STADIUM
ROOF
It
was not until the middle of the 19th century that structures were developed to
provide roof spans necessary for large covered stadiums. The industrial
revolution introduced the use of iron and glass in the building. These two
materials changed the shape of the building and increased the range of
materials and techniques available. The stadiums built could have a form and
structure that would not have been possible earlier. These materials were to be
used later in constructing some of the stadiums that had a form, which could
defy all the laws of stability. This was the first significant change witnessed
in these stadiums during the 19th century. From that era, economic objectives
were started being considered more important rather than making civic
statements. New trends and concepts in the design of stadiums were usually seen
in the modern games.
New
trends and concepts in the design of covered stadiums were usually seen in the
modern games such as FIFA world cup, Olympics, Asiad etc. These games seem to encourage
a country, its architects and its engineers to produce vast edifices, more the
result of the national pride than of suitability for athletics competitions.
Nevertheless, these games have set the pattern of design throughout the world.
A
stadium roof is an inherently large structure - one that is often difficult to
determine the start from the end, simply because each of its exterior sides is
mirror images of each other. A challenge for the designer or architect is to
either accentuate the similarities from side to side or conversely create
"breaks" in the stadium roof structure in order to defeat an Ana
chronic view.
The
stadium is generally symmetrical
with the conscious aim to repeat a similar representation of both horizontal and vertical views.
Symmetry is often seen as a shelter for the fearful and the lazy, and is widely
disputed by the most creative architects.
Roof and Facade
In
roofed stadia, which are becoming more common (particularly in Europe ), the most important step towards a satisfying and
harmonious architectural solution is to avoid having an assertive façade
competing with an equally assertive roof. If one of these elements is dominant,
with the other subdued or completely invisible, the composition may immediately
become easier to handle.
Dominant roof
Roof
is now a day’s most important part of any stadia, it dominated every other
feature of stadia, it contribute to façade, form and geometry of the stadium.
In the past times stadium are without had any covering, now roof is made in
such a way that it can open or close according to the need of people.
Design considerations in Roof design
Following criteria should be adopted in the
design:
•
To keep the roof as low as practical to reduce the stadium’s impact on adjoining
building as much as possible.
•
To make the track, for the retractable roof to move along, as near to flat as
possible to assist with making the retractable roof mechanism simple and,
therefore, more cost effective and less problematic.
The addition of a roof to a stadium,
along with the long-span structure required to support it and maintain clear
sight lines from the stands to the playing field, compounds the pressures on
the design and construction team responsible for an already challenging project.
An openable roof, which necessitates an enormous mechanical device at the top
of the building, adds yet another layer of complexity. Hire a good structural
and mechanization consultant, advises one architect.
A roof, of course, can keep
sports fans comfortable by keeping the elements out and conditioned air in. It
provides a more flexible facility and allows owners to generate additional
revenue by hosting a variety of events year-round. But it is much more than a
means of satisfying these practical requirements. It also serves, in many
cases, as the buildings signature element.
Advantages of roofed stadia over open air stadium
- They provide cover to playing and spectators
area and hence, protect them from bad weather.
- Provide better environmental conditions, both
to spectators as well as players.
- Provide better lighting and acoustical
conditions, especially for television broadcasting.
Open
stadiums used to be financial drain on communities, many facilities were dark
over 200 days a year. On the other hand, enclosing a stadium increases not only
the number of event days, but the revenue.
Disadvantages of roofed stadia over open air
stadium
- High cost of construction.
- Advance technology is required, unavailable in
developing countries.
- Roofing system for sports like cricket, rugby is
yet to be discovered, since they had large playing surface.
- Need high degree of maintenance.
VARIOUS
TYPES OF ROOF DESIGNS
1.
POST
AND BEAM STRUCTURE:
This structural system comprises of a row of columns parallel to the
pitch, supporting a series of beams or trusses, which in turn carry the roof.
Advantages-The post and beam system
is cheap and simple.
Disadvantages- The row of columns
along the pitch obstructs spectator viewing to an unacceptable degree.
This type of roof structure is not
used now days. But still if needed in a place where there is no other option
feasible then the columns should be placed as much away from the pitch as
possible. This will reduce the disturbances to the spectators.
2.
GOAL
POST STRUCTURE
This
is like a post and a single girder spans beam roof with posts only at the two
ends and none in between, the entire length of the roof. A girder depth of
about one twelfth of the length is normally economical. Regular inspection and
maintenance is especially important for this system because the entire roof
structure depends upon a single girder.
Example: Ibrox Park
in Glasgow
Advantages-
• Unobstructed viewing,
particularly if the two columns are placed exactly at the end of the pitch.
• Moderate cost
Disadvantages-
• The system works best when
little or no corner seating is required, thus placing a restraint on the
seating system.
