Uniclass
EPIC
L3521:P41
C232:X4121
CI/SfB
(29)
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ENGINEERS DESIGN GUIDE
Cellular Beams
INTRODUCTION
ENGINEERS DESIGN GUIDE
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.
ENGINEERS DESIGN GUIDE
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
ENGINEERS DESIGN GUIDE
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
ENGINEERS DESIGN GUIDE
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
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.
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
ENGINEERS DESIGN GUIDE
CELLULAR BEAMS
Using CELLBEAM AutoMate
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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
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 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
ENGINEERS DESIGN GUIDE
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
ENGINEERS DESIGN GUIDE
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
ENGINEERS DESIGN GUIDE
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
I
