---- | ----------: | -----: | -----: | ------: | ------: | -------: | ----------: | ----------: | ------: | ------------------ | | 127×76×13 | 13.0 | 127.0 | 76.0 | 4.0 | 7.6 | 474 | 74.7 | 84.6 | 5.37 | Class 1 | | 152×89×16 | 16.0 | 152.4 | 88.7 | 4.5 | 7.7 | 834 | 109.4 | 123.0 | 6.57 | Class 1 | | 178×102×19 | 19.0 | 177.8 | 101.2 | 4.8 | 7.9 | 1,356 | 152.6 | 172.0 | 7.70 | Class 1 | | 203×133×25 | 25.1 | 203.2 | 133.2 | 5.7 | 7.8 | 2,340 | 230.0 | 258.0 | 8.80 | Class 1 | | 203×133×30 | 30.0 | 206.8 | 133.9 | 6.4 | 9.6 | 2,900 | 280.0 | 316.0 | 8.96 | Class 1 | | 254×146×31 | 31.1 | 251.4 | 146.1 | 6.0 | 8.6 | 4,410 | 351.0 | 394.0 | 10.83 | Class 1 | | 254×146×37 | 37.0 | 256.0 | 146.4 | 6.3 | 10.9 | 5,560 | 434.0 | 487.0 | 11.19 | Class 1 | | 305×127×37 | 37.0 | 304.4 | 123.4 | 7.1 | 10.7 | 7,170 | 471.0 | 538.0 | 12.70 | Class 1 | | 305×165×40 | 40.3 | 303.4 | 165.0 | 6.0 | 10.2 | 8,500 | 560.0 | 625.0 | 13.24 | Class 1 | | 305×165×46 | 46.1 | 306.6 | 165.7 | 6.7 | 11.8 | 9,900 | 646.0 | 722.0 | 13.35 | Class 1 | | 356×171×45 | 45.0 | 351.4 | 171.1 | 7.0 | 9.7 | 12,100 | 688.0 | 778.0 | 14.91 | Class 1 | | 356×171×51 | 51.0 | 355.0 | 171.5 | 7.4 | 11.5 | 14,100 | 796.0 | 900.0 | 15.16 | Class 1 | | 356×171×67 | 67.1 | 363.4 | 173.2 | 9.1 | 15.7 | 18,700 | 1,030.0 | 1,180.0 | 15.43 | Class 1 | | 406×140×39 | 39.0 | 398.0 | 142.0 | 6.4 | 8.6 | 12,500 | 628.0 | 712.0 | 16.19 | Class 1 | | 406×178×54 | 54.1 | 402.6 | 177.7 | 7.7 | 10.9 | 18,700 | 930.0 | 1,050.0 | 16.94 | Class 1 | | 406×178×60 | 60.1 | 406.4 | 177.9 | 7.9 | 12.8 | 21,600 | 1,060.0 | 1,200.0 | 17.29 | Class 1 | | 406×178×74 | 74.0 | 412.8 | 179.5 | 9.5 | 16.0 | 27,300 | 1,320.0 | 1,510.0 | 17.55 | Class 1 | | 457×152×52 | 52.3 | 449.8 | 152.4 | 7.6 | 10.9 | 21,300 | 948.0 | 1,070.0 | 17.77 | Class 1 | | 457×191×67 | 67.1 | 453.4 | 189.9 | 8.5 | 12.7 | 29,400 | 1,300.0 | 1,480.0 | 19.09 | Class 1 | | 457×191×74 | 74.3 | 457.0 | 190.4 | 9.0 | 14.5 | 33,300 | 1,460.0 | 1,660.0 | 19.31 | Class 1 | | 457×191×82 | 82.0 | 460.0 | 191.3 | 9.9 | 16.0 | 37,100 | 1,610.0 | 1,840.0 | 19.42 | Class 1 | | 457×191×89 | 89.3 | 463.6 | 191.8 | 10.5 | 17.7 | 41,100 | 1,770.0 | 2,030.0 | 19.53 | Class 1 | | 533×210×82 | 82.2 | 528.3 | 208.8 | 9.6 | 13.2 | 47,500 | 1,800.0 | 2,060.0 | 21.93 | Class 1 | | 533×210×92 | 92.1 | 533.1 | 209.3 | 10.1 | 15.6 | 55,200 | 2,070.0 | 2,370.0 | 22.35 | Class 1 | | 533×210×101 | 101.0 | 536.7 | 210.0 | 10.8 | 17.4 | 61,500 | 2,290.0 | 2,630.0 | 22.58 | Class 1 | | 533×210×109 | 109.0 | 539.5 | 210.8 | 11.6 | 18.8 | 66,700 | 2,470.0 | 2,850.0 | 22.73 | Class 1 | | 533×210×122 | 122.0 | 544.5 | 211.5 | 12.7 | 21.3 | 76,200 | 2,800.0 | 3,240.0 | 22.96 | Class 2 | | 610×229×101 | 101.2 | 602.6 | 227.6 | 10.5 | 14.8 | 75,800 | 2,510.0 | 2,880.0 | 25.00 | Class 1 | | 610×229×113 | 113.0 | 607.6 | 228.2 | 11.1 | 17.3 | 87,300 | 2,870.0 | 3,300.0 | 25.38 | Class 1 | | 610×229×125 | 125.0 | 612.2 | 229.0 | 11.9 | 19.6 | 98,600 | 3,220.0 | 3,720.0 | 25.68 | Class 1 | | 610×229×140 | 140.0 | 617.2 | 230.2 | 13.1 | 22.1 | 112,000 | 3,630.0 | 4,210.0 | 26.00 | Class 2 | | 610×305×149 | 149.1 | 609.6 | 304.1 | 11.8 | 19.7 | 125,000 | 4,100.0 | 4,700.0 | 30.00 | Class 1 | | 610×305×179 | 179.0 | 617.2 | 306.5 | 14.1 | 23.6 | 153,000 | 4,950.0 | 5,710.0 | 30.17 | Class 1 | | 686×254×125 | 125.2 | 677.9 | 253.7 | 11.7 | 16.2 | 118,000 | 3,480.0 | 3,990.0 | 28.02 | Class 1 | | 686×254×140 | 140.0 | 683.5 | 254.5 | 12.4 | 19.0 | 133,000 | 3,890.0 | 4,480.0 | 28.38 | Class 1 | | 686×254×152 | 152.0 | 687.5 | 255.3 | 13.2 | 20.5 | 146,000 | 4,250.0 | 4,910.0 | 28.56 | Class 1 | | 762×267×147 | 147.0 | 754.0 | 264.0 | 11.6 | 16.0 | 152,000 | 4,030.0 | 4,640.0 | 30.77 | Class 1 | | 762×267×173 | 173.0 | 762.0 | 266.7 | 12.8 | 18.8 | 183,000 | 4,800.0 | 5,540.0 | 31.17 | Class 1 | | 762×267×197 | 197.0 | 769.6 | 268.0 | 14.1 | 21.6 | 211,000 | 5,480.0 | 6,340.0 | 31.48 | Class 1 | | 838×292×176 | 176.0 | 834.5 | 291.6 | 12.8 | 16.6 | 222,000 | 5,320.0 | 6,110.0 | 33.66 | Class 1 | | 838×292×194 | 194.0 | 840.7 | 292.4 | 13.8 | 18.6 | 249,000 | 5,920.0 | 6,820.0 | 33.88 | Class 1 | | 838×292×226 | 226.0 | 850.0 | 293.5 | 15.3 | 21.8 | 296,000 | 6,960.0 | 8,050.0 | 34.18 | Class 1 | | 914×305×224 | 224.0 | 910.4 | 304.1 | 14.5 | 18.7 | 322,000 | 7,070.0 | 8,120.0 | 36.76 | Class 1 | | 914×305×253 | 253.0 | 918.4 | 305.5 | 15.9 | 21.3 | 369,000 | 8,040.0 | 9,260.0 | 37.00 | Class 1 | | 914×305×289 | 289.0 | 926.6 | 307.8 | 17.3 | 24.6 | 428,000 | 9,230.0 | 10,700.0 | 37.32 | Class 1 |

