An Innovative and Versatile Mass Timber Product - Glued Laminated Timber


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This presentation provides a comprehensive overview of glued laminated timber, a building material that is a structural composite of lumber and adhesive. The presentation highlights variations of the building material, with an in depth review of the manufacturing processes. In addition it reviews glued laminated timber’s design properties, how the building material can be used within buildings codes and examples of glued laminated timber being used in commercial buildings from the Tacoma Dome to the Raleigh Durham Airport.

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An Innovative and Versatile Mass Timber Product - Glued Laminated Timber

  1. 1. Glued Laminated TimberAn Innovative and Versatile MassTimber ProductTom Williamson, P.E.Managing PartnerTimber Engineering LLCRetired Vice President, APAPast Executive VP, AITC
  2. 2. What is Glulam?Glulam = a structural composite oflumber and adhesives
  3. 3. Anatomy of Glued Laminated TimberLumber LaminationsGlue LinesEnd JointsNatural WoodCharacteristics
  4. 4. Glulam: One of the Original Glued MassTimber CompositesOver 115 years of use worldwide
  5. 5. Original U.S. Glulam StructureUSDA Forest Products Laboratory1934 200975 years of continuous use
  6. 6. Large Cross Sections Are Possible21” x 27” x 110’Note multiplepieces positionedside by sideNo reduction instress values evenif pieces are notedge bonded andload is appliedperpendicular tothe wide face
  7. 7. Unmatched Versatility ofShapes and Spans
  8. 8. Natural Aesthetics of Glulam
  9. 9. An important issue for buildingdesigners is sustainability.First, wood is green. It is theonly naturally renewablebuilding material. Second,Mass Timber is greener. Itmaximizes the strength of thematerial creating smallersections (I-joists in comparisonto sawn joists. Glulams incomparison to an equivalentstrength sawn beam.) Brieflyreview each bullet point above.Glulam is Environmentally FriendlySustainable and Green• Produced from small dimension lumber harvested frommanaged and sustainable forests• Timber resource utilizationoptimized using a wide range oflumber grades• Uses a wide variety of species• Smaller sections required dueto higher strengths• Manufacturing involves lowenergy use process• Uses low formaldehydeemitting adhesives Mass Timber = Green
  10. 10. Glulam Manufacturing StandardANSI A190.1• Specifies product qualificationand quality assurancerequirements• Third-party inspection by anapproved agency is required onan on-going basis• Building codes require that allglulam must bear a grademarkmeeting ANSI A190.1
  11. 11. MaterialPreparationPre-glueLayupEndJointBondingFaceBondingandCuringQualityVerificationFinishMarkingShippingGlulam Manufacturing Process
  12. 12. Lumber Species Used• Traditional softwoods• Douglas Fir & Southern Pine• Other Softwoods• Spruce/Pine/Fir and Hem-Fir• Naturally Durable Softwoods• Alaska Yellow Cedar• Port Orford Cedar• Hardwoods• Mixed species layups
  13. 13. Glulam Adhesive SpecificationsAdhesives used for glulam must meet:ASTM D2559 for Exterior-UseASTM D7247 for heat durability
  14. 14. Again here is a reminder of the four basic appearanceclassifications that we discussed earlier. But to reiterate the lineof distinction between generally stocked beams by your dealerand those that might be used for exposed aesthetics. For use asbeams and headers where you are comparing glulam against theother Mass Timber beams and headers you’ll be dealing with theFraming Appearance category.Appearance Classifications• Framing – Intended for concealed applications and istypically available in 3-1/2” & 5-1/2” widths to matchdimensions of 2x4 and 2x6 framing lumber• Industrial – Intended for concealed applications orwhere appearance is not of primary importance• Architectural – Used where members are exposed toview and an attractive finish is desired• Premium – Available only as a custom order whereappearance is of primary importanceFinishing for Visual AppearanceStrength is not a function of appearance classifications
