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Olmati et al. Olmati et al. Presentation Transcript

  • P. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeRobustness assessment of a steel truss bridgeP. Olmati & K. GkoumasSapienza University of Romepierluigi.olmati@uniroma1.itkonstantinos.gkoumas@uniroma1.itF. BrandoThornton Tomasetti, New Yorkfbrando@thorntontomasetti.comProgressive Collapse and Structural Robustness: An International PerspectiveClay J. Naito, Ph.D., P.E., Associate Professor and Associate ChairKonstantinos Gkoumas, Ph.D., P.E., Associate Researcher
  • 21234Introduction1Consequence factor2Application3Conclusions4OutlineP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • 31234Introduction1Consequence factor2Application3Conclusions4OutlineP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • 4Structural RobustnessStructuralrequirementsMechanicalpropertiesServicepropertiesDurabilitypropertiesDependabilityLoad bearing capacityStabilityDuctilityStiffnessEfficient useComfortAppearanceNot degradation of bothmechanical and servicepropertiesReliabilityRobustnessMaintainabilityPrompt responseIntroductionP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • 5Structural RobustnessStructuralrequirementsMechanicalpropertiesServicepropertiesDurabilitypropertiesDependabilityLoad bearing capacityStabilityDuctilityStiffnessEfficient useComfortAppearanceNot degradation of bothmechanical and servicepropertiesReliabilityRobustnessMaintainabilityPrompt responseIntroductionP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • 6Structural RobustnessDefinitions:1- "The ability of a structure to withstand events like fire, explosions, impactor the consequences of human error without being damaged to an extentdisproportionate to the original cause." (EN 1991-1-7 2006)2- "The robustness of a structure, intended as its ability not to sufferdisproportionate damages as a result of limited initial failure, is an intrinsicrequirement, inherent to the structural system organization." (BontempiF, Giuliani L, Gkoumas K, 2007)3- “Robustness is defined as insensitivity to local failure." (StarossekU, 2009)References:(EN 1991-1-7 2006): "Eurocode 1 – Actions on structures, Part 1-7: General actions – accidental actions."Comité European de Normalization (CEN).(Bontempi F, Giuliani L, Gkoumas K, 2007): "Handling the exceptions: robustness assessment of a complexstructural system." Structural Engineering, Mechanics and Computation (SEMC) 3, 1747-1752.(Starossek U, 2009): “Progressive collapse of structures.” London: Thomas Telford Publishing, 2009.IntroductionP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • Definitions:1- "The ability of a structure to withstand events like fire, explosions, impactor the consequences of human error without being damaged to an extentdisproportionate to the original cause." (EN 1991-1-7 2006)2- "The robustness of a structure, intended as its ability not to sufferdisproportionate damages as a result of limited initial failure, is an intrinsicrequirement, inherent to the structural system organization." (Bontempi F,Giuliani L, Gkoumas K, 2007)3- “Robustness is defined as insensitivity to local failure." (Starossek U,2009)7Structural RobustnessReferences:(EN 1991-1-7 2006): "Eurocode 1 – Actions on structures, Part 1-7: General actions – accidental actions."Comité European de Normalization (CEN).(Bontempi F, Giuliani L, Gkoumas K, 2007): "Handling the exceptions: robustness assessment of a complexstructural system." Structural Engineering, Mechanics and Computation (SEMC) 3, 1747-1752.(Starossek U, 2009): “Progressive collapse of structures.” London: Thomas Telford Publishing, 2009.IntroductionP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • References:(EN 1991-1-7 2006): "Eurocode 1 – Actions on structures, Part 1-7: General actions – accidental actions."Comité European de Normalization (CEN).(Bontempi F, Giuliani L, Gkoumas K, 2007): "Handling the exceptions: robustness assessment of a complexstructural system." Structural Engineering, Mechanics and Computation (SEMC) 3, 1747-1752.(Starossek U, 2009): “Progressive collapse of structures.” London: Thomas Telford Publishing, 2009.8Structural RobustnessDefinitions:1- "The ability of a structure to withstand events like fire, explosions, impactor the consequences of human error without being damaged to an extentdisproportionate to the original cause." (EN 1991-1-7 2006)2- "The robustness of a structure, intended as its ability not to sufferdisproportionate damages as a result of limited initial failure, is an intrinsicrequirement, inherent to the structural system organization." (BontempiF, Giuliani L, Gkoumas K, 2007)3- “Robustness is defined as insensitivity to local failure." (StarossekU, 2009)BA Withstand actionsWithstand damagesProgressive Collapse and Structural Robustness1234P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • Interstate 90 Grand River bridge, Ohio – October, 1996Cause Damage Pr. CollapseIntroduction9P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234Features:- Deck Warren Truss type bridge built in1960, 869 feet (265 m) in length and 150 feet(46 m) in height.The event:- On May 24, 1996, a gusset plate failed on theeastbound span.- The bridge was closed later that day and thetraffic diverted.- The cause originally was attributed to anoverloaded semi-trailer truck.