Source: SCI P363 — Steel Building Design: Design Data (Blue Book). Values for S275/S355 hot-rolled sections per BS EN 10365:2017. Verify against the current SCI edition.

How to Read the UB Designation

A UB designation follows the pattern: depth×width×mass

Example: 457×191×67 UB

• 457 = approximate section depth in mm (actual depth = 453.4 mm)
• 191 = approximate flange width in mm (actual width = 189.9 mm)
• 67 = mass per metre in kg/m (67.1 kg/m)

The depth and width are nominal labels from the serial size group, not exact dimensions. Use the actual values from the table for design calculations.

Span-to-Depth Ratios for UB Sections

For preliminary sizing of simply supported UB beams:

The UK National Annex to EN 1993-1-1 specifies L/200 as the general limit for floor beams carrying non-brittle finishes. This is significantly less restrictive than the AISC L/360 default, meaning UK-designed beams can be shallower than US-designed beams for the same span.

Quick Sizing Examples

• 8 m floor beam (no brittle finishes): Try depth = 8,000/20 = 400 mm → 406×178×60 UB
• 10 m floor beam (brittle finishes): Try depth = 10,000/18 = 556 mm → 533×210×92 UB
• 12 m roof beam: Try depth = 12,000/24 = 500 mm → 457×191×89 UB or 533×210×82 UB

Always verify with a full calculation including bending, shear, deflection, and lateral-torsional buckling checks.

