Brad Miller 3B

8/13/2019 Brad Miller 3B

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SUSPENSION TRAIL BRIDGE

USING SUSTAINABLE MATERIALSRattlesnake Creek, Missoula, Montana

SUSPENSION TRAIL BRIDGE

USING SUSTAINABLE MATERIALSRattlesnake Creek, Missoula, MontanaBrad Miller PE

[email protected]


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PROJECT BACKGROUNDROJECT BACKGROUNDInitial Concept by Others Showed Cablenitial Concept by Others Showed CableStayed Bridge Using Smallwoodtayed Bridge Using Smallwood


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PROJECT BACKGROUNDROJECT BACKGROUNDInitial Concept by Others Showed Cablenitial Concept by Others Showed CableStayed Bridge Using Smallwoodtayed Bridge Using SmallwoodA Similar Bridge Was Well Over BudgetSimilar Bridge Was Well Over Budget


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PROJECT BACKGROUNDROJECT BACKGROUNDInitial Concept by Others Showed Cablenitial Concept by Others Showed CableStayed Bridge Using Smallwoodtayed Bridge Using SmallwoodA Similar Bridge Was Well Over BudgetSimilar Bridge Was Well Over BudgetConsidered 90 Foot Cable Suspension andonsidered 90 Foot Cable Suspension andPrefab Steel Bridges in Preliminary Designrefab Steel Bridges in Preliminary Design


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PROJECT BACKGROUNDROJECT BACKGROUNDInitial Concept by Others Showed Cablenitial Concept by Others Showed CableStayed Bridge Using Smallwoodtayed Bridge Using SmallwoodA Similar Bridge Was Well Over BudgetSimilar Bridge Was Well Over BudgetConsidered 90 Foot Cable Suspension andonsidered 90 Foot Cable Suspension andPrefab Steel Bridges in Preliminary Designrefab Steel Bridges in Preliminary DesignSuspension Bridge Chosen for Aestheticsuspension Bridge Chosen for Aestheticsand to Take Advantage of Smallwood Grantnd to Take Advantage of Smallwood Grant


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SMALLWHAT? SMALLWOODMALLWHAT? SMALLWOODLarge Stands of Lodgepolearge Stands of LodgepolePine in the Northwest Killedine in the Northwest Killedby Pine Bark Beetlesy Pine Bark Beetles


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SMALLWHAT? SMALLWOODMALLWHAT? SMALLWOODLarge Stands of Lodgepolearge Stands of LodgepolePine in the Northwest Killedine in the Northwest Killedby Pine Bark Beetlesy Pine Bark Beetles6 to 9 Inch Diameter Suitable for Joists andto 9 Inch Diameter Suitable for Joists andIntermediate Beams Largely Going to Wastentermediate Beams Largely Going to Waste


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SMALLWHAT? SMALLWOODMALLWHAT? SMALLWOODLarge Stands of Lodgepolearge Stands of LodgepolePine in the Northwest Killedine in the Northwest Killedby Pine Bark Beetlesy Pine Bark Beetles6 to 9 Inch Diameter Suitable for Joists andto 9 Inch Diameter Suitable for Joists andIntermediate Beams Largely Going to Wastentermediate Beams Largely Going to Waste6 Inch Turned Logs From the Nez Perce NFInch Turned Logs From the Nez Perce NFStress Rated and Stockpiled For This Projecttress Rated and Stockpiled For This Project


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SMALLWHAT? SMALLWOODMALLWHAT? SMALLWOODLarge Stands of Lodgepolearge Stands of LodgepolePine in the Northwest Killedine in the Northwest Killedby Pine Bark Beetlesy Pine Bark Beetles6 to 9 Inch Diameter Suitable for Joists andto 9 Inch Diameter Suitable for Joists andIntermediate Beams Largely Going to Wastentermediate Beams Largely Going to Waste6 Inch Turned Logs From the Nez Perce NFInch Turned Logs From the Nez Perce NFStress Rated and Stockpiled For This Projecttress Rated and Stockpiled For This ProjectUse This Sustainable Design Resource Forse This Sustainable Design Resource ForBridge Members to Qualify for Grantridge Members to Qualify for Grant


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Original Cable Stayed Bridge Concept By Othersriginal Cable Stayed Bridge Concept By Others

PRELIM DESIGN STRATEGYRELIM DESIGN STRATEGY


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Original Cable Stayed Bridge Concept By Othersriginal Cable Stayed Bridge Concept By OthersSimilar Bridge Was Well Over Budgetimilar Bridge Was Well Over Budget



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Reduce Cost of Cable Stayed Concept,educe Cost of Cable Stayed Concept,or Revise Conceptr Revise Concept Incorporate Roundwoodncorporate Roundwood


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Reduce Cost of Cable Stayed Concept,educe Cost of Cable Stayed Concept,or Revise Conceptr Revise Concept Incorporate Roundwoodncorporate RoundwoodSimplify Details for Ease of Construction,implify Details for Ease of Construction,Long Term Maintenance, and Aestheticsong Term Maintenance, and Aesthetics


