Shear-strengthening of reinforced &amp; prestressed concrete beams using FRP: Part II — Experimental investigation

Thomas H -K Kang,Moustapha Ibrahim Ary

doi:10.1007/s40069-012-0005-0

Abstract

Abstract The main objectives of this research were to experimentally evaluate the impact of Carbon Fiber-Reinforced Polymers (CFRP) amount and strip spacing on the shear behavior of prestressed concrete (PC) beams and to evaluate the applicability of existing analytical models of Fiber-Reinforced Polymer (FRP) shear capacity to PC beams shear-strengthened with CFRP. The Ushaped CFRP strips with different spacing were applied externally to the test specimens in order to observe the overall behavio r of the prestressed concrete I-beams and the mode of failure of the applied CFRP strips. Results obtained from the experimental program showed that the application of CFRP strips to prestressed concrete I-beams did in fact enhance the overall behavior of the specimens. The strengthened specimens responded with an increase in ductility and in shear capacity. However, it should be noted that the CFRP strips were not effective at all at spacing greater than half the effective depth of the specimen and that fracture of the strips was the dominant failure mechanism of CFRP. Further research is needed to confirm the conclusion derived from the experimental program.

Highlights

Fiber-Reinforced Polymers (FRP) are composite systems of fibers embedded in a polymeric matrix.[1]
No experimental tests have been conducted on prestressed concrete beams shear-strengthened with Carbon Fiber Reinforced Polymers (CFRP) but without internal steel transverse reinforcement
The wire potentiometers (WP) placed at midsection and at loading points of the beam measured the vertical displacement at both east and west faces of the beam.Data from WP1 East in IB10 were compromised during testing, and as a consequence and for comparison reasons, no data from WP1 East located at the east face of the midsection on IB-10 were used in this project

Summary

Introduction

Fiber-Reinforced Polymers (FRP) are composite systems of fibers embedded in a polymeric matrix.[1]. An experimental program is devised to investigate the shear resistance of CFRP externally bonded to prestressed concrete I-beams without transverse reinforcement. No experimental tests have been conducted on prestressed concrete beams shear-strengthened with CFRP but without internal steel transverse reinforcement. All experimental beams are specially designed to fail in shear in order to better study the interaction between the concrete and the externally applied CFRP sheets. Results obtained from the experimental program do expand the relatively small database currently available on CFRP shear-strengthening, and help improve existing analytical models by evaluating and identifying new key parameters. Considering the current database of CFRP strengthened beams, more data derived from large-scale specimen testing are needed in order to account for the scale effect and provide a better prediction of the behavior of externally applied CFRP sheets.

Hypotheses and objectives

Experimental program

Test results and discussion

Conclusions