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

摘要

This paper presents the application of a new generation of externally bonded composite material in flexural strengthening of reinforced concrete beams. The steel reinforced polymer (SRP) composite consists of high-carbon steel unidirectional Hardwire~® fabrics embedded in epoxy resin, and offers high strength and stiffness characteristics at a reasonable cost. In this paper, the mechanical properties of SRP are evaluated and its application in flexural strengthening of RC beams is investigated. Six beams have been tested in three-point bending to study the effect of SRP retrofitting on flexural behavior, failure modes, and crack patterns. Test parameters include variation of the width of SRP sheets and the use of SRP U-wraps to prevent premature failure caused by delamination of the longitudinal sheet. Significant increase in flexural capacity, up to 53%, and pseudo-ductile failure modes were observed in SRP-strengthened beams. Failure was governed primarily by concrete cover delamination at the ends of SRP sheets or concrete crushing. The U-wraps improved flexural stiffness by means of controlling diagonal cracking and providing anchorages to the longitudinal SRP sheets, which reduced their slip. Shear stress concentrations near cut-off points of SRP sheets have also been investigated. An analytical model was used to predict the nominal flexural strength of SRP-strengthened beams.