1.2.1 Roofing and wall material In India, corrugated galvanized iron (GI) sheets are usually adopted as coverings for roofs and sides of industrial buildings. Light gauge cold-formed ribbed steel or aluminium decking can also be used. Sometimes asbestos cement (AC) sheets are also provided as roof coverings owing top their superior insulating properties.
1.2.4 Purlins, Girts and Eave strut Secondary structural members such as purlins and girts span the distance between the primary building structures portal frames or truss-column system). They support the roof and wall covering and distribute the external load to the main frames or trusses. Purlins form a part of the roof bracing system and girts are a part of the wall bracing system of the building. The third type of secondary structural member is the Eave strut. This member is located at the intersection of the roof and the exterior wall and hence acts as both the first purlin and the last (highest) girt. The building’s eave height is measured to the top of this member
1.2.4 Purlins, Girts and Eave strut Secondary structural members such as purlins and girts span the distance between the primary building structures portal frames or truss-column system). They support the roof and wall covering and distribute the external load to the main frames or trusses. Purlins form a part of the roof bracing system and girts are a part of the wall bracing system of the building. The third type of secondary structural member is the Eave strut. This member is located at the intersection of the roof and the exterior wall and hence acts as both the first purlin and the last (highest) girt. The building’s eave height is measured to the top of this member
Reinforced
concrete (RC) is a versatile composite and
one of the most widely used materials in modern construction. Concrete is
a relatively brittle material that
is strong under compression but
less so in tension. Plain,
unreinforced concrete is
unsuitable for many structures as
it is relatively poor at withstanding stresses induced
by vibrations, wind loading, and so on.
To increase its overall strength, steel rods,
wires, mesh or cables can
be embedded in concrete before
it sets. This reinforcement, often known as rebar, resists
tensile forces. By forming a strong bond together,
the two materials are
able to resist a variety of applied forces,
effectively acting as a single structural element.
Whilst concrete has
been used as a construction material since Roman times, the use
of reinforcement, in the form of iron was
only introduced in the 1850s by French industrialist François Coignet, and it
was not until the 1880s that German civil engineer G. A. Wayss used steel as reinforcement.
Reinforced
concrete can be precast or cast-in-place (in situ) concrete, and is
used in a wide range of applications such as; slab, wall, beam, column, foundation,
and frame construction. Reinforcement is generally placed
in areas of the concrete that
are likely to be subject to tension, such as
the lower portion of beams. It is
usual for there to be a minimum of 50 mm cover, both above and below the steel reinforcement, to resist spalling and corrosion which
can lead to structural instability.
There are also a number of types
of non-steel reinforcement that can be used,
predominately as a means of controlling cracking. Fibre-reinforced concrete is a concrete mix
that contains short discrete fibres that are distributed uniformly throughout
the material. Fibres can be made of glass, polypropylene, synthetic and natural materials, as well as steel.
Prestressed concrete allows for
predetermined, engineering stresses to
be placed in concrete members to
counteract the stresses that
occur when they are subject to loading. In ordinary reinforced concrete, stresses are
carried by the steel reinforcement, whereas prestressed concrete supports
the load by induced stresses throughout
the entire structural element.
This makes it more resistant to
shock and vibration than
ordinary concrete, and
able to form long, thin structures with
much smaller sectional areas to
support equivalent loads.
Pre-stressing may be achieved by pre-tensioning or post-tensioning.
See Prestressed concrete for
more information.
Reinforced
concrete is extremely durable and
requires little maintenance. It
has good thermal mass, and is inherently fire resistant. Rebar is
generally made from 100% recycled scrap, and at the demolition stage,
the concrete and rebar are
capable of being separated so that the steel can
be recycled.
However, concrete has
a relatively high embodied energy, resulting from its
extraction, manufacture and transportation. Waste materials can
be included within the concrete mix
such as RCA (Recycled Crushed Aggregate), GGBS (Ground Granulated
Blast-Furnace Slag) and PFA
(Pulverised Fuel Ash),
however, issues such as moisture content and material variability
may make its recycling unviable.
Cooling tower
It
can be necessary to provide cooling to buildings during warm weather, or where there are significant thermal gains (such as solar gain, people and equipment). This cooling is sometimes referred to as comfort cooling. Cooling may also be necessary for refrigeration or for some industrial processes.
Evaporative cooling is one of the methods that can be used to
provide cooling. When water evaporates,
it absorbs significant amounts of heat energy (latent heat, expressed in J/kg). The water itself
does not change temperature, as the energy is
consumed by the physical process of changing its state from liquid to gas.
