flexible retail areas,” explains BuroHappold
Engineering Technical Director Jonathan
“It also meant we averted adding more
load to the slab, as strengthening works on
this structure would have been difficult due
to the loading bay and arena back-of-house
facilities that sit beneath the structure being
in constant use.”
Some modifications were however
needed to the trusses, as they were never
intended to support an underslung steel
frame. ISG and BuroHappold were able to
Although not specifically intended when
versatility of steel structures in the hands of
structural steel experts.
By retaining the slab and the existing steel
trusses, waste is minimised and resources
preserved; both key aspects of the evolving
circular economy agenda. Not to mention the
avoided costs and inconvenience were the
existing slab to be broken out and the trusses
recycled and replaced with a new, bespoke
More thought should be given, particularly
for structures like The O₂ which are likely to be
frequently reconfigured, about how they can
be designed to be adaptable and extendable
so that projects like this become the norm.
This ‘design for deconstruction’ concept should
be extended to all buildings going forward.
Principles for doing this are given here:
The adaptation of the steel trusses at The
O₂ also demonstrates the importance of
material and design data and information in
facilitating the reuse of steel structures. In
this case, BuroHappold was able to obtain the
2006 design information from Severfield and
based on this, assess the existing structure and
propose strengthening measures for the trusses.
For older structures, this is frequently not the
case and often expensive, intrusive surveys and
first designed, the ability to reuse the
trusses for retail units demonstrates the
get hold of the original design details from
Watson Steel (now Severfield).
Using this information, it was decided
that, in order to make the trusses able to
support the extra loads from the new steel
frame as well as some associated plant decks,
a series of 35mm-thick stiffening plates
would be welded to the trusses, while all of
the node connections, approximately 36 on
each truss, had to be strengthened.
Not wanting to overload the slab also had
an effect on what kind of plant equipment
steelwork contractor Bourne Steel could
use during its erection programme and the
MEWPs were deemed to be too heavy
and so a number of spider access units,
which spread their load via stabilisers, were
As the slab was originally built with just
a casino in mind, for today’s retail project it
has been built a little too high. Consequently,
in the area where the slab meets the twostorey
steel frame, the upper level gradually
slopes down by 1m.
“Maximising the floor-to-ceiling heights
testing are required before refurbishment or
adaptation can happen.
SCI is exploring how BIM can be used to
collate and securely store structural steel
information to facilitate projects like Project
Mint in the future. Material traceability,
data security and future-proofing are key
considerations but mill test certificates, blockchain
and open IFC formats are readily available
The UK steel construction sector has been
using what is now called ‘BIM’ for over 30 years,
and capturing the necessary material and
design information to facilitate future reuse of
steel structures is a simple thing for the sector
to do. While there remain significant barriers
to the mainstream reuse of structural steel,
certainly within existing business models,
putting in place a means to facilitate future
reuse of steel makes good sense for the sector
and wider society.
SCI’s R&D into steel reuse includes the EU
projects REDUCE and PROGRESS. The focus of
REDUCE is demountable composite flooring
solutions and the focus of PROGRESS is the
reuse of single storey industrial buildings. Both
projects are exploring the use of BIM to facilitate
the deconstruction and reuse of steel structures.
In-situ steel reuse
Michael Sansom of the SCI discusses the reuse of steel and ‘design for deconstruction’.
on the two-storey zone was important as we
have made provision for mezzanine floors
to be installed, at a later date, on the ground
and first floors,” explains Mr Roynon.
The two steel-framed retail elements are
both stand-alone structures deriving no
stability from the original steelwork malls,
roof or arena, but instead relying on new
concrete lift and stair cores.
Both are nominally based around 7.5m
column spacings, although the grid patterns
are dictated by the radial curve of The O₂.
The retail outlets have required over
1,800t of steel, all of which has been fabricated,
supplied and erected by Bourne Steel.
“It has been a challenging project
working on many work fronts at the same
time across a large area spanning some
400m. We have had an excellent team both
on and off site and have completed the main
works ahead of our contractual programme,”
sums up Bourne Steel Divisional Manager
ISG will begin handing over retail units
from May and the entire project is expected
to be complete by Autumn 2018.
The dome’s supporting
through the steelwork