Cellular Beams Design

Uniclass EPIC

CI/SfB

L3521:P41 C232:X4121

(29) Hh2

ENGINEERS DESIGN GUIDE

Cellular Beams

00

INTRODUCTION

02


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

Westok worked with the Steel Construction Institute to test

cellular beam performance, and to produce design rules and

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.

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

Emirates. Westok will gladly advise of contact details for each

part of the world.

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.

In 2006 Westok introduced a new beam - USFBTM

(Ultra Shallow Floor Beam) - see page 22.

Advisory EngineeringServices

Free Design Service

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

• Secondary Floor Beams - pg 21

• USFBTMs (Ultra Shallow Floor Beams) - pg 23

• Roof Beams - pg 33

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

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

submitted to Westok online.

CPD Seminars

Westok Advisory Engineers

provide CPD seminars covering

all aspects of cellular beam and

USFBTM design and applications.

These can be held at Consultants’

offices on request.

Design & Advisory Meetings

Regionally based Westok Advisory Engineers can attend

Engineers’ offices to help advise on the suitability of cellular

beams and USFBTMs in specific projects, and provide designs

to the Project Engineer without cost or obligation.

To use any of Westok’s Advisory Engineering Services

please contact:

ASD Westok LimitedCharles Roberts Office ParkCharles Street, Horbury JunctionWakefieldWest YorkshireWF4 5FH

Tel: 01924 264121Fax: 01924 280030

Email: [email protected]

www.westok.co.uk

00

CONTENTS

04 - 09

47

46

44 - 45

03

28 - 43

24 - 27

pagesContents

Cellular Beams

10 - 23

Car Park Beams

Roof Beams

CellularColumns


Sustainability

International Markets

Floor Beams

18 Fire Protection19 Fire Engineering with Cellular Beams20 Design Enquiry Form - Primary Floor Beam21 Design Enquiry Form - Secondary Floor Beam22 Ultra Shallow Floor Beams - USFBTM

23 Design Enquiry Form - USFBTM

37 Portalised Curved Cellular Beams38 Achievable Radii39 Reverse or ‘S-Shaped’ Curves40 Tapered Beams & Cantilevers41 Tapered Cellular Beams42 Cantilever Roof Members43 Pitched Roofs Using Tapers

05 What is a Cellular Beam?06 SCI Cellular Beam Software / USFB Software & CellVibe Software 07 Using CELLBEAM AutoMate08 Specifying Cellular Beams09 Avoiding Infills to Cells

11 Floor Beams / Asymmetric Beams / Pre-Cambered Beams12 Service Integration13 Cell Size & Elongated Openings14 Beam Depths16 Column-Free Clear Span Floors17 Floor Vibration / Natural Frequency / Floor Response Factor

25 Floor Beams in Car Parks

29 Straight Roof Beams30 Designing Straight Cellular Roof Beams31 Section Properties for Cellular Roof Beams32 Spine Beams33 Design Enquiry Form - Roof Beam34 Curved Beams35 Curving Process / Economics / Span Range36 Simply Supported Curves

45 Parallel Flanged Columns / Tapered Columns

0004

CELLULAR BEAMS

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


0005

CELLULAR BEAMS

What is a Cellular Beam?

A Universal Beam or Universal Column is castellated which

results in a beam approximately 40-60% deeper than its

parent section - see Fig. 1. The exact finished depth, cell

diameter and cell spacing are very flexible. A cellular beam has

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

Tapered Beams

Fig. 1

Cellular beam profilingFacing page: City Park, Hove


0006

CELLULAR BEAMS ENGINEERS DESIGN GUIDE

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.

USFBTM Software &CellVibe Software

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.


0007

CELLULAR BEAMSENGINEERS DESIGN GUIDE

Using CELLBEAM AutoMate

Westok Design Suite - current at date of publication

As the name suggests, CELLBEAM AutoMate designs the

cellular beam automatically. The Project Engineer inputs loads,

spans and centres, deck type, restraints etc. and is then

asked for limits:

• Is a maximum or precise fixed beam depth required?

