Analisis Kapasitas Fatik Jembatan Komposit Standar Bina Marga dengan Metode Crack Propagation Analysis

Abstract

Throughout its service life, bridge structures are subjected to cyclic loading due to vehicular traffic. This cyclic loading can lead to fatigue failure even when the applied stresses remain below the material's yield strength. In addition to cyclic loading, the fatigue resistance of a bridge structure is also affected by existing structural damage, such as the initiation of microcracks in welded joints. The fatigue strength of out-of-plane gusset joint in composite bridges is lower compared to other welded joint. This study evaluates the fatigue capacity of standard Bina Marga Class A composite bridge girders using the Crack Propagation Analysis method, assuming an initial crack depth of 0,1 mm in the out-of-plane gusset joint. The analysis is conducted based on the principles of Linear Elastic Fracture Mechanics (LEFM) to determine the fatigue capacity of the bridge girder. Subsequently, the fatigue life of the bridge girder is estimated using the traffic conditions on the Binjai–Langsa Toll Road, representing high-density and heavy traffic in Medan and surrounding areas. The presence of a 0,1 mm initial crack in the out-of-plane gusset joint results in the fatigue capacity of the bridge girder being exceeded before the designed service life is reached. This finding indicates that fatigue failure occurs before the designed service life is reached. The estimated fatigue life of the bridge girder is 620.000 cycles or approximately 1,3 years, which accounts for only 2,5% of the intended bridge service life.