Aluminium bridges and overpasses: advantages, design and service life

Why low weight matters

Aluminium density is much lower than steel density, but density alone cannot compare structures: elastic modulus and strength characteristics also differ.

With sound design, lower permanent loads can reduce support requirements and simplify installation of large prefabricated sections.

Corrosion resistance

A protective oxide film forms on aluminium, providing good performance in many atmospheric conditions.

However, the design must account for contact with other metals, drainage, contamination and galvanic corrosion. Corrosion resistance is a property of the system, not just the material.

GOST 4784-2019 identifies aluminium alloy grades by chemical composition, but corrosion behaviour of a finished bridge component also depends on surface condition, contact with other metals, drainage and service environment.

Joints and factory prefabrication

Components are joined by welding or mechanical methods according to alloy, geometry and structural scheme. Many operations can be performed in the factory, where surface preparation, dimensions and welding parameters are easier to control.

GOST R 57352-2016 specifically addresses manufacture of structural aluminium components. For welded joints, it links edge preparation, fit-up and actual welding practice to a qualified procedure. The interval between cleaning and welding must be minimised; the standard sets a maximum of four hours.

During assembly, components are aligned and secured so that post-weld geometry remains within specified tolerances. Distortion and shrinkage are anticipated because correcting geometry after critical joints are made can be more difficult and costly.

What GOST R 57352-2016 governs

GOST R 57352-2016 covers manufacture and surface preparation of structural aluminium components. It does not replace bridge calculations for loads, stability, stiffness and fatigue, but establishes the production discipline needed to realise the structural model in metal.

Design documentation must coordinate materials, execution classes, connections, tolerances, welding procedures, surface preparation and inspection methods. For bridges, these requirements apply alongside specialist bridge design codes and project specifications.

Sespel’s industrial experience

Sespel’s range includes an aluminium road bridge made from alloy 1565Ch. The specification lists a maximum weld length of 15 m and a structural weight approximately 40% below a steel equivalent, benefits particularly relevant to factory manufacture and installation of large spans.

Aluminium infrastructure expertise also extends to modular projects: a high-level passenger platform uses AD31T1 aluminium profile decking and a demountable structure. Website parameters are identified as preliminary design data, refined during detailed design.

Fatigue and stiffness

Cyclic traffic loading is a determining factor for bridges. Connections, welds and stress concentration zones are designed for fatigue life.

Aluminium has a lower elastic modulus than steel. Required stiffness is therefore achieved through profile shape and overall structural action, rather than direct material substitution.

What determines durability?

Service life depends on the structural scheme, manufacturing quality, joint condition, drainage, environment and inspection frequency.

Aluminium’s advantages are best realised when the design prevents standing water, undesirable material contacts and areas that are difficult to inspect.

Manufacturing traceability is important for durability: materials matching certificates, compliance with qualified welding procedures, dimensional inspection and documented deviations. This lets later inspections assess the original structural condition rather than relying solely on visual examination years later.

Advantages of modular solutions

Low component weight and extensive prefabrication suit demountable bridges and passenger platforms. Modules are easier to transport and assemble in confined conditions.

Infrastructure projects particularly require dimensional accuracy, safety in user areas and compatibility with existing engineering systems.