  15. 15. Quality Trademarks
  16. 16. Basic Glulam Design Considerations• Type of member/load application• Determination of allowable designstresses/layup selection• Stress modification factors• Structural analysis• Special design provisions• Connection design /detailing
  17. 17. Member TypeColumnSimple span beamTruss memberCantilever span beam
  18. 18. Unbalanced Layup• Unequal capacityin positive andnegative bending• Primarily for usein simple beamsor shortcantilevers• Requires 5%tension lams onthe bottom of thebeamTension lamination
  19. 19. Balanced Layup• Equal capacity inboth positive andnegative bending• Primarily for usein continuousbeams or longcantilevers• Requires 5%tension lams ontop and bottom ofbeamTension laminationTension lamination
  20. 20. Single Grade Layup• Same lumbergrade andspecies usedthroughout• Primarily for usein axially loadedmembers, suchas columns andtruss chords
  21. 21. US Glulam StandardsDevelopment of Design ValuesDesign values are derived in accordance with:
  22. 22. 1. Sawn Lumber Grading Agencies2. Species Combinations3. Section Properties4. Design Values• Lumber and Timber• Non-North American SawnLumber• Structural GluedLaminated Timber• MSR and MELSources of Design Properties2005 NDS Supplement
  23. 23. Stress Classes Created for SimplicityNDS Stress Classes
  24. 24. Sources of Design Properties IndustryStandards / ICC Codes• ANSI 117 DesignSpecification• APA ICC-ESR CodeReport 1940• Glulam standardsare referenced in theIBC and IRC codes
  25. 25. LVL Hybrid Glulam with LVLOuter Laminations• Full length with nofinger joints required• LVL has greater tensilestrength compared tolumber• 30F-2.1E stress levelachieved• Direct substitute for manySCL productsLVL Laminations
  26. 26. LVL “Hybrid” Glulam• Tested at APA Research Center• 30F - 2.1E stress grade• Approved for use in the U.S. byICC-ESR code reports• Limited to depths of 30” or less
  27. 27. Glulam Design: 2005 NDS1 General Requirements for Building Design2 Design Values for Structural Members3 Design Provisions and Equations4 Sawn Lumber5 Structural Glued Laminated Timber6 Round Timber Poles and Piles7 Prefabricated Wood I-Joists8 Structural Composite Lumber9 Wood Structural Panels10 Mechanical Connections11 Dowel-Type Fasteners12 Split Ring and Shear Plate Connectors13 Timber Rivets14 Shear Walls and Diaphragms15 Special Loading Conditions16 Fire Design of Wood Members
  28. 28. Additional Glulam Design References• AITC “Timber Construction Manual”• McGraw-Hill “APA Engineered WoodHandbook”• McGraw-Hill “Wood Engineering andConstruction Handbook”
  29. 29. Glulam Design: 2005 NDSIncludes both:• Allowable Stress Design(ASD)and• Load and ResistanceFactor Design (LRFD)
  30. 30. High Strength Outer Tension LamsLower Grade Inner LamsMedium Grade Inner Compression LamHigh Strength Outer Compression LamsUnbalanced LayupMedium Grade Inner Compression LamGlulam Layups
  31. 31. Note the “TOP” Stampfor Unbalanced Layup
  32. 32. Specifying Camber• Glulam can be manufactured with camber to offsetthe anticipated dead load deflection• Very important for longer span members
  33. 33. Specifying CamberCan be specified in inches or as a radius of curvature
  34. 34. Comparison of VariousRadius of Curvature Camber ValuesLength 14’ 16’ 18’ 20’ 22’ 24’ 26’2000’ radius 1/8” 1/4” 1/4” 1/4” 3/8” 3/8” 1/2”3500’ radius 1/8” 1/8” 1/8” 1/8” 1/4” 1/4” 1/4”5000’ radius 0 1/8” 1/8” 1/8” 1/8” 1/8” 1/4”The most common stock beam camber is a 3500’ radiusalthough some manufacturers supply stock beams withzero camber.
