lecture 18: case studies: successes and disasters in …mech350/lectures/mech350-lectur… · ·...

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MECH 350Engineering Design I

University of VictoriaDept. of Mechanical Engineering

Lecture 18: Case Studies:

Successes and Disasters in Engineering

© N. Dechev, University of Victoria

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Engineering activities have created tremendous achievements, and spectacular failures in the past.

It is very important for you to learn the “history of engineering” in your spare time. There are numerous books on the subject. Many important lessons can be learned by the study of previous engineering designs.

Always keep up to date in “current engineering events”.

Study of history and current events, will help you learn about the many successes and failures that have occurred, and to understand why they occurred.

Case Studies: Engineering Success/Failure


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Here we will briefly examine various engineering achievements, including:

The CN TowerThe Burj KhalifaThe TitanicThe Panama CanalThe Tacoma Narrows, Brooklyn, and Golden Gate Bridges

Throughout these examples, consider the concepts taught in this course, and how they may have been used/applied.



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Some ‘good examples’ of previous engineering successes and failures, can be found on course web site, under the file name: Eng-SuccessFailure-CaseStudies



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CN Tower Facts:Canadian Engineering Design!

Height: 533 m (1815 ft)Design Team:

NCK Engineering (Structural Engineers)John Andrews (Architects)Webb, Zerafa, Menkes, Housden (Architects)Foundation Building Construction & Canron

Completed: June 26th, 1976Tallest Free Standing Structure on Earth, for almost 31 years. (until 2007)Tallest Observation Deck for 31 years. (until 2008)Cost: $63 Million CDN (1976)

The CN Tower


The CN Tower[Image from: Wikipedia Commons ]

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The Burj Khalifa Facts:Height: 828 m (2717 ft)Design Team:

Skidmore, Owings, and Merrill (Architects and Engineering)Bill Baker (Chief structural engineer)Adrian Smith (Chief Architect)Samsung C&T (Primary Contractor)

Completed: Jan 4th, 2010.Tallest Free Standing Structure on Earth.Tallest Observation DeckCost: $1500 Million (2010)

The Burj Khalifa


The Burj Khalifa[Image from: Wikipedia Commons ]

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Titanic Facts:Largest passenger ship (at the time)46,500 tons, 269 m long, 28 m wide.Capacity (Crew and Passengers): 3547Completed: Mar 31, 1912. Sank April 15, 1912.

Failure (Multiple Causes):Struck an iceburgInsufficient lifeboatsInsufficient equipmentPoor communicationsPoor operationPoor construction materials

The Titanic


The Titanic[Image from: Wikipedia Commons ]

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Tacoma Narrows Bridge


Tacoma Narrows Bridge Facts:Total Length: 1810 mLongest Span: 853 mCompleted: July 1, 1940. Collapsed: Nov 7, 1940.

Failure (Multiple Causes):First use of ‘I-beams’ to support the roadbed, unlike other bridges that used a ‘truss’ under the roadbed.Wind would induce an effect known as ‘flutter’, causing alternating lift on upper/lower surface of road. The period (freq) of the flutter was close to the resonance (nat. freq) of the structure.Resonance & insufficient understanding of ‘all vibration modes’ for the structure.

The Tacoma Narrows Bridge (1940)[Image from: Wikipedia Commons ]

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The Brooklyn Bridge, Golden Gate Bridge


Brooklyn Bridge Facts:Total Length: 1825 mLongest Span: 486 mCompleted: May 4, 1883.

Golden Gate Bridge Facts:Total Length: 2737 mLongest Span: 1280 mCompleted: May 27, 1937.Cost: $35 million (1937)

Brooklyn Bridge, 1896[Image from: Wikipedia Commons ]

Golden Gate Bridge,[Image from: Wikipedia Commons ]

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The Panama Canal


Panama Canal FactsTotal Length: 77 kmWidth: 33.5 m (110 feet)French Construction: 1881-1889 (Halted)US Construction: 1904-1914.Excavation: 47 million cubic meters (enough to cut a 16 foot diameter hole, all the way to the center of the Earth)

Panama Canal[Image from: Wikipedia Commons ]

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There are many types of engineering failures, some more serious than others. In some cases, the most spectacular failures may involve the loss of life, damage to health, cause environmental damage, or even inflict damage to society.

It is vital to study these failures, and understand why they occurred, to prevent similar events in future.

Engineering has special branches to deal with failure, including:Risk AnalysisFailure AnalysisFailure Mode and Effects Analysis (FMEA)Forensic Engineering

Engineering Failures


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What Happened?

Why did it Happen?

What was the Consequence?

What can be done to Prevent this from occurring again?

Recent Engineering Failures:Case Study: Deepwater Horizon Accident


Image of Burning Offshore Drilling Platform [Wikipedia]

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What Happened?

Why did it Happen?

What was the Consequence?

What can be done to Prevent this from occurring again?

Recent Engineering Failures:Case Study: Fukushima I Nuclear Power Plant


Image of Fukushima I (before accident) [Wikipedia]

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Basic Information:Classification: Light Water Reactor (See diagram, next page)Moderator: WaterFuel: Enriched Uranium for units 1,2,4. MOX for unit 3.

Points for Discussion:Electric Power required to shut down reactor, by continuing the flow of water.Water is the “Moderator” and is required to suppress the reaction, and carry heat away from the fuel rodsStorage of Spent Fuel Rods (placed above reactor, in cooling pools)

Case Study: Fukushima I Nuclear Power Plant


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Schematic Illustration of Fukushima Nuclear Plant[Reference: http://dailyenergy.net]

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Schematic Illustration of Fukushima BWR Mark I, Reactor[Reference:http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant]

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Case Study: Canadian CANDU Reactor Design


CANDU Bruce Nuclear Generating Station, Ontario[http://en.wikipedia.org/wiki/CANDU_reactor]

CANDU Reactor Design[http://en.wikipedia.org/wiki/CANDU_reactor]

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There are many reasons for engineering failures:Unidentified operational/environmental conditionsUnpredicted eventsInadequate understanding of fundamental principlesInadequate knowledge of materialsPoor construction/workmanshipNegligence/Carelessness________________________________________________________

Additionally, there are more advanced theories on why engineering failures occur.



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Murphy’s Law: (is an adage/epigram, not actually a law!)“Anything that can go wrong, will go wrong”

Obviously, Murphy’s Law is absurd. However, it does give an engineer pause, and forces him/her to consider:

What if something does go wrong during operation?What are the “failure modes”?How will the design perform while failing or after failure?What are the consequences of failure?

Loss of MoneyLoss of LifeEnvironmental Damage___________________



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Is it possible to “Design for Failure”? In other words, since failure during operation is distinctly possible, can you design your product/process to “fail in a safe/controlled manner”?

Certainly!

Using our structured design process, we can incorporate “Design for Safe Failure” by implementing those principles in the following steps:

Goal StatementsObjectives/ConstraintsSelection Method for Concepts



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Interesting Theories on Engineering Failures:


Recommended Books on Failure Theories:Charles Perrow, Normal Accidents: Living with High Risk Technologies, Princeton University Press, ISBN 0-691-00412-9, First Published 1984, 1999James Reason, Human Error, Cambridge University Press, ISBN 0-521-314194, First Published 1990, 2003

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