• Is a minimum cell diameter required?

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.

Free Design Service

Designs can be requested by phone, fax or e-mail, and can be

responded to by return if required. Multiple options for the

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

designs are totally free of charge or any obligation.

Design Enquiry Forms can be found in this Guide as follows:

• Primary Floor Beams - pg 20

• Secondary Floor Beams - pg 21

• USFBs (Ultra Shallow Floor Beams) - pg 23

• Roof Beams - pg 33

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

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

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.

0008

CELLULAR BEAMS ENGINEERS DESIGN GUIDE

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

approaches:

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)

a 732 Depth in mmb 191 Top tee flange widthc 229 Bottom tee flange widthd 90 Mass in kg/me S355 Steel gradef 450 Cell diameter in mmg 650 Cell pitch

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)

a 1160 Depth in mmb 267 Flange Widthc 134 Mass in kg/md S355 Steel gradee 800 Cell diameter in mmf 1000 Cell pitch

Mark Section Reference

Material Masskg/m

Grade Tee Depths

mm

Cell Data Structural Fire Data

Diam Pitch Section Factor(m-1)

Limiting FlangeTemp °C

Limiting Web Temp °C

1 732 x 191/229 ACB 90 Top UB 457 x 191 x 67Btm UB 610 x 229 x 113

90 S355 S355

327.5404.6

450 650 126 617 650

Douglas Car Park, Isle of Man

Valley Park, Leeds

Cannon Court, Maidenhead

See page 18


0009

CELLULAR BEAMSENGINEERS DESIGN GUIDE

Avoiding Infills to Cells

If your design requires more infilling than suggested below

please consult Westok. Our Advisory Engineers will help you

minimise /eliminate infilling.

CELLBEAM AutoMate already helps minimise infilled cells, but

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

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

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.

CB1

CB2

CB2

CB1

CB1Full web post Full web post

CB2½ infill ½ infill

Fig. 2

Newcastle Car Park Finsbury Pavement, London

FLOORBEAMS

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

Floor Beams


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

FLOORBEAMS

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

Cellular

Cellular

Cellular

Plai

n / C

ellu

lar

Floor Beams

Cellular beams are most commonly used as floor beams. This

enables one or all of the following to be achieved:

• Long Clear Spans

• Service Integration

• Shallow Overall Floor Depths

The decision whether to use cellular floor beams can be easily

summarised:

* 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 long-

spanning secondaries. The primary member could be cellular

or plain, depending on whether services are required in both

directions - See Fig. 3.

Fig. 3

Facing page: Sweet Street, Leeds - 18m clear span


Span Requirement

Services Requirement <9m <12m >12m

No services USFBTM * ✓ ✓✓

Single service opening ✓ ✓✓ ✓✓✓

Normal/heavy services ✓✓ ✓✓✓ ✓✓✓

11

Asymmetric Beams

Many composite cellular

beams are designed

asymmetrically -

see Fig. 4. The top

and bottom tees are

profiled from different

parent sections, thereby

optimising the distribution

of mass. This is particularly

beneficial in designs predominantly governed by deflection

or vibration.

Fig. 4

Pre-Cambered Beams

Long span beams often require the specification of costly pre-

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).

Please consult Westok for specific project requirements.

Services

FLOORBEAMS


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

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

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

• 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

* 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.


National Assembly for Wales, Merthyr Tydfil

Service Integration

Cellular floor beams are used for their ability to integrate

structure and services. This minimises overall construction

height.

Fischrestaurant, Ewald, Germany

Salford University

Phot

o co

urte

sy o

f Arc

elor

Cannon Court, Maidenhead

12

FLOORBEAMS



13

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

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

stiffeners - see Fig. 7.

Fig. 7

14

FLOORBEAMS



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.

