ADVANCED_STRUCTURAL_SYSTEMS.pdf

ADVANCED STRUCTURAL SYSTEMS
T SAI MONIKA 14121AA039
VII SEMETER
UNITS
6,4,2,5
[2014-2019] 7TH SEMESTER [MSPA]

SIMPLY SUPPORTED BEAM
EQUILIBRIUM UNDER SIMPLE TENSION

UNIT 6
CURTAIN WALLS :
TYPES OF CURTAIN WALLS
COMPONENTS OF CURTAIN WALLS
STRUCTURAL PROBLEMS IN CURTAIN WALLS
CONSTRUCTION OF CURTAIN WALLS
ERECTION OF CURTAIN WALLS

CURTAIN WALLS
• CURTAIN WALLING IS A FORM OF VERTICAL BUILDING ENCLOSURE WHICH
SUPPORTS NO LOAD OTHER THAN ITS OWN WEIGHT THAT OF ANCILLARY
COMPONENTS AND THE ENVIRONMENTAL FORCES WHICH ACT UPON IT.
• Although the term is sometimes restricted to metal framed curtain walls,
the above definition embraces many different construction methods
• AS THE CURTAIN WALL IS NON-STRUCTURAL IT CAN BE MADE OF A
LIGHTWEIGHT MATERIAL REDUCING CONSTRUCTION COSTS.
• When glass is used as the curtain wall, a great advantage is that natural
light can penetrate deeper within the building.
• THE CURTAIN WALL FAÇADE DOES NOT CARRY ANY DEAD LOAD WEIGHT FROM
THE BUILDING OTHER THAN ITS OWN DEAD LOAD WEIGHT. THE WALL
TRANSFERS HORIZONTAL WIND LOADS THAT ARE INCIDENT UPON IT TO THE
MAIN BUILDING STRUCTURE THROUGH CONNECTIONS AT FLOORS OR COLUMNS
OF THE BUILDING.
• A curtain wall is designed to resist air and water infiltration, seismic forces
acting on the building and its own dead load weight forces.

WHY IS IT USED / FUNCTION
NATURAL VENTILATION
• LETS IN PLENTY OF NATURAL LIGHT
• HELPS WORKERS IN PROVIDING GOOD HEALTH CONDITIONS AND SHOWING
TRUE COLOURS OF THE ELEMENTS
VIEW
• HELPS IN PROVIDING GOOD PANARAMIC VIEW
• HELPS THE WORKERS INSIDE THE BUILDING TO REMAIN ACTIVE
• IT ALSO ADDS TO THE ANOTHER SELLING POINT FOR RENTING UNITS
AIR TIGHT CONSTRUCTION BOOSTS ENERGY EFFICIENCY
• DUE TO AIR TIGHT FIT IT HELPS TO SEAL THE WARM AIR DURING THE WINTER
AND COOL AIR DURING THE SUMMER MAINTAINING THE INNER TEMPERATURE
OF THE BUILDING
• THE ENERGY EFFICIENCY of THE CURTAIN WALLS PROVIDE HELP KEEP THE
COST OF BUILDING OPERATIONS AS LOW AS POSSIBLE .
WATERPROOF INSTALLATION
• THE SEALANT USED DURING INSTALLATION ACTS AS A MOISTURE PROOF
BARRIER THIS MEANS THAT THE RAIN AND MOISTURE WILL NOT ENTER IN TO
THE BUILDING T SAI MONIKA 14121AA039

TYPES OF CURTAIN WALLS
STICK SYSTEM
• In the stick system mullions [ sticks ] are fabricated
in the shop and installed and glazed in the field
• Sticks are placed between floors vertically to
support individual components, such as horizontal
mullions ,glazing and spandrels
• Loads are transferred through connections at floors
or columns
ADVANTAGES of stick system
. Great Flexibility . waterproof
• Site Modification is possible . easy transportation
DISADVANTAGES of stick system
• Difficulties in quality control
• Relies heavily on site workmanship
• Requires different trades men
• Difficult to accommodate building movements
• Impossible to control water drainage to individual floor
• Too many loose parts and component on site
• More storage space and longer storage time on site

UNIT PANEL SYSTEM / unitized panel system
• For large or labour intensive projects UPS may be
a cost effective alternative to the stick system
• In this system the panels are fabricated and
assembled at the shop and may be glazed there as
well .
• the panels are then taken to the field where they
are attached to a building structure
ADVANTAGES OF UNIT PANEL
• Units are assembled & glazed under controlled
Shop conditions.
• Full pressure equalization drainage system
at each floor
• Accommodates building movements
• Minimizes site operations
• Usually does not require external access
• Shortens Construction Duration
• Enables other subsequent internal trades to
commence works much earlier.

• UNIT AND MULLION SYSTEM
• Similar to the stick system, mullions are
the first tube to be installed in the unit
Spandrel and glazing unit , however,
are inserted into the stick system as a
complete unit. Mullions and units are
shipped separately
• COLUMN COVER AND SPANDREL
SYSTEM
While column cover and spandrel systems
are similar to unit and mullion systems,
they differ in that the building frame is
emphasized with column covers, which act
as sticks.
• POINT LOADED STRUCTURAL
GLAZING SYSTEM
In this system, the vertical framing
member can be comprised of stick, cable,
or another custom structure behind the
glass. Glass is supported by a system of
four-point brackets, and joints are sealed
with silicone.

