Mixed-use
NSC 19
April 19
been formed with in-situ concrete, but from
there upwards the scheme, in its entirety, is
using a steel-framed solution.
The third level of car parking is formed
with steel columns, which are founded
directly on to concrete columns, and steel
beams supporting metal decking and a
concrete topping. The majority of the
project’s floors from this level upwards are
formed compositely.
Overall, the scheme is one large steel
frame sub-divided up by movement joints,
most of which are located either side of the
20 bridges that span the main semi-circular
retail mall. Numerous concrete cores provide
the steel elements with their stability.
“A steel solution is an efficient design
solution, as it requires a smaller and more
manageable workforce than other methods,”
says Laing O’Rourke Project Director Tim
Kelly.
The car parking floors are all based around
an 8.5m × 7.5m column grid pattern, but
above this the spacing changes to a retail grid
of 8m × 8m.
“Different grids have been used as each
one is the optimum size for either car
parking or multiple retail units that will
be located over five levels,” explains Arup
Associate David Ferguson.
The retail grid is mostly the same
throughout the scheme, but reduces in size
slightly to suit the semi-circular shape of the
mall and the irregular boundaries of the site.
The change of column spacings between
the parking and retail levels has necessitated
a raft of transfer structures to be installed at
level one. These are generally 970mm-deep ×
800mm-wide plate girders.
However, as BHC Project Manager Bobby
McCormick explains, a more convenient
option was also employed, wherever possible.
“We tried to swap as many plate girders
as we could to off-the-shelf ArcelorMittal
Histar sections, as they are cost-effective and
require no fabrication.
“We managed to swap circa 1,000t, but
there are still over 2,000t of plate girders used
around the project.”
The plate girders are not the largest steel
members on the site, these are a series of
1,450mm-deep × 1,020mm-wide × 25m-long
beams, each weighing 38t that form the main
service yard.
Above the five levels of retail, the column
pattern changes again to accommodate three
floors of residential apartments. To allow the
column spacing to decrease to a 5.5m × 3.3m
grid pattern, transfer beams up to 840mmdeep
are positioned on top of level five.
Further separate grid patterns are required
for the project’s two hotels. The Roomzzz
aparthotel is positioned above one of the
retail zones and will be constructed around
a regular 6m × 6m rectangular spacing, 20
The main retail mall,
which sits above a car
park, takes shape
The completed scheme
is centred around the
egg-shaped W Hotel
Temporary works
support the John Lewis
floorplates until new
steel columns are
installed
/Braced_frames
/Steel_construction_products#Decking_for_floors
/Composite_construction
/Design_of_steel_footbridges
/Concept_design#Concrete_or_steel_cores
/Design
/Car_parks
/Concept_design#Floor_grids
/Retail_buildings
/Steel_construction_products#Plate_girders
/Fabrication
/Residential_and_mixed-use_buildings
/Residential_and_mixed-use_buildings#Hotels