Wood Products Council is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to CES Records for AIA members. Certificates of Completion for non-AIA members are available on request. Modern Timber Bridges Meeting Today’s Bridge Needs with Strength, Durability and Beauty This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any Paul C. Gilham, P.E., S.E. method or manner of handling, using, distributing, or dealing Chief Engineer, Western Wood Structures, Inc. in any material or product. Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.
Modern Timber Bridges Modern Timber Bridges
Introduction Meeting Today’s Bridge Needs with Strength, Durability and Beauty
Learning Objectives Be Introduced to Concepts of Modern Timber Bridges. Learn How Modern Timber Bridges are Suitable for Most Bridge Applications. Learn Benefits and Constraints of Available Timber Bridge Types. Learn How to Specify Timber Bridges.
Modern Timber Bridges Advantages of Modern Timber Bridges
Keystone Wye Lightweight and strength to carry Rapid City, SD today’s loads 1968 50-75 year life expectancy with minimal maintenance requirements Prefabrication speeds erection time. Timber is not affected by road salts or freeze-thaw cycles. Environmentally friendly Cost Competitive Aesthetically attractive Modern Timber Bridges Modern Timber Bridges
Concepts of Modern Timber Bridges
Use of Glued-Laminated Timbers.
Concepts of Modern Timber Bridges Significant increases in member strength
Use of Glued-Laminated Timbers. Laminations are dried before gluing, reducing seasoning effects. Modern Highway Design Codes Waterproof Adhesives. Conform to ASTM D2559 Structural Engineering Analysis Bond is stronger than wood Computer Modeling and Fabrication Detailing Efficient use of resource Plant Pre-fabrication Ability to manufacture long members
Modern Preservative Treatments Ability to manufacture curved members (camber & arches)
Modern Timber Bridges Modern Timber Bridges
Concepts of Modern Timber Bridges Use of Glued-Laminated Timbers. Concepts of Modern Timber Bridges Use of Glued-Laminated Timbers. Modern highway design codes.
Modern Timber Bridges Modern Timber Bridges Design Codes and Specifications Vehicular Bridges Concepts of Modern Timber Bridges
Design Codes and Specifications
Vehicular Bridges AASHTO Standard Specifications for Highway Bridges
HS20-44 Vehicle (72 kip Truck with three axles)
10,000 lb. rail load AASHTO LRFD Bridge Design Specifications
HL93 Vehicle (HS20-44 Vehicle plus 640 plf lane load)
Crash Tested Rail Systems Geometry (Lane widths, clearances, etc.) Load Distribution Wind & Seismic loads Modern Timber Bridges Modern Timber Bridges Design Codes and Specifications Design Codes and Specifications Vehicular Bridges Vehicular Bridges
Modern Timber Bridges Modern Timber Bridges
Concepts of Modern Timber Bridges Concepts of Modern Timber Bridges
Design Codes and Specifications Use of Glued-Laminated Timbers. Pedestrian Bridges Modern highway design codes. “AASHTO Guide Specifications for Pedestrian Bridges” Structural Engineering Analysis. 85 psf Live Load Computer analysis of structures 50 psf Wind Load Ability to optimize bridge design Suggested Vehicle Loads:
Unless access is prevented or agency specified vehicle. Identifies trouble locations
6 – 10 ft. width: 10,000 lb Truck Greatly reduces design time
Over 10 ft. width: 20,000 lb Truck
42” or 54” high rails with 6” & 8” opening. (50 plf. lateral load) International Building Code
100 psf Live Load
Wind and Seismic based on local requirements
42” high rails with 4” openings. (50 plf. lateral load)
Modern Timber Bridges Modern Timber Bridges
Concepts of Modern Timber Bridges Structural Engineering Analysis.
Concepts of Modern Timber Bridges Use of Glued-Laminated Timbers. Modern highway design codes. Structural Engineering Analysis. Computer Modeling and Fabrication Detailing.
Computer Assisted Drafting
Solid Modeling
Ability to interface with fabrication equipment Modern Timber Bridges Modern Timber Bridges Concepts of Modern Timber Bridges Computer Modeling and Fabrication Detailing.
Concepts of Modern Timber Bridges Use of Glued-Laminated Timbers. Modern highway design codes. Structural Engineering Analysis. Computer Modeling and Fabrication Detailing. Plant Pre-fabrication.
