LIGHT WEIGHT BRIDGE SOLUTIONS: A STRUCTURAL COMPARISON OF ALUMINIUM ALLOYS AND STEEL

Authors:

B S Gokul, Avani S, Sujithra S, Akash J Prakash, Gitanjali N Ramesh

B S Gokul, Department of Civil Engineering, Bishop Jerome Institute, Kollam

Avani S, Department of Civil Engineering, Bishop Jerome Institute, Kollam

Sujithra S, Department of Civil Engineering, Bishop Jerome Institute, Kollam

Akash J Prakash, Department of Civil Engineering, Bishop Jerome Institute, Kollam

Gitanjali N Ramesh, Department of Civil Engineering, Bishop Jerome Institute, Kollam

Abstract - Bridges play a vital role in transportation systems, and their effectiveness depends heavily on the materials used in their construction. For a long time, steel has been the preferred choice for truss bridges because of its high strength, availability, and established design practices. However, issues like corrosion, heavy weight, greater foundation demands, and long-term maintenance can negatively impact the performance and lifespan of steel bridges. The recent focus on durable infrastructure has prompted researchers and engineers to look into alternative materials. Aluminium alloys are known for their high strength-to-weight ratio, excellent corrosion resistance, low maintenance needs, and recyclability. They have become a promising option for lightweight bridge construction, especially in truss designs. Despite these advantages, the use of aluminium alloys in bridge systems remains limited. There are few comparative studies on their performance in truss bridges under actual design conditions. This study aims to fill this research gap by examining how effectively aluminium alloys can replace steel in the Pratt truss bridge system. The main goal is to evaluate and compare the structural efficiency of steel and aluminium alloys in bridge design. The Pratt truss bridge is designed and analyzed using STAAD. Pro software with the relevant load combinations. The initial model was created with conventional structural steel, which was then modified by replacing some secondary members with aluminium alloy 6061-T6 according to the AASHTO design guidelines. The analysis shows that using aluminium alloys significantly reduces structural weight. This leads to lower foundation loads and improved constructability without compromising strength and serviceability standards. Even though aluminium has higher initial embodied energy, it excels in corrosion resistance, durability, low maintenance, and recyclability. This improves the overall life cycle of the bridge system. The study concludes that aluminium alloys are an effective and durable substitute for steel in Pratt truss bridge construction, especially where lightweight design, durability, and long-term performance are important. The findings provide valuable insights into material selection strategies that can facilitate bridge infrastructure development.

Key Words:  Bridges, Steel, Aluminium alloys, Pratt truss bridge, Structural performance