The document discusses large span structures and provides definitions and examples of common structural systems used for large spans. It defines a large span structure as having a span larger than 15-20 meters. Common structural systems described include long span beams, trusses, tensile structures, folded plates, and portal frames. Long span beams are summarized as utilizing parallel beams, composite beams with web openings, cellular composite beams, tapered girders, and haunched composite beams. Long span trusses include Pratt, Warren, north light, saw tooth, Fink, and tubular steel trusses. Tensile structures carry loads only in tension and are used for roofs, with examples of linear, 3D, and

1. CONSTRUCTION AND MATERIALS I (ARC 106)
LECTURERS:
DR.VEDIA AKANSU
DR.UMRAN DUMAN
DR.FATEMAHTAVASOLI
IBTIHAL AL HINDWAN
20192954
MID TERM ASSIGNMENT

2. LARGE SPAN STRUCTURE
1.INTRODUCTION
2.DEFINITION
3.COMMON STRUCTURALSYSTEMS
4. LARGE SPAN BUILDING
5.CONCLUSION
CONTENTS

3. INTRODUCTION TO
LARGE SPAN STRUCTURE
WHAT IS A SPAN?
Span is the distance between two intermediate
supports for a structure, e.g. a beam or a
bridge. A span can be closed by a solid beam
or by a rope. The first kind is used for bridges,
the second one for power lines,
overhead telecommunication lines, some type
of antennas or for aerial tramways. Example of
a span is shown in Fig 1.
Fig 1

4. DEFINITION OF
LARGE SPAN STRUCTURE
• Large-span structures traditionally appear as
long even strip, for example, in bridges,
portal rigid frames, and large-span arenas.
With respect to these structures, vertical load
is the control load. Uncommon consideration
should be paid to deliberate plan of level
foundation with regards to the calculated plan
of large-span structure. In particular, the
power bearing limit of vertical load and the
control upon vertical dislodging will be
improved with the goal that the structure has
adequate quality and solidness to oppose
vertical load as a whole.
• Structures with span larger than 15-20 meters
are regarded to as Long Span Structures. For
Such structures span is unable to be achieved
with ordinary Reinforced Cement Concrete
(R.C.C.) construction. Generally long spans
result in;
1. Flexible
2. column-free internal spaces
3. reduces substructure costs and time to
erect the structure.

5. Large span structures create unobstructed column free spaces greater
than 30m (100 feet) for a variety of functions
VisibilityFlexibility
Manufacturingfacilities
Large Scale Storage
StadiumsAircraft hangars

6. Common structural systems for large span structures
A.Long span beam
B.Long span truss
C.Tensilestructures
D.Foldedplates
E.Shell structure
F.PortalFrames
1. Parallel beam approach
2. Composite beams with
web openings
3. Cellular composite beams
4. Tapered girders
5. Haunched composite
beams
1. Prass truss
2. Waren truss
3. North light truss
4. Saw tooth truss
5. Fink truss
6. Tubular steel truss
1. Linear tensile structure
a.Suspension bridges
b.Cable stayed beams
c. Cable truss
2. 3D tensile structure
a. 3D cable trusses
b. Tensegrity structures
c. Bicycle wheel
3. Surface-Stressed tensile structure
a.Fabric structure
b.Prestressed membrane
c.Pneumatically stressed membrane
d.Grid shell
1. Folded plate surfaces structures
2. Folded plate frames structures
3. Spatial folded plate structures
1. Thin shell structure
2. Folded shell structure
3. Barrel shell structure
4. Timber shell structure
5. Lattice and grid shell structure
6. Hypar and concrete shell structure
1. Duo pitch portal frame
2. Curved portal frame
3. Portal with crane

7. A. Long span beams The use of long span beams realizes an extent of
points of interest, includingversatile, area free inward
spaces, reduced foundationcosts, and diminished steel
erection times. Many long span beams are likewise
very much adjusted to encourage the combination of
administrationswithout expanding the overall floor
depth. Example of long span is shown in Fig 1
Types of long span beams include
1. Parallel beam approach
2. Composite beams with web openings
3. Cellular compositebeams
4. Tapered girders
5. Haunched composite beams
Fig 1

