COMPARATIVE NUMERICAL INVESTIGATION OF STRUCTURAL BEHAVIOR OF ALUMINUM ALLOY AND STEEL BAILEY BRIDGES UNDER DIFFERENT CONFIGURATIONS

Abstract

This study presents a comprehensive numerical investigation into the structural behavior of Bailey bridge systems constructed from aluminum alloy in comparison with conventional steel structures. A three-dimensional finite element model was developed in Midas Civil to analyze a 30.02 m span bridge under two representative configurations: Single-Single (1-1) and Double-Single (2-1), considering both self-weight and combined vehicle loading conditions. The results show that, under self-weight, aluminum alloy structures exhibit internal forces and stresses approximately three times lower than those of steel due to their significantly lower density. However, under combined loading, these differences decrease to 3%–15%, indicating that external loads dominate the structural response. In contrast, due to the lower elastic modulus, aluminum structures exhibit significantly larger displacements, approximately 45%–57% higher than those of steel structures. The findings highlight a fundamental trade-off between weight efficiency and structural stiffness. Aluminum alloy is shown to be a viable alternative material for modular bridge systems, particularly in applications requiring rapid deployment and lightweight construction.