*Co-chairs of the subcommittee that prepared this document. Note: The committee acknowledges the contribution of associate member Paul Kelley. ACI encourages the development and appropriate use of new and emerging technologies through the publication of the Emerging Technology Series. This series presents information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions of committee members. The presented information and recommendations, and their basis, may be less fully developed and tested than those for more mature technologies. This report identifies areas in which information is believed to be less fully developed, and describes research needs. The professional using this document should understand the limitations of this document and exercise judgment as to the appropriate application of this emerging technology.

/pdf/guide-for-the-design-and-construction-of-externally-bonded-3wakai247t.pdf

Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures

Intermediate crack-induced debonding in RC beams and slabs

FRP-strengthened RC beams. I: review of debonding strength models

https://www.quakewrap.com/frp%20papers/Progress-On-Understanding-Debonding-Problems-In-Reinforced-Concrete-And-Steel-Members-Strengthened-Using-FRP-Composites.pdf

Progress on understanding debonding problems in reinforced concrete and steel members strengthened using FRP composites

The structural behavior of reinforced concrete beams strengthened with adhesively bonded fiber-reinforced plastics (FRP) is presented. The experimental work included flexural testing of 2.3-m-long concrete beams with bonded external reinforcements. The test variables included the amount of conventional (internal) reinforcement and also the type and amount of external reinforcement. For comparison, some of the beams were strengthened with bonded steel plates. Theoretical analyses included 2D nonlinear finite-element modeling incorporating a “damage” material model for concrete. In general there were reasonably good correlations between the experimental results and nonlinear finite-element models. It is suggested that the detachment of bonded external plates from the concrete, at ultimate loads, is governed by a limiting principal stress value at the concrete/external plate interface.

Concrete beams strengthened with externally bonded frp plates

A series of 16 under-reinforced beams was tested to study the effectiveness of external strengthening using fiber reinforced plastic (FRP) plates. Plates of glass, carbon and aramid fibers were bonded to the tension side of the beams using a 2-part epoxy. An interative analytical method was developed to predict the stiffness and maximum strength in bending of the plated beam. Increases in stiffness (over the working load range) from 17 to 99 percent and increases in strength (ultimate) from 40 to 97% were achieved for the beams with FRP plates. Predicted and acutal load-deflection curves showed fairly good agreement, although generally the theoretical curves were stiffer. Experimental failure did not occur in the maximum moment region on many of the beams, despite attempts at end anchorages to postpone local shear failure. The ulltimate loads of the beams that did fail in the maximum region were within about 5% of predicted values.

Philip A. Ritchie

Papers

External Reinforcement of Concrete Beams Using Fiber Reinforced Plastics