  • I-35W Bridge, MN – August 1st, 2007Introduction10P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234Postcollapse overhead photos of the bridge, view looking eastNorthDowntownNorthDowntownD-1Cause Damage Pr. CollapseFeatures:- Continuous Steel Deck Truss Bridge over fourpiers- State of the art bridge when built in 1964.- High Strength steel which allowed for thingusset plates.- Truss members consisted of welded box builtup section with perforations.- Geared roller bearings.The event:- At 6:06 pm on August 1st, 2007, the bridgesuddenly collapsed,- 13 people died and more than 150 were injured.
  • 11Structural RobustnessIntroductionP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234StructuralRobustnessProgressiveCollapseSystem structural failure System structural propertyFactors that affect the Structural Robustness:1- Redundancy (Geometry – Construction Details)2- Ductility (Material)3- Contingency Scenario (Degradation, Existing Damage States)
  • 12Structural RobustnessAssessment Methods:A relevant issue related to the structural robustness evaluation, is the choiceof appropriate synthetic parameters describing for example the sensitivity of adamaged structure in suffering a disproportionate collapse.In literature there are differences in the approaches and indexes towards thestructural robustness quantification.IntroductionApproach Indexes- property of the structure orproperty of the structure andthe environment- static or dynamic- linear or non-linear- deterministic or probabilistic1234P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • STRUCTURAL DESIGNPRIMARY SECONDARY TERTIARYLOADSDEAD XLIVE XSNOW XEARTHQUAKE XFIRE X XEXPLOSIONS X X“BLACK SWAN” XMember-basedstructural designConsequence-basedstructural designBlack Swan event:- unpredictable,- large impact on community,- easy to predict after its occurrence.13 IntroductionReferences:Nafday, AM. (2011) Consequence-basedstructural design approach for black swan events.Structural Safety, 33(1): 108-114.P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • 141234Introduction1Consequence factor2Application3Conclusions4OutlineP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • 15UndamagedDamagedCfscenarioConsequence factorConsequence factorscenarioP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • 16Structural Robustness assessmentStiffness matrixKun λiunEigenvaluesKdam λidamConsequence factorConsequence factorRobustness indexRscenario= 100 - CfscenarioN1iunidamiuniscenariof 100)(maxCP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • 17 Consequence factorStructural Robustness assessmentkakbxyN: total eigenvalues numberi: single eigenvalue numbera and b: elementsab N1iunidamiuniscenariof 100)(maxCScenario 1P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234
  • 181234Introduction1Consequence factor2Application3Conclusions4OutlineP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • I-35 West Bridge, Minneapolis, MN• Built 1967• 3 spans, 1067 feet long• 1977 – new wearing surface• 1998 – curbs and railingsreplaced19 Case StudyP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • I-35 West Bridge, Minneapolis, MN20 Case StudyP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone• At 6:05 pm onAugust 1st 2007Bridge Collapsed• 13 People killed &approximately 145InjuredPhoto from aircraft flying overhead.NorthDowntownD-1
  • I-35 West Bridge, Minneapolis, MN21 Case StudyP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone• At 6:05 pm onAugust 1st 2007Bridge Collapsed• 13 People killed &approximately 145InjuredPhoto from aircraft flying overhead.NorthDowntownD-1Security Camera video
  • 22 Analysis ProcedureP. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeNFIMForensic Investigation ModelingThornton Tomasetti was engaged to perform investigation into the causes the collapse by Robins, Kaplan Miller&Ciresi, a national law firm with offices in Minneapolis, Minnesota. Firm partners recruited and oversaw aconsortium of 17 law firms that agreed to provide pro bono legal services to the survivors of the collapse.
