Cellular Beams Design

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C232:X4121

CI/SfB

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ENGINEERS DESIGN GUIDE

Cellular Beams

INTRODUCTION


Westok & Cellular Beams Westok pioneered the use of cellular beams in the early 1990s.

Advisory Engineering Services

Westok worked with the Steel Construction Institute to test cellular beam performance, and to produce design rules and Free Design Service

design software. Since then, the SCI/Westok CELLBEAM AutoMate software has been developed and improved, and remains by far the UK’s most used software for the design of cellular beams. CELLBEAM AutoMate is the only cellular beam software written and supported by the SCI.

Westok provides Engineers with free designs for all its beams. To use this service contact one of Westok’s regional Advisory Engineers, or use the Design Enquiry Forms provided in this brochure. Design Enquiry Forms can be found in this Guide as follows: • Primary Floor Beams - pg 20

Cellular beams have been used in over 25 countries. At the time

• Secondary Floor Beams - pg 21

of publication manufacturing is carried out in the UK, Europe,

• USFB s (Ultra Shallow Floor Beams) - pg 23

the USA, Africa, Australia, New Zealand and the United Arab

• Roof Beams - pg 33

Emirates. Westok will gladly advise of contact details for each part of the world.

TM

Copies of Design Enquiry Forms are also available on Westok’s website at www.westok.co.uk - these can be completed and

Cellular beam use in the UK alone comfortably exceeds 25,000 tonnes per year at the time of publication. Worldwide annual usage exceeds 50,000 tonnes.

submitted to Westok online. CPD Seminars Westok Advisory Engineers

In 2006 Westok introduced a new beam - USFB

TM

(Ultra Shallow Floor Beam) - see page 22.

provide CPD seminars covering all aspects of cellular beam and USFB design and applications. TM

To use any of Westok’s Advisory Engineering Services

These can be held at Consultants’

please contact:

offices on request.

ASD Westok Limited Charles Roberts Office Park Charles Street, Horbury Junction Wakefield West Yorkshire WF4 5FH Tel: 01924 264121 Fax: 01924 280030 Email: [email protected]

www.westok.co.uk 00 02

Design & Advisory Meetings Regionally based Westok Advisory Engineers can attend Engineers’ offices to help advise on the suitability of cellular beams and USFB s in specific projects, and provide designs TM

to the Project Engineer without cost or obligation.


Contents

pages

Cellular Beams

05 06 07 08 09

What is a Cellular Beam? SCI Cellular Beam Software / USFB Software & CellVibe Software Using CELLBEAM AutoMate Specifying Cellular Beams Avoiding Infills to Cells

Floor Beams

11 12 13 14 16 17

Floor Beams / Asymmetric Beams / Pre-Cambered Beams Service Integration Cell Size & Elongated Openings Beam Depths Column-Free Clear Span Floors Floor Vibration / Natural Frequency / Floor Response Factor

Car Park Beams

CONTENTS

18 19 20 21 22 23

04 - 09

Fire Protection Fire Engineering with Cellular Beams Design Enquiry Form - Primary Floor Beam Design Enquiry Form - Secondary Floor Beam Ultra Shallow Floor Beams - USFB Design Enquiry Form - USFB TM

TM

25 Floor Beams in Car Parks

Roof Beams

29 30 31 32 33 34 35 36

Cellular Columns

45 Parallel Flanged Columns / Tapered Columns

Straight Roof Beams Designing Straight Cellular Roof Beams Section Properties for Cellular Roof Beams Spine Beams Design Enquiry Form - Roof Beam Curved Beams Curving Process / Economics / Span Range Simply Supported Curves

10 - 23

24 - 27

37 38 39 40 41 42 43

Portalised Curved Cellular Beams Achievable Radii Reverse or ‘S-Shaped’ Curves Tapered Beams & Cantilevers Tapered Cellular Beams Cantilever Roof Members Pitched Roofs Using Tapers

28 - 43

44 - 45

Sustainability

46

International Markets

47

00 03

CELLULAR BEAMS


Cellular Beams A cellular beam is the modern version of the traditional ‘castellated’ beam, but with a far wider range of applications - for floor beams in particular.

04 00


What is a Cellular Beam?

CELLULAR BEAMS

Fig. 1

A Universal Beam or Universal Column is castellated which results in a beam approximately 40-60% deeper than its

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parent section - see Fig. 1. The exact finished depth, cell diameter and cell spacing are very flexible. A cellular beam has

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up to two and a half times better section properties than its parent section. Variations in how the parent sections are cut allow the following beams to be manufactured:

Beams with Elongated Openings

Pre-Cambered Beams

Curved Roof Beams

Facing page: City Park, Hove

Tapered Beams

Cellular beam profiling

05 00

CELLULAR BEAMS


SCI Cellular Beam Software CELLBEAM AutoMate is the only cellular beam software written and maintained by the Steel Construction Institute. It is available free of charge from Westok. Westok’s Advisory Engineers also use the same CELLBEAM AutoMate software to design cellular beams. Westok has no access to the source code of the program and SCI’s decisions are final on all aspects of the design rules employed within CELLBEAM AutoMate. SCI has embedded several layers of Help Screens (see above) that detail the areas of code and formulae used in the software. There is a full maintenance agreement in place with SCI, so any questions arising may ultimately be answered by SCI. SCI also maintains a line by line audit trail as part of its Quality Assurance. Every change made to the CELLBEAM AutoMate software during or after its original writing can therefore be traced back to source.

USFB Software & CellVibe Software TM

SCI and Westok have also released software to aid in the design of USFBs and to analyse the Response Factor of floors using cellular beams or USFBs. Please contact Westok for further details.

Westok CELLBEAM AutoMate is the only cellular beam software written and maintained by the Steel Construction Institute.

06 00


CELLULAR BEAMS

Using CELLBEAM AutoMate

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designs are totally free of charge or any obligation.

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same beam can be offered should the Engineer wish, and all

responded to by return if required. Multiple options for the

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Design Enquiry Forms can be found in this Guide as follows: • Primary Floor Beams - pg 20

Westok Design Suite - current at date of publication

• Secondary Floor Beams - pg 21 • USFBs (Ultra Shallow Floor Beams) - pg 23

As the name suggests, CELLBEAM AutoMate designs the

• Roof Beams - pg 33

cellular beam automatically. The Project Engineer inputs loads, spans and centres, deck type, restraints etc. and is then

Copies of Design Enquiry Forms are also available on Westok’s

asked for limits:

website at www.westok.co.uk - these can be completed and

• Is a maximum or precise fixed beam depth required? • Is a minimum cell diameter required?

submitted to Westok online. Advisory Engineers In addition to Westok’s office based design service, regional Advisory Engineers are available throughout the UK, Northern Ireland and the Republic of Ireland to attend design meetings to offer advice on initial concepts or to assist with a full design service package.