This produces a cooling effect in its surroundings. So when water evaporates
from the surface of a building, or when sweat evaporates from the skin, this has a cooling effect. Conversely, when water condenses
it releases heat.
Direct
evaporative coolers (sometimes referred to as sump coolers,
swamp coolers, or desert coolers), draw hot, dry air through a continually
dampened pad and supply cool,
humid air.
Indirect evaporative cooling can be achieved by using a heat exchanger to cool the supply air,
by spraying water over
the cooling coils of a conventional chiller or by cooling towers.
Cooling towers reject heat through
the evaporation of water in
a moving air stream within the cooling tower. The temperature and humidity of the air stream increases through contact with the
warm water, and this air is then discharged. The
cooled water is collected at the bottom of the tower.
This process can achieve lower temperatures than air-cooled heat rejection systems.
Cooling towers,
can be small-scale roof-top installations, medium-sized packaged units,
or very large hyperboloid structures sometimes associated with industrial processes or power stations
with their characteristic plume of water vapour in the exhaust air.
Cooling towers can
be open or closed circuit. Closed circuit cooling towers (or fluid coolers) feed the ‘warm’ water over
a 'fill' through which the air is flowing. The cool water is
collected, and the humid air discharged remotely to prevent recirculation. This
closed process relies entirely on the rejection of heat through
the air. The flow of air through the fill can be horizontal (crossflow) or
vertical (counterflow).
In
open-circuit cooling towers (or
wet cooling towers),
the hot humid air is discharged direct to the atmosphere. This can be more
straight forward, however, there is a risk of contamination as the cooling tower is open, and the proportion of water that
evaporates must be replaced resulting in the progressive concentration of
the water. The build up of minerals and other solids in the water must
then be regulated.
Dry cooling towers use a heat exchanger to separate the water from
the air.
The
air flow in cooling towers can
be mechanically driven (induced draft)
or naturally driven (natural draft),
relying on the buoyancy of the warm exhaust air to generate ‘draft’.
The water flow
can be gravity driven or can be a pressurised spray.
In HVAC systems, the cooling tower is
used to reject heat from chiller units which supply chilled water for comfort cooling systems. These will typically cool air in air handling units that is then ducted to the internal spaces of
the building. Water-cooled chillers can be more efficient than air-cooled chillers, but more infrastructure (and so space)
is required.
Concrete frame
High rise buildings and parking garages are normally built using
a concrete frame because it is stronger than many other building
materials. Concrete frame construction utilizes reinforced concrete
columns, as well as concrete slabs and concrete beams to construct the support
structure of the building. Most reinforced concrete is readily available,
but it can be a time-consuming process if it needs to be cast on the
construction site. Unfortunately, building structures often require that
the concrete components are cast on-site. That means that it takes longer
for completion due to the curing process.
The advantages of a concrete frame building structure are that
it can use recycled steel for the reinforced steel portions. The concrete
can also be locally sourced and formed into almost any shape that is
desired. As mentioned above, this can be a time-consuming process, plus
the concrete may need to be substantially engineered if the building is in an
area prone to earthquakes.
The basic
components of a building structure are the foundation, floors, walls,
beams, columns, roof, stair, etc. These elements serve the purpose
of supporting, enclosing and protecting the building structure.
Fig.1.Basic Components of a Building; Image Courtesy: Decole
Mentioned below are the 12 basic
components a building structure.
- Roof
- Parapet
- Lintels
- Beams
- Columns
- Damp
proof course (DPC)
- Walls
- Floor
- Stairs
- Plinth
Beam
- Foundation
- Plinth
1. Roof
The roof forms the topmost component
of a building structure. It covers the top face of the building. Roofs can be
either flat or sloped based on the location and weather conditions of the area.
2. Parapet
Parapets are short walls extended
above the roof slab. Parapets are installed for flat roofs. It acts as a safety
wall for people using the roof.
3. Lintels
Lintels are constructed above the
wall openings like doors, windows, etc. These structures support the weight of
the wall coming over the opening. Normally, lintels are constructed by
reinforced cement concrete. In residential buildings, lintels can be either
constructed from concrete or from bricks.
4. Beams
and slabs
Beams and slabs form the horizontal
members in a building. For a single storey building, the top slab forms the
roof. In case of a multi-storey building, the beam transfers the load coming
from the floor above the slab which is in turn transferred to the columns.
Beams and slabs are constructed by reinforced cement concrete (R.C.C).
5. Columns
Columns are vertical members constructed
above the ground level. Columns can be of two types: Architectural columns and
structural columns. Architectural columns are constructed to improve the
building's aesthetics while a structural column takes the load coming from the
slab above and transfers safely to the foundation.
