The document provides information about the Gherkin building in London. It discusses the building's history, including previous proposals for the site and how Norman Foster's design was developed. It also includes structural details about the diagrid system used in the building's design, which provides stiffness with less steel than a traditional design. Plans and sections of the building are presented at various levels, along with information on wind conditions, foundations, and other structural elements.

1. Structures Seminar
The Gherkin, London
Norman Foster
Client: Swiss Re
Project Manager: RWG Associates
Architect: Foster and Partners
Structural Engineer: Arup
Building Services Engineer: Hilson Moran Partnership
Cost consultant: Gardiner & Theobold
Presented By :
Akshay Aman
Charu Kumari
Manisha Nimesh
Sharda Bhagat
Vikram Bengani

2. Disclaimer
This is not an academic paper.
This is a case study performed as part of a High Rise Structures
Seminar as part of the B.Arch. Programme at School Of Planning
& Architecture.
The authenticity of the data/information cannot be guaranteed
with certainty. However, the information is fairly accurate and
has been collected from the internet while spatial analysis has
been performed by the authors. The various sources have been
cited in the ‘Sources’ page.
This presentation is a condensed version of the author’s
learnings and all the information available on the internet.

3. HISTORY
FROM BOMBING OF BALTIC EXCHANGE TO THE
BUILDING OF THE GHERKIN
 The beginning of the Gherkin's birth starts in 1992 as an
explosion rocked the financial district of London. The
Provisional IRA detonated an explosive device near the Baltic
Exchange and catastrophically injured the building. The
building was torn down and city officials decided to put a
larger tower in its place.
 The Gherkin began as a much larger building that was dubbed
the "Millennium Tower" but which failed to materialise. The
original design of the building raised fears that it could
negatively impact air traffic from Heathrow. There were also
concerns that it may interfere with the sight-lines of St. Paul's
Dome from certain parts of the city. Once the original design
was shot down, Norman Foster created the scaled-down
version that now sits at 30 St Mary Axe.
 Construction began in 2001 and the Gherkin was finished in
December of 2003. It didn't open for the public until almost
half of a year later.
 In response to Norman Foster's Millennium Tower and 30 St
Mary Axe Proposal, the English Heritage supported newer
buildings, but perceived threat of tall buildings. SAVE Britain's
Heritage also played a heavy opposition role over
construction of any new architecture.
 With demand for space for new offices, Swiss Re claimed
that it should be allowed to build "the Gherkin" on the
site, with economic benefit of its jobs, and a huge
investment in the UK economy back to mainland Europe.
Second IRA bombing. St. Mary Axe street
facade of Baltic exchange was completely
blown off. APRIL 1993
Foster started working on the
Millennium Tower right after English
Heritage accepted demolition of the
The Baltic Exchange.(MARCH 1996)
London Millennium Tower(400m)
planning application. August 1996
Entire project of the Millennium Tower abandoned when it was decided that
Swiss Re will buy the site from Kvaerner on condition that planning permission
to knock down Baltic exchange was granted. Late 1997
Swiss Re hinted that unless it was allowed to
build Norman Foster's distinctive circular tower
('the Gherkin') on the site of the old Baltic
Exchange, it would take itself, its jobs and its
huge investment in the UK economy back to
mainland Europe. Early 1998
First IRA bomb close to The Baltic Exchange
10th April 1992
THE GHERKIN: HISTORY IN THE CONSTRUCTION OF THE BUILDING

4. •Height to top of dome: 179.8 m
•Height to highest occupied floor level: 167.1 m
•Number of floors above ground: 40
•Number of basement levels: single basement across whole
site
•Largest floor external diameter (lvl 17): 56.15 m
•Site area: 0.57 hectares (1.4 acres)
•Net accommodations areas:
• Total = 64,470 m²
• Office 46,450 m2
• Retail 1,400 m2
•Office floor-floor: 4.15 m
•Gross superstructure floor area (incl. lightwells): 74,300 m2
•Tower Structural Steelwork
•Total weight of steel (from Arup Xsteel model): 8,358
tonnes of which:
• 29% is in the diagrid
• 24% core columns
• 47% beams
•Total number of primary steel pieces: 8 348
•Total length: 54.56 km
•Diagrid column sizes:
• Ground – level2: 508mm f, 40mm thick
• Level 36–38: 273mm f, 12.5mm thick
•Foundations 750mm diameter straight-shafted piles into
London Clay
•Number of piles: 333
•Total length of piles: 9 km
•Total design capacity: 117,000 Tonnes
•Design Capacity/Weight of Steel = 14tonne Load/tonne of
steel
•Design Capacity/Built Area =1.814tonne load/sqm
•Load on Pile = Average 351 Tonne Load/Pile
•Hoop design tension at level 2: 7 116 kN
•Perimeter column maximum design load: 15,460 kN
•Core column maximum design load: 33,266 kN
•Occupancy = 4,000 workers

