The Leaning Tower of Pisa
The Leaning Tower of Pisa
The Leaning Tower of Pisa
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<strong>The</strong> <strong>Leaning</strong> <strong>Tower</strong> <strong>of</strong> <strong>Pisa</strong>Mike Bartusiewicz, Dong-Hyun Chung, Steve Cullen,Kate Horlocker, Na Ning, & Bin Tong
<strong>The</strong> <strong>Leaning</strong> <strong>Tower</strong>• Construction <strong>of</strong> <strong>Tower</strong>began in 1173 undersupervision <strong>of</strong> architectBonanno <strong>Pisa</strong>no• Bell tower was built asmanifestation <strong>of</strong> city’spride and was meant toreflect rich city <strong>of</strong> <strong>Pisa</strong>http://www.pubs.asce.org/ceonline/ceonline02/0302feat.html
Construction <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• Work on <strong>Tower</strong> ceased in 1178for reasons unknown; studieshave shown that soil on which<strong>Tower</strong> was built would nothave been able to withstandmore construction at that time• Construction began again, butceased in 1278• Had <strong>Tower</strong> been completed atthis time, would havecollapsed because <strong>of</strong> the stresson soilhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.costruzioni.net/images/pisa.h4.jpg
Construction <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• During actual construction <strong>of</strong><strong>Tower</strong> in 1100’s, <strong>Tower</strong> originallyleaned north– Masonry blocks placed on eachlevel to correct lean <strong>of</strong> axis• By end <strong>of</strong> its construction, the<strong>Tower</strong> leaned significantly to theSouth• <strong>Tower</strong> was finally completed in1370; height is 53 mhttp://www.electricedge.com/greymatter/archives/archive-10052003-10112003.htmhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.html
<strong>The</strong> <strong>Leaning</strong> <strong>Tower</strong> Today• From early 1990 untilDecember 2001, <strong>Tower</strong> wasclosed to public because <strong>of</strong>safety issues• Italian engineersimplemented complex $25million rescue plan in orderto stabilize <strong>Tower</strong>• Although <strong>Tower</strong> looks as ifit might collapse at anymoment, in reality, it ismore stable now than atany time in past fewcenturieshttp://www.pubs.asce.org/ceonline/art/art02/0302feat1.jpg
Alternatives to Restoration• In 1838, architect Alessendrodella Gherardesca constructeda walkway around <strong>Tower</strong> base• Water filled the walkway areaafter the excavation extendedbelow water table• Plan increased tilt <strong>of</strong> <strong>Tower</strong> byover one quarter <strong>of</strong> a degree• Gherardesco placed 0.7 meterthick ring <strong>of</strong> concrete aroundwalkway to help stabilize<strong>Tower</strong>, but excavation nearlycaused its downfall
Alternatives to Restoration• In 1934, engineersused grout injection tostabilize the foundation<strong>of</strong> <strong>Tower</strong>• This process led to adisplacement <strong>of</strong> <strong>Tower</strong>• <strong>The</strong> tip <strong>of</strong> <strong>Tower</strong> tilted10 mm more to Southhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.intl.pdx.edu/EdAbroad/2006PhotoContest/Buildings%20&%20Architecture/Buildings%20&%20Arch%201/images/<strong>The</strong>%20<strong>Leaning</strong>%20<strong>Tower</strong>%20<strong>of</strong>%20<strong>Pisa</strong>_jpg.jpg
Alternatives to Restoration• In 1993, 600 Mg <strong>of</strong> leadweights were added tonorth side <strong>of</strong> <strong>Tower</strong>,attached by a removableconcrete ring placedaround base <strong>of</strong> <strong>Tower</strong>– Reduced leaning by nearlyone minute <strong>of</strong> an arc– Reduced moment thatpulled on <strong>Tower</strong> by 10%• Load was increased in1995 to 900 Mg whileengineers attempted toreplace lead weights withground anchorshttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.endex.com/gf/buildings/ltpisa/ltpgallery/freepix/pisaa6y.jpg?x=41&y=49
Alternatives to Restoration• One unique idea was todrill 10,000 holes in<strong>Tower</strong> to significantlyreduce its weight• Replica was to be placednext to <strong>Tower</strong> leaning inopposite direction to holdoriginal tower in placehttp://news.bbc.co.uk/2/hi/europe/1391476.stmhttp://www.stilepisano.it/immagini13/
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• A new restoration idea waspresented in the 1990s– Known as soil extraction, orsoil subsidence– Its goal was to excavate earthfrom beneath <strong>Tower</strong>’sfoundation on its northernside so that <strong>Tower</strong> would tiltback toward perpendicular• Idea was put into motionafter various tests on <strong>Tower</strong>itself and on soilunderneath its foundationhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://torre.duomo.pisa.it/towersposters/english_version/2/sezione.gif
http://www.endex.com/gf/buildings/ltpisa/ltpgallery/telwpis20.gif?x=89&y=55
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• Temporary cables attachedto 3rd level <strong>of</strong> <strong>Tower</strong>– Would support <strong>Tower</strong> ifanything went wrong duringsoil extraction• Lead weights wereattached to ends <strong>of</strong> cablesto ensure that <strong>Tower</strong> wouldremain steadyhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://news.bbc.co.uk/olmedia/790000/images/_793432_pisa2_300gra.gif
