Steel Structure Buildings: What Importers Should Know Before Ordering

A steel structure building is bought as a package, not as a pile of sections: the frame, the secondary members, the connections and the cladding have to arrive together and fit together. The steel itself is ordinary structural steel. What decides whether the building goes up on site is how completely it was specified beforehand.

Short answer

A steel structure building is a pre-engineered frame in ordinary structural steel: columns, beams, purlins, bracing and the cladding carried on them. The primary members are hot-rolled or welded sections, the secondary members cold-formed. The risk sits at the interfaces — if the standard system, the grade, the connection details or the coating are left open, the parts disagree on site.

What the package contains

The primary and secondary steel come from different product families, and a package is only as good as the weakest interface between them — the hole pattern in a column, or the section a purlin sits on.

Which steel, and which standard

Building frames are ordered inside a standard system, and the system follows the buyer’s market rather than the steel. The same building can be drawn in GB, EN, ASTM, JIS, IS or AS/NZS — for example the GB Q235B and Q355B families, the EN S235, S275 and S355 grades, the ASTM A36 and A572 grades, JIS SS400, the IS 2062 series and the AS/NZS 3678 series. The drawings and the order have to name one system, because the designation is what the mill makes, what the certifier tests and what the erector assumes.

• The grade follows the load and the member thickness, not habit
• Designations are not interchangeable — equivalence is read from the standards, not assumed from the letters and numbers
• Where the project is regulated, the route to market belongs to the same decision

What to settle before the order

Most structure disputes are created before production starts. These are the points that decide whether the package is complete:

1. The drawings and the loads, including wind, roof and any crane duty, because the frame is sized from them
2. The standard system, the grade inside it, and the acceptance basis — test certificate and member marking
3. Fabrication and connection details: hole patterns, bolt sizes, welds and end preparations
4. The corrosion system, given as a coating type and a coating mass rather than a coating name
5. The packing and loading plan, because transit damage shows at the ends and the edges
6. Where the package stops: who produces the site drawings, and who supplies the consumables

Send the drawings, the standard, the quantity and the destination port, and the enquiry is worked against those points. See the steel product catalogue, how orders are inspected and certified, or request a quotation.

How the order is documented

Structural orders are normally released against a mill test certificate tracing the heat, the grade and the test results to the lot, commonly in the EN 10204 3.1 format, with the members marked so that a delivered piece can be traced back to it. Where a project calls for it, third-party inspection of the fabricated pieces can be appointed as well. The certificate and the marking are what the checker on site works from.

Related reading

• Structural sections and profiles
• Welded H-beams
• C and Z purlins
• H-beam vs I-beam
• CE marking for structural steel

Frequently asked questions

What steel is used for steel structure buildings?

Columns and rafters are usually hot-rolled H-beams or welded H sections, purlins and girts are cold-formed C or Z sections, bracing is angle, tube or bar, and the cladding is profiled sheet. The grades are the ordinary structural grades of the buyer’s standard system.

Which standard should a steel structure building be ordered to?

The one the buyer’s market works in. GB, EN, ASTM, JIS, IS and AS/NZS are all used for building frames, and the drawings and the order should name the system and the grade, because the testing and the certificate follow that standard.

What is the difference between primary and secondary steel?

Primary steel is the frame that carries the building load — columns, rafters and their connections. Secondary steel is the purlins, girts and bracing that carry the cladding and steady the frame. They arrive in the same package from different product families.

Is a steel structure building cheaper than concrete?

It depends on the span, the height, the site and the labour available, not on the steel alone. Steel frames are often chosen for speed of erection and off-site fabrication, so the useful comparison is a full erected cost rather than a price per tonne of steel.

Send the drawings, the standard, the quantity and the destination port, and the enquiry is worked against those points. See the steel product catalogue, how orders are inspected and certified, or request a quotation.