structural issues and 2009 repairs

8/14/2019 Structural Issues and 2009 Repairs

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Tom Hoffman, P.E.

R-1 Structures Engineer

STRUCTURAL ISSUES


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BRIDGE STATISTICS

BRIDGE IDENTIFICATION NUMBER: 5521180

AGE: Built in 1929

LENGTH: 14 spans,

2,184 feet ROADWAY WIDTH: 26.1 feet

STRUCTURE TYPE: Combination of thru truss, decktruss, and deck plate girders

BIKE / PED ACCOMMODATIONS: None

VERTICAL CLEARANCE ON BRIDGE: 14 feet

MAX VERTICAL CLEARANCE OVER WATER: 95 feet

AVERAGE ANNUALDAILY TAFFIC (2008): 3,150 vehicles per day

WEIGHT CAPACITY: -Restricted since 1994 to

less than 102,000 pounds.-Currently reduced to a singlelane/ 40 ton posting.


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RECENT WORK HISTORY

1990-91 Bridge Rehabil itat ion ProjectAppx $7.0 million in 1989 (Appx. $17.3 in 2007 dollars) Bearings - Some Cleaned, Some Replaced Spot Painting (Span 4-9, bearings)

Deck Replacement With Lightweight System Floor Beam Replacement and Strengthening (some spans) Joint Replacement Bridge Rail

Approach Slab Replacement Concrete Repairs on Piers and Abutments Pier 4 Compression Straps Added (Now occur on Piers 4-8)

-The first strapped in 1974 to arrest crack development

Emergency Repair Contract Compression Band Replacement - $125,000 in 2005

Pier Repairs - $100,000 in 2008

Steel Repairs - $1 m illion estimated in 2009 Maintenance Repair of Bridge Joints 2005, 2006, 2008


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INITIAL PROBLEM IDENTIFICATION

Bridge Condition Rating

Score 3.375 out of a possible 7 points (2009) Scores between 3 and 4 indicate serious deterioration or not

functioning as originally designed Problems are with main carrying members, bearings, joints,

concrete, paint, and wearing surface

Federal Sufficiency Rating

Score 29.2 (2008) out of a possible 100 points Scores less than 65 qualify for Federal funding

Load Restricted

40 Ton limit restricts all overloads, including log trucks and milktrucks

Limited roadw ay vertical clearance of 14-0 Trucks in excess of 14 have struck the bridge on several

occasions, requiring the bridge to be closed for repair


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Truss Terminology


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Channel Piers


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Concrete CompressionStrap Replacement


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Concrete Deterioration


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Concrete DeteriorationPier 3- Before


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Concrete DeteriorationPier 3- After


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Pier 8 Condition(Before)


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Pier 8 Condition

(After)


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Steel and Paint Condition


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Steel and Paint Condition


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Joints


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Bearings


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Recent Repairs-Floorbeams Pier 5 and 8


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Recent Repairs-Bottom Chord


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Recent Repairs-Bottom Chord


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Recent Repairs-Steel Pier


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Recent Repairs-Steel Pier


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Recent Repairs-Gusset Plates


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Other Yellow Flags

Many yellow flags for gussets and strap ties are not being addressedat this time. All red flags, and yellow flags of significance are being

repaired.


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What Now?

1) Paint of Select Areas Some areas are beingblasted and painted to slow deterioration ofcritical areas.

2) Finish Chord Repairs

3) Finish Floorbeam Repairs and Add Troughs

4) Re-Inspect in the Spring Repair as Needed

5) Possibly Paint Selected Truss Members and underJoint Areas

-Chords of Spans 4, 5 and 9- Entire Truss of Spans 6 and span 8,

span 7 (splash zone down)- Under Joint Areas at Piers 3, 5 and 8

- Estimated at $6 Mil lion


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General Questions .

1) Why w as the load posting reduced?

2) What does it mean?

3) Does a single lane really make things better?

4) $64,000 question .Is the bridge safe?


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Questions????

structural issues and 2009 repairs

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