Once answered, the software designs the optimum beam size within those parameters. The Engineer can either accept the beam offered, or may choose to further manipulate it. Links to/from Other Software Packages Westok is actively improving the ability of CELLBEAM AutoMate to link directly with other relevant software packages. At date of publication CELLBEAM AutoMate can be directly linked with ‘CSC Building Designer’ and ‘RAM Structural System’. For up-to-date information on links to any software package please consult Westok.

07 00

CELLULAR BEAMS


Specifying Cellular Beams Given the flexibility of cellular beam geometry, a tabulated specification on drawings is the best way of conveying information to all interested parties.The table shown below is not the only solution, but is one of the most commonly used Douglas Car Park, Isle of Man

approaches: Mark

Section Reference

Material

Mass kg/m

Grade

Tee Depths mm

1

732 x 191/229 ACB 90

Top UB 457 x 191 x 67 Btm UB 610 x 229 x 113

90

S355 S355

327.5 404.6

Cell Data Diam

Pitch

450

650

Structural Fire Data Section Factor Limiting Flange Limiting Web (m-1) Temp °C Temp °C 126

617

See page 18

Notation The standard notation of an asymmetric cellular beam (ACB) using the above example, is as follows: a

b

c

d

e

f

g

≤ ≤ ≤ ≤ ≤ ≤ ≤ 732 x 191/229 x 90kg/m ACB. S355 (450 @ 650) 732 Depth in mm 191 Top tee flange width c 229 Bottom tee flange width d 90 Mass in kg/m e S355 Steel grade f 450 Cell diameter in mm g 650 Cell pitch a

b

Valley Park, Leeds

The standard notation of a symmetrical cellular beam (CUB) is as follows: a

b

c

d

e

f

≤ ≤ ≤ ≤ ≤ ≤ 1160 x 267 x 134kg/m CUB. S355 (800 @ 1000) 1160 Depth in mm 267 Flange Width c 134 Mass in kg/m d S355 Steel grade e 800 Cell diameter in mm f 1000 Cell pitch a

b

Cannon Court, Maidenhead

08 00

650


Avoiding Infills to Cells

CELLULAR BEAMS

Fig. 2

If your design requires more infilling than suggested below

CB1

please consult Westok. Our Advisory Engineers will help you

CB2

minimise /eliminate infilling.

CB2 CELLBEAM AutoMate already helps minimise infilled cells, but

CB1

following the approach described below will provide a practical and economical solution for all parties. In a serviced floor the best approach is to optimise the cell pitch so that no infills are required for the beams on grid. This fixes the cell layout for the intermediate beams. The example

Full web post

CB1

Full web post

shown in Fig. 2 is typical, limiting the infills to only two half cells in every other beam. For primary beams care should be taken to adopt an efficient cell pitch. In regular grids the primary cell data can be chosen

½ infill

CB2

½ infill

so that all incoming secondary beams land on a web-post, thereby avoiding infills. Furthermore, Westok has developed new types of cellular primary beams that do not require any infilling. Even in irregular buildings, infills can normally be limited to no more than an average of one per beam. Please allow Westok to advise.

Newcastle Car Park

Finsbury Pavement, London

09 00

FLOOR BEAMS


Floor Beams 12 to 20 metre clear span floors can now be built at the same depth and cost as short spans.

10

FOR WESTOK’S FREE DESIGN SERVICE PLEASE USE THE FORMS ON PAGES 20 & 21


Floor Beams

Asymmetric Beams

Cellular beams are most commonly used as floor beams. This

Many composite cellular

enables one or all of the following to be achieved:

beams are designed

FLOOR BEAMS

asymmetrically -

• Long Clear Spans

see Fig. 4. The top

• Service Integration

and bottom tees are

• Shallow Overall Floor Depths

profiled from different parent sections, thereby

The decision whether to use cellular floor beams can be easily

optimising the distribution

summarised:

of mass. This is particularly beneficial in designs predominantly governed by deflection

Span Requirement

or vibration. Services Requirement

<9m

<12m

>12m

USFB *

✓

✓✓

Single service opening

✓

✓✓

✓✓✓

Normal/heavy services

✓✓

✓✓✓

✓✓✓

No services

TM

Fig. 4

Services * USFBTM is the new Westok ‘Ultra Shallow Floor Beam’, used to produce very shallow overall floor zones with the concrete contained within the depth of the steel beam. See page 22.

The optimum floor layout uses cellular floor beams as longspanning secondaries. The primary member could be cellular or plain, depending on whether services are required in both directions - See Fig. 3.

Pre-Cambered Beams

Fig. 3

Long span beams often require the specification of costly pre-

Cellular Cellular

Plain / Cellular

Cellular

cambers. Cellular beams are easily pre-cambered as part of the manufacturing process without additional cost - see Fig. 5. Fig. 5

On request, and at no extra cost, Westok is able to offer far tighter camber tolerances than required by the National Structural Steelwork Specification (NSSS). Facing page: Sweet Street, Leeds - 18m clear span

Please consult Westok for specific project requirements.


11

FLOOR BEAMS


Service Integration Cellular floor beams are used for their ability to integrate structure and services. This minimises overall construction height.

National Assembly for Wales, Merthyr Tydfil

Circular Ducts or Rectangular Ducts? If the circular openings in the cellular beam are insufficient for M&E requirements adjacent cells can be opened up to form

Cannon Court, Maidenhead

large, elongated openings. CELLBEAM AutoMate analyses such elongated openings. Elongated openings near mid-span seldom require stiffening, but elongations near supports are more likely to require stiffening. CELLBEAM AutoMate takes account of this requirement. Whilst the choice of circular or rectangular ducting has little or no impact on the cost of the cellular beam, it does have major Photo courtesy of Arcelor

implications on the overall project cost and long-term environmental cost: • circular ducting is up to three times more energy efficient than rectangular ducting * • circular ducting is far cheaper than rectangular ducting

Fischrestaurant, Ewald, Germany

• circular ducting is quieter than rectangular ducting • circular ducting is far easier to clean and requires less frequent cleaning • no impact on the cost of the cellular beam • no impact on the depth of construction

Salford University * Source: Page 105 - Improving Ductwork. A time for tighter air distribution systems ISBN 1 902177 10 4 European Commission Directorate General XVII for Energy Contract No. XVII/4.1031/Z/96-147.

