failure by design inquiry physics

Failure By Design

www.failurebydesign.infoInquiry Physics

www.inquiryphysics.org

Purpose

Tacoma Narrows Bridge CollapseExamine different types of wave

motion and how aerodynamic effects destroyed a structure

Hyatt Hotel Walkway CollapseUse your analytical and deductive

skills to speculate about what caused a structural disaster

Hyatt Walkway CollapseKansas City

Hyatt Regency hotel opened in 198040-story towerFunction blockConnecting atrium with three elevated walkways 117 ft (36 m) long

The Disaster

Atrium crowded with 1500-2000 people for a dance competitionSecond and fourth-floor walkways collapsed114 people killed, over 200 injured

July 17, 1981(one year after opening)

Hyatt Walkway CollapseThe Disaster

The Disaster

2nd-floor walkway designed to hang from 4th-floor walkway, which was hung from roof by three rods along each side of its 117 ft (36 m) length

3rd floor walkway was separate and survived

Hyatt Walkway CollapseThe Disaster

The Puzzle

Since both the 4th and 2nd floor walkways fell, which parts of the walkways could have failed?

Hyatt Walkway CollapseThe Puzzle

The Puzzle

What evidence would you look for to decide which part did fail?


Hyatt Walkway Collapse – The Puzzle

Hyatt Design Animation

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The Puzzle

Have you decided which part most likely failed?

Next is an important clue.


The Puzzle: A Clue

Design ChangeOriginal design used single rods to support both walkways, but they would have been awkward to install and thread.

Each rod would have connected to 4th-floor walkway as shown.

Hyatt Walkway CollapseThe Puzzle: A Clue

The Puzzle: A Clue

Design ChangeAs-built, the single long rods were replaced by a pair of shorter rods connecting to the 4th-floor walkway as shown.


Hyatt Walkway Collapse – The Puzzle: A Clue

Hyatt Design Change

The Puzzle: A Clue

How did the design change affect the physics of the walkway connection?

Now which part do you think failed?

It is time to view the evidence…


The Puzzle: Solution

The 4th-floor hanger rods were found intact, with nuts and washers in place.

Hyatt Walkway CollapseThe Puzzle: Solution


The 4th-floor box beams were separated at the ends, with the 2nd-floor hangers still in place.


Hyatt Walkway Collapse – The Puzzle: Solution

Hyatt Failure Animation

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The design change doubled the load on the 4th-floor box beams.

Original Design As-Built


The Consequences

Engineer of record and project engineer had their Missouri professional engineering licenses revokedEngineering company lost its certificate of authority as an engineering firmMillions of dollars in damages awarded in civil cases brought by victims and their families

Hyatt Walkway CollapseThe Consequences

Design Improvements

Add more hanger rods and box beamsUse larger washersInstall bearing plates to move load to sides of box beams

Flip box beams back-to-back and use web stiffenersHyatt atrium now has one walkway supported by floor columns

Hyatt Walkway CollapseDesign Improvements

Tacoma Narrows Bridge Collapse1940 suspension bridge in Washington state

Location

Tacoma Bridge CollapseLocation

Location

Link between Olympic Peninsula and mainland

Tacoma Bridge CollapseLocation

Design

2800 ft center span

Third-longest in the world in 1940 (5000 ft; 2800 ft center span)Quite narrow (39 feet; two lanes)Bridge deck supported by vertical cables hung from two long cables strung from one shore, over two towers, to other shore

Tacoma Bridge CollapseDesign

Design

To reduce costs, sides constructed of solid 8-foot tall I-beams rather than typical open trusses


Design

concrete sidewalk

two-lane concrete roadway

curb

I-beams

8 ft

39 ft


Early Symptoms

Bridge nicknamed “Galloping Gertie” by drivers who would be startled as cars in front of them would bounce in and out of view.Engineers spent four months trying to reduce the vibrations.

