Single-Lap Shear Tests of Fiber-Anchored and Unanchored EBFRP Systems in Various Configurations and Alignments

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Figure Description:

This figure series illustrates four distinct configurations of Externally Bonded Fiber Reinforced Polymer (EBFRP) systems used in single-lap shear tests to evaluate the effect of anchorage detailing on bond strength and failure modes. Each configuration is designed to isolate and assess how fan anchor geometry, spacing, thickness, and anchoring strategy affect FRP-to-concrete interface performance:

1. No Anchorage (Control Specimen)
   Features bonded FRP strips without any mechanical anchorage. This setup serves as a baseline to assess the pure bond strength and failure by debonding or cohesive pull-off.
2. • FRP Thickness: 0.5 to 6 mm
   • Bonded Length: ~1370 mm
   • Concrete Strength: 17.2–44.7 MPa
3. Single-End Anchorage with Fan Anchor
   Includes a single fan-shaped anchor applied at the loaded end to delay debonding.
4. • Fan Length: 305–610 mm
   • Dowel Diameter: 13/19/25 mm
   • Insertion Depth: 100 mm at 90°
   • FRP Thickness: 0.5 mm
5. Double-End Anchorage with Symmetrical Fan Anchors
   Fan anchors are applied at both the loaded and free ends to investigate symmetric confinement effects.
6. • Fan Length: 205 mm
   • Dowel Diameters: 7–25 mm
   • FRP Thickness: 2/4/6 mm
   • Unbonded Midsection: 150 mm
   • Used to study combined stress redistribution.
7. Multi-Anchor System with Spacing Variations
   Features two or more anchors along the bonded length at 305 or 610 mm spacing to investigate distributed anchorage.
8. • Fan Length: 305 mm
   • Spacing: 305/610 mm
   • FRP Thickness: 1 mm
   • Designed to simulate long-span or continuous retrofit conditions.

Each configuration reflects a progressive enhancement of anchorage complexity, allowing comparative analysis of anchorage efficiency, bond-slip behavior, and failure patterns.