Research Activities: 1998

Strengthening of Bridge G270 with Externally Bonded CFRP Sheet



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Sequential Number


Identification Number


Matching Research Agency

Missouri Department of Transportation (MoDOT)

Principal Investigator

Antonio Nanni, Professor
John Myers, Assistant Professor
Civil Engineering
University of Missouri-Rolla
224 Engineering Research Lab.
Rolla, MO 65409
p(573) 341-4553
f(573) 341-6215

Student Involvement

One (1) graduate student

Project Objective

The proposed project aims to demonstrate the feasibility of externally bonded fiber reinforced polymer (FRP) reinforcement for the flexural strengthening of concrete bridge structures.

Project Abstract

This is a pilot study to apply externally bonded Carbon FRP sheets to strengthen a simple span reinforced concrete solid slab bridge built in 1922. Strengthening with CFRP sheets was accomplished in three days without traffic interruption and preparation consisted of only light sandblasting. Bridge G-270 is the only load posted structure on a heavy truck route that serves a lead mining operation and the objective was to strengthen the bridge to allow removal of the load posting. The strengthening was designed as shown in the report and laboratory and field tests were performed to verify the performance of the work. The laboratory testing included the static flexural test of two full-scale beams and the fatigue bond test of coupon-type specimens. Two reinforced concrete beams, a control beam and a beam strengthened with externally bonded CFRP were tested under four point bending. Coupon-type specimens were used to investigate the behavior of bond between CFRP sheets and concrete under fatigue loading. The field load testing of the bridge, before and after strengthening, was performed by the University of Missouri-Columbia to verify the performance of the bridge after the application of externally bonded CFRP. Field measurements were also conducted to monitor the durability and the strain condition of the strengthened system. The Pennsylvania State University conducted the monitoring of durability by studying the electrochemical effects of the CFRP material on the degradation of the reinforcing steel. Fiber-optic strain sensors were applied to the FRP reinforcement and the concrete to allow for long-term monitoring of the integrity of the FRP reinforcement. This pilot study was successful in that laboratory and field tests indicate that CFRP sheets externally applied to a bridge superstructure strengthens the member and does not show deterioration. Monitoring of the bridge will continue.

Task Description

The implementation of the project is subdivided according to the following tasks: design and full-size laboratory testing; coupon size laboratory testing; field construction; in-situ load testing; in-situ long-term monitoring of strain; and in-situ long-term monitoring of durability.

Anticipated Benefits

As a result of this project load posting can be removed. Several bridges is similar conditions exist in Missouri and surrounding Mid-America states.

Modal Orientation



Project Start Date:04/01/1998
Project End Date:06/30/1999

Relationship to other Research/Projects

This project is related to Destructive and non-
destructive test of bridge J857, highway 72, Phelps County, Missouri

Technology Transfer Activities

Project deliverables include a design protocol for MoDOT

Transportation Research Board Keywords

Bridge, CFRP, durability, external reinforcement and load testing