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Reduce Cost of Cable Stayed Concept,educe Cost of Cable Stayed Concept,or Revise Conceptr Revise Concept Incorporate Roundwoodncorporate RoundwoodSimplify Details for Ease of Construction,implify Details for Ease of Construction,Long Term Maintenance, and Aestheticsong Term Maintenance, and AestheticsImprove What Works, Avoid What Doesnmprove What Works, Avoid What DoesntWorkork


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Look at Existing US Forest Service Backook at Existing US Forest Service BackCountry Pack Bridge Designsountry Pack Bridge Designs


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Typical USFS Suspension Foot Bridge,ypical USFS Suspension Foot Bridge,Kootenai River Near Libby, MTootenai River Near Libby, MT

USFS SERVICESFS SERVICESUSPENSION BRIDGESUSPENSION BRIDGES


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Typical USFS Suspension Pack Bridge Withypical USFS Suspension Pack Bridge WithHanger Cables, Lochsa River In Idahoanger Cables, Lochsa River In Idaho


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Construction of USFS Salmon River Pack Bridgeonstruction of USFS Salmon River Pack BridgeNear Mouth of Wind River, ID (1960)ear Mouth of Wind River, ID (1960)


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75 to 400 Feet, 1930 to 19605 to 400 Feet, 1930 to 1960



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75 to 400 Feet, 1930 to 19605 to 400 Feet, 1930 to 1960Local Materials, Untreated,ocal Materials, Untreated,Replaced Later With Treatedeplaced Later With Treated



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75 to 400 Feet, 1930 to 19605 to 400 Feet, 1930 to 1960Local Materials, Untreated,ocal Materials, Untreated,Replaced Later With Treatedeplaced Later With TreatedLater Bridges Treatedater Bridges TreatedInitiallynitially



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75 to 400 Feet, 1930 to 19605 to 400 Feet, 1930 to 1960Local Materials, Untreated,ocal Materials, Untreated,Replaced Later With Treatedeplaced Later With TreatedLater Bridges Treatedater Bridges TreatedInitiallynitiallyStiffening Trusses Addedtiffening Trusses AddedEarly On To Reduce Bouncearly On To Reduce Bounce



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1X6 Lattice with 2~2X6X6 Lattice with 2~2X6Top and Bottom Chordsop and Bottom Chords



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1X6 Lattice with 2~2X6X6 Lattice with 2~2X6Top and Bottom Chordsop and Bottom ChordsProblems With Splicesroblems With Splicesand Connectionsnd Connections



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1X6 Lattice with 2~2X6X6 Lattice with 2~2X6Top and Bottom Chordsop and Bottom ChordsProblems With Splicesroblems With Splicesand Connectionsnd ConnectionsTowers Hard to Rehabowers Hard to Rehab



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1X6 Lattice with 2~2X6X6 Lattice with 2~2X6Top and Bottom Chordsop and Bottom ChordsProblems With Splicesroblems With Splicesand Connectionsnd ConnectionsTowers Hard to Rehabowers Hard to RehabMany of These Haveany of These HaveLasted 75 Yearsasted 75 Years



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Use Lattice Stiffening Trusses, From Halfse Lattice Stiffening Trusses, From HalfRounds, Face Flat Sides Toward Each Otherounds, Face Flat Sides Toward Each Other

FINAL DESIGN STRATEGYINAL DESIGN STRATEGY


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Use Lattice Stiffening Trusses, From Halfse Lattice Stiffening Trusses, From HalfRounds, Face Flat Sides Toward Each Otherounds, Face Flat Sides Toward Each OtherUse Structuralse Structural-Tees Top and Bottom to Tieees Top and Bottom to TieEverything Togetherverything Together



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Eliminate Stringers For Simplicity and Savingsliminate Stringers For Simplicity and Savings



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Eliminate Stringers For Simplicity and Savingsliminate Stringers For Simplicity and SavingsRun 3 1/8un 3 1/8 Glulu-Lam Deck* Longitudinally overam Deck* Longitudinally overFloorloor-Beamseams



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Eliminate Stringers For Simplicity and Savingsliminate Stringers For Simplicity and SavingsRun 3 1/8un 3 1/8 Glulu-Lam Deck* Longitudinally overam Deck* Longitudinally overFloorloor-Beamseams*Composite Deck Proposed Later & UsedComposite Deck Proposed Later & Used



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Suspension Bridgeuspension Bridge - Lattice Stiffening Trussattice Stiffening Truss

Original Cable Stayed Bridge Conceptriginal Cable Stayed Bridge Concept



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How? What? When??ow? What? When??