12



FLOOR BEAMS

Cell Size & Elongated Openings The choice of cell diameter is very flexible. The only limit within CELLBEAM AutoMate is that the cell diameter cannot exceed 80% of the final beam depth. Using CELLBEAM AutoMate, the Engineer inputs the ‘minimum diameter’ required for services (see Fig. 6), or simply leaves it to the software to choose the optimum should there be no specific diameter required, eg. for lightly serviced buildings or car parks (see Car Parks pages 24 to 27).

Fig. 6 When the design has been carried out to the required depth and cell diameter, the Engineer has the option to open up cells to provide wider openings for elongated ducts. The software checks whether stiffening is required, and designs the

Fig. 7

stiffeners - see Fig. 7.

City Park, Hove. Five elongations in each beam. Some required stiffening, others unstiffened.


13

FLOOR BEAMS


Beam Depths There is no ‘standard’ cellular floor beam. The Engineer inputs the required limits of maximum depth and minimum cell diameter, and CELLBEAM AutoMate designs the optimum beam for the loading and layout. In the absence of any limit imposed by the Engineer the software designs for pure economy of steel. It is good practice to allow CELLBEAM AutoMate to design the optimum beam for pure economy, then re-run shallower options for comparison.

Dolcis House, London - primary beams 620mm but secondaries were more economical at less than 620mm.

Wm Morrisons HQ, Bradford - all beams ‘fixed’ to a depth of exactly 600mm.

14



FLOOR BEAMS

Using CELLBEAM AutoMate, the Engineer has three options to choose from for the depth of a cellular floor beam ‘Fixed’, ‘Maximum’ or ‘AutoMate’. ‘Fixed’ Depth By choosing the ‘Fixed’ option in CELLBEAM AutoMate and entering an exact fixed depth, the software designs the most efficient beam at the exact depth input by the Engineer see Fig. 8.

Fig. 8

Sir John Rogerson Quay, Dublin - all secondary and primary beams exactly 520 mm deep.

‘Maximum’ Depth This option is likely to produce a lighter beam. By selecting the ‘Maximum’ option CELLBEAM AutoMate designs the optimum beam that does not exceed the maximum depth input by the Engineer - see Fig. 9.

Fig. 9

Haymarket, Belfast - beams limited to a maximum depth of 540mm. Secondaries slightly shallower than the primaries.

‘AutoMate’ Depth In some cases the Engineer wants the lightest solution, irrespective of depth. By selecting the ‘AutoMate’ option, CELLBEAM AutoMate simply chooses the lightest possible beam - see Fig. 10.

Fig. 10

Sweet Street, Leeds - 18m span cellular beams, 750mm deep.


15

FLOOR BEAMS


Column-Free Clear Span Floors It used to be believed that the more columns in a multi-storey

Even more importantly, the client is presented with a layout

structure the cheaper the build cost. This was consigned to

of total flexibility for tenants not only on day one, but also for

history in the mid 1990s, when study after study and more

future tenants in decades to come. The benefits to the client

importantly, project after project, proved that clear span, column-

of clear span, column-free construction are huge:

free construction produced almost identical initial build costs. Construction Criteria

Clear Span v Short Span

Depth

Clear span is equal or shallower than short span - see Fig. 11

Speed

With fewer columns and fewer floor beams to erect, clear span floors can be erected almost twice as quickly as traditional short span frames - see Fig. 12

Foundations

Clear span has fewer columns so fewer foundations, allowing the builder to ‘get out of the ground’ sooner. This is especially beneficial in poor or contaminated ground

Overall cost

Equal

Flexibility of use

Clear span offers greater flexibility and more options for current and future occupiers

Sustainability

Clear span buildings will be future proof to changes of tenant/usage, avoiding resource-consuming demolition and rebuild or refurbishment

Fig. 11

Fig. 12

Area completed after 15 pieces erected in a short-span layout

SERVICES SERVICES Short Span

Depth saving Clear Span Cellular

Double the area completed after 15 pieces erected using a clear-span layout

Bishop Auckland Hospital

16



Floor Vibration

Floor Response Factor

When clear-span floors were in their infancy in the early to

However, the SCI Design Guide P354 states that natural

mid-1990s, the initial view was that vibration would often be

frequency is not the most reliable predictor of floor quality.

the governing design criteria. This has since proved not to be

Frequency (the number of times the beam oscillates per second) is

the case. Research and testing has confirmed that clear-span

imperceptible to humans. It is the amplitude that is actually

floors can be of a far superior quality than short-spans.

felt in the form of acceleration. It is possible for a floor with

FLOOR BEAMS

an ‘acceptable’ frequency well above 4Hz to produce an Tests have shown that the vibration performance of composite

unsatisfactory ‘feel’, whilst a floor designed below 4Hz can

cellular beams far exceeded the predicted results. Westok has

produce an exceptionally high quality floor. The SCI’s published

pioneered the testing of long-span floors. Numerous projects

method in P354 for designing floor quality is to calculate the

in the UK and France have been tested in collaboration with

Response Factor ‘R’, which is indirectly proportional to the

the SCI, CTICM and City University. Amongst these tests was

quality of the floor:

Le Colisee II in Paris, with 470mm deep beams spanning 17.1m.

R ≤ 8 Suitable for a general office floor R ≤ 4 Highest quality office floor R ≤ 1 Suitable for hospital operating theatres

Le Colisee, France - 17m span with only 470mm beam depth. One of several floors tested for vibration.

Natural Frequency

Royal Preston Hospital - 17m span floor beams, designed for a floor response R = 1. Suitable for operating theatres.

CELLBEAM AutoMate allows the Engineer to set an appropriate

CellVibe Software

minimum natural frequency in Hz for individual members as a

SCI has produced the CellVibe software for Westok. The

design parameter.

program calculates the Response Factor for any given floor area using cellular beams or USFBs. Contact Westok to receive CellVibe free of charge.

Cannon Court, Maidenhead - 15m span, 530mm deep, carrying 100mm p/c units.


17

FLOOR BEAMS


Fire Protection Fire protection of cellular beams using ‘passive materials’ such as boards or cementicious sprays can be applied in the same way as to a plain rolled section. For intumescents, the ASFP (Association for Specialist Fire Protection) and the SCI have worked together to establish a thorough system. Westok cellular beams may be protected by any ASFP accredited material using the structural failure temperatures from the CELLBEAM AutoMate software. Alternatively, ASFP members can refer to their own publications. CELLBEAM AutoMate software calculates the critical temperature for the web and bottom flange of the cellular beam. By stating these critical temperatures on drawings (see Fig. 13), the Engineer ensures maximum competition for the fire protection package. Armed with this information, any fire protection contractor or intumescent manufacturer is quickly able to calculate their optimum product and correct coating thickness.