Tacoma Bridge CollapseEarly Symptoms

Early Symptoms

Over several months, additions weremade to reduce deck bounce

Added stiffening cables

Added cable stays on sides, connecting main cable to deck

Added hydraulic dampers

Each would fail, one catastrophically

(snapped)

(seals ruined when bridgesandblasted for painting)

(one side slipped on day of collapse)


Wave medium moves perpendicular to direction of wave travel

Transverse Waves

Transverse waves

Nodes are where medium does not move

Antinodes are where the medium moves most


Transverse Waves

Gertie’s Transverse Wave Types

Towers were nodesVarious types: 0 to 8 nodes between towers

Most common type 0 nodes between

towers Double amplitude 2

feet Frequency 8

vibrations/min

Highest amplitude type 2 nodes between

towers Double amplitude 5

feet Frequency 12 vib/min


The Disaster

Midnight storm weakens bridge deck and cable stays

November 7, 1940(four months after opening)

Three people in two cars trapped on bridge as torsion began; they left cars and crawled to safety; one scared dog had to be left behind and later died when bridge fell.

Mid-morning wind reaches 40-45 mphBridge closed at 10 am and bridge begins torsional wave motion

Tacoma Bridge CollapseThe Disaster

Torsional Waves

Torsional (twisting) waves


Tacoma Bridge Collapse – The Disaster

Collapse Movie

Collapse Movie


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Center Span Breaks

11 am: Center span finally breaks apart


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The Puzzle

Why did this bridge oscillate so much?

Why did this bridge fail when other, longer bridges didn’t?

What design changes might have prevented this failure?

Tacoma Bridge CollapseThe Puzzle

Oscillation

Solid I-beam girders, unlike trusses, did not allow wind to flow throughFlexible bridge oscillated vertically (transverse waves) due to vertical forces from “vortex shedding” as wind flowed around side girders



Oscillation

Torsional waves began when center cable stays on one side failed, allowing cable to slip back and forth

As bridge deck tilted, its angle into the wind changed and created new vortices that steadily increased its twisting until failure



Depth Ratios

This shallow bridge was more flexible than other suspension bridges of the time


Bridge Depth/Span RatioTacoma Narrows 8 ft / 2800 ft 1 : 350

Bronx-Whitestone

11 ft / 2300 ft 1 : 209

Golden Gate 25 ft / 4200 ft 1 : 168

George Washington

36 ft / 3500 ft 1 : 97


Width Ratios

This bridge was also narrow, again making it more flexible than

others


Bridge Width/Span RatioTacoma Narrows 39 ft / 2800 ft 1 : 72

Bronx-Whitestone

74 ft / 2300 ft 1 : 31

Golden Gate 89 ft / 4200 ft 1 : 47

George Washington

106 ft / 3500 ft

1 : 33


Deflection Comparisons

More Vertical Deflection


More Torsional Deflection


Design Changes


Use open trusses instead of I-beamsIncrease depth/span & width/span ratiosIncrease bridge weightInstall better dampeners

Bridge rebuilt in 1950 with these changes; new bridge has lasted >50 years


New Bridge Comparison


Old bridge New bridgeDeck design Solid I-beams Open trusses

Depth/span ratio

1 : 350 1 : 112

Width/span ratio

1 : 72 1 : 47

Bridge weight on cables

11,250 tons(1.0 x 108 N)

18,160 tons(1.6 x 108 N)

Hydraulic Dampers

At towers (broken)

At towers & midspan


New Bridge Comparison


1940 Bridge 1950 Bridge


Comparison Photos

Old vs. New


2007 BridgeTacoma Bridge CollapseIn 2007 a new bridge opened adjacent to the 1950 bridgeto alleviate traffic congestion.

References 1

References (1 of 6 pages) USED IN ACCORDANCE WITH “FAIR USE”

PROVISIONS OF COPYRIGHT LAW FORNON-PROFIT EDUCATIONAL PURPOSES

Andradne, R. (2000). Gertie’s last gallop [Online]. Available: http://www.gateline.com/gertie/index.htm or http://www.gateline.com/gertie/Galloping%20Gertie.zip [2001, January 27].

