project 2: Straw Bridge Requirement :
3) Straws parallel overlapping design is not allowed.

6. Project 2: Straw Bridge Requirement :
4) Weights are placed one by one on the straw structure model until it breaks down so as to test the loading ratio.
(Weight: 250ml juice
Juice
Pack

7. Project 2: Straw Bridge Requirement :
5) Weights are placed one by one on the bridge until it breaks down so as to test the loading ratio.
Maximum Loading
Weight of the bridge model
Loading Ratio =

8. Project 2: Straw Bridge Requirement :
6) The bridge should not consist any component touching the ground of the testing platform and nothing can be used to fix the model on the platform.

9. Project 2: Straw Bridge
Testing procedures :
Measure the weight of the bridge model by the electronic balance.

10. Project 2: Straw Bridge
Testing procedures :
2) Place the bridge model on the testing platform which is designed for holding a bridge of over 500mm long.
500mm
Testing platform

11. Project 2: Straw Bridge
Testing Methods:
3) Place weights one by one on the central of the bridge model until it breaks down.
Testing sample

12. Project 2: Straw Bridge
Testing Methods:
3) Place weights one by one on the central of the bridge model until it breaks down.
Testing sample

13. Project 2: Straw Bridge 4) Count the number of weights used.
Testing procedures :
4) Count the number of weights used.
5) Calculate the loading ratio. Higher loading ratio is recorded, higher mark will be given.
Maximum Loading
Weight of the bridge model
Loading Ratio =

14. Project 2: Straw Bridge http://pghbridges.com/basics.htm Information:
Search the information about frame, structure and bridge via internet.
Sample

15. Project 2: Straw Bridge Design consideration: Solution
Weight of the bridge model
Stability
Information
Solution
Bridge structure
Special features of straws

16. Project 2: Straw Bridge Suggested Procedures Design Considerations
Initial Ideas
Final Idea
Solution
Make a bridge model (Cycle 2)
Testing (Cycle 3)
Evaluation (Cycle 3)

17. Project 2: Straw Bridge Assessment: Loading Ratio Size Marks < 5
Not fit
5 and <10
 - - - 1
10 and <15
Fit in 2
15 and <25
  - - - 3
25 and <35 4
35 and <45 5
45 and <55 6
55 and <65 7 65 8
Total
8 + 2

18. Project 2: Straw Bridge Assessment:
e.g. The model’s size fits the testing platform
Weight = 25g
Loading = 4 x 275g = 1100g
Loading ratio = 1100 / 25
= 44
35 and <45 5
Marks = = 7

19. Project 2: Straw Bridge Information: Weights Bridge model
Range = 500 mm

20. Project 2: Straw Bridge Information: Weights Bridge model
Range = 500 mm

21. Project 2: Straw Bridge Information: Weights Bridge model
Range = 500 mm

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