COMPONENTS
OF CURTAIN WALLS
CONCRETE
SLAB

STRUCTURAL PROBLEMS

STRUCTURAL PROBLEMS OF CURTAIN WALLS
• The primary purpose of a curtain wall system is to protect the building interior
against the exterior natural phenomena such as sun exposure, temperature
changes, earthquake, rain, and wind.
• This protection can be separated into two major categories, namely
• STRUCTURAL SAFETY AND INTERIOR ENVIRONMENTAL CONTROL.
• The structural safety problems include failures of wall component, wall facing
material, and fasteners.
• The interior environmental control problems include excessive energy loss, noise
control, mold growth, interior water condensation, and water leakage.
• It is essential to maintain this protection for the life of the building ideally
without periodic repairs or total renovation.
• Unfortunately the life of a curtain wall system can not be more than the building
life due to multiple functional requirements of a curtain wall system.
• For example,
• -sealing functional failure due to sun exposure and/or sealant line stress fatigue caused by various
structural movements of wall components and building frame (such as thermal expansion or
contraction, wind load deflection or rotation, could produce a chain of functional failures.
• -water leakage leading to wetting of insulation material (energy loss) or mold growth (sick air
building) or rusting of connection system leading to structural failure.
• The maintenance and renovation cost of the curtain wall system has a very significant impact on
the life-cycle cost of the building.

1 QUALITY CONSTRUCTION TEAM
• Experienced project managers, factory personnel, iron workers , crane operators , and
similar professionals are needed for a successful project regardless of the type of the
of curtain wall and installation method .
• Even with highly qualified contractors and sub contractors ,factory and field quality
assurance and quality control are often not sufficiently planned or implemented
2 ASSEMBLE A QUALIFIED TEAM
• Project executives should review the credentials of the people performing various
tasks on site .
• There should be an periodic check by the curtain wall consultant engaged by
architect
• Site visits by a qualified professional can help identify problems before and thus
reduces the risk in the future
3 CARELESS ERECTION TECHNIQUES
• Curtain walls with damaged stone , glass, aluminium , metal panels and other
materials caused by reckless transportation during erection on site results in loss of
money and extension in the project completion time to avoid this there should be
careful planning and implementation of protective transportation and erection
• It is compulsory to have experienced curtain wall installers
• Time taken for the installation should not be rushed to make up the lost time from
construction

STICK WALL INSTALLATION SEQUENCE
Establish control lines. Find out from the contractor exactly where the stick wall should
go. Bench marks may be painted on the floor and over the edge of the floors. They must be
visible on all floors before, during and after the construction of the curtain wall
Layout. The layout determines the exact wall placement by the use of offset lines and
finished floor levels developed from the control lines established earlier. This procedure should
be checked and double-checked by more than one person. Each floor must have the proper
amount of room for attaching anchors. Even though the floors are not perfectly level or
plumb, the wall must be.
Anchor plates. One of the most important parts of the building‟s construction is the
placement and the type of anchors used. Anchor plates are bolted, welded or cast into the
structure of the building. The type of anchors used depends on the type of wall design
steel beam construction --------anchors bolted or welded on to the structural beams.
concrete construction------ impediments or weld plates are cast into the concrete floor. This
allows the anchors to be welded or bolted to a steel anchor, instead of being separately
anchored into the concrete at each location.
The location of the anchors must be precise. . Do not use a hand full of washers to make a
bolt fit or attach . Forcing anchors causes poor quality and weakness in the buildings and
curtain wall construction.

Check materials. The materials should arrive on site during the process. Make
arrangements with the contractor prior to their arrival for storage locations or for the
materials to be hoisted to the proper floors as they arrive. Most metal components should be
positioned on the proper floor as they are unloaded from the trucks. Due to the weight of the
glass units they should be positioned next to the columns as they are to be installed. Proper
positioning of the materials will help cut down on continued handling and loss due to
damage.
Erect mullions. The verticals usually are the first item to be installed. These must be
positioned accurately. The verticals usually are about 20 feet to 25 feet and joined by
stacking one on top of the other. Splice sleeves are used to join the mullions. The mullions are
placed on a plane, and the anchors are fastened but not tightened. Once the mullions are
perfectly placed and on the same plane, the bolts are tightened all the way. The next mullion
is installed on top of the previous one and so on.
Install horizontals. After all the vertical mullions are in place and secured, install the
horizontals. Use the manufacturer‟s installation instructions because horizontals can be
anchored in many ways: by clips, screw spline or brackets. The wall could also have certain
areas that must be sealed now. Be sure to follow the proper procedures for this step. Once the
wall is built, it is difficult to correct a mistake.

Seal the corners: Where a wall meets a corner, pre-packaged flashing and sealing units
usually are supplied by the manufacturer and should be used or followed. If the system
develops a leak and you did not follow the manufacturer‟s instructions, your company will
probably be liable for the damages and the responsibility of fixing the problem.
Glaze the wall. The curtain wall can be glazed using different techniques. The wall could
be designed for outside glazing or inside glazing. The framing members could
accommodate 1⁄4-inch glass and spandrels to 1-inch insulating glass units glazing caps must
be removed from the outside of the building. The use of scaffolding or suspended scaffolding
is necessary to install glass in these situations.
Trim. Once the system has been completed, the exterior glazing caps and final sealants
should be applied and installed. The interior usually only requires the installation of drywall
caps and retainers.
Unitized walls
In the case of a unitized wall, the pre-assembled units are hoisted to the proper location in
sequence, snapped together to provide the interlock and anchored to the structure. They
snap and interlock to form a solid unit. The layout and other details of the stick system
apply to the unitized wall as well.