8. 1. Parallel beam
approach
• The parallel beam approachis effective for
spans up to around 14 m. Floor grids comprise
two layers of fully continuousbeams runningin
orthogonaldirections. Services runningin either
direction can be integrated within these two
layers, so that services passing in any direction
can be accommodated within the structuralfloor
depth. Afurther benefit is that, being fully
continuous, the depth of the beams themselves
is reduced without incurring the expense and
complexity of rigid, full strength
connections.This is shown in Fig 1.1 and Fig 1.2
Fig 1.1
Fig 1.2

9. 2. Composite beams with web openings
• Web openings are typically formed in beams to allow services to
pass through the beam. This enables the structural and service
zones to occupy the same space, thereby reducing the
effective overall depth of floor construction for a given spanning
capability. Openings may also be formed for aesthetic reasons, for
instance with cambered beams used to support a roof.
Composite beams with web openings have been shown to be a cost
effective solution for spans in the range 10 to 16 m.
• A particular type of composite beam with web openings is the so-
called cellular beams, which is formed in a specific way. The
alternative way of forming the web openings is simply to cut
them into the plate used to form the web of a plate girder, or into
the web of a rolled section.Example shown in Fig 2.1. The
most appropriate solution to adopt depends on the size, shape and
regularity of the openings, or more commercial drivers such as the
method used by a preferred supplier. Beams with web
openings present no disadvantages in terms of erection and
familiarity as they are much the same as a 'standard' solid
web beam.
• The design of beams with web openings must recognize the fact
that the openings introduce a number of potential failure modes not
found in solid web beams. Around the openings the beam behaves
as a Vierendeel girder, and web post buckling may govern
design Large openings may require stiffening to avoid instability
(buckling) of the web posts. Visual shown in Fig 2.2
Fig 2.1
Fig 2.2

10. 3. Cellular composite beams
• Cellularbeams are a form of beam with multiple
regular web openings, formed by splitting
two rolled sections longitudinally, to form two Tee
sections as shown in Fig 3.1 The two Tees, which
may not come from the same donorsection are then
welded togetherto form an I-section with web
openings which have a characteristicshape
(normally, but not necessarily, circular). The process
used to form cellularbeams enables the bottomhalf
of the final beam to be formed from a heavier donor
section than the top half - in otherwords the bottom
flange can be significantly bigger than the top
flange. This makes sense when, as is often the case,
the beams are to act compositely and thereforea
concreteflange effectively replaces the uppersteel
flange in the final state (the upper steel flange only
needs to be big enough to meet constructionneeds
and serve as a platformfor the shear studs).Different
examples are shown in Fig 3.2
Fig 3.1
Fig 3.2

11. 4. Tapered girders
• Tapered girders can be a cost effective
solution in the span range 10 m to 20 m. They
are anothersolutionthat allows services to be
accommodated within the structuralfloor
zone. The depth of the girder increases
towards mid-span, where applied moments
are greatest, and thereby facilitating hanging
services under the shallowerregions near the
beam supports. It is also possible to form web
openings in tapered girders in regions of low
shear, towards mid-span. These provide more
optionsfor service integration. Understanding
of tapered girders can be reached in Fig 4.1
and Fig 4.2
Fig 4.1
Fig 4.2

12. 5. Haunched composite beams
• Haunches maybe added at the ends of
a composite beam to provide moment
continuity as shown in fig 5.1. The stiffness
and strengthof the connections mean that the
rest of the span can be shallower (the bending
moment diagram is 'lifted' and the effective
stiffness of the beam substantiallyincreased),
and services passed under it. In buildings
where the services are likely to need frequent
replacement (for examplein hospitals ),
hanging the services under the beams rather
than passing them through holes in the webs,
or through a truss, can be advantageous.
Spans in excess of 20 m can readily be
achieved. Haunched composite beam is well
explained in fig 5.2
Fig 5.1
Fig 5.2

13. B. Long span trusses
• A roof truss is a structure that incorporates one or numerous triangular units
that incorporate straight slender members with their ends connected by means
of nodes as shown in fig 1
Trusses are very widely used to serve two main functions:
1. To carry the roof load: - Gravity loads (self-weight, roofing and
equipment, either on the roof or hung to the structure, snow
loads) Actions due to the wind (including uplift due to negative
pressure).
2. To provide horizontal stability: - Wind girders at roof level, or at
intermediate levels if required - Vertical bracing in the side walls and/or in
the gables.
Types of long span trusses
1. Prass Truss
2. Warren Truss
3. North Light Truss
4. Saw Tooth Truss
5. Fink Truss
6. Tubular Steel Truss
Fig 1