6. Damp
Proof Course(DPC)
DPC is a layer of waterproofing
material applied on the basement level to prevent the rise of surface water
into the walls. The walls are constructed over the DPC.
Read
More: Damp Proof Course (DPC)
7. Walls
Walls are vertical elements which
support the roof. It can be made from stones, bricks, concrete blocks, etc.
Walls provide an enclosure and protect against wind, sunshine, rain etc.
Openings are provided in the walls for ventilation and access to the building.
8. Floors
The floor is the surface laid on the
plinth level. Flooring can be done by a variety of materials like tiles,
granites, marbles, concrete, etc. Before flooring, the ground has to be
properly compacted and leveled.
9. Stairs
A stair is a sequence of steps that connects different floors in a building structure. The space occupied by a stair is called as the stairway. There are different types of stairs like a wooden stair, R.C.C
10. Plinth
Beam
Plinth beam is a beam structure
constructed either at or above the ground level to take up the load of the wall
coming over it.
11. Plinth
The plinth is constructed above the
ground level. It is a cement-mortar layer lying between the substructure and
the superstructure.
12.
Foundation
The Foundation is a structural unit
that uniformly distributes the load from the superstructure to the underlying
soil. This is the first structural unit to be constructed for any building
construction. A good foundation prevents settlement of the building.
Read
More: What are foundation?
The basic
components of a building structure are the foundation, floors, walls,
beams, columns, roof, stair, etc. These elements serve the purpose
of supporting, enclosing and protecting the building structure.
Fig.1.Basic Components of a Building; Image Courtesy: Decole
Mentioned below are the 12 basic
components a building structure.
- Roof
- Parapet
- Lintels
- Beams
- Columns
- Damp
proof course (DPC)
- Walls
- Floor
- Stairs
- Plinth
Beam
- Foundation
- Plinth
1. Roof
The roof forms the topmost component
of a building structure. It covers the top face of the building. Roofs can be
either flat or sloped based on the location and weather conditions of the area.
2. Parapet
Parapets are short walls extended
above the roof slab. Parapets are installed for flat roofs. It acts as a safety
wall for people using the roof.
3. Lintels
Lintels are constructed above the
wall openings like doors, windows, etc. These structures support the weight of
the wall coming over the opening. Normally, lintels are constructed by
reinforced cement concrete. In residential buildings, lintels can be either
constructed from concrete or from bricks.
Read
More: Lintel Construction
4. Beams
and slabs
Beams and slabs form the horizontal
members in a building. For a single storey building, the top slab forms the
roof. In case of a multi-storey building, the beam transfers the load coming
from the floor above the slab which is in turn transferred to the columns.
Beams and slabs are constructed by reinforced cement concrete (R.C.C).
5. Columns
Columns are vertical members constructed
above the ground level. Columns can be of two types: Architectural columns and
structural columns. Architectural columns are constructed to improve the
building's aesthetics while a structural column takes the load coming from the
slab above and transfers safely to the foundation.
6. Damp
Proof Course(DPC)
DPC is a layer of waterproofing
material applied on the basement level to prevent the rise of surface water
into the walls. The walls are constructed over the DPC.
Read
More: Damp Proof Course (DPC)
7. Walls
Walls are vertical elements which
support the roof. It can be made from stones, bricks, concrete blocks, etc.
Walls provide an enclosure and protect against wind, sunshine, rain etc.
Openings are provided in the walls for ventilation and access to the building.
8. Floors
The floor is the surface laid on the
plinth level. Flooring can be done by a variety of materials like tiles,
granites, marbles, concrete, etc. Before flooring, the ground has to be
properly compacted and leveled.
9. Stairs
A stair is a sequence of steps that connects different floors in a building structure. The space occupied by a stair is called as the stairway. There are different types of stairs like a wooden stair, R.C.C stair
What is a staircase?
10. Plinth
Beam
Plinth beam is a beam structure
constructed either at or above the ground level to take up the load of the wall
coming over it.
11. Plinth
The plinth is constructed above the
ground level. It is a cement-mortar layer lying between the substructure and
the superstructure.
12.
Foundation
The Foundation is a structural unit
that uniformly distributes the load from the superstructure to the underlying
soil. This is the first structural unit to be constructed for any building
construction. A good foundation prevents settlement of the building.
Reinforced
Cement Concrete Lintel
At present, the lintel made of
reinforced concrete are widely used to span the openings for doors, windows,
etc. in a structure because of their strength, rigidity, fire resistance,
economy and ease in construction. These are suitable for all the loads and for
any span. The width is equal to width of wall and depth depends on length of
span and magnitude of loading.