  • Pier 7Pier 623 Collapse Initiation AreaP. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeFailure InitiationNorth of Pier 6NU10-EU10-WL9L11
  • Pier 7Pier 624 Collapse Initiation AreaP. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeNU10-EU10-WL9L11L11L9U10Failure InitiationNorth of Pier 6
  • WeightTemp. &Const.WeightTemp. &Const.The upper gusset plate is half as thick as it shouldbe.Construction loads increase forces by 3%Forces due to weight of bridge and trafficAdditional forces due to temperature(corroded bearings) and construction load25P. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeL11L9L11L9L11L9U10• Forces due to weight of bridge and traffic• Additional forces due to temperature(corroded bearings) and construction loadFailure InitiationNorth of Pier 6Collapse Initiation Area
  • NTSB Theory – U10 Gusset failed ina “lateral shifting instability”Gusset hinges, tears at top and buckles at bottom26P. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeL11L9L11L9L11L9U10Lower chord fails in buckling• Forces due to weight of bridge and traffic• Additional forces due to temperature(corroded bearings) and construction load• Lower chord fails in buckling• Gusset hinges, tears at top and buckles at bottomFailure InitiationNorth of Pier 6Collapse Initiation Area
  • Gusset plate hingingBUCKLEDTORNRivet hole elongationU27P. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeL11L9U10• Forces due to weight of bridge and traffic• Additional forces due to temperature(corroded bearings) and construction load• Lower chord fails in buckling• Gusset hinges, tears at top and buckles at bottom• Rivet hole elongationFailure InitiationNorth of Pier 6Collapse Initiation Area
  • Structural Robustness assessment – Damage based method28 ApplicationP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234Pier 7Pier 6L11L9U10NTSB 2007
  • 29Single damaged1d2d3d4d5d7d6375942 4535 3823634158 5565 62770204060801001 2 3 4 5 6 7Robustness%ScenarioCf max Robustness42 4535 382358 5565 62773 4 5 6 7ScenarioCf max Robustness83 87 885360866417 13 12474014360204060801001 2 3 4 5 6 7Robustness%ScenarioCf max RobustnessDamage scenario Damage scenariod3 d4 d5 d6 d7 d1 d2 d3 d4 d5 d6 d7ApplicationDSj = diP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234Pier 6Pier 7NorthPier 6
  • 30d1d2d3d4d5d7d6Single damage942 4535 3823158 5565 62773 4 5 6 7ScenarioCf max Robustness83 87 885360866417 13 12474014360204060801001 2 3 4 5 6 7Robustness%ScenarioCf max RobustnessDamage scenario Damage scenario2 d3 d4 d5 d6 d7 d1 d2 d3 d4 d5 d6 d7ApplicationDSj = diP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234Pier 6Pier 7NorthPier 6
  • 311234Introduction1Consequence factor2Application3Conclusions4OutlineP. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone
  • 32• The consequence coefficient Cf can be used primarily as an index toestablish the critical structural members for the global structuralstability or to compare different structural design solutions from arobustness point of view.• The latter implementation of Cf can be helpful for the robustnessassessment of complex structures since it provides an indication onthe key structural elements.• The method applied in this study aims at increasing the collapseresistance of a structure, by focusing on the resistance of the singlestructural members, and accounting for their importance to the globalstructural behavior consequently to a generic extreme event that cancause a local damage.P. Olmati, F. Brando, K. Gkoumas francobontempi.org/persone1234Conclusions
  • 33Thank you!P. Olmati, F. Brando, K. Gkoumas francobontempi.org/personeConclusionsd1d2d3d4d5d7375942 4535 3823634158 5565 62770204060801001 2 3 4 5 6 7Robustness%ScenarioCf max Robustness375942 4535 3823634158 5565 62770204060801001 2 3 4 5 6 7Robustness%ScenarioCf max Robustness83 87 885360866417 13 12474014360204060801001 2 3 4 5 6 7Robustness%ScenarioCf max RobustnessDamage scenario Damage scenariod1 d2 d3 d4 d5 d6 d7 d1 d2 d3 d4 d5 d6 d7Kun λiunEigenvaluesKdam λidamConsequence factorRobustness index