EN 1993-1-1 Design Notes for UB Sections

Section Classification

UB sections in S355 steel are typically Class 1 in bending about the major axis — meaning they can develop full plastic moment capacity with sufficient rotation ductility for plastic analysis. Key classification limits per EN 1993-1-1 Table 5.2:

For the deepest heavy UB sections (e.g., 914×305×289), the web may classify as Class 2 depending on the cw/tw ratio. Check SCI P363 or use the Beam Capacity Calculator for section classification.

Lateral-Torsional Buckling (LTB)

LTB is usually the governing limit state for UB beams without continuous lateral restraint. The elastic critical moment Mcr is calculated per EN 1993-1-1 Clause 6.3.2.2:

• For simply supported beams with uniform moment: Mcr = (π² × E × Iz / Lcr²) × √(Iw/Iz + Lcr² × G × It / (π² × E × Iz))
• The reduction factor χLT depends on the slenderness λLT = √(Wy × fy / Mcr)
• Under the UK National Annex, buckling curve a applies to UB sections in S275 and S355 for strong-axis bending

Shear Check

UB sections have relatively thin webs compared to UC sections, so shear capacity should always be checked. Per EN 1993-1-1 Cl 6.2.6:

Vpl,Rd = Av × (fy / √3) / γM0

Where Av = A - 2btf + (tw + 2r)tf for rolled I-sections (but not less than η × hw × tw). The UK NA specifies η = 1.0 for shear area calculation.

Deflection Check

The UK National Annex specifies:

• General floors and roofs: δ ≤ L/200 (vertical deflection from variable actions)
• Floors supporting brittle finishes: δ ≤ L/360
• Cantilevers: δ ≤ L/180

Note: For office floors designed to L/200 (about 40 mm for an 8 m span), the deflection limit is rarely the governing criterion — strength or LTB typically governs for UB beams. This differs from US practice where L/360 usually governs.

Frequently Asked Questions

What is the difference between a 457×191×67 UB and a 457×191×74 UB? Both sections share the same nominal depth (457 mm) and width (191 mm), but the 74 kg/m version has a thicker web (9.0 mm vs 8.5 mm) and thicker flanges (14.5 mm vs 12.7 mm). This gives the heavier section 13% more plastic section modulus (1,660 cm³ vs 1,480 cm³) and 13% more second moment of area (33,300 cm⁴ vs 29,400 cm⁴). Use the 67 kg/m version for lightly loaded beams and the 74 kg/m version where slightly higher capacity is needed without moving to the next serial size.

What steel grade is standard for UK UB sections? S355J2 to BS EN 10025-2 is the standard grade. For thicknesses up to 16 mm, Fy = 355 MPa; for 16-40 mm, Fy = 345 MPa. S275J2 may be specified for cost savings on lightly loaded members. For heavy sections (flange thickness > 100 mm), grade S355J2 may have reduced yield strength per EN 10025-2 — check the mill certificate or specify S355K2 for fracture-critical applications.

How do I convert UB design from BS 5950 to EN 1993-1-1? The main changes are: (1) partial factors — γM0 = 1.00 (vs γm = 1.0 in BS 5950) and γM1 = 1.00 (buckling); (2) section classification follows EN 1993-1-1 Table 5.2 with different c/t limits; (3) LTB uses Mcr-based slenderness (χLT method) instead of the BS 5950 Pb method; (4) deflection limits from the UK NA (L/200 general vs BS 5950 Table 6 typical L/300). Use the Beam Capacity Calculator with EN 1993-1-1 selected for automatic conversion.

Which UB sections are most commonly used in UK building construction?

For multi-storey office and residential buildings, the most commonly specified UB sections are: 203×133×25 to 305×165×54 for secondary beams (spanning 6-9 m at 3 m centres), 356×171×51 to 457×191×89 for primary beams (spanning 8-12 m), and 533×210×92 to 610×229×140 for long-span primary beams (spanning 12-16 m). For portal frame construction typical of industrial buildings, 406×178×60 to 610×229×140 UB are commonly used for rafters, and 457×191×82 to 610×305×179 for columns. The SCI publication P363 and the Tata Steel Interactive Blue Book provide guidance on preferred (stock) sections maintained in mill rolling programmes.

Can I substitute a UC (Universal Column) section for a UB beam?

Yes, UC sections are frequently used as beams, particularly when: (1) the beam depth must be minimised (UC sections are deeper for the same mass than UB sections would be — wait, actually UC sections are more "squat": deeper for the same width, offering more Iy per kg), (2) the beam is subjected to significant axial load (beam-column application), or (3) the beam depth is constrained by headroom requirements at a given mass. A 305×305×97 UC has a depth of 307.9 mm with Iy = 22,300 cm^4 — comparable to a 356×171×67 UB (depth 363.4 mm, Iy = 18,700 cm^4). The UC provides 19% more strong-axis stiffness at 45% more mass but in a shallower depth. Always check LTB for UC sections used as beams, as the different flange proportions (wider, thinner) affect the elastic critical moment.