Fig. 14 CELLBEAM AutoMate asks the user for the ‘Building Type’, then uses the appropriate fire load factors in its beam analysis see Fig. 14. The fire protection element within CELLBEAM AutoMate is based on the numerous full-scale fire tests carried out on cellular beams in the UK and France.

Fig. 13

St Vincent Street, Glasgow - conventional fire protection on cellular beams.

18

Finsbury Pavement, London - intumescent protected cellular beams.



FLOOR BEAMS

Fire Engineering with Cellular Beams Various options exist to ‘fire engineer’ structural frames which use cellular beams. • Beam Optimisation for Intumescents In extreme cases it may be beneficial to slightly increase the steel section if this allows a significantly thinner coat of intumescent to be used (see photo top right). It is likely that this will only be viable in 120 minute fire ratings, and in very lightweight beams with high section factors. • Unprotected Alternate Floor Beams A relatively new but increasingly popular approach uses the

Robin Hood Airport, Doncaster - the Project Engineer and Westok developed a design for cellular beams and intumescent paint thickness, to minimise the overall cost.

method described in SCI publication P288, in which up to half the number of floor beams can be left unprotected, even for buildings requiring a 120 minute fire period (see photo centre right). Long span cellular beams are included in this approach. • Unprotected Steel Frames BS5950 Part 8 and DD9999 allow many steel frames requiring 30 or 45 minutes to be totally designed without fire protection. For all of the above please consult Westok for advice and designs.

Leeds Nuffield Hospital - alternate floor beams were unprotected

Wm Morrisons HQ, Bradford - for quality control the off-site fire protection company used contrasting paint colours to denote the different fire periods within the building.


19

PRIMARY

DESIGN ENQUIRY FORM

CONTACT DETAILS

FLOOR BEAM

Company:

Name:

Address:

Email: Tel: Fax:

PROJECT DETAILS

Project Title: Beam Ref:

LAYOUT

Layout Type: Composite Span:

m

Bay Centres:

m Bay Centres:

Side 1

Secondary Beam Centres:

Building Type:

Non-Composite

m

Side 2

(please tick as appropriate)

Office

Car Park

Storage

Education

Other

NOTES

Mid Span Third Points

Quarter Points Other

INSITU CONCRETE

(please specify in Notes area)

mm

Slab:

Thickness:

Deck Type: Grade: Weight:

PC UNITS LOADING Note: Exclude self-weight of deck & slab

N/mm2 Normal

Thickness:

Lightweight mm

Mass:

kN/m2

Live:

kN/m2

Partitions:

kN/m2

Ceiling & Services:

kN/m2

Other:

kN/m2

Maximum Beam Depth:

mm

Minimum Cell Diameter:

mm

* Natural Frequency:

Hz

† Live Load Deflection:

mm

unfactored unfactored unfactored unfactored

LIMITS

Top Mesh:

leave blank if no limit


*unless otherwise instructed 4.0 Hz for offices & 3.0 Hz for car parks


† DEFLECTION: DEFLECTION DUE TO DEAD-LOAD SHOULD NOT BE A CRITICAL FACTOR, AS CELLULAR BEAMS CAN BE PRE-CAMBERED WITHOUT COST.

20

PLEASE PHOTOCOPY THIS FORM & FAX YOUR ENQUIRY TO WESTOK: 01924 280030

SECONDARY

DESIGN ENQUIRY FORM

CONTACT DETAILS

FLOOR BEAM

Company:

Name:

Address:

Email: Tel : Fax:

PROJECT DETAILS


LAYOUT

Span: Building Type: (please tick as appropriate)

NOTES

Non-Composite

Layout Type: Composite m

Centres:

mm

Top Mesh:

m

Office Storage Car Park Education Other

INSITU CONCRETE

Slab:

Thickness:

Deck Type: Grade: Weight:

PC UNITS LOADING Note: Exclude self-weight of deck & slab

N/mm2 Normal

Thickness:

mm

Mass:

kN/m2

Live:

kN/m2

Partitions:

kN/m2

Ceiling & Services:

kN/m2

Other:

kN/m2

Maximum Beam Depth:

mm


mm

* Natural Frequency:

Hz


mm


LIMITS

Lightweight



* unless otherwise instructed 4.0 Hz for offices & 3.0 Hz for car parks


† DEFLECTION: DEFLECTION DUE TO DEAD-LOAD SHOULD NOT BE A CRITICAL FACTOR, AS CELLULAR BEAMS CAN BE PRE-CAMBERED WITHOUT COST.


21

FLOOR BEAMS


Ultra Shallow Floor Beams - USFB

TM

A tried and tested method of construction in the UK and elsewhere is to combine the concrete slab within the depth of the steel beam in order to create extremely shallow or slim floor construction. Westok USFB (Ultra Shallow Floor Beam) is the most flexible TM

Bristol Paediatric Unit - beam depth 320mm, span 7.2m, load 7.5kN/m2 + heavy point load.

and practical approach to this type of construction. USFB s can be pre-cambered at no additional cost and TM

There is no ‘standard’ beam size or depth. Each design is

without impact on the already short lead time. The beams are

carried out to achieve the exact depth required by the Engineer

manufactured from ex-stock steel, ensuring that the supply of

or client. There is no incremental increase in beam depth. If a

steelwork does not compromise the critical path.

depth of (say) 193mm is required, Westok Advisory Engineers will design a beam to exactly 193mm etc.

A separate USFB Design Guide and USFB AutoMate software TM

TM

is available from Westok. USFB s comprise pronounced asymmetric cellular tees, to TM

provide a wide bearing for either pre-cast units (a minimum 75mm bearing is used in Westok’s designs unless requested otherwise) or a profiled metal deck (minimum 50mm bearing offered). Cells along the length of the beam allow the passage of rebar to tie the slabs either side of the web - see Fig. 15.

