Montana Truss Rehabilitation Projects Lozeau Bridge over the Clark Fork Dearborn River High Bridge...

Montana

Truss Rehabilitation Projects

Lozeau Bridge over the Clark Fork

Dearborn River High Bridge

Van Buren Street over the Clark Fork

Lozeau Bridge Over the Clark Fork

Lozeau Bridge Near Superior, Montana

• Constructed 1924 Near Thompson Falls, MT

• Moved & Reconstructed During WWII in 1944

• USFS With Permission From the War Department

• Used POW Labor, Local Aggregate

• Reconstructed in 1998 by MDT

• Column Encasement or Replacement

Lozeau Bridge

•Existing columns had been patched in places

•Original intent was to repair spalled/unsound areas

•During construction, discovered some areas that were far worse than expected.

Challenges and Solutions

Challenges and Solutions• Need to Raise and Support Truss

• To Repair or Replace Substructure Units and Bearings

• No End Floor Beams

• Can’t Jack Against Bottom Chord

• Solution – Use Jacking Frame

• Lift Truss From Above Using Cradle under Truss Pins

• Supports Stringers From Jacking Frame Easily

Lozeau Bridge

• Column Encasement or Replacement

Lozeau Bridge

•Superstructure was temporarily supported by a jacking frame

•Columns and cap were completely replaced at the end piers

•Columns were jacketed with a reinforced concrete shell at the center pier


Challenges and Solutions• Attach New Railing to Lightweight Truss or Deck

• Attach Truss Rail Posts to Steel Stringers and Curbs

• Railing Independent of Truss

• Approach Spans Rail Posts Bolted to Curbs and Stringers

Lozeau Bridge

Challenges and Solutions• Timber Decks - Maintain Historic Deck Material Type and

Minimize Dead Load

• Pentachlorophenol

• Running Planks

• 5 1/8” Glued-Lam Deck

• Nail Lam Deck at End Spans

• BMP for Use of Treated Wood in Aquatic Environments

Lozeau Bridge


Dearborn River High Bridge Near Augusta, MT

• Built 1897 by the King Bridge Co. Cleveland, OH

• Lewis and Clark County, Before Highway Dept.

• Unusual Mid-Deck Truss, Only One Remaining?

• Reconstructed in 2003 by MDT

• Venetian Red

• Rock Embankment Stabilization


•Existing Abutment was founded on an unstable rock outcropping

•Unstable rock mass was threatening existing columns


• Rock Embankment Stabilization


Caisson knocked partially out from under bearing

Unstable rock mass


• Need to Raise and Support Truss

• Stabilize Rock Slope at End

• Replace all Substructure Units and Bearings

• Can’t Jack Against Bottom Chord

• Solution – Deck is to be Removed and Replaced, Remove Lightweight Truss to Bank

• Use Special Bolted Lifting Points and Spreader Beams



• Abutment Replacement & Rock Stabilization

• Remove unstable rock mass by controlled blasting

• Stabilize slope by rock bolting

• Socket the new abutment into competent rock

• Stabilize approach with gabion baskets



• Drilled shaft Excavation at Abutment No. 5



• Abutment No. 5



• Abutment Replacement & Rock Stabilization



• Abutment Replacement & Rock Stabilization – Before & After



• Substructure Replacement

• Reusing the existing stone in the new abutment



• Substructure Replacement

Reusing the existing stone in the new approach span footings



• Replace / Repair Old Bearings

New Elastomeric Bearings


New Expansion Bearing Sole Plate


• Timber Deck - Maintain Historic Deck Material Type and Minimize Dead Load

• Creosote

• 3 1/8” Glued-Lam Deck• Transverse & Longitudinal


• Most Agencies Do Not Use Creosote Now



• Attach New Railing to Lightweight Truss or Deck

• Longitudinal Decking - Attach Posts to Floor Beams for Approach Spans

• Transverse Decking - Attach Posts to Structural Tubes in Plane of Deck Between Deck Panels

• Rail Posts Independent of TrussDearborn River

High Bridge


• OVERCOAT PAINT SYSTEM

• Restored original color of bridge – “Venetian Red”• High pressure water blast and mechanical cleaning• Moisture cure urethane overcoat system• Make sure paint system is compatible with existing paint



Van Buren St. Over the Clark Fork

Van Buren Street Bridge - Missoula, MT

• Built 1892-3 on Higgins Avenue

• Washed out in Flood 1908

• Salvaged & Moved Upstream to Van Buren Street

• Sidewalks Outside Truss Removed

• Converted to Pedestrian Use in 1975

• Reconstructed by Missoula County in 2004

• Miscellaneous Truss Repairs – Eyebar Hanger

Van Buren Street Pedestrian Bridge


• Miscellaneous Truss Repairs - Verticals



• Miscellaneous Truss Repairs – Top Flange Repair


• All of the top flanges on the built-up floor beams were severely rusted and needed replacement.

•The existing flange angles were removed and used as a template to drill holes in the new angles


• End Frame Replacement



• Heat Straightening & Heat Shortening

• The existing eye bars elongated over the years• Performed heat shortening to remove slack• Left cables in place



• Timber Decks - Maintain Historic Deck Material Type and Minimize Dead Load

• Penta in Light Oil for Pedestrian Usage

• 3 1/8” Glued-Lam Deck

• Re-sawn for Traction




• Attach New Railing to Lightweight Truss or Deck

• Attach to Steel Stringers

• Independent of Deck or Truss

• Allows Easy Future Deck Replacement

• Note Attachment of Decorative Light-posts at

• Floor-beam Locations.Van Buren Street Pedestrian Bridge


Construction Costs

• Lozeau Bridge – 1998 Total Cost $1,500,000 $190 / Sq. Ft.

• Dearborn R. High Br. – 2003 Total Cost $1,000,000 $250 / Sq. Ft.

• Van Buren Br. – 2004 Total Cost $350,000 $60 / Sq. Ft.

Design Resources• Heat Straightening - Holt

• Heat Shortening Details and Specs – AREMA and Old DOT Standards

• Old Steel Sections - Old Books

• AASHTO

Questions?

Pictures

Lozeau Bridge

Lozeau Bridge

Pictures


Pictures

Van Buren Street Bridge

Pictures

Montana Truss Rehabilitation Projects Lozeau Bridge over the Clark Fork Dearborn River High Bridge...

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