TYPES OF QUESTIONS RELATED TO UNIT 6
DEC 2013
What is a curtain wall? Why is it used ? illustrate its components show its location in a
typical building?
APR 2013
What is curtain wall ? illustrate its components with neat sketches.
FEB 2015
What is function of a curtain wall their components and their structural problems?
SEPT 2015
Explain about different types of curtain walls and their components with neat sketches .
JAN 2016
Describe the procedure of design of any one type of curtain wall .give neat sketches
Feb 2017
Explain different curtain walls their construction and erection.

UNIT 4
STRUCTURAL SYSTEMS :
SINGLE AND DOUBLE LAYER GRIDS ,
BRACED DOMES , RIBBED DOMES ,
PLATE TYPE DOMES , NETWORK DOMES ,
• LAMELLA DOMES , GEODESIC DOMES ,
• GRID DOMES BRACED AND FOLDED STRUCTURES

SINGLE LAYERED GRIDS
• A grid can be comprised of two or more sets of parallel members
intersecting each other at an angle and loaded perpendicular to their
planes. If all the members of a grid are in the same plane, it is called a
single-layer grid.
• There are different types of single-layer grid used as the main structural
systems for roofs and floors.
• These interconnected patterns consist of two-way, three-way or four-way
configurations, with the most common pattern being rectangular grid in
which the intersecting elements are perpendicular to each other.
• The diagonal grid, in which the members are oriented in an oblique
manner to the supporting structure along the edge, has great rigidity (or
stiffness
Two way grid

• The three-way single-layer grids are generally used for larger span or when the structure is
subjected to large concentrated loads. This system has a more even stress distribution that
the two-way grids.
• The four-way grids are made of a combination of rectangular and diagonal grids. These
systems are not commonly used. For up to almost 30 ft span single-layer grids are efficient,
however, for larger spans double-layer grids are more appropriate, which can be used for
spans up to about 300 ft.
• Since grids are very rigid structures, they require members that are shallower than planar
systems. The span to depth ratio for single layer rectangular grids is about 30 and for
diagonal grids is about 40.
Three way grid
Four way grid

• Double layer grids are extensions of single-layer grid systems, which consist of
two sets of parallel beams connected to each other at right or oblique angles
and loaded by forces perpendicular to the plane of the grid.
DOUBLE LAYERED GRIDS
• Even though DLGs are customarily made of parallel planes, it is possible to
create free-forms by modifying the shape of the top and bottom layers
independently.
• There are generally two main types of DLGs:
• Direct (Truss) Grids: In this type of system the members of the top and bottom
layers are in the same plane resulting in a series of intersecting planar trusses.
• Space Grids: These are made of a series of polyhedral units with triangular, square,
pentagonal or hexagonal bases.
• DLGs can be used for floors or roofs of multi-story buildings (though a majority of
systems are used for roofs).
• The roof system in most cases consists of purlins supported by joints, however, in some
cases the top layer directly supports the roof. In addition, DLGs have been used for
vertical or inclined walls.

Double layer grid configuration can also be considered to have been generated by the close
packing of platonic solids such as tetrahedra, octahedra, etc., placed next to each other and
connected at joints (sometimes with additional members).

BRACED DOMES
• Braced domes are a typical example of three dimensional structure in which
any applied load is distributed between many members which may be at a
considerable distance .
• This leads to an even distribution in the structure
• These are subdivided into
• 1] frame or skeleton type [single layered dome]
• 2] truss type [double layered dome ]
• 3] stressed skin type in which covering forms an integral part of the structural
system
• 4] formed surface type in which sheets are bent and intersected along their
edges to form the main skeleton of the dome
• Braced domes posses great stiffness due to the lack of internal columns
• The rise of a braced dome can be as flat as 1/7 of the diameter or as high as ¾
th of the diameter
• For diameters larger than 60m double layer grids are recommended
• The ratio of the thickness to the diameter of the double layered braced dome is
in the range of 1/30 to 1/60

Two
way
3
way
3
way

RIBBED DOMES
• Domes have been used to cover structures since ancient times. their. One such innovation started
in Muslim Spain in the 10th century.
• It is the construction of Star Ribbed Domes, where a pair of parallel arches is rotated to intersect
and produce a star pattern.
• To avoid the congestion at the apex of a dome resulting from many ribs meeting at the same
point Arab-Muslim builders used two arches which were separated from each other.
• By rotating this pair of arches, we divide the dome surface into star-like shapes composed of
regular polygon cells.
• The central polygon is a regular convex polygon, and when parts of the ribs are omitted at the
center, these polygons turn into regular stars.
• Next to the central polygon, there is one row of triangular cells, followed by a number of kite
shaped cells which increase in size as we move from the center of the dome towards its edges. The
number of the different shapes of these cells equals to the number of rotations applied to the
original pair of arches

Ribbed dome is the earliest style of braced dome that has been
constructed.
A ribbed dome consists of a number of identical meridional
solid girders or trusses , interconnected at the crown by a
compression ring.
the ribs are also connected by concentric rings to form grids in
trapezium shape. The ribbed dome is usually stiffened by
a steel reinforced concrete tension ring at its base.

PLATE-TYPE DOMES
• are usually described as domes, totally or partly consisting of planes with more than 3
edges, braced by structural cladding such as plates or by bars in a triangular pattern.
• It seems that this concept may be extended to regarding the plate dome, or plate
structure in general, as an independent and just as basic a structural family as the
lattice structure, so basic in fact that it is the exact dual of the lattice structure.
Plate domes are highly efficient structurally when shaped, proportioned to withstand
loads without bending or twisting. domes should satisfy the following conditions:
• The plate should not be so thin that deformations would be large
compared with the thickness.
• Shearing stresses normal to the surface should
be negligible.
• Points on a normal to the surface before it is
deformed should lie on a straight line after
deformation.
• And this line should be normal to the
deformed surface.

