Confined Concrete in Fiber-Reinforced Polymer Partially Wrapped Square Columns: Axial Compressive Behavior and Strain...

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Reinforced concrete (RC) columns are often strengthened using fiber-reinforced polymer (FRP) strips.
• Partial wrapping strengthening technique (PWST) is common, but the confinement mechanism is less understood than full wrapping (FWST).

Purpose of the Study:

• To experimentally investigate the behavior of confined concrete in FRP partially wrapped square columns under axial compression.
• To evaluate the effects of FRP strip width and thickness on stress-strain behavior.
• To develop and validate a new design-oriented stress-strain model for these columns.

Main Methods:

• Experimental investigation of FRP partially wrapped square columns under axial compression.
• Utilized particle image velocimetry (PIV) for non-contact strain measurement.
• Compared experimental results with existing design-oriented stress-strain models.

Main Results:

• Axial and hoop strains were larger at the mid-plane of adjacent FRP strips compared to the mid-plane of individual strips.
• Significant variation in hoop strains was observed along the column height.
• Existing models showed limitations in predicting the behavior of partially wrapped columns.

Conclusions:

• The study provides crucial insights into the confinement mechanism of FRP partially wrapped columns.
• A new design-oriented stress-strain model was proposed and validated.
• The proposed model demonstrates superior accuracy compared to existing models for FRP partially wrapped square columns.