Easiest Way to Describe This Structure andasiest Way to Describe This Structure andHow it Goes Together, is to Go Through theow it Goes Together, is to Go Through theConstruction Sequenceonstruction Sequence


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CONSTRUCTION SEQUENCEONSTRUCTION SEQUENCE

Cable Anchorsable AnchorsPier Tower Footingsier Tower Footings


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Towers and Cablesowers and Cables


Cables Connectionsables Connections


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Smallwood Floormallwood Floor-beams, Braces, and Stiffeningeams, Braces, and StiffeningTrusses With Split Ring Shear Connectorsrusses With Split Ring Shear ConnectorsSUSTAINABLE MATERIALSUSTAINABLE MATERIALS



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Floorloor-beams, Braces, and Stiffening Trusseseams, Braces, and Stiffening Trusses

SUSTAINABLE MATERIALSUSTAINABLE MATERIALS


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Special 4X12 Composite Deck Made Frompecial 4X12 Composite Deck Made From50% Sawdust and 50% Recycled Plastic0% Sawdust and 50% Recycled PlasticSUSTAINABLE MATERIALSUSTAINABLE MATERIALS


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Steel Plates and Cones Installedteel Plates and Cones Installedon Towers as Climbing Deterrentn Towers as Climbing Deterrent


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Concrete Approaches and Vinyl Coated Meshoncrete Approaches and Vinyl Coated Mesh


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4x88x Rubber Matsubber Mats Recycled Tiresecycled TiresSUSTAINABLE MATERIALSUSTAINABLE MATERIALS


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RIBBON CUTTINGIBBON CUTTING

April 21, 2006pril 21, 2006


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RIBBON CUTTINGIBBON CUTTING

April 21, 2006pril 21, 2006


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Rattlesnake Creek Pedestrian Bridgeattlesnake Creek Pedestrian Bridge


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DESIGN GUIDELINESESIGN GUIDELINES

Cable Sag Should be 8% to 10% of Spanable Sag Should be 8% to 10% of Span


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Cable Sag Should be 8% to 10% of Spanable Sag Should be 8% to 10% of SpanDeck Camber is for Aesthetics etc, Consider 1%eck Camber is for Aesthetics etc, Consider 1%of Span, Check ADAf Span, Check ADA


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85 psf Pedestrian Load with Allowable Reduction5 psf Pedestrian Load with Allowable ReductionAccording to AASHTO, but Not Less Than 65 psfccording to AASHTO, but Not Less Than 65 psf


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85 psf Pedestrian Load with Allowable Reduction5 psf Pedestrian Load with Allowable ReductionAccording to AASHTO, but Not Less Than 65 psfccording to AASHTO, but Not Less Than 65 psfConsider Snow, Light Vehicles, and 1,000 Poundonsider Snow, Light Vehicles, and 1,000 PoundPoint Load if the Bridge is for Horsesoint Load if the Bridge is for Horses


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Approximate Hanger Forces as Uniform Loads forpproximate Hanger Forces as Uniform Loads forMain Cables Forces, Close Enough for Small Br.ain Cables Forces, Close Enough for Small Br.s


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Approximate Hanger Forces as Uniform Loads forpproximate Hanger Forces as Uniform Loads forMain Cables Forces, Close Enough for Small Br.ain Cables Forces, Close Enough for Small Br.sH=wL=wL2/(8d) V=wL/2 T=(H(8d) V=wL/2 T=(H2+VV2)1/2/2


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Approximate Hanger Forces as Uniform Loads forpproximate Hanger Forces as Uniform Loads forMain Cables Forces, Close Enough for Small Br.ain Cables Forces, Close Enough for Small Br.sH=wL=wL2/(8d) V=wL/2 T=(H(8d) V=wL/2 T=(H2+VV2)1/2/2Check T on Back Span if Angle is Differentheck T on Back Span if Angle is Different


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Factor of Safety for Cables and Connections = 3.0actor of Safety for Cables and Connections = 3.0


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Factor of Safety for Cables and Connections = 3.0actor of Safety for Cables and Connections = 3.0Cable Anchors Sized So That Wable Anchors Sized So That Wanchornchor > 2V, and2V, and


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Factor of Safety for Cables and Connections = 3.0actor of Safety for Cables and Connections = 3.0Cable Anchors Sized So That Wable Anchors Sized So That Wanchornchor > 2V, and2V, andEarth Pressure on Front Face < 2000 psfarth Pressure on Front Face < 2000 psf


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Design Sway Bracing and/or Sway Cables for Windesign Sway Bracing and/or Sway Cables for Wind


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Design Sway Bracing and/or Sway Cables for Windesign Sway Bracing and/or Sway Cables for WindAASHTO Specifications ControlASHTO Specifications Control


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Use Rule of Thumb For Stiffening Truss by Johnse Rule of Thumb For Stiffening Truss by JohnRoeblingoebling


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Use Rule of Thumb For Stiffening Truss by Johnse Rule of Thumb For Stiffening Truss by JohnRoeblingoeblingTreat as Equivalent Simple Span = 0.4Sreat as Equivalent Simple Span = 0.4Sfor Live Load Onlyor Live Load Only


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Rattlesnake Creek Pedestrian Bridgeattlesnake Creek Pedestrian BridgeQuestions????uestions????

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