Steel Bridge Girders: Types, Fabrication Process and Quality Checks

by alltech-group

Short answer: Steel bridge girders are the main load-carrying beams of a bridge. Quality depends on the right girder type, certified materials, controlled welding and thorough testing, so choose a fabricator with proven experience and documented quality control.

What Is a Steel Bridge Girder?

A girder is a large beam that carries the weight of the deck and traffic across a span and transfers it to piers and abutments. Steel offers high strength, relatively light weight and fast erection compared with many alternatives.

Common Types of Steel Girders

Rolled beam girders. Standard steel sections used for shorter spans.

Plate girders. Built up by welding steel plates into an I shape. They are flexible in size and suit medium to long spans.

Box girders. Closed hollow sections with high torsional stiffness, used for longer spans and curved alignments.

Truss girders. Frameworks of members, suitable for long spans and railway bridges.

Composite girders. Steel girders connected to a concrete deck so they act together, improving efficiency.

The Fabrication Process

Design and drawings are prepared and approved to the applicable standard.
Materials are procured with mill test certificates.
Plates are cut to shape using precise cutting equipment.
Plates are assembled and welded into girders, using controlled welding procedures.
Stiffeners, bearings and connections are added.
Straightening and dimensional checks confirm accuracy.
Non-destructive testing examines welds.
Surface preparation and protective coating guard against corrosion.
Trial assembly may be done in the workshop to confirm fit.
Marking, packing and dispatch to site.

Quality Checks That Matter

Material testing and traceability
Welder qualification and approved procedures
Weld inspection by visual, ultrasonic, magnetic particle, dye penetrant or radiographic methods
Dimensional tolerance checks
Coating thickness and adhesion tests
Documentation covering every stage

Choosing a Supplier

Experience with similar bridges and spans
Approvals and certifications recognised by the owner or authority
Workshop capacity and modern fabrication equipment
Quality management system
Ability to meet the required standards for your region
Delivery schedule and logistics
Support during erection

Which is better, plate girder or box girder?

It depends on span, alignment and loads. Your bridge designer decides.

How are girders protected from corrosion?

Through blasting and protective paint systems, or weathering steel or galvanising in some cases.

Can girders be fabricated to international standards?

Yes, with the design standard and testing requirements agreed in the contract.

Heavy Engineering at Alltech

Alltech India Limited’s heavy engineering division builds steel bridge girders, including girders for railway use. Contact us with your drawings or requirements.

Alltech India Limited
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