All cuts and bores are fabricated
Proper tools and equipment to fabricate large members
Allows quick jobsite assembly
Protects treating envelope and prevents jobsite contamination.
Modern Timber Bridges Modern Timber Bridges Concepts of Modern Timber Bridges Plant Pre-fabrication.
Concepts of Modern Timber Bridges Use of Glued-Laminated Timbers. Modern highway design codes. Structural Engineering Analysis. Computer Modeling and Fabrication Detailing. Plant Pre-fabrication. Modern Preservative Treatments.
EPA registered pesticides
Effective prevention of decay and Insect attack
Complete treatment envelope
Modern Timber Bridges Modern Timber Bridges Concepts of Modern Timber Bridges Concepts of Modern Timber Bridges Modern Preservative Treatments. Modern Preservative Treatments. Modern Timber Bridges Modern Timber Bridges Concepts of Modern Timber Bridges Concepts of Modern Timber Bridges Modern Preservative Treatments. Modern Preservative Treatments.
Chemical Minimization
Product cleanliness
Inspection and rejection
Fixation
Field Installation Guidelines
BMP Quality Control & Certification
Treated without BMPs Treated with BMPs
Modern Timber Bridges Modern Timber Bridges Concepts of Modern Timber Bridges Concepts of Modern Timber Bridges Modern Preservative Treatments. Modern Preservative Treatments.
Modern Timber Bridges Modern Timber Bridges Concepts of Modern Timber Bridges Modern Preservative Treatments.
Bridge Types (Benefits and Constraints) Boardwalks Longitudinal Deck Bridges Girder Bridges Side Girder Bridges Truss Bridges Arch Bridges Suspension Bridges Covered Bridges Modern Timber Bridges Modern Timber Bridges
Pedestrian Bridges Design Codes and Specifications
Bridge Types (Benefits and Constraints) Bridge Types (Benefits and Constraints)
Boardwalks Boardwalks Used in wetlands and sensitive areas.
Used with multiple short spans. (8’ to 12’ lengths)
Light pier foundations (drilled in concrete piers, timber piles, premanufactured pin foundations, helical anchors)
Modern Timber Bridges Modern Timber Bridges
Pedestrian Bridges Pedestrian Bridges Design Codes and Specifications Design Codes and Specifications Bridge Types (Benefits and Constraints) Bridge Types (Benefits and Constraints)
Boardwalks Boardwalks
Driven Timber Piles Helical Anchor Installation
Modern Timber Bridges Modern Timber Bridges
Pedestrian Bridges Design Codes and Specifications Bridge Types (Benefits and Constraints)
Boardwalks Vehicular Bridges Design Codes and Specifications Bridge Types (Benefits and Constraints)
Longitudinal Deck Bridges Spans from 10’ to 40’ Low Clearance Requirements Made from glued laminated deck panels Easy installation
Diamond Pier Foundation Modern Timber Bridges Modern Timber Bridges
Vehicular Bridges Design Codes and Specifications Bridge Types (Benefits and Constraints) Bridge Types (Benefits and Constraints)
Longitudinal Deck Bridges (Slab type Bridge) Girder Bridges Most Common Bridge Structure Longitudinal girders with transverse deck panels Spans to 80 ft +
Modern Timber Bridges Modern Timber Bridges
Bridge Types (Benefits and Constraints) Bridge Types Girder Bridges Girder Bridges
Glulam deck and rails Diaphragms & Rod Bracing
Modern Timber Bridges Modern Timber Bridges
Vehicular Bridges Design Codes and Specifications
Bridge Types Bridge Types (Benefits and Constraints)
Girder Bridge Girder Bridge Modern Timber Bridges Modern Timber Bridges
Vehicular Bridges Design Codes and Specifications
Bridge Types (Benefits and Constraints) Bridge Types
Girder Bridge Side Girder Bridges Used where clearance below bridge is limited.
