EVALUASI INERSIA PENAMPANG BALOK KASTELA DENGAN PENDEKATAN NUMERIK

Abstract

Castellated beams are widely used in long-span structures such as buildings, bridges, and transmission towers. In addition, castellated beams facilitate the integration of utility systems, including pipelines, air-conditioning ducts, and cables. Increasing the depth of a castellated beam profile results in a higher moment of inertia, thereby enhancing its flexural capacity compared to a standard profile. This study examines the influence of web opening variations on the moment of inertia of castellated beams through a numerical approach. The research was conducted in three stages: (1) modeling using MSC Nastran Patran software, (2) processing data by presenting the cross-sectional area due to openings, stiffness in the elastic condition, and comparison of inertia to the cross-sectional area, and and (3) evaluating the moment of inertia using numerical and conventional methods. The modeled beam is a cantilever type subjected to monotonic loading with various opening configurations. The section used is a steel IWF 200 × 100 × 55 × 8 mm profile, modified into a castellated beam with a profile size of 280 × 100 × 5.5 × 8 mm. The variations include web opening spacing (55 mm, 85 mm, 115 mm, and 140 mm) and opening angles (45°, 55°, and 65°) with a beam length of 2,000 mm. The study resulted in a simple formula for calculating the moment of inertia of castellated beams, given by kL³/3E. Calculations using this formula are highly accurate, with a maximum deviation of 10% from numerical analysis. This equation provides a practical and efficient tool for estimating the moment of inertia in castellated beam design