The main entrance
foyer
NSC 13
February 19
the local bearing stresses between the two
materials, an enlarged surface area was
required, which exceeded the plan area of
the concrete column below.
“This was achieved by casting a 2.85m
steel section into the concrete, along with
a number of shear studs which acted in
combination with a stiffened baseplate to
transfer the bearing stresses.”
For efficient service integration, plate
girders with bespoke holes have been used
throughout the structure to accommodate
the services within their depth.
However, steelwork contractor Billington
Structures says the beams have been
over-engineered with more holes than are
immediately needed, giving the building the
flexibility to accommodate future tenants
that may have more service needs than the
anticipated immediate commercial user.
The structural frame also has a composite
design, with the plate girder beams
supporting metal decking and a concrete
topping. This solution was chosen as it is the
most economical way to create floors with
long column-free spans.
Steelwork forms the superstructure from
the ground up but, before this part of the
project began, main contractor Bowmer +
Kirkland (B+K) had already completed some
substantial preliminary substructure works.
Located on the plot of a former Odeon
cinema, B+K started on site in early 2017
and commenced with a 21-week demolition
programme. It then deepened the existing
basement into a two-level subterranean
zone, excavating the ground to its new 10m
depth and surrounded the perimeter with a
reinforced concrete liner wall.
Once these lower groundworks had
been completed, which also included the
installation of foundations and casting a
ground floor slab, the steel erection was able
to begin.
Steel erection followed on behind the
slip-formed core construction, which was at
level 10, when the first beams and columns
were lifted into place.
“The building has one large core
containing seven lift shafts and two
staircases, which is a more efficient use of
space as opposed to two separate cores,” says
B+K Project Manager Mark Taylor.
As the core was constructed, Billington
Structures supplied cast-in plates in
readiness for its steel erection programme.
Once its main work was under way, the
company also installed steelwork and
flooring inside the core to form access areas
on each floor level.
The steel frame is fairly repetitive with
every floor the same, with the exception
of two set-backs located on the first and
eleventh levels. The first floor is set back
along the main Oxford Street elevation,
creating a double-height entrance foyer.
Along this elevation, the perimeter
columns have been encased with an
architectural precast concrete finish in order
to match the building’s overall cladding
system.
A series of fabricated box sections, set
back from the main columns, allows for a
covered exterior pedestrian thoroughfare
and supports the building’s two-storey high
glazed reception elevation.
A number of transfer beams were
required at level 11 to support the columns
forming the upper set-back and terrace area.
“This led to a particularly heavy primary
plate girder being used which was also
supporting the floorplate’s long span beams,”
says Mr Bebbington.
“As this member was at the far end of
the structure, detailed tower crane planning
was key to ensuring it was within the radius
of reach and the crane’s capacities. The
heavy end forces on this member created a
challenge at the steel-to-concrete interface.
Traditional studded cast-in plates were
not feasible so instead a pocket detail was
developed. This detail was developed in
close collaboration with the site team and
Billington to ensure buildability.”
The building’s main cladding system
consists of precast panels, with each panel
weighing up to 7t and measuring two storeys
high. The panels are connected to a series
of brackets, factory welded to all of the
perimeter beams.
More than 2,700 brackets are needed to
support the cladding and, because of the
deflection criteria imposed on the steelwork,
slightly larger members than would
ordinarily be required were used for the
building’s frame.
The Landmark is scheduled to complete
in Summer 2019.
Commercial
Visualisation of the
completed scheme A typical floorplate
/Steel_construction_products#Standard_open_sections
/Welding#Drawn_arc_stud_welding.2C_process_783
/Service_integration
/Composite_construction
/Composite_construction
/Steel_construction_products#Plate_girders
/Steel_construction_products#Decking_for_floors
/Construction#Steel_erection
/Design#Concrete_or_steel_cores
/Facades_and_interfaces
/Construction#Tower_cranes
/Welding