Flexural Strengthening of RC Beams Using Steel Reinforced Polymer (SRP) Composites

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Title: Flexural Strengthening of RC Beams Using Steel Reinforced Polymer (SRP) Composites

Author(s): Y.J. Kim, A. Fam, A. Kong, and R. El-Hacha

Publication: Special Publication

Volume: 230

Issue:

Appears on pages(s): 1647-1664

Keywords: concrete beam; flexure; Hardwire®; sheet; steel-reinforcedpolymer; strengthening

Date: 10/1/2005

Abstract:
This paper presents the application of a new generation of externallybonded composite material in flexural strengthening of reinforced concrete beams. Thesteel reinforced polymer (SRP) composite consists of high-carbon steel unidirectionalHardwire® fabrics embedded in epoxy resin, and offers high strength and stiffnesscharacteristics at a reasonable cost. In this paper, the mechanical properties of SRP areevaluated and its application in flexural strengthening of RC beams is investigated. Sixbeams have been tested in three-point bending to study the effect of SRP retrofitting onflexural behavior, failure modes, and crack patterns. Test parameters include variationof the width of SRP sheets and the use of SRP U-wraps to prevent premature failurecaused by delamination of the longitudinal sheet. Significant increase in flexuralcapacity, up to 53%, and pseudo-ductile failure modes were observed in SRP-strengthened beams. Failure was governed primarily by concrete cover delamination atthe ends of SRP sheets or concrete crushing. The U-wraps improved flexural stiffness bymeans of controlling diagonal cracking and providing anchorages to the longitudinalSRP sheets, which reduced their slip. Shear stress concentrations near cut-off points ofSRP sheets have also been investigated. An analytical model was used to predict thenominal flexural strength of SRP-strengthened beams.