NETWORK DOMES
GRID DOMES

LAMELLA DOMES

• Geodesic domes are usually
hemispheres (parts of spheres, like
half a ball) made up of triangles. The
triangles have 3 parts:
• the face - the part in the middle
• the edge - the line between corners
• the vertex - where the edges meet
GEODESIC DOMES
The triangles create a self-
bracing framework that
gives structural strength
while using a minimum of
material.

ADVANTAGES OF
GEODESIC DOMES
DISADVANTAGES OF
GEODESIC DOMES

TYPES OF GEODESIC DOMES

BRACED STRUCTURES
• A braced frame is a structural system is commonly used
in structures subject to lateral loads.
• The addition of a bracing frame increases a structure's stability against
lateral loads such as wind loading and seismic pressure.
• The members in a braced frame are generally made of structural steel,
which can work effectively both in tension and compression.
• The beams and columns that form the frame carry vertical loads, and the
bracing system carries the lateral loads.
• Braced frames reduce lateral displacement, as well as the bending
moment in columns, they are economical, easily erected and have
the design flexibility to create the strength and stiffness required.
• The positioning of braces however, can be problematic as they can
interfere with the design of the façade and the position of openings.
• Buildings adopting high-tech or post-modernist styles have responded to
this by expressing bracing as an internal or external design feature.

Bracing systems
• The resistance to horizontal forces is provided by two bracing systems:
• Vertical bracing
• Bracing between column lines (in vertical planes) provides load paths for the
transference of horizontal forces to ground level.
• Framed buildings required at least three planes of vertical bracing to brace both
directions in plan and to resist torsion about a vertical axis.
• Horizontal bracing
• The bracing at each floor level (in horizontal planes) provides load paths for the
transference of horizontal forces to the planes of vertical bracing.
• Horizontal bracing is needed at each floorlevel, however, the floor system itself may
provide sufficient resistance. Roofs may require bracing.
TYPES OF BRACING
.1 Single diagonals
2 Cross-bracing
3 K-bracing
4 V-bracing
5 Eccentric bracing

• Trussing, or triangulation, is formed by inserting diagonal
structural members into rectangular areas of a structural frame,
helping to stabilize the frame. If a single brace is used, it is
sufficiently resistant to tension and compression
• Cross-bracing (or X-bracing) uses two diagonal member
• crossing each other. These only need to be resistant to
tension, one brace acting to resist sideways forces at a time
depending on the direction of loading.
• As a result, steel cables can also be used for cross-bracing.
• However, this provides the least available space within
the façade for openings
• Braces connect to the columns at mid-height.
• This frame has more flexibility for the provision of openings and
results in the least bending in floor beams.
• K-bracing is generally discouraged in
• seismic regions because of the potential for column failure
Types of bracing
K-bracing
Single diagonal bracing

• This involves two diagonal members extending from the top
two corners of a horizontal member and meeting at a
center point at the lower horizontal member, in the shape of
a V.
• Inverted V-bracing (also known as chevron bracing)
involves the two members meeting at a center point on the
upper horizontal member.
• This can mean that when the braces reach their resistance
capacity, the load must instead be resisted in the bending of
the horizontal member.
• this is commonly used in seismic regions and allows for doorways
and corridors in the braced bays.
• It is similar to V-bracing but instead of the bracing members
meeting at a center point there is space between them at the
top connection.
• Bracing members connect to separate points on the beam
• This is so that the 'link' between the bracing members absorbs
energy from seismic activity through plastic deformation.
• Eccentric single diagonals can also be used to brace a frame.
V-bracing
Eccentric -bracing

FOLDED STRUCTURES
• Folded structures are spatial structures formed by the elements in the plane,
different in form and materialization
• Folded structures differ in: geometric form,
• the form of a base over which they are performed,
• the manner of performance,
• methods of forming stiffness,
• function and position in the building,
• and the material they are made of.
• By using folded structures different spatial forms can be made.
The straight elements forming folded construction can be of various shapes:
rectangular,
trapezoidal
triangular.
By combining these elements
we get different forms resulting
in a variety of shapes and
remarkable architectural
expression.

Based on geometric shape folded structures can be divided in

The shape of folded structures affects
the transmission of load and direction
of relying of folded structures.
Based on these parameters
we can do the division in
linear folded plate structure,
radial folded plate structure,
spatial folded plate structure.

DEC 2013
Differentiate between the following types of domes
A] geodesic domes *B]lamella domes c] grid domes
Apr 2013
With the help of neat sketches explain the following types of structural systems
A] single layer grids B] double layer grids
FEB 2015
Explain about
A] single and double layer grids B] plate type domes C] geodesic domes
Braced and folded structures
SEP 2015 JNA 2016 FEB 2017
Write short notes on
A] geodesic domes B] braced domes C] ribbed domes D ] network domes

UNIT 2
STRUCTURAL ELEMENTS :
BEAMS AND SLABS ,
ARCHES AND CATENARIES,
VAULTS , DOMES AND CURVED MEMBERANES,
TRUSSES , PORTAL FRAMES, SPACE FRAMES

BEAMS
• Beam is the horizontal member of a structure carrying transverse loads
• Beam is a structural element that is capable of withstanding load primarily by
resisting bending.
• Beam is rectangular in section . Beam carry the floor slab
• Beams experience compressive, tensile, and shear stress as a result of the load applied
on it
• Beam transfer all the loads including its self weight to the columns or walls
TYPES OF BEAMS
Simply supported beams
Fixed beams
Cantilever beams
Continuous beams
Overhanging beams

