Civil Engineering Reference
In-Depth Information
Chapter 18
Steelwork
John Rushton
Peter Brett Associates LLP, UK
doi: 10.1680/mosd.41448.0309
CONTENTS
18.1
Introduction to steel
design
309
18.2
History
313
This chapter outlines an approach to steel design from the viewpoint of a consulting designer
practising in the UK. The approach when applied in other countries/markets will apply but
should acknowledge local design and construction practice. Rather than a comprehensive
guide to steel design this chapter presents summaries, design guidance and sources of
information on aspects of design and construction in steelwork with the aim of achieving a
successful design. There is a considerable body of published material available, primarily from
the Steel Construction Institute (SCI) and the British Constructional Steelwork Association
(BCSA). A list of key references and further reading are provided at the end of the chapter.
18.3
What is a successful
steel design?
316
18.4
Design responsibility
318
18.5
Design/analysis/detail
design - a virtuous
circle
319
18.6
Design parameters
(cost, construction)
320
18.7
Preliminary structural
steelwork
arrangements
331
18.8
Challenges and
opportunities
332
18.9
Case study of the
reconstruction of a
1920s steel framed
office building
335
18.10 Conclusion
338
18.11 References
338
18.1 Introduction to steel design
The designer is often asked to consider whether a steel
structure is appropriate when compared with a competing
structural material, most likely to be reinforced concrete. The
superstructure cost of a single storey building might account
for 25%, in multi-storey residential buildings 10-15%, and in
non-residential in the region of 10%, but the structural inter-
face with building fabric and services can be a significant cost
parameter.
At the outline proposals stage, option appraisals involv-
ing column spacing, floor systems and cladding support will
normally require liaison with the architect. The building ser-
vices engineer's input is often required in terms of plant room
size, location and the distribution of vertical and horizontal
service routes.
When a client or a design team decides that a steel solu-
tion is appropriate, the designer may review steel variants as a
finer development of the concept appraisal stage. Knowledge
of structure cost is needed to assist in the designer's decisions.
Section 18.1.7 provides an aid to preliminary steelwork arrange-
ments that would form the initial modelling concepts from
which detail design is derived, probably using a 3D analysis,
detail design and drawing software. This section is positioned
near the end of the chapter in an effort to emphasise that con-
sideration of construction, detailing and cost issues addressed
below should precede use of detailed design software or the
output is unlikely to provide a successful steel design
contrasts with continental practice where precast concrete com-
petes strongly with steel up to 30 m spans and hybrid frames
of concrete columns, glulam beams and deep decking are com-
mon relative to the UK. The designer in the UK needs to follow
a standard approach of portal framed solutions and associated
secondary structures, roofing and walling details to achieve cost
effective solutions. Sometimes a portal based solution is not
appropriate particularly in mixed storage and office buildings
where the office content is above approximately 20%.
18.1.2 Multi-storey commercial
Steel's market share of the competitive steel versus concrete
commercial building frame market is close to 70% (2011) in
the UK but if spans are less than 9 m concrete will be a strong
contender. Structural economy needs balancing with architec-
tural and building services requirements. Lowest cost structural
steelwork, 'minimum weight' schemes can sometimes lead to
an overall higher cost if interface constraints are ignored.
For example, a main framing grid of 9 m × 9 m, deemed most
economic from a structural viewpoint is likely to need sec-
ondary steelwork framing to support cladding between the col-
umns spaced at 9 m centres or panelised cladding systems with
spanning capability. If perimeter columns are spaced, at 6 m
centres, secondary cladding element cost reduces by an order
of magnitude compared to any additional cost of structure. It
is important to keep in mind the contribution that structure can
make in keeping the overall building details cost effective.
18.1.1 Single storey
More than 90% of low-rise single storey buildings in the UK
are constructed in steel, most in portal framed steelwork. This
18.1.3 Residential
Cold formed lightweight steel sections are extensively used
in residential construction integrated into secondary wall and