14. 1. Prass Truss
• A Pratt truss includes vertical members and
diagonals that slope down towards the center, the
oppositeof the howe truss as shown in fig 1.1 .The
interior diagonals are undertension under balanced
loadingand vertical elements under compression.
If pure tension elements are used in the diagonals
(such as eyebars ) then crossing elements may be
needed near the centerto accept concentratedlive
loads as they traverse the span. It can be
subdivided, creating Y- and K-shaped patterns.
Example of prass truss is shown in fig 1.2
• This truss is practical for use with spans up to 250
feet (76 m) and was a common configuration for
railroad bridges as truss bridges moved from wood
to metal. They are staticallydetermine bridges,
which lend themselves well to long spans.
Fig 1.1
Fig 1.2

15. It is possible to add secondary members in Pratt truss to:
• Create intermediate support points for applied loads
• Limit the buckling length of members in compression (although in a 2D truss, the
buckling length is only modified in one axis).

16. 2. Warren Truss
The Warren truss consists of longitudinal
members joined only by angled cross-
members, forming alternately
inverted equilateraltriangle-shaped spaces
along its length, ensuring that no
individual strut, beam, or tie is subject to
bendingor torsional straining forces, but only
to tension or compression as shown in fig 2.1.
Loads on the diagonals alternatebetween
compression and tension (approachingthe
center), with no vertical elements, while
elements near the centermust support both
tension and compression in response to live
loads. This configuration combines strength
with economy of materials and can therefore
be relatively light. The girders being of equal
length, it is ideal for use in prefabricated
modularbridges. It is an improvement over
the Neville truss which uses a spacing
configuration of isosceles triangles. A good
example of warren truss is shown in fig 2.1
Fig 2.1
Fig 2.2

17. 3. North Light Truss
• North light trusses are traditionally used for short spans in
industrial workshop-type buildings as shown in fig
3.1. They allow maximum benefit to be gained from
natural lighting by the use of glazing on the steeper pitch
which generally faces north or north-east to reduce solar
gain. On the steeper sloping portion of the truss, it is
typical to have a truss running perpendicular to the plane
of the North Light truss, to provide large column-free
spaces. It is shown in fig 3.2
• The use of north lights to increase natural daylighting can
reduce the operational carbon emissions of buildings
although their impact should be explored using dynamic
thermal modelling. Although north lights reduce the
requirement for artificial lighting and can reduce the risk
of overheating, by increasing the volume of the building
they can also increase the demand for space heating.
Fig 3.1
Fig 3.2

18. 4. Saw Tooth Truss
• A saw-tooth roof is a roof comprising a series
of ridges with dual pitches either side as shown
in fig 4.1. The steeper surfaces are glazed and
face away from the equatorto shield workers
and machinery from direct sunlight. This kind
of roof admits natural light into a deep plan
buildingor factory as shown in fig 4.2
Fig 4.1
Fig 4.2

19. 5. Fink Truss
• A fink roof truss is traditionallythe most commonly
used truss type, providing a simple, adaptableand
cost efficient roofing solution.
• The “fink” is a basic webbed truss design that
provides the most economical roof solution.
• The web members form a ‘W’ as shown in fig 5.1 to
provide a high strength structure with good load-
carrying capacity. The roof load is transmitted
entirely to support on the wallplates.
• The fink truss can also be used as a support for other
trusses by doublingor trebling the number of plies,
i.e. in a “hip” roof.
• Due to its design flexibility, the fink truss is the most
frequentlyused truss in roof design. With a large
variety of spans up to 14 metres and pitch range
from 10° to 60°, the finks truss offers a cost effective
and versatile roof solution. Example is shown in fig
5.2.
Fig 5.1
Fig 5.2

