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spans 20–90 m
Tapered portal frames
Columns and rafters whose depth follows the bending moment – the core of every efficient pre-engineered building.
Solution · Built-up steel members
Built-up steel: sections made for your structure
Welded plate I-sections, tapered portal frames, plate girders, box columns and crane runway girders – shaped to the forces in each member instead of a mill catalogue. Here is how built-up compares with hot-rolled, and when each one is the right choice.
- Any depth
- Beyond mill catalogues largest rolled I ≈ 1,100 mm
- 15–30 %
- Less frame steel typical for long-span portals
- SAW
- Automatic web-to-flange welding
- EXC3 · CC3
- Certified fabrication
Two ways to make a steel member
A hot-rolled section – W, UB, UC, IPE, HEA/HEB or H-beam – comes from the steel mill in fixed catalogue sizes. Its depth, flange and web are linked, and the section is the same over its full length. A built-up section is made in the fabrication shop from steel plate: a web and two flanges, cut to size and joined with continuous fillet welds. Every dimension can be chosen freely and can change along the member.
Neither is better in general. Hot-rolled sections are efficient for short spans and standard framing; built-up members win where spans are long, forces vary along the member, or the section needed is deeper, heavier or more special than any mill rolls. World Steel produces both – and most of our pre-engineered buildings and structural steel frames combine built-up primary members with hot-rolled and cold-formed secondary steel. This page explains the trade-offs so you can choose with confidence.
Built-up members
What we build from plate
Built-up fabrication covers the members that carry the largest forces in a structure.
spans 20–90 m
deep & long
Plate girders
Deep welded girders with stiffeners for transfer beams, long-span floors, platforms and bridge girders.
heavy duty
Box columns & crane girders
Box and heavy welded columns, crane runway girders with wide top flanges and stiffeners for crane buildings.
same 30 m span
Built-up next to hot-rolled
A uniform hot-rolled frame (grey) beside a tapered built-up frame (red) for the same span and load.
应用领域
Where built-up members are used
01
Long-span buildings
Factories, warehouses, hangars and sports halls with clear spans.
02
Crane buildings
Heavy columns and runway girders for overhead cranes.
03
Transfer structures
Plate girders carrying columns over open floors.
04
Bridges & platforms
Girders for footbridges, pipe bridges and conveyor supports.
05
Heavy industry
Mill buildings, power and process plants, mining structures.
06
High-rise & seismic
Heavy columns, box columns and special moment-frame members.
工程设计
Side by side: what really differs
Built-up members cost more per tonne to make – plate must be cut, assembled, welded and straightened – but they usually need fewer tonnes. Hot-rolled sections cost less per tonne to fabricate but are sized for the peak force along their whole length.
That is why the comparison that matters is cost per building, not cost per tonne: on long-span portal frames built-up is usually lower; on short spans and simple framing hot-rolled often wins. Availability matters too – in many markets plate is easier to source than large rolled sections.
工程设计
Material where the forces are
In a portal frame the bending moment peaks at the knees and drops towards the apex and the column bases. A tapered built-up frame is deep where the moment is high and shallow where it is low, with flanges and webs sized segment by segment – our engineers optimise every frame for weight.
For long-span portals this typically saves 15–30 % of frame steel compared with uniform hot-rolled sections, and reduces foundation loads and shipping weight. The actual saving depends on the span, loads and code.
规范与合规
Codes for built-up and hot-rolled members
Design and fabrication standards treat welded and rolled sections differently – for tolerances, residual stresses and buckling. Key references:
United States
- AISC 360Design of steel members – incl. slender-web plate girders and built-up members
- AWS D1.1Structural welding – web-to-flange welds and dimensional tolerances of welded members
- ASTM A6Rolled shapes and plate – dimensions and tolerances
- ASTM A572 / A36 / A992Plate and shape grades
- IAS AC472 WSC 已认证Metal building systems fabricators – World Steel MB-268
- Largest rolled I
- W44 series (about 1,120 mm deep) – deeper members are built-up
Australia / NZ
- AS 4100Steel structures – different section constants αb for welded and rolled members
- AS/NZS 3679.2Welded I sections (WB, WC)
- AS/NZS 3679.1Hot-rolled bars and sections
- AS/NZS 3678Hot-rolled structural plate
- AS/NZS 1554.1 / AS/NZS 5131Welding and fabrication – World Steel certified CC3
- Largest rolled UB
- 610 UB – heavier and deeper members are welded beams and columns (WB / WC)
Europe
- EN 1993-1-1Members – welded I-sections use lower buckling curves than rolled
- EN 1993-1-5Plated structural elements – slender webs and stiffeners
- EN 1090-2 WSC 已认证Execution and tolerances of welded components – World Steel EXC3
- EN 10025Hot-rolled plates and sections
- EN 10034Tolerances of rolled I and H sections
- Largest rolled I
- HL 1100 / HD columns from selected mills – availability and lead time vary
Vietnam
- TCVN 5575Steel structures – design
- TCVN 170:2007Fabrication, assembly and acceptance
- JIS G3101 / TCVN 1651SS400 plate and structural steel commonly used locally
- Export projects
- Design and fabrication to AISC, AS/NZS or EN as specified by the client
摘要仅供参考——以项目技术规格书、所采用的规范版本及主管机构要求为准。
工程设计
How a built-up member is made
Plates from certified mills are CNC-cut, tapered webs nested to minimise scrap, and flanges and web assembled on an H-beam line. Continuous fillet welds are made with automatic submerged-arc welding, then flanges are straightened and end plates, stiffeners and holes added.