• The goal post system tends,
from the visual point of view, to create a ‘boxy shed’ that cannot be coaxed
around a curve or corner with any degree of grace and is difficult to link
smoothly with adjacent stands.
This system is therefore most
likely to be appropriate where separate stands are required on the sides of the
pitch with no intention of extending the roof other than in a straight line.
3.
CANTILEVER STRUCTURES
A cantilevered roof is held
down by weight or otherwise securely fixed at one end while its other end
facing the playing area hangs free and unsupported. A variation of this system
is a propped cantilever.
Example:
Watford football Stadium
Watford football Stadium, Watford
Advantages-
•Such a structure can provide
completely unobstructed viewing for virtually any length of stand while
spanning depths of 45m or even more, the limiting factor being cost rather than
technology.
• Cantilever roofs can be
very dramatic, exploiting the excitement engendered by the structure with no
apparent means of support.
• The cantilever is as
suitable for continuous bowl shaped roofs as for isolated stands. In bowl
stadia, the individual frames can arranged as a closely spaced series of
vertical elements fluidly following a circular or elliptical plan form, which
is a great planning advantage.
Disadvantages-
• Where the rear seating rows
must be very distant from the playing field the cantilever becomes markedly
expensive and it may be found that a roof of the goal post type, for instance,
can be made cheaply.
• The reversal of forces
caused by the wind uplift can be particularly destructive in the case of a
cantilever roof.
• A cantilever roof rises to
the highest point at the back of the stand- the street side as it were- and may
therefore appear taller and more intimidating to the passers by than
alternative forms of structures enclosing a similar seating system.
• A cantilevered roof
thrusting boldly out into space without any visible means of support provides
not only an aesthetic opportunity but also a risk. Great care and some self
restraint is required if an obtrusive, out of scale result is to be avoided.
4.
CONCRETE SHELL STRUCTURE
Shells are thin surfaces
which are curved in one or two directions, deriving their strength from the
geometric shape rather than the thickness or firmness of the material. They
include cylindrical, domed, conical and hyperbolic shapes and offer the
possibility of very elegant roof forms. A shell as thin as 75mm or 100mm may
easily span 100m.
Example:
Palazetto dello Sport in Rome By Annibale Vitellozi and Pier Luigi
Palazetto dello Sport in Rome , Italy
Advantages-
• Shell structures have the
potential of great visual elegance. Such innovative forms require very thorough
testing of architectural character using both computer modeling and physical
scale models
• If carefully detailed, shells
can be self finished both underneath and on the upper surface. The lattice
requires sufficiently steep drainage falls to ensure rapid and complete
disposal of rainwater.
Disadvantages-
• Specialist designers and
engineers should be used as the mathematics required is advanced.
• If in-situ concrete is
used, the framework costs will be very high since a ‘birdcage’ or similar type
of scaffold will be required. A pre-cast concrete solution should be used or a
combination of in-situ and pre-cast concrete should be used.
5.
COMPRESSION/ TENSION RING
Such a roof consists of an
inner tension ring and outer compression ring, the two being connected by
radial members who maintain the geometry of the overall doughnut shaped
structure and carry the roof covering.
Example:
Seoul
Seoul
Olympic stadium, Seoul
Advantages-
• Very great stand depths can
spanned with comparative ease (up to 60m)
• This roof type cab fitted
aesthetically and technically fit into an existing bowl stadium.
• The inner perimeter is
completely column free, so that there are no obstructions to the spectators.
• The roof has a light,
weightless appearance as seen from the stadium interior and is unobtrusive or
even invisible from the exterior.
• Transparent or translucent
roof coverings are possible in this roof form.
• Some of these types allow
temporary or permanent roof cover over the playing area as well.
Disadvantages-
This structural system can be used only in
bowl form of a stadium.
6.
TENSION STRUCTURES
These are the roofs in which all the primary forces are
taken by the members acting in tension alone, such as cables. They are always
more economical in material than other forms of structure, but must be
carefully stabilized and restrained against any deformation which could cause
parts of the system to go into compression. There are 3 types of tension
systems- catenary cable, cable net and the membrane.
Example:
Olympic Stadium complex, Munich
Don valley Stadium, Sheffield
King fahd Stadium, Riyadh
King fahd Stadium, Riyadh , Saudi Arabia
Advantages-
• Cable net or fabric roofs
can be designed to lend an airy, festive appearance to a stadium especially
when seen from a distance.
• If a transparent membrane
is used the spectators underneath may have a lighter, more open feel than with
opaque roofs.
• Tension structures can be
adapted to many stadium layouts and do not dictate a particular plan form.
Disadvantages-
- Very
sophisticated design is needed for all tension structures and it is best
to use structural engineers with previous experience and a track record of
successful designs.
- More
systematic and intensive maintenance is required than with other
structural forms.