20. 6. Tubular Steel Truss
TubularSteel Truss are used for large span
constructionssuch as factories, industry worksheds,
shoppingmalls, huge exhibition centre, multiplexes etc.
Example in fig 6.1 They are generally used for spans as
large as 25-30m.
ADVANTAGES OF TUBULAR STEEL ROOF
TRUSSES:-
•30% to 40% less surface area than that of an equivalent
rolled steel shape. Therefore, the cost of maintenance,
cost of painting or protective coatings reduce
considerably.
•The moisture and dirt do not collect on the smooth
external surface of the tubes. Therefore, the possibility
of corrosion also reduces.
•The ends of tubes are sealed. As a result of this, the
interior surface is not subjected to corrosion. The
interior surface do not need any protective treatment.
•They have more torsional resistance than other section
of the equal weight.
Fig 6.1
Fig 6.2

21. ADVANTAGES OF TRUSSES
• Trusses consume a lot less material compared to beams to span the same length and transfer moderate to
heavy loads. However, the labour requirement for fabrication and erection of trusses is higher and hence
the relative economy is dictated by different factors. In India these considerations are likely to favor the
trusses even more because of the lower labour cost. In order to fully utilize the economy of the trusses the
designers should ascertain the following:
a) Method of fabrication and erection to be followed, facility for shop fabrication available,
transportation restrictions, field assembly facilities.
b) Preferred practices and past experience.
c) Availability of materials and sections to be used in fabrication.
d) Erection technique to be followed and erection stresses.
e) Method of connection preferred by the contractor and client (bolting, welding or riveting).
f) Choice of as rolled or fabricated sections.
g) Simple design with maximum repetition and minimum inventory of material.

22. C. Tensile structure A tensile structure is a structure
elements carrying only tension and
no compression or bending.Atensile
membrane structure is most often
used as a roof, as they can
economically and attractively span
large distances. These type of
structure is commonly found in
sports facilities, warehousing and
storage buildings, and exhibition
venues
Types of Tensile Structures
1. Linear Tensile Structures
2. Three-dimensional Tensile
Structures
3. Surface-Stressed Tensile
Structures

23. Types of Tensile Structure
1. Linear Tensile Structures
Linear tensile structures are the structure in which the all the
member are in linear tensile forces. This linear members are
supported by the compression members , but the major loads are
carried out by tensile members. Common example of these structure
is cable suspended bridges. The main pillars acts as compression
members, but the whole load is carried out by the cables which are
in tension.
Linear tensile structures are further classified into following types,
• Suspension bridges
• Cable-stayed beams or trusses
• Cable trusses
Suspension bridge
Cable stayed bridge
Cable truss

24. 2. Three-Dimensional
Tensile Structures
Three-dimensional tensile structures, is a
compilation of elements that are primarily in
tension, with the compression being transferred to a
central mast and down into the ground. The most
common occurrenceof three-dimensionaltension
can be seen at sports arenas and usually serve as
roofs for these structures.
Three-dimensional tensile structuresare further
classified into following types,
• 3D cable trusses
• Tensegrity structures
• Bicycle wheel (can be used as a roof in
a horizontalorientation)
Bicycle Wheel
3D Cable truss Tensegrity structures

25. 3. Surface-Stressed
Tensile Structures
Surface-stressed tensile structuresare
same as other2 tensile structure, but
the surface members are tension
bearing members. Fabric tensile
structuresare the great examples
of Surface-stressed tensile structures,
where the vertical pillars hold the
special designed fabric which is in
tension.
Surface-Stressed tensile structures
are further classified into following
types
• Fabric structure
• Prestressed membranes
• Pneumaticallystressed membranes
• Grid shell
Fabric Structure
Prestressed membranes
Pneumaticallystressed membranes Grid shell

26. D. Folded plates
Folded platesare assemblies of flat plates rigidly connected
together along their edges in such a way that the structural
system capableof carrying loadswithout the need for
additionalsupportingbeams along mutual edges. Example
is shown in fig 1
Types of Folded Structure
Based on geometric shape folded structurescan be divided
into:
1. Folded platesurfaces structuresfig 1.1
2. Folded plateframes structuresfig 1.2
3. Spatial folded platestructuresfig 1.3
Fig 1.1
Fig 1.2
Fig 1.3
Fig 1

27. The Principle of Folding
The structural characteristics of folding structures depend
on-
• The pattern of the folding.
• Their geometrical basic shape.
• Its material.
• The connection of the different folding planes.
• The design of the bearings.
Structural Behavior of Folding Structural Condition Of
Folding Structures.
Load Distribution process
• At first, the external forces are transferred to the shorter
edge of one folding element.
• There, the reaction as an axial force is divided between
the adjacent elements.
• Then the forces transferred to the bearings.

