Experimental Ductility of Compression-Controlled Flexural Members Using CFRP Grid to Confine Concrete

Area of Science:

• Civil Engineering
• Materials Science
• Structural Engineering

Background:

• Over-reinforced concrete members with non-yielding reinforcement (e.g., FRP composites) often exhibit brittle flexural failure initiated by concrete crushing.
• Traditional design aims for ductile failure initiated by steel yielding, followed by concrete crushing.

Purpose of the Study:

• To investigate the effectiveness of concrete confinement using carbon fiber reinforced polymer (CFRP) grid tubes in the compression zone.
• To improve the flexural behavior and ductility of over-reinforced concrete members.

Main Methods:

• Experimental testing of rectangular concrete beams.
• Comparison of a control beam (no grid reinforcement) with a beam incorporating CFRP grid tubes in the compression zone.
• Analysis of flexural behavior and ductility under load.

Main Results:

• The beam with embedded CFRP grid tubes demonstrated improved ductility compared to the control beam.
• Ductility enhancement ranged from approximately 20-30%, depending on the evaluation criteria.
• Significant improvement was observed despite the low volume and mechanical properties of the CFRP grid.

Conclusions:

• The proposed method of concrete confinement using CFRP grid tubes is a valid approach to enhance ductility.
• This technique effectively improves the flexural behavior of compression-controlled, over-reinforced concrete members.
• CFRP grid confinement offers a promising solution for mitigating brittle failure in such structural elements.