- Fabric
roofs require very careful detailing of rainwater guttering.
7.
AIR SUPPORTED ROOF
An air supported roof
consists of plastic membrane which forms an enclosure, either on its own or in
combination with a wall structure, and supported by positive internal pressure
provided by fans. These membranes are commonly PVC polyester, sometimes with
cable enforcement in the case of larger roofs.
Example:
Silverdome in Pontiac , USA , Frankfurt stadium, Germany
Silverdome
in Pontiac , USA
Advantages:
- Air
supported roofs are relatively low in cost.
Disadvantages:
- Full
enclosure is vulnerable to damage.
- Design
life is relatively short.
8.
Space Frame
A space frame is a grid of
structural members which is three dimensional in shape and also stable in three
dimensions, unlike, a roof truss, which is stable on;ly its own plane. Such
frames can be constructed of any material but are commonly of steel.
Example:
San Siro in Milan
San Siro in Milan ,Italy
Advantages:
- Capable
of spanning large distances.
- Suitable
for all over roofs with only perimeter support.
Disadvantages:
- A
space frame is efficient and sensibly only if spanning in two directions.
Plan proportions should roughly square, and preferably not have a
length-to-width ratio greater than 1.5 to 1.
- Space
frames tend to be expensive.
Necessity
of stadium roofs
An excerpt from Ian Fraser
“Clarity and simplicity, eliminating
the superfluous, while emphasizing what was there. Always paid attention to
scale and proportions – that came naturally.”
Shading
from the Sun
For afternoon matches, which
are the majority, the main stand should face east with a minimum of spectators
having to look in to the sun from a west-facing stand.
Section Through a typical roof of a stadium
In all cases the efficiency of a roof in
shading its occupants from the sun, and the extent of shadow it casts upon the
pitch at different times of the date and year, must be studied by computer
modeling. Such modeling should proceed
in parallel with wind tunnel testing, especially if the playing surface is to
be natural grass, because “it is now generally accepted that a combination of
shading from sunlight and reduced airflow at pitch level has an adverse effect
on the durability and quality of grass” to quote Britain’s Football Stadia
Advisory Design Council.
Shelter from Wind and Rain
As
far as plan shape is concerned, designers should note Rudolf Bergermann’s
advice that continuous roofs arranged in a circle or ellipse, as opposed to
separate roofs with gaps between, normally have a calming effect on the air
inside the stadium. This creates more conditions that are more comfortable for
spectators and performers such a experience at the Don Valley Stadium in the U.K.
Apart from these parameters for roof design
of any stadium, detailed study should be done using scaled models and wind
tunnels. In these studies, the following factors should be investigated:
1.
Prevailing wind directions and velocities on site
2. Prevailing
air temperature, humidity and precipitation conditions throughout the year (both
rain and snow)
3. Local
patterns of air turbulence caused by surrounding buildings and by the proposed
stadium design
Apart
from this, care should be taken to have clear heights beneath the roof and the
columns supporting the roof so as not to disturb spectator’s views.
San
Nicola Stadium, Bari , Italy
Like many other Renzo
Piano buildings, this building is also iconic in nature. An example of a
stadium set out of town, in a setting that was best suited for the design. The
site topography was changed to accommodate the design within it.
GENERAL STATISTICS:
Architect: Renzo
Piano, Shunji Ishida, Ottavio di Brasi, Alain
Location: Bari , Apulia ,
Italy
Year of Construction: 1987-90
Uses: Football,
Athletics.
Construction System: Membrane Structure Frame Supported
Building
Structure: R.C.C. Structure.
Capacity: 60,000
Cost of Construction: Unknown
Height- 43.84m
Membrane covered area- 13,000m2
Site area- 600,000m2
The
San Nicola stadium in Bari was specially
constructed for the 1990 Soccer World Cup hosted by Italy
The reinforced concrete petals are
constructed on site. Each semi-circular section is supported by four pillars,
adding elegance and lightness to the structure and contributing to the
spectator's perception of spaciousness and calmness.
DESIGN REQUIREMENTS:
The
San Nicola Stadium was originally created as a venue for the 1990 FIFA World
Cup tournament, providing a field and tracks for soccer (football), athletics
and uninterrupted views for 58 000 spectators.
Interior
View of the San Nicola Stadium
THE STRUCTURE
Solution
The
design is based on a series of 26 modules, which vary in dimension but are
similar in form. Each module is referred to as a "petal" with a
canopy above, due to its scalloped appearance. Structurally, the modules stand
as separate elements; their only connection is via a delicate fabric infill
canopy.