5. SITE PLAN

6. Ground floor and first floor consist of reception and a series
of shops at outer edge of the building with the arcade.
Third to sixteenth floor is the office of swiss re insurance
company.
There are private dining area at 38-40 floors.
The basement is used for the parking (only two wheelers , no
four wheelers are allowed in the parking).
The design provides column-free floor space, light and views,
and incorporates many sustainable building design features.
Spiralling light wells allow the maximum amount of sunlight
to flood the interiors.
Atria between the radiating fingers of each floor link
together vertically to form a series of informal break-out
spaces. Each floor rotates 5 degrees from the one below.
INTRODUCTION

7. 6TH FLOOR PLAN

8. 21ST FLOOR PLAN

9. 33RD FLOOR PLAN

10. 39TH FLOOR PLAN

11. 40TH FLOOR PLAN

12. FRAMING PLANS
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20. Background of "diagrid" structure
The early era, tall building relied on portal frame and fix
joint to resist lateral and wind load. Latter the structure
build higher, more load and forces have to consider in the
structure. Additional bracing in the form of diagonal placed
in between the structure to take the lateral load. Portal
frames are insufficient in the lateral forces for the tall
building. Diagonal bracing make the structure resist wind
forces instead creating stronger frame connection.

21. When the building built higher, K and X bracing was added
to resist moment from beam to column. This structure was
place internally near the core to reduce the obstructive of
façade design or internal layout.
The idea of exterior diagonal bracing simply used as secondary
member to provide rigidity to the building.
The braced tube structure John Hancock Building in Chicago was
designed by Fazlur Kahn in, 1968.
Brace tube Structure
Brace Tube Structure
John Hancock Building,
Chicago
Brace Bundle Tube Building
Brace Bundle Tube is creating a perimeter bracing tube
structure to support the tall building. The plan of the
building is divided into large grid and the volume is
reducing back toward the top to reduce wind resistance
while providing larger and stronger connection at base.

22. Brace Bundle Tube Building

23. DiA-GRiD = DiAgonal + GRiD
free standing structure without internal core.
The presence of this civic
structure has influenced Norman
Foster & Arup explore diagrid
system in the future. The diagrid
structure began appear in
contemporary steel design after
initial example project – The
London GLA, Gherkin Tower
(Swiss Re) and Hearts Tower.
Water Tower by Valdamir Shukov

24. How diagrid works?

25. Original diagonal bracing member laid over exterior structure as supplementary
support. However, the current diagrid system that used in exterior structures is
primary mean of support.
Diagrid tower is model as vertical cantilever. The size of diagonal grid is defined by
the dividing tower height into series of modules.
How diagrid works?
Diagrid “tube” does not have the sufficient strength to achieve stability in the
structure. Ring beam connection to the floor edge can tied diagrid with the floor and
the core.
Normally multiple floors interesting with each long diagonal of the grid, these
intersections will occur at the nodes as well as the several instances along the
diagonal.
When the diagonal bracing extends over several stories, each floor’s edge beam can
frame into the diagonal members providing connection the core to support the floor
edge beam.

26. “diagrid is a series of triangle that combine gravity and
lateral support into one, making the building to be stiff,
efficient, and lighter than a traditional high rise”
Cantor Seinuk from WSP

27. These diagonals were affected by the width and height ratio.
The base of the building have to designed to resist moment while the top have to
resist the shear force. As a result, the foundation of a diagrid system is more
concentrate on a point to reach stability
The diagonal members in diagrid carry shear and moment. The optical angle of
the diagrid will dependent on the building height and module. The expected
optimal angle for diagonal members for diagrid structure will fall in the range of
60° to 70°.
“ a pure steel diagrid tower doesnot require a core for lateral resistance ”

28. Diagrid nodes
(1) pin node
Not rigid pin connection can be used in the symmetrical structure since the
structure have balance load.
(2) Rigid Node
the needs of rigid nodes to assist the structure to support during the construction
process.

