1 Nov 2012

Bridge Building Challenge

From Our Changing World, 9:34 pm on 1 November 2012

By Alison Ballance

An arch bridge design, and many of the 36 bridges

Richard Cryer, Chris Barber and team with their arch bridge, and Alessandro Palermo amidst some of the 36 bridges built solely from MDF and glue.

Bridge building has been one of the litmus tests for second year University of Canterbury civil engineering students for almost 20 years. Canterbury University structural engineer Alessandro Palermo from Civil and Natural Resources Engineering challenges his students to build a bridge using just MDF (medium density fibreboard) and glue – and then test it to destruction while it is placed across the river that runs through the university. The 4-metre long bridge must hold first one and then two people, and then break when the third person walks on. Prizes are awarded for aesthetic design and structural efficiency.

This year, one hundred and ninety students built 36 bridges, and Alison Ballance headed along to the university’s civil engineering lab to find out how the competition works, and to see some of the novel bridge designs - while they were still in one piece.

Bad weather meant the competition was postponed by two days, allowing students Richard Cryer and Chris Barber time to paint and decorate their bridge. However, they report they underestimated the flexibility of MDF, and their arch bridge deformed and bent so much that it became too short and fell in the river! Student Courtney McCrostie was pleased that her team’s bridge performed exactly as required, breaking when the third person stood on it.

Courtney McCrostie with her team's bridge, and that bridge being tested

Courtney McCrostie with her team's bridge before testing (left), and breaking as required with three people on it (right).

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