Vertical load resisting system
Each
module is precast concrete, supported by a series of concrete frames. Springing
from these massive petals are elegant roof canopies. The primary structure for
the canopy is a pair of steel cantilevered arms, which transfers loads by
flexure. The maximum spacing between the arms in each module varies from about
18m at the halfway line to 21m at the ends. A maximum cantilever of 40m is at
the field's halfway line. A secondary structure consists of 3 braced arches
parallel to the cantilever arms and is supported on a "U" truss that
links the ends of the cantilever arms at one end, and on the seating structure
at the other end. The braced arches are stabilized laterally at their fifth
points by tubular props against the cantilever arms. Support and curvature to
the fabric canopy is provided by the braced arches. The fabric canopy transfers
loads to the secondary and primary structures by membrane action.
The
initial sketch by Renzo Piano
Lateral
load resisting system. A rigid concrete frame for the upper tier seating stand
resists horizontal shear loads in both directions, including possible seismic
activity. The cantilevered canopy portal is tied into the seating structure by
pre-stressed threaded bars, providing a rigid connection. The relationship
between the cantilevered arms and the "U" truss is so that it acts as
a portal frame when resisting loads that are parallel to the front edge of the
frame. Effectively, the primary structure resists loads through flexure.
Symbiosis between nature and advanced technologies
Bird eye View of Oita
Stadium, Japan
GENERAL
STATISTICS:
Architect:
kisho kurokawa
&associates (KKAA)
Location:
japan
Year
of Construction: 2002
Uses: football
Capacity: 45,000
Cost
of Construction: not known
Dimensions: 500,000 sq.feet
Oita Stadium was chosen as an
arena for the World Cup Games in 2002. It is nicknamed "Big Eye" as
the stadium's roof opening looks like a human eye.
Structural system
The
main structure comprises a steel frame and precast concrete panels. This
approach increase the factory built modules, reduced the time spent on
construction work and succeeded in drastically reducing costs. One of
advantages of Oita
Development of technology for opening and closing a
huge roof
A
mechanism was developed whereby two sections of spherical movable roof are
supported by pinpoints on 25 sliding dollies on one side, which move along a
rail installed at upper part of the main arch to open and close the roof.
Teflon, a film with outstanding translucency has double the transparence of its
alternatives; allow natural light to come into the field. The use of
ultra-modern teflon membrane panels with 25% light-permeablity removes the need
for artificial lighting during daylight hours.
In
order for the field to get proper sunlight exposure, the elliptical roof
opening runs along the north-south axis. The economical structure of the main
beam arch with perpendicular horizontal-running sub-beams corresponds to the
elliptical shape of the roof opening.
INDIRA
GANDHI SPORTS COMPLEX. NEWDELHI
LOCATION
The Indira Gandhi Stadium
Complex (hereafter I.G.
stadium Complex) is situated
on the bank of River Yamuna
at the Indraprastha Estate in
New Delhi
HISTORY
The complex was built, along
with other sports complexes to
provide the necessary
facilities for hosting the IX Asian
Games in 1982
INFRASTRUCTURE
The 44 hectares complex
comprises of the following:-
Indoor Stadium
Four Public Plazas
Administrative Block
Players Block
Velodrome
Along
with the above, adequate parking facilities and other ancillary facilities like
telephone booths, ticket booths, bookstall etc. are also
provided.
The entire complex is extensively landscaped.
SALIENT
FEATURES
- The
stadium has a diameter of 150 mtrs and has a capacity of 25000 spectators.
- Since
the inside area had to be column free, the roof is supported on eight
reinforced concrete towers called Pylons along the periphery.
- These
towers act as the main service cores housing all arena lighting services,
air handling units for air conditioning system, a grand staircase for
spectators and other auxiliary services.
- The
entire stadium is divided in three main levels, viz ground level (+ 0.0
Lvl.), intermediate podium level (+ 3.9M) and foyer level.
THE
ROOF
There
are three parts to the roof:
·
Central
compression ring
·
Trusses in the segmental areas between the
main reinforcement concrete towers
·
Roofing
and insulation
Allianz Arena, Munich , Germany
Key
facts
Client: Muenchener Stadion
Gesellschaft
Architect: Herzog & de
Meuron/ArupSport
Arup
services:
Architecture, structure, acoustics
Date: Completion 2005
Capacity: 66 000
Main
uses: Football,
pop concerts
Key
Features
ETFE
envelope pillows
Changeable
envelope colour
Landscaped
esplanade car park
This new home for two
football clubs, Bayern Munich and TSV 1860, is also the venue for the opening
game and one semi-final of the 2006 World Cup. The stadium’s unusual form and
skin of translucent ETFE pillows make it instantly recognizable. The effect is
enhanced at night by special lighting that allows the colour of the façade to
change to match the colours of the team playing. A three-tier seating bowl
ensures that all spectators have good views and are close to the action. The
seating configuration accommodates the requirements of two distinctly different
home crowds, as well as the wide range of VIP and media provisions during and
after the World Cup.