29. Diagrid Joint
(i) diagrid structure sit external and the envelope or curtain wall will clad on floor
structure,
(ii) diagrid structure sit internal and the envelope have to clad on the diagrid.
There are two main joint for the diagrid structure: welding or
bolting. This have to rely on the what appearance require for
the design. for example when the structure to be expose,
welding cans provides better aesthetic value.
In the contrast, if the structure will be expose to external
and cannot be visible, bolt and nut will be the better choice.
Awelding connection is needed if the diagrid structures
decided to architectural exposed it but required more skillful
workers .
Somehow, if the structure are to be clad or concealed like
Hearts Tower, the diagrid can choose to bolted on site for
speed erection.
Welding joint for the Swiss Re
Tower interior

30. The gravity and vertical load from the building will distribute toward the apex of the
diagonal structure. Somehow, it will affected by the height and angle of the
diagonal.
The vertical forces will be divide/disperse into the other diagonal member.
Compression and tension result in the diagonal will transfer into the bottom
section.
Vertical Load

31. the lateral load happened toward the "flange" of the structure receiving directional
wind load. this will result the lateral load into two part; windward and leeward.
As a consequence, these diagonal members receiving two different direction of
force load. It will respond relatively. The structure able to resist both force and
achieve equilibrium.
Lateral Load

32. DEMERITS OF DIAGRIDS:
1) As of yet, the Diagrid Construction techniques are not thoroughly explored.
2) Lack of availability of skilled workers . Construction crews have little or no
experience creating a DiaGrid skyscraper.
3) The DiaGrid can dominate aesthetically, which can be an issue depending upon
design intent.
4) It is hard to design windows that create a regular language from floor to floor.
5) The DiaGrid is heavy-handed if not executed properly.
MERITS OF DIAGRIDS:
1) The Diagrid structures have mostly column free exterior and interior, hence free and
clear, unique floor plans are Possible.
2) The Glass facades and dearth of interior columns allow generous amounts of day lighting
into the structure.
3) The use of Diagrids results in roughly 1/5th reduction in steel as compared to Braced
frame structures.
4) The construction techniques involved are simple, yet they need to be perfect.
5) The Diagrids makes maximum exploitation of the structural Material.
6) The diagrid Structures are aesthetically dominant and expressive.

33. Diagrid (diagonal + grid) is a design for constructing large buildings with steel that
creates triangular structures with diagonal support beams. It requires less structural
steel than a conventional steel frame.Hearst Tower in New York City, designed by
Sir Norman Foster, reportedly uses 21 percent less steel than a standard design.
The Diagrid also obviates the need for large corner columns and provides a better
distribution of load in the case of a compromised building.

36. The perimeter ‘diagrid’ structure The perimeter steel structural solution was developed
specifically for this building in order to address the issues generated by the unusual geometry in
a manner that was fully integrated with the architectural concept and generated the maximum
benefit for the client.
The final solution was one of a number of approaches that were assessed in detail for overall
structural efficiency, internal plannning benefits, buildability, cost and risk. The design avoids
large cantilevers and keeps the light-wells free of floor structure by inclining the perimeter
columns to follow the helical path of the six-fingered floors up through the building.
A balanced diagrid structure is formed by generating a pattern of intersecting columns spiralling
in both directions. The addition of horizontal hoops, which connect the columns at their
intersection points and resist the forces arising from the curved shape, means that the
perimeter structure is largely independent of the floors.
The hoops also turn the diagrid into a very stiff triangulated shell, which provides excellent
stability for the tower. This benefit of the diagrid means that the core does not need to resist
wind forces and can be designed as an openplanned steel structure providing adaptable internal
space.
Foundation loads are also reduced compared with a building stabilised by the core.