What is the typical lead time for UB sections in the UK?

Standard UB sizes maintained in Tata Steel's rolling programme have typical lead times of 2-4 weeks from UK stockholders (Barrett Steel, AJN Steelstock, Murray Steel, etc.). Non-stock sections may require a rolling slot, with lead times of 8-12 weeks. For time-sensitive projects, always confirm availability with the stockholder before finalising the design. The SCI maintains a list of preferred sections that are regularly rolled; specifying from this list reduces cost and lead time. For very large projects (typically >100 tonnes of a single section), the mill may offer a specific rolling with reduced per-tonne cost.

Typical UKB Applications by Building Type

Always verify the preliminary sizing with a full EN 1993-1-1 calculation including LTB, shear, and deflection checks. Use the Beam Capacity Calculator for automated verification.

UKB vs UC — When to Use Which

Universal Beams (UKB) and Universal Columns (UC) are both hot-rolled I-sections, but their proportions serve different structural purposes. UKB sections have relatively narrow flanges and thin webs optimised for bending efficiency about the major axis, while UC sections have wider, thicker flanges and thicker webs for axial compression capacity and buckling resistance about both axes.

Key differences:

• Flange proportions: UKB sections have flange width-to-depth ratios of approximately 0.4-0.5, while UC sections have ratios of approximately 0.8-1.0 (UC sections are nearly square)
• Weak-axis radius of gyration r_y: For the same mass per metre, UC sections have approximately 50-80% larger r_y, dramatically reducing KL/r for weak-axis buckling
• Torsional constant It: UC sections have 3-5 times the torsional stiffness of UB sections of similar mass, making them preferable for members subjected to torsion
• Section depth for a given mass: UB sections are deeper (more efficient in bending), while UC sections are shallower and wider (better for compression and moment frames)

UC sections may be substituted for UB beams when: headroom constraints require a shallower beam at a given mass; the beam carries significant axial load (beam-column in a moment frame); or torsional loading is present (spandrel beams supporting cladding). When using a UC as a beam, always recalculate Mcr for LTB — the wider flanges provide more warping stiffness Iw, potentially improving LTB resistance compared to a UB of similar mass.

Web Stiffener Requirements for UB Sections

Concentrated loads on UB beams (from incoming beams framing into the web, from column base plates on transfer beams, or from heavy point loads) may require web stiffeners to prevent local web yielding and web buckling. Per EN 1993-1-5, stiffeners are typically required when the applied force exceeds the web bearing capacity F_Rd calculated per Cl. 6.2.6.2.

Full-depth transverse stiffeners should be provided on both sides of the web when:

• The concentrated force exceeds 50% of the web bearing capacity
• The beam depth exceeds 500 mm and the point load exceeds 200 kN
• The concentrated load is applied to only one flange (creates an eccentric force couple in the web)
• The beam is subject to significant axial compression (reduces the web's ability to redistribute stress around the load point)

Stiffener design follows EN 1993-1-5 Section 9: the stiffener plus an effective width of web (taken as 15tw on each side for interior stiffeners) acts as a compression member. The stiffener outstand must meet the Class 3 limit (b/t less than or equal to 14epsilon for S355) to prevent local buckling. Stiffener-to-web welds must transfer the full stiffener force.

Try it now: Check your beam sizes with our free UK Steel Beam Capacity calculator →

Related Pages

• UK Steel Section Guide — UB, UC, PFC, CHS, SHS
• UK Steel Beam Sizes — UB, UC, PFC Chart
• UK Steel Design Guide — BS EN 1993, National Annex & SCI
• EN 1993-1-1 Beam Design Guide
• European Beam Sizes — IPE, HEA, HEB
• Metric Steel Sections — IPE, HEA, HEB, UB, UC
• Beam Bending and Shear Calculator
• Full Section Properties Database
• How to Verify Calculator Results
• Disclaimer

This page is for educational reference only. All section data sourced from SCI P363 (Blue Book) and BS EN 10365:2017. Verify dimensions and properties against the current SCI edition, mill certificates, and the applicable National Annex before procurement or design. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent PE/SE or CEng verification.

Design Resources

Calculator tools

• Beam Bending and Shear Calculator
• Beam Displacement and Sag Tool
• Beam Calculator — SFD, BMD & Reactions
• Beam Optimizer — Find Most Efficient Section
• Beam Span Table Tool

Design guides

• Steel Beam Calculator Guide
• Beam Capacity Worked Example
• Beam Deflection Worked Example
• Steel Beam Design Workflow
• Steel Beam Span Reference