PENGARUH INDEKS KELANGSINGAN TERHADAP KINERJA KOLOM BETON BERTULANG PADA BANGUNAN TAHAN GEMPA

Abstract

Columns are the main vertical structural elements responsible for transferring loads from the upper components to the foundation; therefore, their performance plays a crucial role in ensuring the stability and safety of buildings. One of the key parameters affecting column behavior is the slenderness index, defined as the ratio between the effective length and the radius of gyration of the cross-section. A higher slenderness index indicates a more slender column, which is more susceptible to structural instability, especially under the combined influence of axial and lateral seismic loads that induce second-order effects (P–Δ effects). This study aims to analyze the influence of slenderness index on the internal force capacity and behavior of reinforced concrete columns in seismic-resistant frame systems. The analysis was performed using an elasto-static and numerical approach, applying the Moment Magnification, Moment Amplification, Iteration, and Geometric Stiffness Matrix methods with variations in slenderness ratio between short and slender columns. Observed parameters include axial force, bending moment, shear force, and lateral deformation. The results show that increasing the slenderness index amplifies the moment due to P–Δ effects and reduces the nominal strength of the column. Slender columns exhibit greater lateral deformation and lower stability than short columns. Therefore, the slenderness effect must be thoroughly considered in the design of reinforced concrete columns to ensure adequate stiffness, stability, and ductility of structures under seismic loading.