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

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

15

FLOORBEAMS



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

‘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

‘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

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

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

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

16

FLOORBEAMS



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

Bishop Auckland Hospital

SERVICES

Short Span Clear Span Cellular

Depth saving

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

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

Even more importantly, the client is presented with a layout

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

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

of clear span, column-free construction are huge:

Fig. 12

Column-Free Clear Span Floors

It used to be believed that the more columns in a multi-storey

structure the cheaper the build cost. This was consigned to

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

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

free construction produced almost identical initial build costs.

Fig. 11

SERVICES

17

FLOORBEAMS



Floor Vibration

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

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

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

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

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

Tests have shown that the vibration performance of composite

cellular beams far exceeded the predicted results. Westok has

pioneered the testing of long-span floors. Numerous projects

in the UK and France have been tested in collaboration with

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

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

Natural Frequency

CELLBEAM AutoMate allows the Engineer to set an appropriate

minimum natural frequency in Hz for individual members as a

design parameter.

Floor Response Factor

However, the SCI Design Guide P354 states that natural

frequency is not the most reliable predictor of floor quality.

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

imperceptible to humans. It is the amplitude that is actually

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

an ‘acceptable’ frequency well above 4Hz to produce an

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

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

method in P354 for designing floor quality is to calculate the

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

quality of the floor:

R ≤ 8 Suitable for a general office floor

R ≤ 4 Highest quality office floor

R ≤ 1 Suitable for hospital operating theatres

CellVibe Software

SCI has produced the CellVibe software for Westok. The

program calculates the Response Factor for any given floor

area using cellular beams or USFBs. Contact Westok to

receive CellVibe free of charge.

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

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

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

18

FLOORBEAMS



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.

St Vincent Street, Glasgow - conventional fire protection on cellular beams. Finsbury Pavement, London - intumescent protected cellular beams.

Fig. 13

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 cel-

lular beams in the UK and France.

Fig. 14

19

FLOORBEAMS



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

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.

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

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

PLEASE PHOTOCOPY THIS FORM & FAX YOUR ENQUIRY TO WESTOK: 01924 28003020

PRIMARY FLOOR BEAMDESIGN ENQUIRY FORM

CONTACT DETAILS Company:

Address:

Name:

Email:

Tel:

Fax:

PROJECT DETAILS Project Title:

Beam Ref:

LAYOUT Layout Type:

Span:

Bay Centres:Side 1

Non-CompositeComposite

NOTES

INSITU CONCRETE Slab:

Deck Type:

Grade:

Weight:

Top Mesh:

Thickness:

LightweightNormal

PC UNITS Thickness: Mass:

mm

N/mm2

mm kN/m2

LOADINGNote: Exclude self-weight

of deck & slab

Live: kN/m2

unfactored

Partitions: kN/m2

unfactored

Ceiling & Services: kN/m2

unfactored

Other: kN/m2

unfactored

LIMITS

*unless otherwise instructed4.0 Hz for offices &

3.0 Hz for car parks

mm

mm

Hz

mm

Maximum Beam Depth:

Minimum Cell Diameter:

* Natural Frequency:

† Live Load Deflection:leave blank if no limit

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

leave blank if no limit


(please tick as

appropriate)

Office

Storage

Other

BuildingType:

mBay Centres:Side 2

Mid Span

Third Points

Quarter Points

Other (please specify in Notes area)

Secondary Beam Centres:

m

m

Car Park

Education

21PLEASE PHOTOCOPY THIS FORM & FAX YOUR ENQUIRY TO WESTOK: 01924 280030

SECONDARY FLOOR BEAMDESIGN ENQUIRY FORM

CONTACT DETAILS

PROJECT DETAILS

Company:

Address:

Name:

Email:

Tel :

Fax:

Project Title:

Beam Ref:

LAYOUT Layout Type:

Span:

BuildingType:

Non-Composite

(please tick as

appropriate)

Composite NOTES

mCentres:

Office

Storage

Car Park

Education

Other


Deck Type:

