Analysis of the Center of Gravity and Moment of Inertia of Concrete Beam and Column Cross-Sections Using Manual and AutoCAD Methods in a Simple Building: the Barracks of Infantry Bengkulu

Abstract

Concrete beams and columns are important structural elements that support the strength, stability, and safety of a building. This study aims to compare the centroid and moment of inertia of concrete beam and column cross-sections calculated using manual methods and AutoCAD in the Barracks D project of the 847th TP Infantry Battalion in Bengkulu. This study uses a descriptive comparative method. The analysis was conducted on cross-sections in the support areas, namely B1–K1 and B2–KP, and in the field areas, namely B1, B2, and K1. AutoCAD modeling was carried out using Polyline, Region, and Massprop commands to determine the geometric properties of each cross-section. The results show that the field-area cross-sections have very similar results between the manual and AutoCAD methods. The difference in centroid coordinates was 0.00%, while the moment of inertia deviation was very small, approximately 0.00000004%. However, larger differences were found in the support areas. The X-coordinate differences were 58.58% and 64.29%, while the Y-coordinate differences were 33.28% and 40.00%. The moment of inertia differences were 4.32% and 4.01%. The manual method provides detailed calculation steps but requires more time. AutoCAD is faster and more efficient, especially for complex cross-sections. However, its accuracy depends on the drawing data and only represents gross cross-sectional geometry.