TYPES OF LOADING ON BEAMS
• Concentrated load
• Uniformly distributed load
• Uniformly varying load
• Arbitrary load

SLAB
a large, thick, flat piece of stone or concrete, typically square or rectangular in shape. Is
used as a walking surface and load bearing surface in buildings
• A Reinforced Concrete Slab is the one of the most important component in abuilding.
• It is a structural element of modernbuildings.Slabs are supported on Columns and Beams.
• RCC Slabs whose thickness ranges from 10 to 50 cm are most often used for the
• construction of floors and ceilings.
• Thin concrete slabs are also used for exterior paving purpose
A concrete slab can be cast in two ways: It could either be prefabricated or cast in situ.
Prefabricated concrete slabs
are cast in a factory and then transported to the site ready to be lowered into place
between steel or concrete beams.
They may be pre-stressed (in the factory), post-stressed (on site), or unstressed. Care
should be taken to see that the supporting structure is built to the correct dimensions
to avoid trouble with the fitting of slabs over the supporting structure.
In situ concrete slabs
are built on the building site using formwork . Formwork is a box-like setup in which
concrete is poured for the construction of slabs.
For reinforced concrete slabs, reinforcing steel bars are placed within the formwork
and then the concrete is poured.
CONSTRUCTION PROCESS OF SLAB

Types of Slabs
• FLAT SLABS
• RIBBED AND WAFFEL SLABS
• CORRUGATED SLABS
Flat Slab:
A flat slab is a one-way or two-way system with thickenings in the slab at the columns
and load bearing walls called „drop panels‟
Advantages
• Simple formwork
• No beams
• Minimum structural depth
• Doesn‟t require
• shear reinforcement
• Disadvantages
• Medium spans
• Generally not suitable for supporting brittle (masonry) partitions
• Drop panels may interfere with larger mechanical ducting
• Vertical penetrations need to avoid area around columns
• For reinforced flat slabs, deflection at the middle strip may be critical.

Ribbed and waffle slabs
Ribbed and waffle slabs provide a lighter and stiffer slab than an equivalent
flat slab, reducing the extend of foundations. They provide a very good form
where slab vibration is an issue, such as laboratories and hospitals.
Benefits
Flexible
Relatively light, therefore less foundation costs
and longer spans are economic speed of
construction
Fairly slim floor depths
Robustness
Excellent vibration control
Thermal mass
Good for services integration
Durable finishes
Fire resistance Corrugated
, usually where the concrete is poured into
a corrugated steel tray. This improves
strength and prevents the slab bending
under its own weight. The corrugations run
across the short dimension, from side to
side.

reinforcement Design in Slabs
one way slab
has structural strength in shortest direction.
Main reinforcement should be along slab‟s short direction
two way slab
has structural strength in two directions .
Main reinforcement runs both in short and long direction and stay
perpendicularly with one another.

ARCH
An Arch is a structure constructed of wedge-shaped unit.
It spans an opening to support the weight of the wall and other superimpose load.
Arches are classified according to:-
1. Shape 2. Number of Centers 3. Workmanship and Material Used
SHAPE NO.OF CENTERS MATERIALS
1. FLAT ARCH
2. SEMI CIRCULAR
3. POINTED
4. STILTEDARCH
5. SEGMENTAL
6. HORSHE SHOE
7. RELEIVING
8. SEMI –
ELLIPITICAL
9. VENETIAN
10. FLORENTINE
1. ONE
2. TWO
3. THREE
4. FOUR
5. FIVE Centred
arches
1. STONE ARCH
2. BRICK ARCH
3. CONCRETE
ARCH

• An arch is a pure compression form.
• It can span a large area by resolving forces into compressive
stresses and, in turn eliminating tensile stresses.
• This is sometimes referred to as arch action.
• As the forces in the arch are carried to the ground, the arch
will push outward at the base, called thrust.
• As the rise, or height of the arch decreases, the outward
thrust increases.
• In order to maintain arch action and prevent the arch from
collapsing, the thrust needs to be restrained, either with
internal ties, or external bracing, such as abutments

Stone Arch 1. Rubble Arches Weak and use for
comparatively inferior work. Made by stones which
are dressed, roughly shaped and sized as voussoirs
Mortar is used for binding stones
2. Ashlars Arches Made by stones which are fully
dressed and in proper shape of voussoir. Lime or
cement mortar is use as binding material. Use for
making Flat arches
1. Concrete block-unit Arch Made with pre
casted concrete blocks.(moulds in shape of
voussoirs) Good appearance and size of
arch achieved due to perfections.
Cement mortar is used as a binding
material and joints are thin.
2. 2. Monolithic Arch Made with cast-in-
situ concrete, either plain or reinforced.
Suitable for large span. The thickness is
15cm for arches upto 3m span.

3. Gauged Arch Made with bricks which
are prepared to exact size and shape of
voussoir. Joints are fine , thin and truly
radial. Lime putty is use as a binding
material.
4. Purpose made brick Arch Made with
special bricks which are manufactured in
exact shape and size of voussoirs. This is
very fine workmanship. Lime putty is
used as a binding material.
1. Rough Arch Made with ordinary bricks
Joints are wedge-shaped with greater
thickness at extrados and smaller
thickness at intrados. Not used for
exposed brick work.
2. 2. Axed or Rough-cut Arch Made with
wedge shaped bricks Joints are of
uniform thickness. Not so attractive
due to wedge shaped bricks which are
not finely dressed.