Grade:

Weight:

m

Top Mesh:

Thickness:

LightweightNormal


mm

N/mm2

mm kN/m2


of deck & slab

Live: kN/m2

unfactored

Partitions: kN/m2

unfactored


unfactored

Other: kN/m2

unfactored

LIMITS

* unless otherwise instructed4.0 Hz for offices &

3.0 Hz for car parks

mm

mm

Hz

mm

Maximum Beam Depth:

Minimum Cell Diameter:

* Natural Frequency:

† Live Load Deflection:leave blank if no limit

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



22

FLOORBEAMS ENGINEERS DESIGN GUIDE

Ultra Shallow Floor Beams - USFBTM

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 USFBTM (Ultra Shallow Floor Beam) is the most flexible

and practical approach to this type of construction.

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

carried out to achieve the exact depth required by the Engineer

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

depth of (say) 193mm is required, Westok Advisory Engineers

will design a beam to exactly 193mm etc.

USFBTMs comprise pronounced asymmetric cellular tees, to

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.

Fig. 15

Rebar

Any

dept

h

Pre-cast units

Metal decking

75mmmin bearingfor PC units

50mmmin bearing

for metal decking

USFBTMs can be pre-cambered at no additional cost and

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

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

steelwork does not compromise the critical path.

A separate USFBTM Design Guide and USFBTM AutoMate software

is available from Westok.

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

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

23


Address:

Name:

Email:

Tel:

Fax:


Beam Ref:

LAYOUT Span:

Distance to adjacent beam LHS:

Distance to adjacent beam RHS:

m

m

m


Deck Type:

Grade:

Weight:

Top Mesh:

Thickness:

LightweightNormal


mm

N/mm2

kN/m2


of deck & slab

Live: kN/m2

unfactored

Partitions: kN/m2

unfactored


unfactored

Other: kN/m2

unfactored

NOTES

StructuralTopping

Thickness: Mass: kN/m2

mm

mm

LIMITS

* unless otherwise instructed

we will assume min. 75mm Precast,

or min. 50mm Insitu

ULTRA SHALLOW FLOOR BEAM USFBTM

mm

mm

mm

Hz

Maximum Depth D1:

Maximum Depth D2:

* Bearing Dimension X:

Min. Natural Frequency



mm† Live Load Deflection:leave blank if no limit

EITHER

OR

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

ULTRA SHALLOW FLOOR BEAM - USFBTM

D1 D2

X

DESIGN ENQUIRY FORM


24

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.

Car Park Beams

25

CAR PARK BEAMS


Facing page: Amersham Car Park

Fairhill Car Park, Ballymena


Milton Keynes Car Park

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:

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

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.

Capitol Car Park, Douglas, Isle of Man

26

CAR PARK BEAMS


Sainsburys, Clapham

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

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.


Newcastle-upon-Tyne

Douglas, Isle of Man

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.

27

CAR PARK BEAMS


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

Westok Cellular Beam Car Parks Depth Allowed

Oliver Road, Thurrock 474mm

Cambridge 475mm

Scotland Street, Sheffield 500mm

Douglas, Isle of Man 525mm

Crowne Plaza, Dublin 525mm

Sunwin House, Bradford 536mm

Sainsburys, Clapham 580mm

Amersham 600mm

Ulster Hospital, Belfast 620mm

Buxton Pavilion 650mm

Crystal Peaks, Sheffield 650mm

Sunderland Sunniside 650mm

Newcastle 1 & 2 691mm

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


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Blackpool Car Park, Cork

Layout

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

secondary beams, frame centres vary considerably. The choice

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

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

centres in car parks across the UK.

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.

Natural frequency for beams within car parks may be reduced

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

that longer span floors actually perform better for vibration

than short span floors - directly opposite to the conventional

wisdom of the mid-1990s.

28

ROOF BEAMS

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

Straight Roof BeamsThe 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.