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FOR WESTOK’S FREE DESIGN SERVICE PLEASE USE THE FORM ON THE OPPOSITE PAGE

ULTRA SHALLOW FLOOR BEAM

DESIGN ENQUIRY FORM

CONTACT DETAILS

USFB

TM

Company:

Name:

Address:

Email: Tel: Fax:

PROJECT DETAILS


LAYOUT

INSITU CONCRETE

Span:

m

Distance to adjacent beam LHS:

m

Distance to adjacent beam RHS:

m

mm

Slab:

Weight:

PC UNITS

LOADING Note: Exclude self-weight of deck & slab

Top Mesh: Thickness:

Deck Type: Grade:

N/mm2 Normal

Lightweight

Thickness:

mm

Mass:

kN/m2

Structural Topping Thickness:

mm

Mass:

kN/m2

Live:

kN/m2

Partitions:

kN/m2

Ceiling & Services:

kN/m2

Other:

kN/m2


LIMITS

NOTES

EITHER Maximum Depth D1:

mm


OR Maximum Depth D2:

mm

* unless otherwise * Bearing Dimension X:

mm

Min. Natural Frequency

Hz


mm


instructed we will assume min. 75mm Precast, or min. 50mm Insitu

ULTRA SHALLOW FLOOR BEAM - USFB

TM


† DEFLECTION: DEFLECTION DUE TO DEAD-LOAD SHOULD NOT BE A CRITICAL FACTOR, AS USFB s CAN BE PRE-CAMBERED WITHOUT COST.

D1

D2

X

TM


23

CAR PARK BEAMS


Car Park Beams Above and beyond any aesthetic and safety appeal, cellular car park beams are used for their economy. At the date of publication 70% of the car parks constructed using cellular beams were Design & Build contracts, where the project contractor used cellular beams as the most economical solution.

24



CAR PARK BEAMS

Capitol Car Park, Douglas, Isle of Man

Floor Beams in Car Parks Without doubt, one of the most advantageous uses of cellular beams is within car park construction. At 16 metre spans under car park loadings a cellular beam is an extremely efficient structural member. In addition to its lighter weight a cellular beam provides three significant benefits in car park construction: Fairhill Car Park, Ballymena

1. Pre-Cambers Cellular beams can be pre-cambered at no cost during production to offset a proportion of the dead-load deflection. Large cambers allow the natural drainage of surface water and eliminate the need for additional screed. 2. Appearance & Personal Security The large web openings provide a light and airy interior to Milton Keynes Car Park

improve personal security, increasingly demanded by clients for modern parking areas. 3. Smoke Ventilation Health and safety regulations dictate the need to consider the problems of smoke ventilation. The regular web openings accelerate smoke dispersion compared to solid-web beams, and can avoid the need to use a forced ventilation system.

Facing page: Amersham Car Park


25

CAR PARK BEAMS


Beam Depth There are no ‘standard’ beam depths for car parks. The table opposite on page 27 shows the range of beam depths used in the earliest 25 Westok cellular beam car parks. The depth is not dictated by the cellular beam - the client and Engineer determine the depth allowed, and using CELLBEAM AutoMate, the Engineer can design the optimum cellular beam at that exact depth. Newcastle-upon-Tyne

Economy Whilst the appearance of cellular beams is a persuasive factor, the most common reason for using cellular car park beams is economy. Steel itself has become the dominant material for constructing multi-storey car parks, and cellular beams are used in more steel-framed car parks than any other type of steel beam. At the date of publication well over half of the MSCPs built

Sainsburys, Clapham

using cellular beams have been Design & Build projects, where either the main contractor or steelwork contractor chose to use cellular beam construction because it produced the most economical overall building.

Douglas, Isle of Man

26


CAR PARK BEAMS


Westok Cellular Beam Car Parks

Depth Allowed

Layout Whilst most car parks in the UK are designed with 16m

Oliver Road, Thurrock

474mm

secondary beams, frame centres vary considerably. The choice

Cambridge

475mm

of beam centres has little or no impact on the economy of

Scotland Street, Sheffield

500mm

cellular beams, which have been used at 3.6m, 4.8m and 7.2m

Douglas, Isle of Man

525mm

centres in car parks across the UK.

Crowne Plaza, Dublin

525mm

Sunwin House, Bradford

536mm

Sainsburys, Clapham

580mm

Amersham

600mm

Ulster Hospital, Belfast

620mm

Buxton Pavilion

650mm

Crystal Peaks, Sheffield

650mm

Natural frequency for beams within car parks may be reduced

Sunderland Sunniside

650mm

to as low as 3Hz for individual members. Research has shown

Newcastle 1 & 2

691mm

that longer span floors actually perform better for vibration

Fairhill, Ballymena

693mm

St Andrews, Norwich

694mm

Telford College, Edinburgh

699mm

Buttercrane, Newry

700mm

King Street, Belfast

700mm

Prospect, Sunderland

700mm

Waitrose HQ, Barking

700mm

Cork 1 & 2

750mm

IKEA, Leeds

775mm

ASDA, Rawtenstall

820mm

Longer Spans Cellular car park beams are also very economical at spans beyond the traditional 16m. The longest span supplied by Westok for a UK car park is 28m. In the USA spans in excess of 20m are commonplace, and almost all use cellular beams.

than short span floors - directly opposite to the conventional

Photo courtesy CMC Steel Group

wisdom of the mid-1990s.

Inn of the Mountain Gods Hotel & Casino, New Mexico, USA - 28.3m clear span

Blackpool Car Park, Cork


27

ROOF BEAMS


Straight Roof Beams The cellular beam owes its existence to its ancestor, the castellated beam of the 1970s and ‘80s. Like castellated beams, the principle benefit of a cellular beam is its ability to span a long distance at a much lighter weight than a plain I-beam.

28

FOR WESTOK’S FREE DESIGN SERVICE PLEASE USE THE FORM ON PAGE 33


ROOF BEAMS

Straight Roof Beams Comparison with Plain Universal Beams Traditional castellated beams were renowned for their economy as long span roof beams. Cellular beams possess all the same attributes, but with far greater economy. The production process considerably improves the section properties of the parent beam used, thus saving enormous weight compared to plain Universal Beams - see Fig. 16.

RASE, Stoneleigh - 40m span - the project was originally designed using trusses but was changed by the project steelwork contractor to cellular beams for their cost saving benefits and to reduce lead-time.

It should be noted that as steel prices increase, so the economy of a cellular beam improves compared to plain Universal Beams, due to the weight saving. For a full table of comparisons with plain Universal Beams, see page 31.

Gala Bingo, Newcastle - 50m span - cellular beams were used in preference to ‘jumbo’ plain beams and plate girder options. Cellular beams were chosen for economy and lead-time.

Cellular Beam 906 x 229 x 101kg/m

Fig. 16 Plain UB 686 x 254 x 170kg/m

Inertia 170300cm4

Inertia 171301cm4

Weight Saving - 40%

Extreme Lengths Whilst any span can be achieved by splicing together two or

Comparison with Trusses

more beams, there is often a visual preference to avoid plated

Beyond the range of portal-frame construction, cellular beams

splices. Cellular beams are commonly supplied in very long

are the ideal solution. A cost comparison between cellular

lengths, with no impact on programme and at little or no

beams and trusses invariably favours cellular beams. Built-up

extra cost. Lengths up to 27m are commonplace. For longer

truss fabrication is more labour intensive and painting costs

lengths please consult Westok as local transport restrictions

are considerably higher.

may apply.