THE CATENARY AND THE ARCH ACTIONS
CATENARY ARCH
It is a type of the arch that is formed
when a rope or chain hanging loosely
between two different fixed points
A curved structure designed to
carry loads across a gap formed
mainly due to compression
The geometry of the curve further
effects the cost and stresses
Arches can
be three
pinned ,
two pinned
or rigid

• If a flexible chain or rope is loosely hung between two fixed points, it hangs in a curve
that looks a little like a parabola, but in fact is not quite a parabola; it is a curve
called a catenary, which is a word derived from the Latin catena, a chain.
• A catenary is the name for a curve that occurs naturally when a chain of uniform
density is allowed to hang.
• CATENARY ITSELF IS A FORM OF ARCH
• The theoretical advantage is that mass is minimized. As mass is often a good for cost
Decrement, it follows that catenary structures are often cheap (the structure is to be
built out of metal girders, because girders tend to be straight).
• The catenary is the natural shape of a hanging chain, which must, by definition, be
loaded purely in tension. If the shape is inverted to form an arch, then that arch would
be loaded purely in compression.
• In either case, you've got a (somewhat) complicated shape, but a very simple load
path, and this means that it's a relatively simple job to make sure that the structural
stress is optimised (the trade is between safety margin and material mass).
CATENARY

Catenary
Suspension Bridge
The stainless steel-plated arch is in the shape
of an inverted, weighted catenary curve. It
spans 630 feet at ground level from outer
edge to outer edge and is 630 feet high,
making it the tallest man-made monument
in the US. Designed by Eero Saarinen

1. ARCH 1. CATENARY
1. IS A PURE COMPRESSION
FORM
2. ARCH IS AN
INDEPENDENT SYSTEM
3. ARCH HAS VARIOUS
CLASSIFICATION
4. THERE ARE VARIOUS
NUMBER OF FORMS
FOR ARCHES
1. IS A PURE TENSION
FORM
2. CATENARY IS A FORM
OF ARCH
3. CATENARY IS ONLY ONE
4. THERE ARE NOT MANY
SHAPES ONLY FEW
FORMS CAN BE
CONSTRUCTED
5. THE INVERTED FORM OF
ARCH IS CALLED A
CATENARY

VAULTS
Vault is an architectural term for an arched form used to provide a space with a
ceiling or roof.[
An arched structure , usually of masonry , used as ceiling or canopy or as a support
for the roof.
TYPES OF VAULTS
• Barrel vault
• Groin vault
• Rib vault
• Cloister vault
• Fan vault
• Net vault
• Annular vault
• Rampant vault
• Catalan vault
Elements of vaults
• ABUTMENT A structure built to support the lateral pressure of an
arch or span, e.g. at the ends of a bridge
• IMPOST Top course of a pillar or a wall that supports the arch or
vault.
• INTRADOS Inner curve of an a arch or vault.
• VOUSSIOR A wedge shaped or tapered stone used to construct an
arch or a vault .

Effects & solutions
• Brick, stone and concrete are materials strong in compression, but weak in tension (if
the structural breadth increases, the material has to be supported by many columns or it
collapses).
• Solution: • This problem is solved by steel structures or the use of steel reinforced
concrete - the tensile strength of steel is significantly more than that of bricks, stone or
plain concrete. • The technique was cheap, fast, ecological and durable.
• Gives more volume at a lower costs than
adding floor area .
• It looks good over other forms of
construction .
• Dead load can be reduced by economizing
foundation and supporting system.
• The curved shapes often used for concrete
are naturally strong structures.
• Using RCC as a building material reduces
both material cost and the construction cost.
• As concrete is relatively inexpensive and
easily cast into compound curves
• Increased cooling or heating costs
• Good labour and supervision necessary.
• Raise of roofs may be a disadvantage .
• Shuttering problem .
• Since concrete is porous material,
concrete vaults or domes often have issues
with sealing. If not treated, rain water can
seep through the roof and leak into the
interior of the building.
ADVANTAGES AND DISADVANTAGES

• MATERIALS USED
Bricks , stone , timber ,
wood, Rcc are used
generally.
• In stone barrel vault
due to the problem of
fenestration , they
provide a small
window which restricts
the more light.
• Bricks are installed
vertically ( not
radially ) and are
leaning at an angle. •
Its construction doesn‟t
require centering.

WITHOUT BEING STRUCTURALLY
WEAKENED MUST BE BUTTRESSED ALONG
ITS ENTIRE LENGTH BY HEAVY WALLS .
A VAULT IS A CEILING OF BRICK ,
CONCRETE, STONE , TIMBER ,ETC
BUILT IN PRINCIPLE OF ARCH
AN ELONGATED FORM OF ARCH
DOMES CAN BE SUPPORTED BY
COLUMNS OR PIERS
A DOME IS AN ELEMENT OF
ARCHITECTURE THAT RESMBLES THE
HOLLOW UPPER PART OF A SPHERE.
DOMES VAULTS
AN ARCH ROTATED AROUND ITS CENTRAL
AXIS
IT CANNOT BE LIGHTED EXCEPT AT
THE ENDS
IT CAN BE LIGHTED AT THE
CENTRAL AXIS

DOMES
DOMES:
Domes are curved architectonic structures with no angles or corners, similar to
the upper half of a sphere.
Despite their apparent fragility, domes are strong structures and have been
used in buildings since ancient times . the earliest domes were made of stone.
MATERIALS:
STONE, BRICK ,CONCRETE , MUD ,GLASS, WOOD ,METAL ,PLASTIC

• Beehive dome
• Bulbous dome
• Cloister vault
• Crossed-arch
dome
• Geodesic
dome
• Hemispherical
dome
• Onion dome
• Oval dome
• Parabolic
dome
• Sail dome
• Saucer dome
• Umbrella
dome
TYPES OF DOME
• Domes are concave from below, they can reflect
sound and create echoes.
• The earliest domes in the Middle East were built
with mud-brick and, eventually, with baked brick
and stone.
• Wooden domes were protected from the weather
by roofing such as copper or lead sheeting.
• Brick domes were the favoured choice for large-
space monumental coverings until the Industrial
Age, due to their convenience and dependability.
• The domes in the churches where semi-domes
(apse), for example, echoed the chants of the
people.