41. STRUCTURAL ELEVATION
41

43. DIAGRID SYSTEM
INTERLOCKING DETAILS
A-frame • Aluminum coated tube steel • series
of two-stories-high, end to end arrangement. •
one full diamond is four-stories tall.
There is a special connector that transfers
loads, both vertically and horizontally at the
“nodes” which are rigid monolithic and welded
together.
The diagonals are CHS members, with cross
section between 508 x 40 mm at the lowest
floors and 273 x 12.5 mm at the top, while the
chord members have RHS, 250 x 300 mm with
wall thickness of 25mm. The circular central
core, which has constant diameter along
elevation, does not contribute to the lateral
resistance and rigidity, being a simple frame
structure.
The elements of the facade.:
Openable glass screen.
Perforated aluminium louvers (internal
sun-screen).
A column casing of aluminium.
Façade frame of extruded aluminium.
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44. DIAGRID SYSTEM
INTERLOCKING DETAILS
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54. Fine
soils
M
SILT
coarse
0.02 - 0.06
mm
medium
0.006 - 0.02
mm
fine
0.002 -
0.006 mm
CLAY < 0.002 mm

55. Month of year
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
01 02 03 04 05 06 07 08 09 10 11 12 1-12
Dominant Wind dir.
Wind probability
>= 4 Beaufort (%) 34 31 35 31 37 28 32 35 27 30 28 33 31
Average
Wind speed
(kts) 10 9 10 9 10 9 9 9 9 9 9 9 9
Average air temp. (°C) 7 7 9 13 15 19 21 20 18 14 9 7 13

56. FORM OF THE BUILDING: THE GHERKIN
 The design for 30 St Mary Axe was actually developed from ideas
that were used in the Climatroffice design by Buckminster Fuller in
the 1970s. This building was never constructed, but it was supposed
to be a free-form glass skin which allowed the building to have its
own microclimate.
 It would have been very difficult in the 1970s to design and build
such a complex structure. However, thirty years later, Foster was
able to use advanced parametric modeling to design 30 St Mary Axe
whose final design is very reminiscent of the Climatroffice design
 The shape of the tower is influenced by the physical environment
of the city. The smooth flow of wind around the building was one
of the main considerations.
 The variation of the diameter of the plants is significant, it
measures 49 meters at the base, 56.5 at its widest, narrowing to
26.5 on the top floor, which is what gives it the appearance of
"Rocket" or "cucumber" as the Londoners have been baptized.
 The fact that the tower bulges out in the middle, reaching its
maximal diameter at the 16th floor, also helps to minimise winds
at its slimmer base.
 Environmentally, its profile reduces wind deflections compared
with a rectilinear tower of similar size, helping to maintain a
comfortable environment at ground level, and creates external
pressure differentials that are exploited to drive a unique system
of natural ventilation
COMPUTER SIMULATION OF
WIND FLOW FLOWS AROUND THE
BUILDING
SKETCHES SHOWING THE WIND
MOVEMENT AROUND THE BUILDING.
THE GHERKIN: FORM OF THE BUILDING

57. BUILDING USE AND FUNCTIONALITY
 At a time 4000 workers can be accommodated.
 Net accommodations areas:
Office 46,450 m2
 Retail 1,400 m
 Total weight of steel : 8,358 tonnes of which:
29% is in the diagrid
24% core columns
47% beams
The designers and owners of the building also wanted to discourage
motor vehicle use by the building’s tenants. The basement of the
building provides three times the bicycle space, 118 spaces, than the
minimum required [1][13]. The building does not have car parking for
visitors or employees, just 5 handicap spaces and 52 motorcycle spaces
 The total weight of steel used is approximately 11,000 tones.
DIVERSE OCCUPANTS
 In the past couple of years, the Gherkin has changed from a
bespoke owner-occupied London headquarters for insurance
company Swiss Re, to a prime multi-let office building, with all
but one floor occupied.
 On the downside, the building is not very spatially efficient.
The central lift, services core and six spiralling light wells
around the perimeter mean that only 63% of its gross floor
area is useful space.
CELLULAR OFFICES FOR LAWYERS
 The building is extremely popular with law firms, because the
rectangular spaces can take cellular offices Originally, the
circular floor plates were conceived of as open-plan spaces,
but this was not practical for lawyers, who need to have
confidential one-to-one discussions with clients. In addition,
the open lightwells allow sound to travel between six floors at
a time, which could compromise confidentiality.
SHARED FLOORS
 The 19th floor is shared by four companies, the smallest of
which is the five-strong Primus Guaranty, which has a tiny
dealing floor and three cellular offices in one rectangular
finger.
 Sharing this floor called for an internal corridor to be wrapped
around the central core of the building to reach the lift lobby.
RESTAURANTS AND RECEPTION DOME
 Tenants make regular and enthusiastic use of the restaurants
and glass dome at the peak of the building to entertain clients.
 The 65-cover restaurant and five private dining rooms are
reserved for tenants and members of the exclusive London
Capital Club. The reception room in the dome can be hired by
outsiders.