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• First soil extractionoccurred on February 9,1999– Extracted by means <strong>of</strong>corkscrew drills• At first, <strong>Tower</strong> showed nosign <strong>of</strong> rotation, but thenrotated toward the Northhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://torre.duomo.pisa.it/towersposters/english_version/10/perforazioni.gif
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• <strong>Tower</strong> had rotated sevenseconds <strong>of</strong> an arc towardthe North by February 23,1999, but then it rotatedback toward the South– Occurred as a result <strong>of</strong>strong, cold windsfrom the North– <strong>Tower</strong> soon began torotate back toward theNorth after winds haddiminishedhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.endex.com/gf/buildings/ltpisa/ltpgallery/lavori/ltpreud1498gb.jpg?x=23&y=70
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• Soil extraction was stopped after <strong>Tower</strong> had rotated atotal <strong>of</strong> eighty seconds <strong>of</strong> an arc by June 1999• Three <strong>of</strong> the lead weights were removed in July 1999,and this resulted in a discontinuation <strong>of</strong> rotationhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.waidev2.com/php/IMAGES/HC_ThisDayInHistory/58---Image_large.jpg
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• Main soil extraction began in the year 2000, afterpreliminary extractions had shown vast improvement• <strong>Tower</strong> had a tendency to rotate to the East throughoutthe process, so soil also had to be extracted fromfoundation’s west side• <strong>Tower</strong> continued to move northward, and slowly the leadwas removed from the structurehttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.endex.com/gf/buildings/ltpisa/ltpgallery/lavori/ltpreud1498gc.jpg?x=52&y=59
Restoration <strong>of</strong> <strong>The</strong> <strong>Tower</strong>• Restoration process was finished on June 6, 2001• <strong>Tower</strong> had returned to position it was in before 1838• Restoration process moved <strong>Tower</strong> 1,830 seconds <strong>of</strong> an archttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.rod.beavon.clara.net/pisa.htm
Problems and Costs <strong>of</strong>Implementing• Stabilization <strong>of</strong> <strong>Leaning</strong> <strong>Tower</strong>provided difficulties <strong>of</strong> its own– <strong>Tower</strong> was originallyconstructed on weak,compressible soil, whichincreased instability <strong>of</strong> <strong>Tower</strong>– Ground on south side <strong>of</strong><strong>Tower</strong> had to be treated withdelicacy because anydisturbance could result infalling <strong>of</strong> <strong>Tower</strong>– Original design <strong>of</strong> <strong>Tower</strong> hadto be respected throughoutthe process to conservemonument’s characterhttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.endex.com/gf/buildings/ltpisa/ltpgallery/22nov02/ltp3064rx.jpg
Other Items <strong>of</strong> Interest• <strong>The</strong>re are 294 stairs totop <strong>of</strong> <strong>Tower</strong>• <strong>Leaning</strong> <strong>Tower</strong> weighsabout 14,700 metric tons• About three millionpeople visit <strong>Tower</strong>annually• <strong>The</strong>re are seven bells on<strong>Tower</strong>, largest <strong>of</strong> whichweighs 3.5 tonshttp://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.endex.com/gf/buildings/ltpisa/ltpinfo.htmhttp://www.endex.com/gf/buildings/ltpisa/ltpgallery/22nov02/ltp3096rx.jpg
Conclusion• Restoration process wasvery difficult to execute– Soil on which <strong>Tower</strong> wasbuilt was very unstable– <strong>Tower</strong>’s original design hadto be maintained• Soil extraction was asuccessful process thatsaved <strong>Tower</strong> fromcollapse
<strong>The</strong> Future <strong>of</strong> <strong>The</strong> <strong>Leaning</strong> <strong>Tower</strong>• Speculation on whetherrestoration process willbe beneficial in future– Pr<strong>of</strong>essor Burland, whooversaw the restorationprocess, believes <strong>Tower</strong>may stay in its currentcondition– Pr<strong>of</strong>essor Burlandspeculates that <strong>Tower</strong> maybegin rotating again, and in300 years, <strong>Tower</strong> will bewhere it was in 1990s• <strong>Leaning</strong> <strong>Tower</strong> wasreopened to public onDecember 15, 2001http://www.pubs.asce.org/ceonline/ceonline02/0302feat.htmlhttp://www.funnypictures.net.au/userimages/user1680_1165895778.JPG
Works Cited• http://www.pubs.asce.org/ceonline/ceonline02/0302feat.html• http://news.bbc.co.uk/2/hi/europe/1391476.stm• http://www.endex.com/gf/buildings/ltpisa/ltpinfo.htm• http://www.endex.com/gf/buildings/ltpisa/ltpbooking.htm• http://www.answers.com/topic/leaning-tower-<strong>of</strong>-pisa• Images:– http://www.costruzioni.net/images/pisa.h4.jpg– http://www.electricedge.com/greymatter/archives/archive-10052003-10112003.htm– http://www.stilepisano.it/immagini13/– http://news.bbc.co.uk/olmedia/790000/images/_793432_pisa2_300gra.gif– http://www.endex.com/gf/buildings/ltpisa/ltpgallery/ltpgallery.htm– http://torre.duomo.pisa.it/towersposters/english_version/– http://www.intl.pdx.edu/EdAbroad/2006PhotoContest/Buildings%20&%20Architecture/Buildings%20&%20Arch%201/index.htm– http://www.funnypictures.net.au/userimages/user1680_1165895778.JPG
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