Billah, K.Y., & Scanlan, R.H. (1991, February). Resonance, Tacoma Narrows bridge failure, and undergraduate physics textbooks. American Journal of Physics, 59(2), 118-124. Available: http://www.ketchum.org/billah/Billah-Scanlan.pdf [2001, January 27].

Edge, R. (1998). String and sticky tape - and other fun experiments [Online]. Proceedings of the Hands on - Experiments in Physics Education International Conference. Duisburg, Germany. Available: http://ubntint.uni-duisburg.de/hands-on/files/autoren/edge/edge.htm [February 8, 2001].

Elliot, E. (undated). Tacoma Narrows bridge video [Online]. Available: http://www.camerashoptacoma.com/narrows.asp [2001, February 4].

Expedia, Inc. (2000). Tacoma, Washington [Online map]. Available: http://maps.expedia.com/pub/agent.dll [2001, February 10].

Exponent, Inc. (undated). Hyatt walkway collapse [QuickTime Video; Online]. Available: http://www.exponent.com/multimedia/cases/hyatt.html [2001, January 27].

Failure By Design

References 2

References (2 of 6 pages)

Fuller, R.G., Lang, C.R., & Lang, R.H. (2000). Twin views of the Tacoma Narrows bridge collapse. College Park, MD: American Association of Physics Teachers [http://www.aapt.org].

Gies, J. (1963). Bridges and men. Garden City, NY: Doubleday.

Groutt, P. (1996). University of Maryland physics lecture-demonstration facility [Online]. Available: http://jedlik.phy.bme.hu/~hartlein/physics.umd.edu/deptinfo/facilities/lecdem/lecdem.htm#hp[2001, February 8].

Hanley-Wood LLC. (2000). Q&A: squash blocks and web stiffeners [Online]. Available: http://www.jlconline.com/jlc/qana/framing/squash_blocks/ [2001, February 10].

Harris, C.E. & Rabins, M.J. (1992). Engineering ethics: The Kansas City Hyatt Regency walkways collapse (NSF Grant Number DIR-9012252) [original version of Lowery (1999) online document]. College Station, TX: Texas A&M University, Department of Philosophy and Department of Mechanical Engineering.

Institute for Structural Analysis. (1997). Tacoma Narrows Bridge (1940) failure [Online]. Available: http://www.cis.tugraz.at/ifb/img/others/tacoma/tacoma.htm [2001, January 28].

James, M.N. (undated). Failure as a design criterion [Online]. Available: http://www.tech.plym.ac.uk/sme/FailureCases/Failure.htm [2001, February 5].

Jensen, J.N. (2000). Civil engineering case study [Online]. Available: http://www.acsu.buffalo.edu/~jjensen/cie.htm [2001, February 17].

Failure By Design

References 3


Ketchum, M. (undated). Mark Ketchum’s bridge engineering page [Online]. Available: http://www.ketchum.org/bridges.html [2001, February 8].

Koughan, J. (1996). The collapse of the Tacoma Narrows bridge, evaluation of competing theories of its demise, and the effects of the disaster on succeeding bridge designs [Online]. Available: http://www.me.utexas.edu/~uer/papers/paper_jk.html [2001, January 27].

Lank, S., Robinson, M., Sevigny, S., Steger, M., & Tsai, J. (1997). Smash and crash: The Kansas City Hyatt Regency walkway collapse [Online]. Available: http://www.people.virginia.edu/~jtt3e/hyatt/paper.htm [2001, February 17].

Lou, B. (undated). Bridge and resonance [Online]. Available: http://instruction.ferris.edu/loub/media/BRIDGE/Bridge.htm [2001, February 4].

Lowery, L. (1999). Engineering ethics: The Kansas City Hyatt Regency walkways collapse [Online]. Available: http://lowery.tamu.edu/ethics/ethics/hyatt/hyatt1.htm and http://lowery.tamu.edu/ethics/ethics/hyatt/hyatt2.htm [2001, January 28].

