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Critical Load

+Learning Objectives

Learn about structural engineering

Learn how to reinforce the design of a structure to hold more weight.

Use mathematical calculations for testing

Practice communication skills through written and oral exercises

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Millau Viaduct

Millau, France

World’s Tallest Bridge

2460m long434m pylon height270m road height

December, 2004

Critical LoadGreat Structures of the World

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Skyscraper of Cards

2010 World RecordHouse of Cards

Made of 218,792 cards, measuring 10.39m long, 2.88m tall and wide. No glue or tape; just cards

Built by Bryan Berg in 2010

Critical LoadGreat Card Structures of the World

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Venetian Macao-Resort-Hotel in Macau, China, on 10 March 2010.

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Force is placed on a structure

Structure can support up to a certain force created by the weight

At a certain point, the structure will fail, breaking

The maximum force the structure can sustain before failure is known as the “Critical Load”

Critical LoadWhat is Critical Load?

Force

Force

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+Critical Load

A high critical load is not the only parameter to considerIs the best bridge made by filling a canyon with

concrete? It certainly would have a high critical load!

Consider also the weight of the structureLighter is better, given the same critical load

These two parameters are combined in an “Efficiency Rating”:

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Efficiency

+Critical Load

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Groups of 2

Up to 10 cards + 1m tape

Devise a plan to build a load bearing structure Should have a flat top Support load with base area of

10x10cm at least 8 cm above the table

No altering of cards allowed – just tape!

No wrap-ups of tape Tape is used to connect cards only

Your Turn

+Critical Load

Your efficiency rating:[Load at Failure] / [# of cards used]

Predict what the rating of your design will be

Build your designTest it!Discuss improvements, then repeat

exercise for a second design

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Your Turn