Glass Fibre Reinforced Polymer (GFRP) internal reinforcing bars are being increasingly considered as a potential corrosion free alternative to regular and stainless steel reinforcing bars. In spite of the availability of code provisions governing both design and certification of the GFRP bars, their use within concrete structures is currently limited to very specific applications unless some behaviour aspects are further investigated. In particular, crack control, ultimate member deformability and the behaviour of the bent GFRP bars are areas in need of such further investigation.
An experimental program was conducted consisting of 24 large-scale beams reinforced with various types of GFRP and steel bars complying with CSA certification standards. The results of which show that the stress in the bent bar stirrups at beam failure exceeded minimum code-prescribed values for design (CSA S6, CSA S806, ACI440). An alternative bend-less system of shear reinforcement using straight double headed bars was successful as shear reinforcement but did however result in significant reductions to member deformability.
A critical review of the various design provisions incorporating GFRP shear reinforcement, it was found that many of the design codes use conservative shear reinforcement strengths coupled with unconservative values of either the angle of inclination of the compression strut or the concrete contribution to shear resistance. A new relationship for the inclination of the compression strut was proposed for use within the Simplified Modified Compression Field Theory which when combined with the bend/anchor strength of the shear reinforcement correlate well with the experimental results. Also, it was determined that the design strain limits for GFRP shear reinforcement should not be increased until more detailed studies on the long-term performance of the stirrups are conducted. Finally, advanced analysis techniques like layered sectional- and finite element-analysis both gave excellent analytical estimates of the experimental beam response.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/65672 |
| Date | 22 July 2014 |
| Creators | Johnson, David Tse Chuen |
| Contributors | Sheikh, Shamim A. |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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