Case studies on 1.St Mary Axe (The Gherkin) & 2. Shanghai World Financial Center based on their architectural & construction details.

1. HIGH RISE STRUCTURES
CASE STUDY
1. THE GHERKIN
2. SHANGHAI FINANCIAL CENTRE

2. DONE BY,
R SHABARINATH,
B.ARCH-
NIT NAGPUR

3. 30. ST MARY AXE
(THE GHERKIN)
3
LOCATION: LONDON
HEIGHT : 179.8M
NO.OF FLOORS: 40
FLOOR AREA 47,950 sq m (516,100 sq ft)
ARCHITECT: Norman Foster, Ove Arup & partners,
Ken Shuttleworth
YEAR: 2001-2004
BUILDING TYPE: Commercial and retail tower
The Gherkin has a stretched egg shape with the
Diameter of the largest floor being 56.1M

4. LOCATION
LONDON
4

8. ● The variation of the diameter of the floors is significant,
measuring 49m at the base, 56.5m in the widest part,
narrowing to 26.5m on the top floor, which is what gives the
appearance of “rocket” or “cucumber”.
● The oval shape achieves an average surface of 1,400 square
meters per floor, which rises to 1,800 at level 16 and drops
to 600 at 34.
● The form offers advantages in the interior as the possibility
of orthogonal arrangement in the area of desks and, in the
center, a rectangular area of bathrooms and stairs. Most of
the rooms have an exterior view and only 3% of the Swiss
Re’s spaces are closed.
THE FORM

9. ● 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, and the form was
inspired by a sea-sponge and thus
biomimicry
● Minimum impact on the local wind
environment.
● ‘user-friendly’ column free office
spaces with maximum primary
space adjacent to natural light.
● Good physical and visual
interconnectivity between floors.

10. Classification/ Category of the concerned High-rise
Has an exterior structural support from a Steel Diagrid system
There are two main structures
1. Diagrid
a. Diagrid is the main structure which is resisting horizontal and gravity
loads
2. Core
a. Resisting the vertical & gravity loads
Diagrid
core

12. SCHEMATIC REPRESENTATION
OF THE PERIMETER DIAGRID
STRUCTURE
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

15. Sequence of construction
1. Core steel completely erected with access stairs and a
small amount of temporary bracing
2. Deck core was placed
3. Diagrid columns and nodes were erected
4. Erecting radial members, installing hoop to complete the
diagrid
5. Complete floor framing and decking
6. Concrete floor

16. LOAD DISTRIBUTION & STRUCTURAL DESIGN
● STRUCTURAL DIAGRID
○ The diagrid provides vertical support to the
floors while allowing for a column free
interior space.
○ Implementation of the diagrid system allows
the radial form.
○ Combination of steel members and rigid
node connectors
○ Diagrid column sizes vary throughout -
larger towards the base
○ There are 19 hoop structures that prevent
the diagrid from splaying out

18. WIND LOAD
SHAPE
The overall cylindrical shape allows for the
wind to move around the building
How does this shape affect the horizontal
wind loads?
● Decreased Buffeting
● Reduced Vibrations
● Diminished Fluttering

19. WIND EFFECT

20. LATERAL LOAD
These loads are all absorbed through the
glass facade and eventually transferred to
the diagrid.
LATERAL LOAD GLASS FACADE
DIAGRID

21. ● The pressurized air from the wind
passes into the building through a
natural ventilation system, which is
incorporated through a double skin.
● The double-skin facade zones
encased by clear glazing presume
that air between curtain wall
layers will absorb solar heat

23. LOAD TRACING

24. The perimeter diagrid is formed from intersecting steel tubes that frame the light wells
● designed 360° steel nodes to connect the complex diagrid together. The nodes consist of three steel
plates, welded together at different angles. The connections helped to make the diagrid
straightforward and cost-effective to build.

25. Diagrid Structure
● Aluminum coated tube steel
● Series of two stories high , end to end
arrangement
● one full diamond is four-stories tall.

