Bridge Building

Paper Bridge (finished version)

This is how our paper bridge looked when finished

Paper Bridge W.T. V1

The bridge held 17 nuts during the first Weight Test (W.T.). We therefore decided to add as much weight as we could find

Paper Bridge W.T. V2

The second Paper Bridge Weight Test (W.T.) held a much higher weight, as seen by the picture above

Bridge Builder 2016

Requirements that had to be met:

Deck 12 meters above the water
Standard Abutments
No Pier
No cable anchorages
Medium strength Concrete
Standard two lanes
Pratt through Truss
Carbon steel components
Compression force/strength ratio cannot exceed 0.40 (+/-0.01)
Tension force/strength ratio cannot exceed 0.45 (+/-0.01)
15% of all bridge members must be hollow tubes (+/-1%) - We have 4 hollow tubes out of 29 members.

4/29 = 0.137 * 100% = 13.7% = 14%

Lowest possible cost - Our bridge costs $322,582.28.

Net forces (compression and tension) on each joint:

Diagram of labelled joints and members:

Net force on each joint:

These were calculated by using the given tension and compression force on each members, to find the net force on the member. The x and y force on each joint was found by adding the force of each member in the direction it was pulling/pushing on the joint, using the cosine of the members at a 45 degree angle. The x and y forces were then plugged into an equation (adding x and y squared and square rooting it) to find the resulting net force.

Calculations: Link to Spreadsheet