Spans to 80 ft +
Requires floor beams and purlin secondary framing. (not ledgers)
Modern Timber Bridges Modern Timber Bridges
Pedestrian Bridges Design Codes and Specifications Bridge Types Bridge Types (Benefits and Constraints) Side Girder Bridges Side Girder Bridges
Modern Timber Bridges Modern Timber Bridges
Pedestrian Bridges Design Codes and Specifications
Bridge Types Bridge Types (Benefits and Constraints)
Truss Bridges (Bowstring or Parallel Chord) Truss Bridges (Pony Truss, Bowstring or Parallel Chord) Spans from 85’ to 200’ Pony Truss Bridge Light weight members 8’ x 100’ Significantly more fabrication and connecting steel Beaverton, Oregon More complicated erection procedures
Truss can be above or below deck Modern Timber Bridges Modern Timber Bridges
Pedestrian Bridges Design Codes and Specifications
Bridge Types (Benefits and Constraints) Bridge Types
Truss Bridges (Pony Truss, Bowstring or Parallel Chord) Truss Bridges (Pony Truss, Bowstring or Parallel Chord) Bowstring Truss Bridge 10’ x 135’ Beaverton, Oregon
Modern Timber Bridges Modern Timber Bridges
Bridge Types Bridge Types Truss Bridge Truss Bridges Martis Creek Bridge Cosumnes River Bridge 32’ x 147’ Two Lane Vehicle Bridge 10’ x 410’ Rancho Murieta, CA Truckee, CA
Modern Timber Bridges Modern Timber Bridges
Bridge Types Arch Bridges Bridge Types (Benefits and Constraints) Arch Bridges
Spans from 100’ to 200’
Larger Members than trusses
Less fabrication and connection steel
More complicated erection procedures
Arches can be above or below deck
More complicated foundations
Hopland Casino Bridge - 18’ x 180’ w/ 15 ton truck Hopland, California Modern Timber Bridges Modern Timber Bridges
Bridge Types Bridge Types Arch Bridges Arch Bridges
Modern Timber Bridges Modern Timber Bridges
Bridge Types (Benefits and Constraints) Bridge Types (Benefits and Constraints) Arch Bridges Arch Bridges
Centennial Garden Bridge - 8’ x 100’ Longview, WA
Modern Timber Bridges Modern Timber Bridges
Bridge Types (Benefits and Constraints) Bridge Types Arch Bridges Arch Bridges
Cascade Highlands Bridge 10’ x 80’
Bend, OR
South Prairie Creek/Lower Burnett Road Bridge - 14’ x 398’ Buckley, WA Modern Timber Bridges Modern Timber Bridges
Bridge Types Suspension Bridges (Caternary or Cable Stayed) Bridge Types (Benefits and Constraints) Suspension Bridges (Caternary or Cable Stayed)
Spans from 100’ to 400’
Very small members
Cable and Tower Designs are significant
Must include cable anchorage to foundations to the the longitudinal elements.
Modern Timber Bridges Modern Timber Bridges
Bridge Types Bridge Types Suspension Bridges (Caternary or Cable Stayed) Suspension Bridges (Caternary or Cable Stayed)
Hiroshima Airport Bridge – Hiroshima, Japan 16’ x 475’
Modern Timber Bridges Modern Timber Bridges
Bridge Types (Benefits and Constraints) Bridge Types (Benefits and Constraints) Covered Bridges Covered Bridges
Special Case of Truss or Girder Bridge Special Case of Truss or Girder Bridge
Alpental Ski Bridge - 10’x185’ three span parallel chord truss bridge with roof Modern Timber Bridges Modern Timber Bridges
Specifying Timber Bridges Recap: Length, Clear Span, Center to Center of Abutments, Out to out. Consider Scour Potential, 100-year Flood Elevation & Stream Protection Modern Timber Bridges combine the use of glued-laminated Width. (Based on anticipated traffic) timbers, the most recent highway design codes, computer Governing Building Code. (Determines Vehicle Load, Live Load, assisted analysis and detailing methods and environmentally Wind and Seismic Loads) appropriate preservative treatments to provide structures Bridge Style (Include slope and/or camber). capable of carrying today’s design loads and durable enough Rail Configuration. for a 75 year life expectancy. Clearance Constraints, if any. Several common structural systems including slabs, beams, Pre-qualified bridge supplier. trusses, arches, and suspension structures can be Calculations & Shop Drawings stamped by Professional Engineer. implemented in constructing timber bridges. Certificates of Conformance for glulam, steel shapes, hardware and Specifying a timber bridge includes identifying length and preservative treating. width required, the governing building codes, bridge and rail Foundation Design (Designed by Consultant or Bridge Supplier) style preferred and quality assurance measures.
Modern Timber Bridges