TRUSSES
a truss is a structure comprising one or more triangular units constructed with straight
members whose ends are connected at joints referred to as nodes.
• Trusses are categorized into 3 groups depending on the shape of the top chord
• 1 TRIANGULAR ROOF TRUSS
• simple triangular geometric shape
• web bracing
• straight top chord
• 2 CRESCENT ROOF TRUSSES
• 3 OTHER TYPE

ROOF TRUSS STRESS TYPES
ROOF TRUSS PANEL POINTS

PORTAL FRAMES
• A portal frame consists of vertical member called Columns and top member
which may be horizontal, curved or pitched.
• Rigidly connected
• The base of portal frame may be hinged or fixed.
• Portal frames are made in a variety of shapes and sizes.
• They are usually made from steel, but can also be made from concrete or timber.
• The portal structure is designed in such a way that it has no intermediate columns,
as a result large open areas can easily be created within the structure.
• Portal Frames are generally used for single storey construction which require a
large unobstructed floor space ie
• Factories , bridges
• Shopping Centres , large sheds
• Warehouses , via ducts

Advantages
• Speed and ease of erection
• Building can 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.
• Connected together in factories by welding and site connections should be bolted.
Disadvantages
• Although steel is incombustible it has a poor resistance to fire as it bends easily when
hot.
• Subject to corrosion
ADVANTAGES AND DISADVANTAGES OF STEEL PORTAL FRAMES

SPACE FRAMES
• A space frame is a truss-like, lightweight rigid structure constructed from
interlocking struts in a geometric pattern.
Space frames usually utilize a
multidirectional span, and are often used to
accomplish long spans with few supports.
They derive their strength from the inherent
rigidity of the triangular frame; flexing loads
(bending moments) are transmitted as tension
and compression loads along the length of each
strut.
Space frames are an increasingly common
architectural technique especially for large roof
spans in modernist commercial and industrial
buildings petrol pumps ,exhibition halls , atriums
,lighting towers ,stadiums , airport hangers, toll
plaza etc.

• ROOFING MATERIALS USED
1]Polycarbonate sheets, 2 ] fiberglass reinforced plastic sheets or glazing used for covering,
to provide aesthetically beautiful sky light systems .
However, colour-coated steel sheets. alluminium sheets and asbestos sheets are also used
depending on the purpose and usage of the building
APPLICATIONS:
Malls, Food courts, Transport terminals, Schools, Pools, Arenas, Entertainment, Hospitals, Hotels, Corporate &
Commercial Buildings, Convention centers
BENEFITS:
• Minimum structure weight
• Long clear spans & cantilevers
• Accommodates concentrated loads
• Suits irregular supports or plan geometry
• Variable depth for roof drainage is built in
• Pre-assembly allows project acceleration
• Pre-finished to avoid site painting & inspection
• All service lines can run through frame
• Frame can be a feature without ceiling
• Simple modification or dis-assembly for re-use
SALIENT FEATURES
1) Enormous Spanning Capability. 2) Light Weight 3) High Aesthetics
4) High Resale Value 5) Higher Safety Factor 6) Extension With Additional Unit

TYPES OF QUESTIONS FROM UNIT 2
DEC 2013
What is the basic difference between a horizontal slab and a dome ? Which one do u
think can carry more load or covering the same area ? Explain with reason
Short notes on catenaries
Apr 2013
What is the difference between the following structural elements
a] Beams and slabs b] Arches and catenaries
Short notes on a] catenary b] curved membranes
FEB 2015
Explain in detail the structural forces and aspect of
a] Beams and slabs b] types of trusses
SEP 2015 Explain different types of beams and their structural behaviour
Short notes on vaults a] curved members b] portal frames c] space frames
JNA 2016
List the various structural elements and illustrate their use in structural systems
FEB 2017
Short notes on a] domes and curved membranes b] arches and catenaries c] trusses
d] portal and space frames

UNIT 5
SPACE FRAMES :
FOLDED PLATES , SHELLS
CYCLONICAL SHELLS,
HYPERBOLIC PARABOLOIDS,
FREE FORMS
CABLE STRUCTURES : SIMPLY CURVED SUSPENDED ROOFS,
COMBINATION OF CABLES AND STRUTS

FOLDED PLATES
Folded plates are assemblies of flat plates rigidly connected together along their
edges in such a way the structural system capable of carrying loads without the
need for additional supporting beams along mutual edges

Based on geometric shape folded plates can be divided in

SHELL
THE TERM “SHELL” IS USED TO DESCRIBE THE STRUCTURES WHICH POSSESS
STRENGHT AND RIGIDITY DUE TO ITS THIN, NATURAL AND CURVED FORM SUCH AS
SHELL OF EGG, A NUT, HUMAN SKULL, AND SHELL OF TORTISE.
A SHELL STRUCTURE IS A THIN CURVED MEMBRANE OR SLAB USUALLY OF
REINFORCED CONCRETE THAT FUNCTIONS BOTH AS STRUCTURE AND
COVERING.
• SINGLE CURVATURE SHELL: ARE CURVED ON ONE LINEAR AXIS AND ARE
A PART OF A CYLINDER OR CONE IN THE FORM OF BARREL VAULTS AND
CONOID SHELLS.
• DOUBLE CURVATURE SHELL: ARE EITHER PART OF A SPHERE, OR A
HYPERBOLOID OF REVOLUTION.
• . THE TERMS SINGLE AND DOULBE CURVATURE ARE USED TO DISTINGUISH
THE COMPARITIVE RIGIDITY OF THE TWO FORMS AND COMPLEXITY OF
CENTRING NECESSARY TO CONSTRUCT THE SHELL FORM.