Martin, R. (1999a). Hyatt Regency walkway collapse [Online]. Available: http://www.eng.uab.edu/cee/REU_NSF99/hyatt.htm [2001, January 28].

Martin, R. (1999b). Tacoma Narrows bridge collapse [Online]. Available: http://www.eng.uab.edu/cee/REU_NSF99/tacoma.htm [2001, January 28].

Failure By Design

References 4


Meador, G. (1997). Activity #2: Slinky waves [Online]. Available: http://www.teachingtools.com/SlinkyShindig/activ2.html [2001, February 8].

Moore, K.S. (1999). Large amplitude torsional oscillations in a nonlinearly suspended beam: A theoretical and numerical investigation [Online]. Available: http://www.math.lsa.umich.edu/~ksmoore/ [2001, February 4].

Neyman, P. (undated). Torsion wave representation [Online]. Available: http://sps1.phys.vt.edu/~pat-man/LiNC/movies/torsion.mov [2001, February 5].

Petroski, H. (1985). To engineer is human: The role of failure in successful design. New York: St. Martin’s Press. Available for purchase at: http://www.amazon.com/exec/obidos/ASIN/0679734163

Petroski, H. (1994). Design paradigms: Case histories of error and judgment in engineering. New York: Cambridge University Press. Available for purchase at: http://www.amazon.com/exec/obidos/ASIN/0521466490

Rogers, K. (1997). The Tacoma Narrows bridge disaster [Online]. Available: http://137.142.19.40/seconded/second/Kent/Kent.html [February 8, 2001].

Russell, D. (2000). Vibration and wave animations [Online]. Available: http://www.kettering.edu/~drussell/Demos.html [2001, February 4].

Failure By Design

References 5


Scott, S. (undated). Tacoma Narrows bridge [Online]. Available: http://people.mn.mediaone.net/sscott2/Text_Files/gertie.html [2001, February 8].

Smith, D. (1974, March 29). A case study and analysis of the Tacoma Narrows Bridge failure [Online]. Unpublished manuscript, Carleton University, Department of Mechanical Engineering, Ottawa, Canada. Available: http://www.civeng.carleton.ca/Exhibits/Tacoma_Narrows/DSmith/photos.html [2001, February 7].

Tan, B.T., Thompson, M.C., & Hourigan, K. (1998). Simulated Flow around Long Rectangular Plates under Cross Flow Perturbations [Online]. International Journal of Fluid Dynamics, 2(1). Available: http://sibley.mae.cornell.edu/IJFD/1998_vol2/paper1/paper1.html [2001, February 8].

Underwater Atmospheric Systems. (undated). Tacoma Narrows bridge [Online]. Available: http://www.nwrain.com/~newtsuit/recoveries/narrows/narrows.htm [2001, February 8].

United States Geological Survey. (1992, May 13). Tacoma, Washington, United States [Online image]. Available: http://terraserver.microsoft.com/image.asp?S=14&T=1&X=168&Y=1635&Z=10&W=2 [2001, February 10].

Failure By Design

References 6


Washington State Department of Transportation. (2008). SR 16 - New Tacoma Narrows Bridge [Online]. Available: http://www.wsdot.wa.gov/projects/sr16narrowsbridge/ [2008, March 6].

Washington State Department of Transportation. (2007a). NTPAW Tacoma Narrows Bridge Tour [Online image]. Available: http://www.flickr.com/photos/wsdot/1129855059/ [2008, March 6].

Washington State Department of Transportation. (2007b). View from the Top [Online image]. Available: http://www.flickr.com/photos/wsdot/829349869/ [2008, March 6].

The author thanks the Exponent engineering company (http://www.exponent.com) and its webmaster for agreeing to provide their animation of the Hyatt Regency walkway collapse.

Failure By Design

www.failurebydesign.info

Inquiry Physics

www.inquiryphysics.org

All images used under the “educational fair use” provisions of copyright law.

This presentation is Creative Commons licensed for free distribution for non-commercial use when attributed to Granger Meador

failure by design inquiry physics

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