Electronic Theses and Dissertation

Kolom beton bertulang merupakan elemen struktural kritis yang menentukan stabilitas bangunan. Kegagalan kolom akibat beban aksial diawali dengan terkelupasnya selimut beton, yang dapat menyebabkan kehancuran struktur jika tulangan sengkang tidak mampu mengekang inti beton secara memadai. Penelitian ini bertujuan mengkaji efektivitas Natural Fiber Reinforced Polymer (NFRP) serat abaka sebagai perkuatan eksternal kolom pendek beton bertulang penampang lingkaran, menganalisis perilaku kegagalan, dan mengevaluasi akurasi modelmodel
analitis eksisting. Metode eksperimental menggunakan spesimen kolom pendek (D = 205 mm, H = 615 mm, f'c = 25 MPa) dengan tulangan longitudinal BjTS 420 D10 dan tulangan transversal spiral BjTP 280 P8. Pengekangan NFRP diaplikasikan dengan metode wet lay-up pada tiga konfigurasi: full wrapped, partial wrapped, dan spiral wrapped menggunakan resin epoxy Sikadur-330. Variasi 1, 2, dan 3 lapis diterapkan pada konfigurasi full wrapped. Pengujian dilakukan dengan pembebanan aksial monotonik hingga kegagalan. Hasil penelitian menunjukkan pengekangan NFRP serat abaka secara signifikan meningkatkan kapasitas aksial
kolom. Kolom tanpa kekangan (NC) memiliki kapasitas 742,27 kN. Konfigurasi spiral (CS-NFPC) menunjukkan performa terbaik dengan kapasitas 910,27 kN (+22,6%) dan indeks daktilitas μ = 20,90 (+346%). Konfigurasi partial (CP-NFPC) menghasilkan kapasitas 844,25 kN (+13,8%) dengan μ = 6,915 (+48%). Pada full wrapped, dua lapis (CF-NFPC-2L) optimal dengan kapasitas 897,71 kN (+21,0%) dan μ = 4,87, sedangkan tiga lapis mengalami degradasi menjadi 818,94 kN akibat penjeratan void. Pola kegagalan bertransformasi dari mode getas pada NC menjadi daktil dan terkendali pada kolom terkekang NFRP. Kekakuan elastis meningkat
dengan rasio 1,13–1,43 terhadap kolom kontrol. Regangan tulangan utama tereduksi 85–93% pada spesimen full wrap. Analisis menggunakan delapan model teoretis (Mander Termodifikasi, Lam-Teng, Samaan, Toutanji, Miyauchi, Saafi, ACI 440.2R-17, Spoelstra-Monti) menunjukkan prediksi konservatif dengan rasio Qeks/Qanl = 0,93–1,20. Model Lam-Teng dan ACI 440.2R-17 memberikan akurasi terbaik untuk aplikasi desain. Penelitian ini membuktikan bahwa serat abaka
sebagai material NFRP layak digunakan sebagai alternatif ramah lingkungan untuk perkuatan kolom beton bertulang.

Kata kunci: NFRP, serat abaka, kolom pendek beton bertulang, pengekangan
eksternal, kapasitas aksial, daktilitas, model konstitutif.

Reinforced concrete columns are critical structural elements determining building stability. Column failure due to axial loads begins with spalling of the concrete cover, which can cause structural collapse if the transverse reinforcement is unable to adequately confine the concrete core. This research aims to examine the effectiveness of abaca fiber Natural Fiber Reinforced Polymer (NFRP) as external strengthening for circular crosssection short reinforced concrete columns, analyze failure behavior, and evaluate the accuracy of existing analytical models. The experimental method used short column specimens (D = 205 mm, H = 615 mm, f'c = 25 MPa) with BjTS 420 D10 longitudinal reinforcement and BjTP 280 P8 spiral transverse reinforcement. NFRP confinement was applied using wet lay-up method in three configurations: full wrapped, partial wrapped, and spiral wrapped using Sikadur-330 epoxy resin. Variations of 1, 2, and 3 layers were applied to the full wrapped configuration. Testing was conducted with monotonic axial loading until failure. Results showed that abaca fiber NFRP confinement significantly increased column axial capacity. Unconfined columns (NC) had a capacity of 742.27 kN. The spiral configuration (CS-NFPC) showed the best performance with capacity of 910.27 kN (+22.6%) and ductility index μ = 20.90 (+346%). The partial configuration (CP-NFPC) produced capacity of 844.25 kN (+13.8%) with μ = 6.915 (+48%). For full wrapped, two layers (CF-NFPC-2L) was optimal with capacity of 897.71 kN (+21.0%) and μ = 4.87, while three layers experienced degradation to 818.94 kN due to void entrapment. Failure patterns transformed from brittle mode in NC to ductile and controlled mode in NFRPconfined columns. Elastic stiffness increased with ratios of 1.13–1.43 relative to control columns. Main reinforcement strain was reduced by 85–93% in full wrap specimens. Analysis using eight theoretical models (Modified Mander, Lam-Teng, Samaan, Toutanji, Miyauchi, Saafi, ACI 440.2R-17, Spoelstra-Monti) showed conservative predictions with Qexp/Qanl ratios of 0.93–1.20. Lam-Teng and ACI 440.2R-17 models provided the best accuracy for design applications. This research proves that abaca fiber as an NFRP material is feasible for use as an environmentally friendly alternative for strengthening reinforced concrete columns. Keywords: NFRP, abaca fiber, reinforced concrete short