HYPERBOLIC PARABOLOIDS
• A hyperbolic paraboloid is a doubly-curved surface that resembles the shape of a
saddle, I.E it has a convex form along one axis, and a concave form on along the
other.
• It is also a doubly-ruled surface, that is, every point on its surface lies on two
straight lines across the surface
• . Horizontal sections taken through the surface are hyperbolic in format and
vertical sections are parabolic.
• The fact that hyperbolic paraboloids are doubly-ruled means that they are easy
to construct using a series of straight structural members.
• As a consequence they are commonly used to construct thin „shell‟ roofs.
• These can either be formed using timber or steel sections, that are then clad, or
they can be constructed using concrete.
• The use of hyperbolic paraboloids as a form of thin shell construction was
pioneered in the post-war era, as a hybrid of modern architecture and structural
engineering.
• By being both lightweight and efficient, the form was used as a means of
minimizing materials and increasing structural performance while also being
capable of achieving impressive and seemingly complex designs.

• Rather than derive their strength from mass, like many conventional roofs, thin shell
roofs gain strength through their shape.
• The curvature of the shape reduces its tendency to buckle in compression (as a flat
plane would) and means that they can achieve exceptional stiffness.
• By being braced in two directions they experience no bending and are able to
withstand unequal loading, whether dead loads (such as equipment hung from the
ceiling), or live loads (such as wind).
• Hyperbolic paraboloid shell roofs can be constructed using reinforced concrete with
a shell thickness of just 50 mm for diagonal spans up to 35 m.
• By using simple pre stressing cables to resist tension forces, concrete hyperbolic
paraboloid roofs can span over 24 feet, with thicknesses of less than 40 mm.

• Free-form structures and domes can be used to cover large expanses of space in a
variety of venues.
• Arenas, atria, museums, houses of worship, and industrial buildings all require large
covered areas without intermediate columns.
• In order to realize these large structures effectively, design professionals should shape
these buildings to take advantage of form both as a structural element and for
architectural expression.
• But few construction systems allow full geometric freedom and economic efficiency.
Until now.
FREE FORMS
The GeometricaL System
• Geometry, and the building system used to realize it, are clearly interrelated. Unless
the right combination of structural system and overall geometry are used, the resulting
structures may not be feasible.
• Solutions with joist, for example, are limited to planar trusses in an array, and work in
only one direction.
• Solutions with machined joints, such as ball-joint systems, must minimize the number
of nodes, as these are expensive.
• Thus, with traditional construction systems, some geometries become impractical even
if they could result in material savings.
• Geometrica's bulding system solves these problems.

• INTRODUCTION
• A cable is a flexible structural component that offers no resistance when compressed
or bent in a curved shape.
• Technically we can say cable has zero bending rigidity.
• It can only support tensile loading.
• Cables are often used in engineering structures for support and to transmit load
from one point to another when used to support suspension roofs, bridges and trolley
wheels, cables form the main load carrying element in the structure.
• In analysis of cables the weight of cable itself is rejected .
• We assume that cable is flexible . Due to its flexibility cables offers no resistance to
shear or bending.
• Being inextensible the cable has constant length before and after the load is
applied. As a result once the load is applied the geometry of cable remains fixed.
• The easiest structure type to think is a tension structure to resist only tensile force
are cables
• the simplest are those which sustain only unidirectional tension as represented by a
cable or thin rod.
• A cable is the main component of cable supported bridge or suspended roof
structures that are classified as follows
CABLES

Types of Cables There are generally two types of cables structure
. 1- Suspension type Cables.
2- Stayed type Cables.
• The suspension cables must be anchored at each end of the bridge, since any load
applied to the bridge is transformed into a tension in these main cables
• . The main cables continue beyond the pillars to deck-level supports, and further
continue to connections with anchors in the ground.
• There are two major classes of cable-stayed bridges:
• harp and fan.
• In the harp or parallel design, the cables are nearly parallel so that the height of
their attachment to the tower is proportional to the distance from the tower to
their mounting on the deck.
• In the fan design, the cables all connect to the top of the towers.
• The fan design is structurally superior with minimum moment applied to the towers
but for practical reasons the modified fan is preferred especially where many cables
are necessary.

ASSUMPTIONS
Cables are pure tension members.
Used as
Supports to suspension roofs
Suspension bridges
Trolley wheels
Self weight of cable is neglected in analysis of above structures
When used as cables for antennas or transmission lines, weight is considered.

DEC 2013
Explain the difference between a plane frame and a space frame illustrate some of the
commonly used space frames
Apr 2013
What is a space frame ? Illustrate with sketches different types of space frames .give the
situations in which each can be advantageously used
What is a cable structure ? With the help of neat sketches illustrate the different type of
cable structures .give the situation in which one of these can be used
FEB 2015
What is the function of space frame and where is it used ?
Explain about function of folded plates
Short notes on cables and struts hyperbolic paraboloids
SEP 2015
What is folded plate system ? How and where do you use it ? Explain the structural
difference between a folded plate roof and flat roof
Short notes on cable structures portal frames
JAN 2016
Explain the difference between shell and folded plate structures what are the
advantages and disadvantages of these?
FEB 2017
Explain the following space frames cable structures cyclonical shell

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