Below: 37.5m beams delivered in a single length for Galpharm Stadium

Facing page: Fulham Broadway Swimming Pool


29

ROOF BEAMS


Designing Straight Cellular Roof Beams Cellular roof beams are designed using CELLBEAM AutoMate. The user inputs the loading and layout information, and AutoMate chooses a suitable cellular beam size. The user has the option to limit the beam depth should eaves height be an issue. Unless it is essential to do so the user should not limit

Fulham Broadway Swimming Pool - 26m lengths delivered to site

depth, thereby allowing AutoMate to choose the lightest solution - see Fig. 17.

Fig. 17 Cellular beams can be designed either simply-supported or as

Audi, Newport - 25.5m lengths delivered nine days after order

portal frames. See pages 36-37 for a fuller explanation. CELLBEAM AutoMate is capable of designing complex cantilevers. Westok Advisory Engineers are available to offer assistance.

Galpharm Stadium, Huddersfield Town FC

Stamford Bridge, Chelsea FC

30


ROOF BEAMS


Standard UB Section Size

Section Properties for Cellular Roof Beams Cellular beam geometry is extremely flexible. Changing the cell data alters the beam depth, resulting in a range of section properties from a single parent section. For example: Parent UB:

762x267x147kg/m

• Cells

800mm diam @ 1000mm centres

• Resulting Depth 1141mm • Ixx

382897cm4

• Cells

750mm diam @ 1125mm centres

• Resulting Depth

1078mm

• Ixx

337666cm4

Therefore, Section Property Tables for this type of beam are of very limited help to the Engineer. However, FOR INDICATION PURPOSES ONLY, the table (right) can be used for preliminary beam sizing. The example in Fig. 18 (which is highlighted in the table, right) indicates the typical weight saving a cellular beam displays over a standard Universal Beam. It should be noted that as steel prices increase, so the economy of a cellular beam improves compared to plain Universal Beams, due to the weight saving. Fig. 18 Standard UB 686 x 254 x 170kg/m

Cellular Beam 906 x 229 x 101kg/m

Inertia 170300cm4

Inertia 171301cm4

Weight Saving - 40%

A full design must be carried out in CELLBEAM AutoMate which performs all the necessary checks for secondary effects as required by BS5950.

1016 1016 1016 1016 1016 1016 1016 1016 914 914 914 914 914 914 838 838 838 762 762 762 762 686 686 686 686 610 610 610 610 610 610 610 533 533 533 533 533 457 457 457 457 457 457 457 457 457 457 406 406 406 406 406 406

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

305 305 305 305 305 305 305 305 419 419 305 305 305 305 292 292 292 267 267 267 267 254 254 254 254 305 305 305 229 229 229 229 210 210 210 210 210 191 191 191 191 191 152 152 152 152 152 178 178 178 178 140 140

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

487 438 393 349 314 272 249 222 388 343 289 253 224 201 226 194 176 197 173 147 134 170 152 140 125 238 179 149 140 125 113 101 122 109 101 92 82 98 89 82 74 67 82 74 67 60 52 74 67 60 54 46 39

Cellular Beam Ixx

Ixx

1020400 908900 806600 722100 643200 552900 480300 406900 719600 625800 504200 436300 376400 325300 339700 279200 246000 240000 205300 168500 150700 170300 150400 136300 118000 209500 153000 125900 111800 98610 87320 75780 76040 66820 61520 55230 47540 45730 41020 37050 33320 29380 36590 32670 28930 25500 21370 27310 24330 21600 18720 15690 12510

1684318 1468573 1085867 915994 915994 737838 737838 554621 486808 486808 737838 629621 554621 486808 382897 342081 342081 342081 342081 342081 222718 171301 171301 171301 171301 139273 125069 222718 171301 139273 125069 107646 107646 83924 83924 75521 65363 55511 49297 49297 42738 42738 35662 35662 44195 35662 35662 27435 22983 27435 27435 22983 22983 16515 14801


Section Size 1398 1389 1490 1480 1480 1364 1364 1257 1149 1149 1364 1263 1257 1149 1141 1137 1137 1137 1137 1137 915 906 906 906 906 805 800 915 906 804 800 796 796 689 689 686 687 615 612 612 609 609 609 609 544 609 609 532 534 532 532 534 534 462 470

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

419 419 305 305 305 305 305 292 267 267 305 292 292 267 267 267 267 267 267 267 229 229 229 229 229 210 210 229 229 210 210 210 210 191 191 191 152 178 178 178 178 178 140 140 171 140 140 171 127 171 171 127 127 127 102

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

388 343 249 222 222 201 201 176 173 173 201 194 176 173 147 134 134 134 134 134 125 101 101 101 101 101 92 125 101 101 92 82 82 82 82 74 67 67 60 60 54 54 46 46 67 46 46 45 39 45 45 39 39 37 33

31

ROOF BEAMS


Spine Beams Hit and miss spine beams are a common method of increasing usable floor space in a single storey building. Cellular beams efficiently span three, four or even five bays between columns, creating vast open floor areas at minimum cost. Cellular spine beams also eliminate expensive rafter/ spine dropped haunch arrangements - see Fig. 19.

ASDA, Hartlepool - typical connection of incoming rafter within the depth of a cellular spine beam.

Fig. 19

Simple connection into a cellular valley beam

M3 Services, Winchester - cellular spine beams and curved cellular rafters.

Costly dropped haunch beneath a plain valley beam

• Cellular spine beams can be cambered for drainage, free of charge. • Asymmetric sections maximise efficiency where

Middlebrook Leisure Centre - 2.5m deep cellular spine beams, 42m span.

subjected to lateral torsional buckling - see Fig. 20. Fig. 20

Asymmetric cellular spine beam

Athlone Mail Distribution Centre - incoming rafters with an end-plate connection on to the toes of the cellular spine beam.

