Analisis Ekuivalensi Penampang Kolom Beton Bertulang Menjadi Concrete Filled Steel Tube (CFST) Terhadap Perpindahan Lateral dan Story Drift

Abstract

The growth of high-rise buildings increases the demand for structural systems with high strength and stiffness. Concrete-Filled Steel Tube (CFST) columns, consisting of steel tubes filled with concrete, are a promising alternative. This study analyzes the equivalence of the reinforcement area in reinforced concrete columns to CFST wall thickness, evaluates the B/t ratio based on SNI 1729:2020, determines the required compact wall thickness, and compares structural responses in terms of lateral displacement and inter-story drift. A quantitative descriptive comparative method was applied using ETABS to model the Integrated Lecture Building of the University of Palangka Raya. Three models were analyzed: the existing reinforced concrete column (Model 1), the reinforcement-equivalent CFST (Model 2), and the SNI 1729:2020-based CFST (Model 3). Model 2 produced wall thicknesses of 1.874–3.532 mm with B/t ratios exceeding the λmax limit, indicating slender sections. Model 3 required wall thicknesses of 13, 9, and 6 mm to satisfy compact criteria. CFST columns reduced lateral displacement by 7.34–22.70% and inter-story drift by 6.63–23.07%.