Enhancing seismic resilience of piloti frames through AFRP strengthening: An integrated experimental and analytical study

Reinforcing existing structures with aramid fiber-reinforced polymer (AFRP) sheets is a practical strengthening solution owing to their high tensile strength, low self-weight, and ease of installation. This technique is particularly suitable for Piloti-type buildings widely used in South Korea. The experimental program consisted of three ground-story Piloti reinforced concrete (RC) frame specimens, including one unretrofitted reference specimen and two AFRP-retrofitted specimens. The main test variables were the AFRP strengthening condition and the column configuration. Experimental results showed that the AFRP-retrofitted specimen with the same rectangular column configuration exhibited an 18.97% increase in positive peak lateral load and an average ductility enhancement of approximately 2.85 times compared with the unretrofitted specimen. Under cyclic loading, the retrofitted specimens showed improved seismic resistance and more stable structural behavior. Damage observations indicated that AFRP sheets delayed crack widening, local deterioration, and severe damage progression. In addition, nonlinear ZeusNL analysis showed good agreement with the experimental results, confirming its reliability in predicting the cyclic response of AFRP-strengthened frame specimens.