Bridge Challenge @ Ngee Ann 2009

Kranji Sec sent 2 teams of 8 students to take part in the Bridge Challenge 2009 organised by Ngee Ann Polytechnic. The aim was to build the strongest and lightest bridge within 6 hours, using bamboo skewers, vaguard sheet, limited string and glue.

These are the rules of the competition:

Materials
On Day 1of the competition, every team will be given the
following materials for their use:

8” Satay sticks (Pack of 180 sticks) - 5 packs
Ball string - 2 m
630 x 510 mm Vanguard sheet - 2 pcs
A4 paper - 2 pcs
4” x 5/16” Glue sticks (Pack of 12 sticks) - 1 pack


Dimensions
The bridge must span across two supports placed 600 mm apart (the width of each bridge support is 50 mm). The bridge may span straight from one support to the other. The width of the bridge must be at least 150 mm throughout the entire span. There is no limit to the height of bridge.


Judging Criteria
- Strength factor [Failure Load/(weight of bridge +
penalty weight)] 50%
- Design (Structural concept) 15%
- Construction (Workmanship) 15%
- Aesthetics & Innovation (Profile, shape and etc) 15%
- Fact Sheet 5%

The participants

Team 1:

1. Yow Kai En (3B)
2. Foo Chuan Ri (3A)
3. Grayson Chang Fanyao (3D)
4. Jasmend Yow (3F)

Team 2:

1. Yap Hong Yi Desmond (3A)
2. Ng Shao Hui (3B)
3. Tham Chin Siong (3B)
4. Quek Hong Wei (3A)

Pre-Competition

We started preparing only after Common Test. I foolishly thought with 3 weeks, it should be more than sufficient to prepare for the competition.

Unfortunately, I was rudely surprised at the slow pace of work the teams are producing.

Hence I went to research and build a bridge prototype (which they are suppose to do...) to give them something to base on and to benchmark against their miserable effort. Credit of the design goes to Garret Bridges (http://www.garrettsbridges.com/design/trussdesign). So I spent half a day and created this:

Team 2 decided to follow my design with some modifications. It was strong and sturdy but was also very heavy.

Team 1 will use the design based on previous bridge competition that Kranji took part in. The design was very light but the load that it can handle is questionable...

Day 1

Both teams started at 1030 am....

and ended at 430 pm. The 6 hours might sound like a long time but both teams only barely manage to finish on time.

I heaved a huge sigh of relief...

Here the some designs from other schools:

and of course the 2 bridges from Kranji!

Day 2 - Judging

The bridges are loaded at the centre as shown. Loading will stop when the bridge breaks or the maximum load of 30 kg is reached.

In addition, the participants need to explain their design concept to the judges themselves.

Some videos of the loading for our 2 bridges. The jerkiness is due to youtube...:

Team 1

Team 2

Results
Here's a summary of the results of all the bridges at the challenge:


So how did Kranji fare?

Remember, it's not the based on the absolute load but the load factor, which is calculated by the load supported by the bridge divided by the mass of the bridge. E.g. for Team 1, their score is

Team 1 load factor: 10000 / 170 = 58.8

This score actually places them among the top 5! And they went on to win the Merit award!




Team 2 was the highlight of the competition (almost everyone wants to take a look at the Kranji bridge) because it's the only bridge that supported the maximum load of 30 kg. However, they lost in terms of load factor to Pasir Ris Crest which manage to support 16 kg with their bridge that has a mass of only 190 g.... Still, a very good job by Team 2 and they clinched the 2nd place - Silver Award!



Congratulations to all participants! Hopefully you enjoyed and more importantly learned something from this experience. I know I did.... :)