26. The special connector
That transfer both vertically and horizontally at the nodes
which are rigid monolithic and welded together
DIAGRID INTERLOCKING DETAILS

27. Connections
A special connector that transfers loads,
both vertically and horizontally at the
“nodes” which are rigid monolithic and
welded together.
● Core
○ Rigid connections of steel beams and
columns
● Diagrid
○ Rigid node connections at intersecting
members

28. ● There are 360 total nodes
● The nodes transfer loads both horizontally and vertically
● The node itself is composed of three welded steel plates
● The plates are oriented at oblique angles in order to
facilitate the complex geometry of the structure
● HSS - round sections bolted to the plates in order to
facilitate the diagrid structure

29. CORE DESIGN CONSIDERATIONS
● The core is the primary system for
transferring vertical gravity loads to the
foundation system.
● It is a rigid frame made up of moment
connectected steel members.
● The core acts as a tie back to the hoop
structure preventing splay.

30. ● The structure system of the core is rigid
using moment frames.
• Provides rigidity
• Resists torsion
• Increases stiffness
● The core’s central, symmetrical
placement within the building does
not allow torsion as an effect from
lateral loading.
● High structural stiffness is
advantageous when dealing with
loose soil types

31. The Gherkin has a core 9 meters wide
and 36 meters long split into five
separate sections to provide additional
strength

32. ELEVATORS
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.
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.

33. Floor plate had a 5 degree rotation in each
level to allow for more light ventilation
with wedge shaped light wells.

34. BUILDING MATERIALS
● 10,000 tons of steel have been used, of which 29% corresponds to the
diagonal structural steel
○ 29% is in the diagrid
○ 24% core columns
○ 47% beams
● In the foundations, 750mm diameter beams were used that were
embedded straight in the clay of London, in total 333 piles.
● It took 24,000m2 of glass, 5,500 glass panels in the form of a diamond.

35. ELEMENTS OF FACADE
● Openable glass screen
● Perforated aluminium
louvers (internal
sunscreen)
● A column casing
aluminium
● Facade frame of extruded
aluminum

36. FOUNDATION
Built on London Clay
● Soil has low bearing capacity
○ More piles required
○ Piles must be driven deeper
● Poor horizontal shear strength
● Organic material in the soil
● Susceptible to settling

37. CONCRETE PILES
● 333 PILES ARE USED
● 2.5 FEET DIAMETER ( 750MM)
● Average length of piles: 27 m
● Total length of piles: 9 km
● Total design capacity: 117,000 Tonnes
● Because of site restrictions caused by London
clayey soil & to create monolithic foundation, all
piles and pile caps were poured in one day

38. TECHNIQUES
● The external grid of the facade is
formed by panels of triple thickness:
double glass towards the outside and a
laminated glass towards the interior, to
optimize the entrance of light without
removing views
● On each floor, a series of interstices
with 6 pipes acts as a natural
ventilation system, functioning as a
double glazing.
● The pipes are used for cooling in the
summer, extracting the hot air from the
building, and for heating in the winter.
● In addition, these allow for an easier
entry of light, with a consequent
reduction in lighting costs.

39. TECHNIQUES
● It has an incredibly aerodynamic shape, in spite of its monolithism; the design well-deservedly
● Gaps in each floor create six shafts that serve as a natural ventilation system for the entire building,
even though required firebreaks on every sixth floor interrupt the "chimney".
● The shafts create a giant double glazing effect; air is sandwiched between two layers of glazing and
insulates the office space inside

40. Shanghai World
Financial Center
40
LOCATION: SHANGHAI, CHINA
TOTAL HEIGHT : 492M
NO.OF FLOORS: 101
The building is a Commercial, retail and hotel tower
with a Total Area of 380,000 SqM
It was completed in the Year 2008.
The Building has a central service core with
column free office spaces around it.
It also has a total of 91 elevators.

41. LOCATION
Shanghai, China
41

43. The Shanghai World Financial Centre was
conceived at the time of planning to be the
world’s tallest structure.
Its design was essentially made up by cutting
2 cosmic arches out from a square prism and
with a trapezoidal cut out at the top.
This design also allowed greater
aerodynamics and resultant reduction in
wind loads.
FORM

44. No 2 floors have a
repeated layout in the
Financial Centre
building.
The common feature
being the central service
core that runs along the
entire building along
with the 4 mega
columns at the corners.
FLOOR PLANS

45. ELEVATION
PLAN

46. The World Financial Centre falls under
category of Outrigger structure.
5 Major components of the Structure are :
● Core Walls
● Mega Columns
● Belt truss
● Outrigger truss
● Mega Diagonals
CATEGORY OF THE STRUCTURE & LOAD
DISTRIBUTION

47. The structure of the building is made of
structural steel and reinforced concrete.
The Compressive and Bending forces are
carried to the ground with the use of the
diagonal braced frames and outrigger
trusses.

