Shear Repair of P/C Box Beams using CFRP Fabric

KYDOT

July 27, 2011Salt Lake City, Utah

Kentucky Transportation Cabinet Kentucky Transportation Center University of Kentucky

RAC/TRB Summer Meeting

Objective Retrofit P/C Spread Box Beams using carbon fiber

reinforced polymer (CFRP) fabric to increase Shear

Capacity

CFRP CLOTH/FABRIC

CFRP Fabric

+ Resin

Steel P

late

(A36 Stee

l)

Ultimate Load = 3.25 kip

1”1”

hCFRP = 0.0066”

wCFRP = 0.0051 lb/ft wSteel = 0.19 lb/ft ≈ 37 wCFRP

hSteel = 0.056”

≈ 8.5 hCFRP

CFRP Fabric vs. Steel

Task #1

Material Testing

CFRP Fabric Test Specimens

Task #2

Beam Testing

45o

Beam Strengthening

Beam Testing

Beam Testing

Task #3

Field Application

Bridge on KY 3297 over Little Sandy RiverCarter County, Kentucky

Shear Cracks inP/C Box Beams

Cracks Growing at an Alarming Rate

SevereShear

Cracks

Original Solution

Replace the Superstructure - Cost: ~ $600,000 - Close Bridge to Traffic

Alternate Solution

Use CFRP Fabric - Cost: $105,000 (Design, Repair, and 3-years Monitoring)

- Bridge Remains Open to Traffic

Placement of CFRP FabricStep 1:Surface

Preparation

Placement of CFRP FabricStep 2:

Crack Injection and Filling of Voids

Step 3:Apply Primer

Placement of CFRP Fabric

Step 4:Apply Carbon

Fabric

Placement of CFRP Fabric

Step 5:CFRP Fabric on Outside Face Painted to Match Concrete Color

Placement of CFRP Fabric

Task #4

Monitoring

Scaffolding Used for Monthly Bridge Monitoring

Bridge Monitoring (10/01 to 12/06)

CFRP Fabric on Inside Faces of the Beams Was Not Painted to

Match Concrete Color

Crack Monitor

No Crack Movement Since Repair Was Completed in October 2001

Crack Monitor on Inside Beam Face

- Cost Effective: $105,000 for Repair vs.$600,000 for Replacement

- Repair is Effective: No Crack Movement Since Repair was Completed in

October 2001

- No Detour- No Traffic Control- No Traffic Disruption

Conclusion

!!!!! HURRAY !!!!!!

Associated Press November, 2001

The State Journal, December, 2001

The Daily Independent

November 2001

Other CFRP Projects in KY 9 Bridges Strengthened with CFRP 3 Bridges Strengthened With Steel FRP

Thank Youand

Have a Nice Day

KY