28. Application of folded structures
As a roof structure
As a floor structure
As a wall structure
As steel sheet pile

29. Advantages and Disadvantages of folded plates
Advantages
• Very light form of construction. To span 30 m
shell thickness required is 60 mm only.
• The use of concreteas a building material
reduces both materials cost and a construction
cost.
• Longer span can be provided.
• Flat shapes by choosing certain arched shapes.
• Estheticallyit looks good over otherforms of
construction
Disadvantages
• Shutteringis difficult.
• Greater accuracy in formwork is
required.
• Good laborand supervision
necessary.
• Rise of roof may be a disadvantage.

30. E. Shell structure
• A shell structure is a light weight construction using shell elements. These elements
are usually curved and are assembled to large structures
• It covers large floor spaces with economical use of materials of construction
• The thickness of shells range from 75 mm to 150 mm
• Shell roofs are generally adopted for hangers, sport auditoriums, exhibition halls,
industrial buildings, operas as shown in fig 1 and a variety of other large span
structures where uninterrupted floor space is required
• Its efficiency is based on its curvature (single or double), which allows a
multiplicity of alternative stress paths and gives the optimum form for transmission
of many different load type
Types of shell structures:
1. Thin shell structure
2. Folded shell structure
3. Barrel shell structure
4. Timber shell structure
5. Lattice and grid shell structures
6. Hypar and concrete shell structures
Fig 1

31. 1.Thin shell structure
• Thin shell structures are light weight constructions
using shell elements
• A thin shell is defined as a shell with a thickness
which is very small compared to its other
dimensions and in which deformations are not large
compared to thickness
• These elements are typically curved and
are assembled to large structures.
• Membrane action in a shell is primarily caused by
in-plane forced (plane stress), though there may be
secondaryforces resulting from flexural
• Though the ideal thin shell must be capable
of developing both tension and compression
2.Folded shellstructure
• The folded plates are the typical two-
element construction
• North light is achieved in this roof structure by truss
elements cast in the plates
• The edge plates are small because they
are supported by columns.
Thin shell structure
Folded shell structure

32. 3.Barrel shell structure
• The barrel shell is a series of very thin arches
that share their compressive strengths with one
another.
• This relationship of compressive forces allow
for the barrel shell to support very large amounts
of weight as long as the weight is distributed
proportionally.
• Barrel shells with a consistent thickness are very
weak against the concentrated loads. The barrel
shell is formed like the arch that transfer the
compressive loads to the ground.
• Barrel shells can be used in a variety of different
applications.
4.Timber shell structure
• The timber shell structure consists of wooden
planks to form the ribs.
• These planks are approximately 3 x 16 cm, and
several interlocked layers are used to form
each rib.
• These planks are screwed together, usually no
glue is used. Each layer of planks is continuous
in one direction.
• Filler boards are installed between these planks
Barrel shell structure
Timber shell structure

33. 5.Lattice and grid shell structure
• Grid shell structures are structures made of grid
or lattice forms, set into a double curve.
• Grid shell structures can be made from almost
any material, as long as the material can be set
into a nearly even grid and can be bent enough to
achieve a double curve.
• Most of the materials used for grid shell
structures are wood and steel.
6.Hypar and concrete shells
• Concrete shells were brought into the post-
classical by Heinz Isler.
• There is little further reinforcement required for
the 7 cm, thick shells, and they have no
measurable deflection.
Lattice and grid shell structure
Hypar and concrete shells

34. Advantages and Disadvantages of Shell
Structures
Advantages
• Thickness is small relative to other
dimensions.
• Considerablereduction in the self-weight of
the structure.
• Attraction of elegant simplicity of curved
shell forms that utilize the natural strength
and stiffness of shell form with great
economy in the use of material.
• Continuityand Curvature – The essential
ingredients of a shell structure.
Disadvantages
• More expensive than a part framed structure,
cost of labor, the constructionof centering of
shell is very high.
• While rigidity and strength are in many cases
desirable attributesof shell structures, there
are some important difficulties that occur
precisely on account of unavoidablerigidity.
• A tiny weakness or imperfection on the
covering can cause the whole structureto
fall.

