Kajian Fenomena Tekuk pada Batang Tekan Jembatan Rangka Baja dengan Pendekatan LRFD dan Software Midas Civil

Abstract

Buckling in compression members of steel truss bridges poses a serious structural concern, as it diminishes both capacity and stability. This study evaluates the critical load (Pcr), critical stress (Fcr), and slenderness ratio (λ) using two approaches: the theoretical LRFD method and simulation via MIDAS Civil Academic 2023. The procedure encompasses a literature review, data collection (steel profiles and loads per SNI 1725:2016), modeling of a Warren truss in MIDAS Civil, and buckling analysis that accounts for the effective length factor (K).The highest Pcr was 35,139.05 kN (LRFD) and 371,22 MPa (MIDAS), found in member B50-TC4 (H350x550x12x16), while the lowest was 47.54 MPa (LRFD) and 48.75 MPa (MIDAS) in member B50-TB3 (H200x100x5.5x8). The highest Fcr was 369.28 MPa (LRFD) and 369.33 MPa (MIDAS), whereas the lowest Fcr was 47.54 MPa (λ = 190.71) and 48.75 MPa (λ = 188.33). The deviation between the two methods ranged from 0,51%-5% for Pcr 0,27%-3,27%, for Fcr, 0,25%-2,53%, for λ, and 1%–3% for the effective length factor. The Fcr–λ curve indicates that eight members experienced inelastic buckling (λ ≤ 110), while five experienced elastic buckling (λ ≥ 110). However, all cross-sectional profiles remain safe, as their slenderness ratios are within the allowable limits. The findings demonstrate strong agreement, confirming the accuracy and reliability of MIDAS Civil for further analysis. These results can serve as a valuable reference for technical studies and evaluations of bridge structures