58.  There are 18 passenger lifts in the building.
 378 people can be vertically transported
through the building at speeds up to 6m
per second at any time.
 In addition, there are goods and firefighter
elevators, as well as a car park elevator to
the reception from the basement.
 Two special shuttle elevators serve the top
floors of the building.
KONE Alta™ fulfilled the architects’
requirements for customized elevator cars and
signalization.
 3 different levels:
 Low rise go from lobby to level 12.
 Medium rise lifts go from lobby to
22 stopping from level 11.
 High rise lifts go from lobby to 34
stopping from level 22.
 Shuttle lift goes from level 34 to
level 39.
ELEVATORS
IN THE CORE
ELEVATORS
ELEVATORS IN BUILDING

59. FIRE FIGHTING METHODS:
• Swiss Re falls within the guidance of inner London Section 20 requirements for fire
safety.
• Every sixth floor , the atria feature gardens which control and purify air movements as
well as dividing the building into fire compartments.
• The unusual light well arrangement leads to a fire escape strategy based on a variation
of phased evacuation.
• In this case all six floors linked by a set of light wells are evacuated in the case of a fire on
any one of them.
• Where only two floors are linked then those two constitute the first phase. So the light
wells are designed following the guidance for simultaneous evacuation, which allows
them to be open to the accommodation.
• Because the light well base floors are protected by sprinklers on the overhanging soffits
above, they can be used as office space too.
• A system of smoke curtains form smoke reservoirs in the light wells, and others delay the
transport of smoke from accommodation into the light wells.
• Natural ventilation is used for smoke clearance for the light wells and the accommodation.
• The building is sprinkle red, including arrays of window sprinklers on part of the façade of levels 2 and 3, to protect a glazed opening in the
compartment floor of level 4, directly above.
• However sprinklers have not been fitted in the 12m high domed space that forms the very top of the building.
• The Tower has two firefighting shafts with dedicated lifts.
• The use of dedicated smoke detectors in each lobby which cause the vent to open in that lobby, as well as at the top of the smoke shaft and the
top of the stair.
• During a fire temperatures can be such that the window glazing may break and thus allow cool air to enter and hot gas to escape.
• Alternatively, temperatures may be such that the fire has not engulfed a large area and is not severe enough to actually break the glass.
• In both cases the temperature reached in the compartment and the duration of a fire is dependent on the amount of ventilation, and it is
assumed that sprinkler activation has not prevented the fire from growing.
FIRE FIGHTING IN THE BUILDING
The spiral lightwell
arrangement allows for a fire
escape strategy based on a
variation of phased evacuation.
The building is divided into fire
safety zones at every sixth and
second floor . this allows for
the evacuation of one area at a
time as opposed to a whole
building at once.

60. Installation of over smoke curtain barriers. Concealed
within the ceiling voids of each of the 39 floors, the Smoke
Stop™ smoke curtain barriers were developed to deploy in
the event of fire, channelling smoke away from occupant
and out of the building. This effective strategy for
containing and channelling smoke would ensure that
Gherkin’s 41 floors were protected from filling with smoke
and provide occupants with a safe means of escape. THE
SYSTEM OF SMOKE CURTAIN FORMS THE SMOKE
RESERVOIR IN THE LIGHTWELL. NATURAL VENTILATION IS
USED FOR THE SMOKE CLEARANCE FROM THE
LIGHTWELL.
The smoke containment curtain is automatically lowered by a control
signal to a desired height, or the entire opening is closed, thus closing can
be programmed for two phases.
Suitable for the fire-proof fire closing of horizontal and vertical surfaces.
Appearance: The frame structure and the top box is normally galvanized,
powder coated in any desired RAL colour. Can be mounted also above
suspended ceilings.
Applications: factories, warehouses, shopping centres, buildings with lobby
and atria
VERTICAL SMOKE CURTAIN BARRIERS IN THE GHERKIN
WORKING OF THE SMOKE CURTAIN BARRIER

