Title: External Reinforcement of Concrete Beams Using Fiber Reinforced Plastics

Author(s): Philip A. Ritchie, David A. Thomas, Le-Wu Lu, and Guy M. Conelly

Publication: Structural Journal

Volume: 88

Issue: 4

Appears on pages(s): 490-500

Keywords: adhesives; beams (supports); composite materials; epoxy resins; flexural strength; glass fibers; plastics, polymers, and resins; tests; reinforcing materials; shear properties; stiffness; Structural Research

DOI: 10.14359/2723

Date: 7/1/1991

Abstract:
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 two-part epoxy. FRP is attractive for this application due to its good tensile strength, low weight, and resistance to corrosion. An iterative 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 percent were achieved for the beams with FRP plates. Predicted and actual 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 anchorage to postpone the local shear failure. The ultimate loads of the beams that did fail in the maximum region were within about 5 percent of predicted values.