29

ROOFBEAMS


Weight Saving - 40%

Plain UB686 x 254 x 170kg/m

Inertia 170300cm4

Cellular Beam906 x 229 x 101kg/m

Inertia 171301cm4

Facing page: Fulham Broadway Swimming Pool


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.

Extreme Lengths

Whilst any span can be achieved by splicing together two or

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

splices. Cellular beams are commonly supplied in very long

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

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

lengths please consult Westok as local transport restrictions

may apply.

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.

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

Straight Roof Beams

Comparison with Plain Universal Beams

Traditional castellated beams were renowned for their econ-

omy 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.

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.

Fig. 16

Comparison with Trusses

Beyond the range of portal-frame construction, cellular beams

are the ideal solution. A cost comparison between cellular

beams and trusses invariably favours cellular beams. Built-up

truss fabrication is more labour intensive and painting costs

are considerably higher.


30

ROOF BEAMS ENGINEERS DESIGN GUIDE

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

depth, thereby allowing AutoMate to choose the lightest

solution - see Fig. 17.

Fig. 17

Cellular beams can be designed either simply-supported or as

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.

Fulham Broadway Swimming Pool - 26m lengths delivered to site

Galpharm Stadium, Huddersfield Town FC

Stamford Bridge, Chelsea FC

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


31

ROOFBEAMSENGINEERS DESIGN GUIDE

Section Properties for Cellular Roof Beams

610 x 305 x 238 209500610 x 305 x 179 153000610 x 305 x 149 125900610 x 229 x 140 111800610 x 229 x 125 98610610 x 229 x 113 87320610 x 229 x 101 75780533 x 210 x 122 76040533 x 210 x 109 66820533 x 210 x 101 61520533 x 210 x 92 55230533 x 210 x 82 47540457 x 191 x 98 45730457 x 191 x 89 41020457 x 191 x 82 37050457 x 191 x 74 33320457 x 191 x 67 29380457 x 152 x 82 36590457 x 152 x 74 32670457 x 152 x 67 28930457 x 152 x 60 25500457 x 152 x 52 21370406 x 178 x 74 27310406 x 178 x 67 24330406 x 178 x 60 21600406 x 178 x 54 18720406 x 140 x 46 15690406 x 140 x 39 12510

222718 915 x 229 x 125171301 906 x 229 x 101139273 804 x 210 x 101125069 800 x 210 x 92107646 796 x 210 x 82107646 796 x 210 x 8283924 689 x 191 x 8283924 689 x 191 x 8275521 686 x 191 x 7465363 687 x 152 x 6755511 615 x 178 x 6749297 612 x 178 x 6049297 612 x 178 x 6042738 609 x 178 x 5442738 609 x 178 x 5435662 609 x 140 x 4635662 609 x 140 x 4644195 544 x 171 x 6735662 609 x 140 x 4635662 609 x 140 x 4627435 532 x 171 x 4522983 534 x 127 x 3927435 532 x 171 x 4527435 532 x 171 x 4522983 534 x 127 x 3922983 534 x 127 x 3916515 462 x 127 x 3714801 470 x 102 x 33

Standard UB

Section Size Ixx

1016 x 305 x 487 10204001016 x 305 x 438 9089001016 x 305 x 393 8066001016 x 305 x 349 7221001016 x 305 x 314 6432001016 x 305 x 272 5529001016 x 305 x 249 4803001016 x 305 x 222 406900914 x 419 x 388 719600914 x 419 x 343 625800914 x 305 x 289 504200914 x 305 x 253 436300914 x 305 x 224 376400914 x 305 x 201 325300838 x 292 x 226 339700838 x 292 x 194 279200838 x 292 x 176 246000762 x 267 x 197 240000762 x 267 x 173 205300762 x 267 x 147 168500762 x 267 x 134 150700686 x 254 x 170 170300686 x 254 x 152 150400686 x 254 x 140 136300686 x 254 x 125 118000