61. DESIGN AND CONSTRUCTION
 The Gherkin is essentially an elongated, curved, shaft with a
rounded end that is reminiscent of a stretched egg. It is
covered uniformly around the outside with glass panels and is
rounded off at the corners. It has a lens-like dome at the top
that serves as a type of observation deck.
 The design of the Gherkin is heavily steeped in energy
efficiency and there are a number of building features that
enhance its efficiency.
 There were open shafts built in between each floor that act
as ventilation for the building and they require no energy for
use.
 The shafts pull warm air out of the building during the
summer and use passive heat from the sun to bring heat into
the building during the winter. These open shafts also allow
available sunlight to penetrate deep into the building to cut
down on light costs. It has been said that 30 St. Mary Axe
uses only half of the energy that a similarly-sized tower
would use.
Architectural style
21st century contemporary iconic design
sustainable design features:
• maximising natural daylight and ventilation;
• minimising heating and cooling through a ventilated double-skin façade.
 Windows open when the external temperature
is between 20 degrees Celsius to 26 degrees
Celsius and wind speed is less the 10 mph.
VENTILATION: AIR MOVEMENT THROUGH THE LIGHTWELL

62.  On each floor, a series of interstices with 6 pipes made of natural
ventilation system, functioning as a double glazing.
 Pipes used for cooling in the summer, drawing warm air from the
building, and for heating in winter. They also allow for easier entry
of light, with a consequent reduction in the cost of lighting.
 The systematic internal microclimate and solutions for energy
savings have led to a 50% reduction in energy consumption in any
case necessary for a building of this size.
 The façade consists of two layers of glass (the outer one double-glazed)
enclosing a ventilated cavity with computer-controlled blinds. A system of
weather sensors on the outside of the building monitors the temperature,
wind speed and level of sunlight, closing blinds and opening window panels
as necessary.
 The building's shape maximises the use of natural daylight, reducing the
need for artificial lighting and providing impressive long-distance views even
from deep inside the building
SUSTAINABLITY : THE GHERKIN
 The tower is aerodynamically designed to reduce wind load on the structure,
whilst the lower part tapers so that wind wraps around the tower.
 The six fingers of accommodation on each floor, configured with light wells
in between, maximize daylight penetration.
 The façade design with advance glazing technologies, ventilated cavities and
blinds , provides up to 85% solar protection.
 Gas is the main fuel used hence it will only generate half the carbon
emission.
 Overall energy serving is up to 50%.

63.  The ventilation system reduces conventional air conditioning use
due to the aerodynamic shape of the building, which creates air
pressure differentials in the double skin and moves air up the
building and across offices, as seen in the computer generated
ventilation models to the left.
 Additionally, lights are on level and motion sensors, reducing
unnecessary lighting. All of this helps to reduce the building’s
heating and cooling loads and its total energy needs. Within the
double skin façade are blinds that can intercept solar radiation,
at a 15% solar transmission rate, and the building can then
reclaim heat from the solar radiation or reject it depending on
the cooling or heating needs of the building
 The glass panels in the atriums are also tinted to reduce glare
and solar gain

64. THE SERVICE
CORE THE ELEVATORS- 18
PASSENGER LIFTS
THE OFFICE
AREA
Core area at centre
This building has a core 9 meters wide and 36 meters long split into
five separate sections to provide additional strength
THE CORE
The core takes a portion of the
vertical gravity loads and is a
secondary structure to the diagrid.
The core acts as a tie back to the
hoop structure preventing splay. The
structure system of the core is rigid
using moment frames.
 Provides rigidity
Resists torsion
 Increases stiffness

65. • 35 km of steel, 10 thousand tons were used to build the Swiss Re
• 24,000 square meters of glass were used for the exterior of the
building, equivalent to five football fields.
• The building was designed to use recycled or recyclable materials
whenever possible
MATERIALS
• The glazing to the office areas consist of a double –glazed outer and a
single –glazed inner screen.
• Sandwiched in between is the ventilated cavity which reduces heating and
cooling requirements.
• The solar-control blinds intercept solar gain before it enters the office
environment.
• The façade is clad with double-paned glass that is
filled with argon.

66. The elements of the facade.
• Openable glass screen.
• Perforated aluminium louvers (internal sun-screen).
• A column casing of aluminium.
• Façade frame of extruded aluminium.
Distance between each floor:4200mm
Each closed steel frame height: 16800mm
Each glass height: 4200mm
Other than one curved , other glass are all flat.
Gherkin London.
Windows open on the
outer skin to allow air
to enter the cavity
between the inner and
outer skin.
SITE TEMPERATURE
Temperature range:
• 22 degrees in December
• 94 degrees in June
The change in temperature effects the
expansion of the steel members.