  35. 35. Glulam Connections Can Be ComplexThe NDS Provides Solutions
  36. 36. NDS Connection Design ProvisionsThe NDS design provides nominallateral and withdrawal values fordowel type connectors (nails,screws, bolts) and specialtyconnectors such as shear plates,split rings and timber rivetsAllowable = nominal xadjustment factorsAdjustment factors account for awide range of different end useapplicationsAll applicable to glulam
  37. 37. Durability and Long Term PerformanceStrategies for durable glulam construction• Keep glulam dry• Focus on design and construction details• Focus on moisture management• Use appropriate preservative treatments whenexposed to the elements or• Specify naturally durable and decay resistivewood species• Numerous examples of glulam structures 50-100years old worldwide
  38. 38. Interior ApplicationsDurability Not Typically An Issue
  39. 39. Pedestrian Bridge - 105 ft. span
  40. 40. Pedestrian Bridge – 120 ft. span
  41. 41. Glulam Electric Utility Structures
  42. 42. Tri-Level Highway BridgeKeystone Wye – S.D.Originalinstallation196819882009Over 40 yearsof exposureto the elements
  43. 43. Preservative Treatment of GlulamU.S. Standards American Wood Preservers Standard (AWPA U1) UC1 Interior, dry Insects UC2 Interior, wet Decay and insects UC3 Exterior, above ground Decay and insects UC4 Ground contact Decay and insects UC5 Salt water Salt water organisms American Association of State Highway andTransportation Officials (AASHTO) Above ground Ground contact, fresh water Ground contact, salt waterU.S. building codes require treatment of exposed glulam
  44. 44. Selecting Preservative TreatmentsFor GlulamApplicable treatments are a function of species and whethertreatment is before or after gluingSee EWS S580C for details
  45. 45. Naturally Durable Species• Port Orford Cedar 22F-1.8E• Alaska Yellow Cedar 20F-1.5E• Western Red Cedar 16F-1.3E• California Redwood 16F-1.1E
  46. 46. Alaska Yellow Cedar (AYC)Santa Monica, CA Reservoir Cover
  47. 47. Connection Serviceability Issues• Temperature – not of major importance• Humidity and moisture – major concernsexposed end grain• contact with concrete or masonry• moisture entrapment• ambient conditions / dimensional changes
  48. 48. Effects of MoistureSeasoningcheckingIs it of structuralconcern?
  49. 49. Examples of CheckingSide checksBottom glue line checkEndchecks
  50. 50. Checking vs. Delamination• Checking is a natural phenomena associated with naturaldrying of the glulam• Delamination is a deterioration of the glue bond whenexposed to moisture• The introduction of wet-use (durable) adhesives in themid 1940’s virtually eliminated delamination in the U.S.• This is assured by requiring adhesives to meet D2559and by conducting daily quality control checks using acyclic delamination test
  51. 51. Testing byAPAconducted toevaluate impact of checking• Guidelines established for whatsize checks are OK without anengineering analysis• Checking rarely affectsstructural performance• Published in an Owners Guideto Checking• One of the industry’s mostwidely distributed publications
  52. 52. Proper Use of Flashing and End Caps forLong Term ServiceabilityIssue: prevent direct wateringress into glulam• Re-direct the water flowaround the connection• Use preservative treatedglulam or durable speciesEnd caps andflashing used
  53. 53. Proper Glulam Beam toConcrete or Masonry Connection• Prevent contact withmasonry• Use steel bearing plateunder beam• Maintain minimum of½” air gap at endNote gapat endNote steelbearingplate
  54. 54. Proper Glulam Arch Base ConnectionNote flashing ontop of glulamNote open shoeallowing water to drainAfter 25 years in service
