Evaluasi perilaku kolom beton bertulang akibat perkuatan (studi kasus concrete jacketing dengan baja tulangan dan GFRP rebar)

Abstract

Concrete jacketing is a strengthening technique involving the addition of new reinforcement and concrete to existing structural elements with optimized dimensions. In recent developments, Glass Fiber Reinforced Polymer (GFRP) bars have emerged as a promising alternative to conventional steel reinforcement, offering nearly three times higher tensile strength. This study numerically investigates the behavior of reinforced concrete columns under three conditions: unstrengthened (Specimen A), strengthened with steel-reinforced jacketing (Specimen B), and strengthened with GFRP-reinforced jacketing (Specimen C). The analysis focuses on load capacity, stress distribution, material performance, and plasticity levels. The unstrengthened column measures 70×70 cm with 20D25 BJTD 40 reinforcement, while the jacketed columns measure 80×80 cm with an additional 20 bars of 10 mm diameter. All column models have a height of 4 m and are idealized using fiber element modeling with 20 fiber hinges. The maximum load capacities were 313.5 kN (A), 395.45 kN (B), and 367.23 kN (C). The highest concrete compressive stress was observed in Specimen A (12.96 MPa), while the maximum initial tensile stress in steel reinforcement occurred in Specimen B (505.1 MPa). The peak tensile stress in the jacketing reinforcement was also in Specimen B (514.33 MPa). All models exhibited concrete cracking in tension zones and rebar yielding, classified under Immediate Occupancy (IO) performance level. Plasticity levels of tensile reinforcement predominantly ranged from B to E, while compressive concrete zones showed B–C behavior in Specimen A and A–B in Specimens B and C.