67. TOWER STRUCTURAL STEEL WORK
Total weight of steel: 8,358 ton of which:
• 29% is in the diagrid
• 24% core columns
• 47% beams
Steel in foundation:
• 750mm diameter straight-shafted piles into London clay
• Number of piles: 333
• Total length of piles: 9km
• Total design capacity: 117,000 tonnes
Because of site restrictions and in order to create a monolithic foundation, all piles and pile
caps were poured in one day.
The heart consists of a solid block of steel of 240 by 140
mm.

68. • Despite its curved shape, there is actually only
one piece of curved glass – the lens at the top of
the building which is 2.4m in diameter and weighs
250kg.
• The glass dome at the top of the building provides
360 degree views of London
Façade material:
7,429 glass panes for external skin(recycled
glass) made from intersecting tubular steel
sections which give vertical support to the
floors, rendering them column free. The grid is
highly resistant to wind loading and weighs
2,500

69. EXTERNAL CLADDING SYSTEM
OVERVIEW OF THE FAÇADE:
The building’s exterior cladding systems consists of full glazed, double-
skinned façade comprising approximately of 5,500 flat triangular and
diamond shaped glass panels. These metal and glass prefabricated panels
are fixed to the diagrid.

70. • The smooth flow of wind around the building was
one of the main considerations.
• Minimum impact on the local wind environment.
• The tower is aerodynamically designed to reduce
wind load on the structure, whilst the lower part
tapers so that wind wraps around the tower.
AIR LATERAL LOADING
• These loads are all absorbed through the glass
façade and eventually transferred to the diagrid.
• The pressurized air from the wind passes into the
building through a natural ventilation system, which
is incorporated through a double skin.
An aerodynamic
form, reducing
effects of wind
WIND

71. SHAPE
Wind load
The overall cylindrical shape allows for the wind
to move around the building.
How does this shape effect the horizontal wind
loads?
• Decreased buffeting
• Reduced vibrations
• Diminished fluttering
CONNECTIONS
Diagrid
• There is a special connector that transfers
loads, both vertically and horizontally at
the “nodes” which are rigid monolithic
and welded together.
• Rigid node connections at intersecting
members.
Core
• Rigid connections of steel beams and
columns.

72. Ventilation for the entire building is heavily
dependent on the six shafts that span the
entire building. The natural ventilation and air
circulation that occurs within these shafts
supplements the air conditioning in the building
for about 40% of the year
NATURAL VENTILATION AND LIGHTING SYSTEM
Differing air pressures and double skin façade allow for natural ventilation
•Six spiralling light wells allow daylight to flood down onto the floors
•Windows and blinds are computer controlled
•Solar blinds to reclaim or reject heat
•Windows open when external temperature is between 20°C and 26°C and
wind speed is less than 10 mph
The shafts are essentially light wells in that light travels through these
wells and naturally light the six radial fingers of the building.

75. Sources
http://www.archinomy.com/case-
studies/669/30-st-mary-axe-the-gherkin-
london
https://prezi.com/sxt_dfdzmijt/case-study-
for-the-gherkin/
http://www.webpages.uidaho.edu/arch504u
kgreenarch/casestudies/swissre1.pdf
http://www.coopersfire.com/system/files/pri
vate/CaseStudy_The_Gherkin.pdf
http://skyscrapercenter.com/building/30-st-
mary-axe/2369
http://faculty.arch.tamu.edu/media/cms_pa
ge_media/4433/30StMaryAxe_1.pdf

76. http://www.greendesignetc.net/Buildings_09/Building_Shen_Yuming_paper.pdf
http://www.engagingplaces.org.uk/teaching%20resources/art63639
http://www.engagingplaces.org.uk/teaching%20resources/art63639
http://www.archinomy.com/case-studies/669/30-st-mary-axe-the-gherkin-london
http://www.sustainablebuild.co.uk/sustainable-building-around-world.html
http://brandondonnelly.com/post/67910871416/who-knew-gherkins-were-so-aerodynamic
http://www.fosterandpartners.com/projects/30-st-mary-axe/gallery/
http://www.building.co.uk/30-st-mary-axe-a-gherkin-to-suit-all-tastes/3111783.article
http://www.skyscrapernews.com/swiss.htm
http://www.slideshare.net/adadarmon/swiss-re-building-london
http://faculty.arch.tamu.edu/media/cms_page_media/4433/30StMaryAxe_1.pdf