Repair of Traffic-Impacted Box Beam Bridge

Hawkins Road Crossing Interstate 94 in Michigan

January 1983:Impact Breaks 7 Strands

March 1983:Second Impact Breaks 2 More Strands

The Original Shop Drawings

Repair Approach

Use District Maintenance Crew Repair Each Strand Using

Splice Chuck Coupler Hex Splice Sleeve and Two ¾ inch Diameter A449 Rods (one

right hand thread and left hand thread on the other to allow tensioning)

Hardware cost is about $175 per strand but delivery is a long five months

Splice Chucks

Cutting Damaged Strands

Installing Splice Chucks

Installing Splice Chucks

Drilling for Void Form Attachment

Installing Turnbuckles

Tensioning Rods with Stain Gauges

Installing Tensioning Rods

Strain Gauge

Tensioning Computation

Tensioning allowed for losses that had occurred during the 25 year life of the bridge

Tensioning

Tensioning was accomplished in 4 passes from the inside to the outside of the beam

All Strands Repaired

Deflecting Beams

A preload was used so that the repair-concrete would be in compression after the preload removal

A New Bridge Opening Height

Preparation for Form Attachment

Preparation of Form

Form Release Agent Applied

Form Installation

Creating Vibration Access

Final Deflection Verification

Concrete Delivery

Concrete Quality Control

Concrete Quality Control

Placing of Concrete

Vibration of Concrete

Repair Completed!

Four Months After Completion of First Repair:

Bridge was hit for the third time

Most of the splices done earlier were intact, indicating a durable repair

The damage this time was 19 of the 25 strands of the fascia beam, 7 strands of the first interior beam and 4 strands of the second interior beam.

The repair involved replacement of the fascia beam with a solid concrete beam and repair of the interior beam using the successful approach of the earlier repair.

Post Script

Shortly after the second repair was completed the bridge was hit a fourth time. This time it only suffered a nick in the solid fascia beam.