32


DESIGN ENQUIRY FORM

CONTACT DETAILS

ROOF BEAM

Company:

Name:

Address:

Email: Tel: Fax:

PROJECT DETAILS


LAYOUT

Type:

m

Span: Restraint:

OR

Rafter

Full

Centres: OR

NOTES

Spine Beam m Partial

Spacing of Restraints: Purlin pitch

(Use notes if a fuller description necessary)

LOADING

Live:

kN/m2

Cladding, Purlins & Services:

kN/m2

Wind Uplift:

kN/m2

Wind Down:

kN/m2

Minimum Dead:

kN/m2

Other:

kN/m2

Maximum Beam Depth:

mm


mm

Approx. Radius:

m


(used against wind uplift) unfactored unfactored

LIMITS



RADIUS

if applicable

FOR TAPERS, CANTILEVERS, PORTAL FRAMES ETC. THAT ARE NOT EASILY CATERED FOR BY THIS FORM, PLEASE USE THE ‘NOTES’ AREA PROVIDED TO DESCRIBE YOUR REQUIREMENT. ALTERNATIVELY, CALL WESTOK’S ADVISORY ENGINEERS ON: 01924 264121

NOTES


33

ROOF BEAMS


Curved Beams Cellular beams are the perfect solution for curved roof applications, combining a considerable weight saving compared with plain sections and a low-cost curving process.

34



ROOF BEAMS

Economics Plain or Cellular Beams? Cellular beams offer economies compared to plain universal beams due to weight savings of up to 40% and the ease of curving. The relative cost of plain and cellular beams depends on many factors, but may be summarised as: Tight Radius

Medium Radius

Large Radius

Plain

Plain/Cellular

Cellular

Plain/Cellular

Cellular

Cellular

Up to 16m span > 16m span ASDA, Tamworth

Please consult Westok for specific advice

Curving Process

Span Range The economic span range of curved cellular beams depends

Step 1

on the loading and frame centres, but may be generalised as: Roof Type Curved Portal

Two beams are split, the first using a special top tee cut

Curved Simply-supported

<20m

20 - 40m

>40m

✓

✓✓

✓✓✓

✓✓✓

✓✓✓

✓✓✓

(red) and the second using a special bottom tee cut (grey). In summary, the greater the span, the greater the economy of curved cellular beams compared to curved plain beams.

Step 2

A bottom tee is curved to the required radius. Step 3

A top tee is curved and welded to the bottom tee. The process is repeated using the remaining tees to create a pair of curves. Facing page: Liverpool FC Academy

Glasgow Rangers FC Academy


35

ROOF BEAMS


Parkland Textiles, Nottingham - 36m span

Simply Supported Curves Most curved cellular beams are designed simply supported, or with a relatively nominal degree of end fixity. Compared to simply supported plain UBs huge economies are achieved. Plain UBs are curved by specialist section bending companies. This adds to both cost and lead-time. Cellular beams are curved as part of the standard production process,

Liverpool FC Academy - simply supported spans of 44m.

usually without cost or any impact on lead-time. These economies become more pronounced as spans increase, due to the high strength to weight ratio of cellular beams. Even designed simply-supported, the span range of cellular beams extends way beyond that of plain UBs. To date, spans of up to 55 metres have been built using curved cellular beams.

Cardiff Retail Park - simply supported spans up to 53m.

36



ROOF BEAMS

Portalised Curved Cellular Beams It is possible to reduce the steel weight or extend the span range of cellular beams by designing them as part of a portal frame. CELLBEAM AutoMate does not in itself carry out a frame analysis, but used in conjunction with proprietry frame design

Trafford Park, Manchester - curved cellular rafters with separate plated beam haunches.

packages it is quite straightforward to produce an appropriate portal cellular rafter design. Portalised cellular members must be designed elastically. Both straight or curved rafters may be included as frame members. The design method is to model the overall frame forces and moments, and introduce the cellular section within the appropriate length of the frame members. There are two options of designing the haunched ends of such rafters. Whilst it is possible to weld a traditional tapered

ALDI, Runcorn - 42m span curved portal frame. A Design & Build project in which this solution proved more economical than curved plain UBs.

haunch to the underside of the cellular beam, it is far more common to fabricate a totally separate haunch, made from plate - see top two photographs. CELLBEAM AutoMate software caters for end fixity and axial loads - see Fig. 21.

Leeds United FC Academy - 38m span curved rafters with nominal haunch. A Design & Build project in which the 830mm deep cellular rafter proved to be more economical than an 838 x 292 plain curved UB.

Fig. 21 Full output graphics can be viewed on screen to allow assessment of moment, shear and deflected profiles for the member - see Fig. 22. Fig. 22


37

ROOF BEAMS


Achievable Radii Most cellular beams can be curved in house at little or no cost. However, certain tight curves cannot, in which case Westok works with a specialist section bending company. The table to

Wakefield School - Type B curve

the right shows the approximate radii achievable for each type. Type A Curved in-house, therefore at minimum cost Type B Curved in collaboration with a section-bending company

Typical Beam Depth (mm) 450

The radius achievable in-house is not dependent on the overall span, but on the length of the individual beams that form the

650

span. Therefore, a tighter radius can be achieved by introducing a splice as shown in Fig. 24 below. Splices at 1/3 points allow an even tighter radius.

850

Fig. 24 1100

1350

Length of Beam (m)

Minimum Radius Type A (m)

Minimum Radius Type B (m)

10 12 14 16

20 30 40 50

15 15 15 15

14 16 18 20

50 60 80 95

20 20 20 20

14 16 18 20

60 75 90 110

30 30 30 30

14 16 18 20

65 80 100 125

35 35 35 35

16 18 20 22

95 115 140 170

45 45 45 45

This table is simplistic and conservative. Please consult Westok for specific advice.

Wellcome Foundation, Melksham - Type A curve

38


ROOF BEAMS


Reverse or ‘S-shaped’ Curves An increasingly popular form of roof construction is the use of ‘S-shaped’, or ‘Reverse’ curves. Cellular beams are frequently chosen to achieve such a roof shape. The ‘S’ is formed by joining together two single curves of equal or differing radii. There are no restrictions regarding where the curve must change direction, or the different radii that can be joined together. The joint at the change of direction can be welded by the project steelwork contractor, or in most cases the steelwork contractor gives this additional scope of work to Westok.

Above and below: South Lakeland Leisure Centre, Carnforth

Imperial Select Motor Dealership, Boksburg, South Africa

Photo courtesy of MACSTEEL

Winchester M3 Motorway Services


39

ROOF BEAMS


Tapered Beams & Cantilevers Cellular beams provide the most economical method of producing tapered steel members.

40



ROOF BEAMS

Tapered Cellular Beams Cellular beams provide the most economical method of producing tapered steel members - see Fig. 25. Fig. 25 Step 1: Profile at angle of required taper

Dunfermline Athletic FC - 21m cantilever with uniform cells

Step 2: Spin one tee 180˚ and re-weld

Tapered beams can have cells of uniform size, cells of varying size or no cells. This affects the relative cost - see Fig. 26. Fig. 26 Minimum cost

Uniform diameter cells full length - provides the most efficient design, combined with the minimum amount of weld length.