48. The use of the Diagonal
Braced Frame along with
the Outrigger trusses
that were fixed to the
mega columns helped in
reducing the weight of
the building by more
than 10%.
Elevation showing the
structural components

49. ❖ Exhibit Braces and Outriggers are used to stabilize
and support structures to ensure extra support.
❖ The Exhibit and Display Braces are used to stabilize or
support a corner span of truss that may need extra
strength.
❖ The Outrigger trusses are an angled piece of truss that
slopes back or in front of a vertical upright / leg
providing additional support.
❖ The use of outrigger trusses helped in reducing the
thickness of the concrete shear walls of the service
core.
LINE DIAGRAM SHOWING THE FORCES

50. MEGA COLUMNS
❖ The columns of the mega structure are of mixed
structural steel and reinforced concrete.
❖ The steel column is of a size capable of fully
transferring the vertical component of the load in
the diagonals to the composite columns.
Steel boxes with infilled
concrete as Diagonal
members

51. One of the 2 Mass Dampers
that are located on the 90th
floor
They reduce the amplitude of
vibrations in the building due
to the strong lateral forces like
earthquakes or strong winds.
In addition to the mass
dampers, the opening on the
top also helps in countering
the wind forces.

52. The building has a central
core with all the Services
concentrated in the centre.
CORE CONSIDERATIONS
The building had 2 primary
sections - Offices on the lower
⅔ and hotels on the upper ⅓
part.
This was part of the core design
consideration and a resulting
reduced size of core on the
upper levels

53. Shanghai WFC has tremendous heating and cooling loads
making the engineering of the HVAC systems very complex.
Calculations for the peak cooling load in the summer were
found to be around 2.1 billion BTU per day.
When analyzing the cooling loads, the major heat factor was
found to be the sunlight. The building is completely clad in
glass, with very little structural member to absorb that energy.
Also since most of the southward facing windows are angled
back, they receive both horizontal and vertical sun rays,
making the heating more intense.
For each square foot, the cooling costs $1.11, making the
yearly overall cost over 2.2 million dollars for the whole
building

54. The core of the building is built
using RCC and Steel frames and the
diagonal bracings and outrigger
truss using structural steel.
The diagonals were constructed
using hollow steel sections infilled
with concrete. This further helped
in reducing the amount of steel
used.
The slabs were using concrete and
the outer wall facade cladded using
laminated glass panels.
Building Materials

55. The modular outrigger trusses when used, helped the contractors to build at
the rate of one floor in every 3 days.
BUILDING TECHNIQUES
Workers fixing steel plates over
the outrigger truss.
Over this, steel rebars were
placed and concrete poured
inorder to create much large
column free spaces inside.

56. Building such tall towers meant that
concrete needed to be transported to
such tall distances.
They made use of super tall concrete
pumping machines to pump the
concrete to the higher floors.
This usually takes a lot of time and the
concrete needs to mixed at a very high
speed or else it will set inside the
pipes.

57. The glass panels were large and heavy and were lifted to
the floors using cranes form the ground.
High speed winds were to be considered while doing this
since handling it was difficult.
The windows were fixed by suspending it using
winches and then bolting it to the brackets made
on the external framework form outside.
BRACKETS

58. ● The foundation was made using a pile
structure.
● The ite had a soft marine clay soil.
● The foundation was originally designed for
a building that was only 1,500 feet, even
still the structure must be able to resist a
massive amount of forces.
● These forces include high base overturning
and high shear demand near the base.
FOUNDATION
The foundation structure of the tower

59. ● The foundation consisted of 2200 piles
each at a depth of 250 feet ( 76M)
● Since the building was originally
designed for 1500 ft, the foundation was
also laid considering the load
calculations for that.
● Later the structural systems were
changed inorder to increase the height
of the building by 150 ft.
Total Dead Load: 590,315,651 LBS
Total Live Load: 330,640,000 LBS
Total Horizontal Load: 11,100,000 LBS

60. 60
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