Cellular Beam

Ixx Section Size

1684318 1398 x 419 x 3881468573 1389 x 419 x 3431085867 1490 x 305 x 249915994 1480 x 305 x 222915994 1480 x 305 x 222737838 1364 x 305 x 201737838 1364 x 305 x 201554621 1257 x 292 x 176486808 1149 x 267 x 173486808 1149 x 267 x 173737838 1364 x 305 x 201629621 1263 x 292 x 194554621 1257 x 292 x 176486808 1149 x 267 x 173382897 1141 x 267 x 147342081 1137 x 267 x 134342081 1137 x 267 x 134342081 1137 x 267 x 134342081 1137 x 267 x 134342081 1137 x 267 x 134222718 915 x 229 x 125171301 906 x 229 x 101171301 906 x 229 x 101171301 906 x 229 x 101171301 906 x 229 x 101139273 805 x 210 x 101125069 800 x 210 x 92

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

A full design must be carried out in CELLBEAM AutoMate

which performs all the necessary checks for secondary effects

as required by BS5950.


Weight Saving - 40%

Standard UB686 x 254 x 170kg/m

Inertia 170300cm4

Cellular Beam906 x 229 x 101kg/m

Inertia 171301cm4


32

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.

Fig. 19

• Cellular spine beams can be cambered for drainage,

free of charge.

• Asymmetric sections maximise efficiency where

subjected to lateral torsional buckling - see Fig. 20.

Fig. 20

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

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

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

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

Simple connection into a cellular valley beam

Costly dropped haunch beneath a plain valley beam

Asymmetric cellular spine beam

33


Address:

Name:

Email:

Tel:

Fax:


Beam Ref:

LAYOUT NOTES

ROOF BEAMDESIGN ENQUIRY FORM


Type:

Span:

Restraint:

Rafter

Centres:

Full

m

Spacing of Restraints:Purlin pitch

Partial

OR Spine Beam

OR

m

LOADING Live: kN/m2

unfactored

Cladding, Purlins & Services: kN/m2

unfactored

Wind Uplift: kN/m2

unfactored

Wind Down: kN/m2

unfactored

LIMITS mmMaximum Beam Depth:

Minimum Dead: kN/m2

(used against wind uplift) unfactored

Other: kN/m2

unfactored


mmMinimum Cell Diameter:leave blank if no limit

RADIUS mApprox. Radius:if applicable

NOTES

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

(Use notes if a fuller description necessary)

ROOF BEAMS


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


ROOFBEAMS

FOR WESTOK’S FREE DESIGN SERVICE PLEASE USE THE FORM ON PAGE 33 35

Curving Process

Step 1

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

(red) and the second using a special bottom tee cut (grey).

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.

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:

Please consult Westok for specific advice

Span Range

The economic span range of curved cellular beams depends

on the loading and frame centres, but may be generalised as:

In summary, the greater the span, the greater the economy of

curved cellular beams compared to curved plain beams.

Tight Radius

Medium Radius

Large Radius

Up to 16m span Plain Plain/Cellular Cellular

> 16m span Plain/Cellular Cellular Cellular

Glasgow Rangers FC Academy

ASDA, Tamworth

Facing page: Liverpool FC Academy


Roof Type <20m 20 - 40m >40m

Curved Portal ✓ ✓✓ ✓✓✓

Curved Simply-supported ✓✓✓ ✓✓✓ ✓✓✓

ROOF BEAMS



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

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,

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.

Liverpool FC Academy - simply supported spans of 44m.

Parkland Textiles, Nottingham - 36m span

ROOFBEAMS

FOR WESTOK’S FREE DESIGN SERVICE PLEASE USE THE FORM ON PAGE 33 37

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


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

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

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.

Full output graphics can be viewed on screen to allow

assessment of moment, shear and deflected profiles for the

member - see Fig. 22.