35. F. Portal Frames
Portal frames are a type of structuralframe,
that, in their simplest form, are characterized
by a beam (or rafter) supported at either end
by columns, however, the joints between the
beam and columns are 'rigid' so that the
bendingmoment in the beam is transferred to
the columns. Portal Frames are generally used
for single story constructionas shown in fig
1.1 which require a large unobstructedfloor
space. Portal frames are made in a variety of
shapes and sizes. They are usually made from
steel, but can also be made from concreteor
timber. The portal structureis designed in
such a way that it has no intermediate
columns as shown in fig 1.2, as a result large
open areas can easily be created within the
structure.
Fig 1.1
Fig 1.2

36. Types of portal frames
1. Duo pitch portal frame Fig 1
2. Curved portal frame Fig 2
3. Portal with crane Fig 3
Fig 1
Fig 2
Fig 3

37. Application of portal frames as roofs and walls
• A high percentage of roofs are covered
with composite profile metal sheets
with a colored external skin.
• These composite sheets have
approximately 50mm of insulation
sandwiched between two thin metal
sheets or aluminum sheets. Coated steel
is lowest in cost but limited in life due
to the durability of the finish.
Aluminum develops its own protective
film. Profile sheets are quick to erect,
dismantle and repair.
• Galvanized steel purlins span between
the steel rafters.
• Wall panels.

38. Advantages and Disadvantages of Portal
Frames
Advantages
• Speed and ease of erection
• Buildingcan be quickly closed in and
made water tight.
• Framework prefabricated in a workshop
and not affected by weather.
• Site works such as drainage, roads etc, can
be carried out until framework is ready for
erection.
• No weather hold up during erecting the
framework.
• Connectedtogetherin factories by welding
and site connectionsshould be bolted.
Disadvantages
Although steel is incombustibleit has a
poorresistance to fire as it bends easily
when hot.
Subject to corrosion

39. Example of a large span building
Beijing Daxing InternationalAirport
• The phoenix-shaped Beijing Daxing InternationalAirport
has become a new iconic building in the Chinese capital.
• Designed by Zaha Hadid Architects, ADP Ingenierie and
Beijing Institute of Architectural Design (BIAD), the
terminal building has a total GFA of over 700,000m² and is
designed to have a maximum capacity of 100 million
passengers every year, relieving pressure on the Beijing
Capital International Airport.
• The new airport is also designed to be a super transportation
hub for Beijing – beneath the terminal building there will be
three underground railway stations with a total area of
200,000m² for five railway lines to allow easy transfer for
passengers to various means of transportation.
• In realizing this second international airport for Beijing,
Arup was appointed as the fire engineering consultant by the
Beijing Institute of Architectural Design, and later to carry
out peer review and value engineering for the steel roof
structure by the Beijing New Airport Construction
Headquarters.

40. Optimizing the roof structure
• The roof of the terminal building is a large-span and
complex hyperboloid steel grid structurecovering over
350,000m²and containingmore than 170,000 steel
members. It is supportedby giant C-shape columns
seamlessly connectingwith the roof curvature.
• Arup engineers, with the help of in-house developed
software, studied the structuralconfiguration, loading,
vertical support system reactions and the structural
deflection and displacement. Atotal of 420 load
combinationswere considered and 38 different cross
section sizes were employed in the superstructure.Our
analysis revealed that therewas roomfor design
optimization.
• With extensive experience in long span steel structuresand
structuraldesign optimization, Arup proposed various
strategies for the different zones of the terminal to improve
the roof truss patternsand reduce unnecessarystructural
depth and member sizing.

41. CONCLUSION
• All the structuresdiscussed above have their own advantages and disadvantages. Therefore it is
very important that the constructionfirm of the different large span structuresis able to tackle
all the issues by considering the different elements of large span structuressuch as design,
installationand materials and consider which structuralsystems is suitablefor the large span
structurerequired to be constructed.
• You tubevideo link https://www.youtube.com/watch?v=U7iqjVyVqtE&t=194s

42. THANK YOU