and consequently offered the stability that was
needed for the new upper steel-framed levels.
Interestingly, the areas beneath the new
cores were some of the few parts of the
scheme, which did require the installation of
new piled foundations.
Throughout the structure, the concrete
columns were strengthened with concrete
jackets, installed on every floor. The only
exception were some areas where the
internal architectural vision required a
slimmer solution and in these places steel
strengthening collars were installed.
From level 16, new steel columns were
installed on top of the existing concrete
members. However, the existing grid pattern
is based around a column spacing of 6.1m
× 7.6m. This was deemed to be slightly
restrictive for the new floorplates and so some
column positions have been omitted, with the
upper floors having just one row of internal
columns and spans of up to 12m.
All of the steelwork erected by Bourne
is standard S355 grade, and the beams are
all custom-made plate girders, with depths
ranging from 525mm to 665mm. Modular
pieces for the perimeter, weighing up to 7t,
were also introduced to reduce the number of
pieces to be lifted.
Commenting on the steelwork programme,
Bourne Steel Project Manager Theodoros
Pitrakkos says: “The floorplates are generally
repetitive up to level 25, but level 26 has a
step-back creating a terrace.”
“Considerable planning was required
to devise a construction programme that
allowed the works to be continuous. To
achieve this, the floorplate was split into three
main areas and the steelwork was built three
floors at a time. Primary activities involved
welding fittings to cast-in plates in the core
walls for beam connections, steelwork
erection, metal decking installation and onsite
painting. These activities continuously
rotated throughout the floorplate to meet
programme.”
With the steel frame starting at Level
16, Bourne’s main challenge was dealing
with high winds during construction, while
maintaining the programme and the tight
erection tolerances. Because the site is a
confined high-rise plot, there was limited
storage space and so the steel was generally
erected directly from the delivery trailer by
tower crane in conjunction with MEWPS.
Summing up, Bourne Steel’s engineering
team say: “Due to the nature of the project
and the high standards that were required
from MACE, AKT II and importantly the
architects HCLA. It was even more imperative
to have a close relationship during the
design and build process, to ensure it met all
expectations.
“As all steelwork in its final state
was visually exposed, as a team we
“We chose steel to transform the
Hylo structure because it is a
lighter material than concrete. ”
reviewed all end connections and column
splices throughout to insure they were
architecturally-pleasing, but at the same time
ensuring they met the design requirements.”
Hylo is due to complete in spring 2021.
According to CIT, the tenants will enjoy the
latest building amenities and specification
with unparalleled views across London,
while the landscaped roof terraces, breakout
spaces and dining areas will create a relaxed
environment away from traditional desks.
In addition, they will benefit from generous
locker and shower facilities, as well as cycle
storage for over 400 bikes. An expansive
ground floor reception incorporating a
modern lounge and cafe will make Hylo a
social hot spot all day.
Commercial
NSC 25
Jun 20
Hylo will be a tall
landmark structure
overlooking the northern
perimeter of the City of
London
Cellular
beams have
been used for
the new upper
floors
Site constraints meant
steelwork had to be
erected immediately
from the delivery
vehicles
/Concept_design#Structural_options_for_stability
/Concept_design#Concrete_or_steel_cores
/Concept_design#Floor_grids
/Steel_construction_products#Plate_girders
/Welding
/Construction#Steel_erection
/Paint_coatings#Application_of_paint_coatings
/Construction#Tolerances
/Construction#Tower_cranes
/Design
/Visually_expressed_structural_forms
/Simple_connections#Column_splices
/Simple_connections#Column_splices