Fig. 21

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

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. 22

38

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

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

The radius achievable in-house is not dependent on the overall

span, but on the length of the individual beams that form the

span. Therefore, a tighter radius can be achieved by introduc-

ing a splice as shown in Fig. 24 below. Splices at 1/3 points

allow an even tighter radius.

Fig. 24

Typical Beam Depth (mm)

Length of Beam

(m)

Minimum Radius

Type A (m)

Minimum Radius

Type B (m)

45010121416

20304050

15151515

65014161820

50608095

20202020

85014161820

607590110

30303030

110014161820

6580

100125

35353535

135016182022

95115140170

45454545

This table is simplistic and conservative. Please consult Westok forspecific advice.

Wellcome Foundation, Melksham - Type A curve

Wakefield School - Type B curve

39

ROOFBEAMS


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.Winchester M3 Motorway Services

Imperial Select Motor Dealership, Boksburg, South Africa


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Above and below: South Lakeland Leisure Centre, Carnforth

40

ROOF BEAMS


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


41FOR WESTOK’S FREE DESIGN SERVICE PLEASE USE THE FORM ON PAGE 33

ROOFBEAMS

Dunfermline Athletic FC - 21m cantilever with uniform cells

Harlequins RFC - bespoke cells


Tapered Cellular Beams

Cellular beams provide the most economical method of

producing tapered steel members - see Fig. 25.

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.

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.

Fig. 25

Step 1: Profile at angle of required taper

Step 2: Spin one tee 180˚ and re-weld

Above and facing page: Hull KC Stadium - 29m span cantilever with bespoke cells

15m

762 x 267 x 173kg/m

13m

457 x 191 x 74kg/m

42

ROOF BEAMS


Cantilever Roof Members

Cellular beams are frequently the preferred choice for

cantilevers. This is due to the production process, which

achieves the two key requirements for a cantilever:

• great depth and therefore huge inertia at the support

• minimum depth and therefore minimal weight at the tip

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.

Fig. 27

Project: Carlisle Utd FC

CELLBEAM AutoMate allows Engineers to design tapered

cantilevers, (see Fig. 28) but most Engineers ask Westok’s

Advisory Engineers to design them due to the additional

complexity of manipulating the section geometry. The design

service is free of charge.

Fig. 28 Cantilever design using CELLBEAM AutoMate.

Burton Albion FC - 16m cantilever

Rushden & Diamonds FC

Dunfermline FC - 21m cantilever


Westok & Stadia

Barnsley FC

Bradford City FC

Bristol City FC

Burton Albion FC

Cardiff City FC

Carlisle Utd FC

Celtic FC

Chelsea FC

Cheltenham Town FC

Chester City FC

Doncaster Racecourse

Doncaster Rovers FC

Dundee FC

Dunfermline Athletic FC

East Fife FC

Exeter RUFC

Forest Green Rovers FC

Grantham Town FC

Harlequins RFC

Hibernian FC

Huddersfield Town FC

Hull City FC

Ipswich Town FC

Kidderminster Harriers FC

Kilmarnock FC

Livingstone FC

Macclesfield Town FC

Montrose FC

Newcastle Falcons RFC

Newmarket Racecourse

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

43

ROOFBEAMS


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

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

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

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

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.


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

Fig. 30 Double taper design with CELLBEAM AutoMate.

44

COLUMNS

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


45

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.

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.

Parkland Textiles, Nottingham

Facing page: Ideal Hardware, Chessington


Churchill Court, Trafford Park

Porsche Showroom, Liverpool

Holmes Place, Merton


46

SustainabilityWestok 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 multi-

storey 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).

SUSTAINABILITY


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International MarketsCellular 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

Emirates. Westok will gladly advise of contact details for each

part of the world.

Best Buy, Colma, California USA

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Marizburg College, South Africa

Matrade, Kuala Lumpur, Malaysia

Fischrestaurant, Ewald, Germany

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ACST

EEL

47

INTERNATIONAL MARKETS

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

ASDWestok.PartoftheASDmetalservicesgroup.

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Cellular Beams Design

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