Members are inspected for dimensions and welds to AWS D1.1, AS/NZS 5131 or EN 1090-2 tolerances, shot-blasted and coated, with full traceability from plate heat number to coating report.
工程设计
Built-up or hot-rolled? A quick guide
Choose built-up for long spans, varying forces, heavy or deep members, crane girders, box sections and large numbers of repeated frames. Choose hot-rolled for short spans, uniform members, small quantities of many sizes and when rolled sections are readily available.
Not sure? Send us your drawings: our engineers compare both options for weight, cost and delivery and recommend the best mix for your project.
技术规格
Our built-up range
- I-sections
- Uniform or tapered, equal or unequal flanges, hybrid grades (higher-strength flanges with a lighter web)
- Plate girders
- Deep girders with transverse and bearing stiffeners, cambered, with bolted or welded splices
- Columns
- Heavy welded H columns, box and cruciform columns, stepped crane columns
- Crane girders
- Runway girders with wide top flanges, stiffeners and rail fixings – see crane runway systems
- Materials
- ASTM A572 Gr 50 / A36, AS/NZS 3678 Gr 250–350, EN 10025 S275–S355, JIS SS400 / SM490 – with 3.1 certificates (see plate grades)
- Hot-rolled & cold-formed
- Hot-rolled sections and cold-formed purlins and girts supplied in the same package where they are the better choice
流程
How we deliver
- 1
Compare options
Built-up and hot-rolled schemes compared for weight, cost and lead time.
- 2
Optimised design
Member-by-member optimisation and connection design to your code.
- 3
Plate procurement
Certified plate from approved mills with full traceability.
- 4
Automatic fabrication
CNC cutting, H-beam assembly, SAW welding and straightening.
- 5
Inspection & coating
Dimensional and weld inspection, blasting and coating or galvanizing.
- 6
Packing & delivery
Marked, bundled and shipped with erection drawings and dossier.
EN 1090 EXC3 · CE
AS/NZS 5131 CC3
IAS AC472FAQ
常见问题
What is a built-up steel section?
A member made in the fabrication shop from steel plates – usually a web and two flanges joined with continuous fillet welds. Unlike hot-rolled sections, its depth, flange width and plate thicknesses can be chosen freely and can vary along the member.
Is built-up steel weaker than hot-rolled steel?
No. Both are designed to the same codes and strengths. The codes account for differences such as welding residual stresses – for example, welded sections use specific buckling curves in EN 1993 and section constants in AS 4100 – and the designer sizes the member accordingly.
Which is cheaper?
Per tonne, hot-rolled is usually cheaper to fabricate. Per building, built-up often costs less on long spans and heavy structures because it needs less steel. The answer depends on span, loads, quantities and local availability – we compare both for your project.
How much steel does a tapered frame save?
For long-span portal frames, typically about 15–30 % of frame steel compared with uniform hot-rolled sections. Short spans save less; the exact figure comes from the design of your building.
How are the web-to-flange welds made?
With automatic submerged-arc welding (SAW) on an H-beam line, using qualified procedures and consumables, followed by straightening and visual and dimensional inspection – plus UT or MT where the specification requires it.
Can you supply hot-rolled sections too?
Yes. We use hot-rolled sections where they are the better choice – for example bracing, short beams and secondary framing – and supply them in the same package as the built-up members.
New Zealand
Philippines
Built-up or hot-rolled for your project?
Send us your drawings or building data – our engineers compare both options and return the most economical scheme with a delivered price.
Full comparison
Built-up vs hot-rolled – criterion by criterion
Typical behaviour for building and industrial structures. The cheapest solution is usually a mix: rolled sections where catalogue sizes fit, built-up members where forces or spans call for them.
| Criterion | Built-up (welded plate) | Hot-rolled (UB · UC · IPE · HE · W) |
|---|---|---|
| Section sizes | Any depth, flange and web – tapered, haunched, asymmetric | Fixed catalogue sizes, constant section |
| Steel weight | Lower on long spans and heavy loads – material placed where the forces are | Higher when the nearest catalogue size is oversized |
| Fabrication cost per tonne | Higher – cutting and welding of flanges and webs | Lower – cut, drill and connect |
| Total cost | Lowest for long spans, deep girders, crane and transfer beams | Lowest for short and medium spans, columns, secondary beams |
| Depth range | From ≈ 200 mm to 2,000 mm and beyond | Up to ≈ 610 mm (AU UB), 600 mm (IPE), 1,000 mm (HE), ≈ 1,100 mm (W) |
| Availability & lead time | Plate is widely available in all grades; lead time = fabrication | Depends on mill rolling cycles and stock of the exact size and grade |
| Grades | Any plate grade incl. S460, weathering, Z-quality | Limited by what is rolled in each size |
| Residual stress & buckling | Welding residual stresses – own buckling curves and slenderness limits | Rolling residual stresses – standard buckling curves |
| Tolerances & quality control | Fabrication tolerances (EN 1090-2, AS/NZS 5131, AWS D1.1); weld inspection | Mill tolerances (EN 10034, ASTM A6, AS/NZS 3679.1) |
| Fire & corrosion | Thin webs raise the section factor – more protection per tonne | Compact sections – lower section factor |
| Shipping | Tapered members nest well; long members split with bolted splices | Standard lengths 12 – 18 m |
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