  55. 55. Lessons Learned to Ensure Durableand Long Life Glulam Structures• Keep glulam dry whenever possible• Account for moisture effects• High moisture = mold, decay, insect attack•Protect from direct exposure to elements•Use preservative treatments•Use naturally durable species• Design connections for long term performance•Allow for movement due to moisture changes•Design to avoid moisture entrapment•Avoid direct contact with masonry and concrete
  56. 56. Exposed Glulam vs. Unprotected Steel inASTM E119 Fire Test
  57. 57. Glulam After ASTM E119 Fire TestChar rate =1/40” per minuteor1-1/2” per hour
  58. 58. Characteristics of Glulam in Fire• Wood is an excellent heatinsulator• Develops a char layer afterfire exposure• Self-extinguishing after firesource removed• Retains significant residualstrength after being exposedto fire10-3/4 x 16-1/2Glulam beam after 90minutes of fire exposureretains 60% of its capacity
  59. 59. Fire Rating for GlulamTwo accepted firerating methodsrecognized in the U.S.• IBC Empirical Method• NDS Mechanics BasedModelFRTFlame spread coatings
  60. 60. 1- 302-24 Outer Tension LamsTypical Glulam Beam Layup24F-V4 Doug Fir (12 Lamination Example)1 - L2 Grade Inner Comp. Lam6 - L3 Grade Core Lams2 - L2 Dense Grade Outer Comp. LamsFor 1-hour fire rated beam: substituteadditional tension lam for core lam1- L1 Grade Outer Tension Lams1 - L2 Grade Inner Ten. Lam
  61. 61. Fire ProtectionTension Lam Provisions
  62. 62. Stock beamsoften used inresidentialand lightcommercialconstruction
  63. 63. Stock Beam ManufacturingManufactured in long lengths, varying cross-sections,usually unbalanced, minimal camber
  64. 64. Glulam Beams Stored at Distribution Yard
  65. 65. Glulam Beams Shipped to Job SiteProper handlingProper storage
  66. 66. Roof BeamsStock Beams - Typical Uses
  67. 67. Stock Beams - Typical UsesGarage Door Headers
  68. 68. Stock Beams - Typical UsesSimple Span Floor Beams
  69. 69. Continuous Span Floor BeamsStock Beams – Typical Uses
  70. 70. IJC Beams and HeadersStock Beams - Typical Uses
  71. 71. • 9-1/2", 11-7/8", 14" & 16" depths• 3-1/2", 5-1/2" & 7" widths• Zero or 3500 ft radius camber• Typical lay-up combinations• 24F - 1.8E DF & SP• 30F - 2.1E Hybrid• 30F - 2.1E SPI-Joist Compatible (IJC)Stock Glulam Beams
  72. 72. Advantage of 3-1/2”and 5-1/2” Widths2x4 and 2x6 Framing Width CompatibleNo 3/8” OSB or otherfiller pieces neededFrames Flush
  73. 73. Axial Loading CombinationsTypical Layup Combinations for Glulam LoadedPrimarily In An Axial Condition Such as a ColumnSpecies Combination No. GradeDouglas Fir No. 2 L2No. 5 L1Southern Pine No. 47 N2MNo. 50 N1DAlaska Yellow Cedar No. 70 L2No. 71 L1
  74. 74. Tall wall framing with glulam columnsTypical Column Uses
  75. 75. Typical Column UsesTall wall framing with glulam columns
  76. 76. Examples of GlulamCustom Beams and Arches
  77. 77. Bullitt CenterSeattle, WA
  78. 78. LeMay America’s Car MuseumTacoma, WA
  79. 79. Airport Terminal Victoria, B.C.
  80. 80. Raleigh Durham Airport
  81. 81. Light Rail Transit CenterVancouver, B.C.
  82. 82. Chicago Bears FootballPractice Facility
  83. 83. Disney Twin Rink Ice ArenaAnaheim, CA.
  84. 84. Chemical Storage FacilityPortland, OR
  85. 85. Cathedral of LightOakland, CA
  86. 86. 2010 Olympic Skating OvalRichmond, B.C.
  87. 87. Toronto Ontario Art Gallery
  88. 88. Tacoma Dome - Tacoma, WA510 foot clear span
  89. 89. Copyright MaterialsThis slide presentation is protected by US andInternational Copyright laws. Reproduction,distribution, display and use of the slides in thispresentation without written permission of thepresenter is prohibited.© T. Williamson – Timber Engineering LLC2013
  90. 90. Additional Glulam Informationwww.apawood.orgQuestions Regardingthis Slide Show?Tom Williamson, P.E.T. Wiliamson – Timber Engineering