Harlequins RFC - bespoke cells

Medium cost

Bespoke cells that vary in diameter - also minimises weld length, but the design is likely to be slightly heavier. Highest cost

No cells - by far the most expensive option. The beam is not expanded so is heavier than a cellular taper. More critically, it also requires a long length of weld. Apart from the cost of the weld, there is also difficulty in maintaining straightness due to the amount of heat input necessary. Above and facing page: Hull KC Stadium - 29m span cantilever with bespoke cells


41

ROOF BEAMS

Westok & Stadia Barnsley FC


Cantilever Roof Members

Bradford City FC

Cellular beams are frequently the preferred choice for

Bristol City FC

cantilevers. This is due to the production process, which

Burton Albion FC

achieves the two key requirements for a cantilever:

Cardiff City FC Carlisle Utd FC

• great depth and therefore huge inertia at the support

Celtic FC

• minimum depth and therefore minimal weight at the tip

Chelsea FC Cheltenham Town FC Chester City FC Doncaster Racecourse Doncaster Rovers FC

Long cantilevers are often designed using two or even three different beam sizes to minimise the overall weight of the rafter with huge benefit to project cost - see Fig. 27.

Burton Albion FC - 16m cantilever

Dundee FC Dunfermline Athletic FC

Fig. 27

East Fife FC Exeter RUFC Forest Green Rovers FC

15m 762 x 267 x 173kg/m

Grantham Town FC Harlequins RFC

13m 457 x 191 x 74kg/m

Hibernian FC Huddersfield Town FC

Project: Carlisle Utd FC

Hull City FC Ipswich Town FC Kidderminster Harriers FC Kilmarnock FC Livingstone FC

CELLBEAM AutoMate allows Engineers to design tapered cantilevers, (see Fig. 28) but most Engineers ask Westok’s

Macclesfield Town FC

Advisory Engineers to design them due to the additional

Montrose FC

complexity of manipulating the section geometry. The design

Newcastle Falcons RFC

service is free of charge.

Newmarket Racecourse

Dunfermline FC - 21m cantilever

Northampton Town FC Oxford United FC Partick Thistle FC Reading FC Ross County FC Rushden & Diamonds FC Shrewsbury Town FC St Mirren FC Walsall FC Warrington Wolves RLFC Watford FC Worcester RFC Wycombe Wanderers FC

Fig. 28

Cantilever design using CELLBEAM AutoMate.

Rushden & Diamonds FC

42



ROOF BEAMS

Pitched Roofs Using Tapers A basic portal frame is likely to produce the cheapest cost ‘shed’ up to spans of about 25 metres. However, there are often cases where the haunched portal frame is not appropriate to the needs of a client. These are likely to be: • where column widths need to be minimised • where eaves height is critical, eg. planning issues or expensive cladding • where a more aesthetically pleasing appearance is required • extreme spans beyond the range of portal frames

Centennial Park, Elstree - 36m clear span. 500mm at eaves, 750mm at apex.

In such cases a tapered cellular beam is often the optimum solution - see Fig. 29. As with cantilevers, tapered single storey roof beams are usually designed by Westok for the Project Engineer. The design service is totally free of charge or obligation. Fig. 29

Kingston Park, Newcastle - 38m clear span. 550mm at eaves, 935mm at apex.

A tapered beam minimises the height to the underside of the eaves

Fig. 30

The deepest point of a tapered rafter is at mid-span where the maximum inertia is required

Double taper design with CELLBEAM AutoMate.

IFB Zeebrugge, Belgium - 53m clear span. 1200mm at eaves, 1500mm at apex.


43

COLUMNS


Cellular Columns As building height increases, cellular columns become increasingly economical compared to other solutions.

44


COLUMNS

Parallel Flanged Columns As building height increases, cellular columns become increasingly economical compared to other solutions. High-bay columns in today’s ‘super sheds’ are a particularly suitable application, where the increased inertia of a cellular beam will minimise the deflections in the tall columns. Cellular columns are most efficient in cases where axial loads are small, such as gable columns, portal legs, wind-posts and valley columns. CELLBEAM AutoMate is capable of designing cellular columns but most Engineers prefer to use the services of Westok’s Advisory Engineers to carry out such designs completely free of charge. Churchill Court, Trafford Park

Porsche Showroom, Liverpool

Parkland Textiles, Nottingham

Tapered Columns The initial reason to use any form of tapered column is likely to be one of aesthetics. However, once it is decided that a tapered column is appropriate, a cellular taper will be the most economical solution. There are no restrictions on the shape of taper. Cell diameters can be uniform or can vary in proportion with the degree of taper.

Facing page: Ideal Hardware, Chessington

Holmes Place, Merton

45

SUSTAINABILITY


Sustainability Westok is fortunate and delighted that cellular beams help to create buildings that use less steel and minimize the lifetime costs and environmental burdens associated with construction. Reduced use of Raw Steel

• Cellular beams use 25 - 50% less steel than plain beams

• 25 - 50% lighter loads to transport

Minimum Lifetime Costs / Environmental Burden The most important factor by far in the longevity of multistorey buildings is maximizing the flexibility of layout for future tenants. Cellular floor beams produce column-free, long span floors at the same overall cost as the short spans of the 1980s. Today’s clear span structures will not have to be demolished due to lack of flexibility. Furthermore, cellular beams allow the adoption of circular ducting without increasing the overall depth of construction. Circular ducting is up to three times more energy efficient than rectangular ducting. (See page 12).

46


INTERNATIONAL MARKETS

International Markets Cellular beam use in the UK alone comfortably exceeds 25,000 tonnes per year, at the time of publication. Worldwide annual usage exceeds 50,000 tonnes. Cellular beams have been used in over 25 countries. At the time of publication manufacturing is carried out in the UK, Europe, the USA, Africa, Australia, New Zealand and the United Arab Photo courtesy MACSTEEL

Emirates. Westok will gladly advise of contact details for each part of the world.

Photo courtesy of Arcelor

Marizburg College, South Africa

Fischrestaurant, Ewald, Germany

Photo courtesy CMC Steel Group

Matrade, Kuala Lumpur, Malaysia

Best Buy, Colma, California USA

47

Tel: 01924 264121 Fax: 01924 280030 Email: [email protected]

Design and photography by threeonedoublenine. www.3199. com. au

ASD Westok Limited, Charles Roberts Office Park, Charles Street, Horbury Junction, Wakefield, West Yorkshire WF4 5FH

www.westok.co.uk

ASD Westok. Part of the ASD metal services group.

10/08

Cellular Beams Design

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