Main reinforcement is provided at the
bottom and half of these bars are cranked at the ends. Shear stirrups are
provided to resist transverse shear as shown in fig.
R.C.C boot lintels are provided over
cavity walls. These will give good appearance and economical. A flexible D.P.C
is provided above as shown in fig.
What is a lintel?
A lintel is a
beam placed across the openings like doors, windows etc. in buildings to
support the load from the structure above. The width of lintel beam is equal to
the width of wall, and the ends of it is built into the wall. Lintels are
classified based on their material of construction.
What are the types of lintel in
construction?
Lintels are
classified as:
1. Timber Lintels
2. Stone Lintels
3. Brick Lintels
4. Reinforced Brick Lintel
5. Steel Lintel
6. Reinforced Concrete Lintel
What is a steel lintel?
These are
used when the superimposed loads are heavy and openings are large. These
consist of channel sections or rolled steel joists. We can use one single
section or in combinations depending up on the requirement.
When used singly, the steel joist is either embedded in concrete or cladded
with stone facing to keep the width same as width of wall. When more than one
units are placed side by side, they are kept in position by tube separators.
Reinforced
Cement Concrete Lintel
At present, the lintel made of
reinforced concrete are widely used to span the openings for doors, windows,
etc. in a structure because of their strength, rigidity, fire resistance,
economy and ease in construction. These are suitable for all the loads and for
any span. The width is equal to width of wall and depth depends on length of
span and magnitude of loading.
Main reinforcement is provided at the
bottom and half of these bars are cranked at the ends. Shear stirrups are
provided to resist transverse shear as shown in fig.
R.C.C boot lintels are provided over cavity walls. These will give good appearance and economical. A flexible D.P.C is provided above as shown in
What is a lintel?
A lintel is a
beam placed across the openings like doors, windows etc. in buildings to
support the load from the structure above. The width of lintel beam is equal to
the width of wall, and the ends of it is built into the wall. Lintels are
classified based on their material of construction.
What are the types of lintel in
construction?
Lintels are
classified as:
1. Timber Lintels
2. Stone Lintels
3. Brick Lintels
4. Reinforced Brick Lintel
5. Steel Lintel
6. Reinforced Concrete Lintel
What is a steel lintel?
These are
used when the superimposed loads are heavy and openings are large. These
consist of channel sections or rolled steel joists. We can use one single
section or in combinations depending up on the requirement.
When used singly, the steel joist is either embedded in concrete or cladded
with stone facing to keep the width same as width of wall. When more than one
units are placed side by side, they are kept in position by tube separators.
3. Cantilever
Beam
If a beam is fixed at one end and set
to be free at the other end, it is termed as a cantilever beam. The beam
distributes the load back to the support where it is forced against a moment
and shear stress. Cantilever beams allow the creation of a bay window,
balconies, and some bridges.
3. Cantilever
Beam
If a beam is fixed at one end and set
to be free at the other end, it is termed as a cantilever beam. The beam
distributes the load back to the support where it is forced against a moment
and shear stress. Cantilever beams allow the creation of a bay window,
balconies, and some bridges.
3. Cantilever
Beam
If a beam is fixed at one end and set to be free at the other end, it is termed as a cantilever beam. The beam distributes the load back to the support where it is forced against a moment and shear stress. Cantilever beams allow the creation of a bay window, balconies, and some bridges.
T-section beam
This type of beam is mostly
constructed monolithically with a reinforced concrete slab. Sometimes, Isolated
T-beam is built to increase the compression strength of concrete.
Added to that, inverted T-beam can
also be constructed according to the requirements of loading imposed.
L-section
beam
This type of beam is constructed
monolithically with a reinforced concrete slab at the perimeter of the
structure
Steel cross sectional shapes
include:
There are various steel beam
cross-sectional shapes. Each cross-sectional shape offer superior advantages in
a given condition compare with other shapes.
Square, rectangular, circular,
I-shaped, T-shaped, H-shaped, C-shaped, and tubular are examples of beam
cross-sectional shapes constructed from steel.
L-section
beam
This type of beam is constructed
monolithically with a reinforced concrete slab at the perimeter of the
structure
Steel cross sectional shapes
include:
There are various steel beam
cross-sectional shapes. Each cross-sectional shape offer superior advantages in
a given condition compare with other shapes.
Square, rectangular, circular,
I-shaped, T-shaped, H-shaped, C-shaped, and tubular are examples of beam
cross-sectional shapes constructed from steel.
The floor space index (FSI) or floor
area ratio (FAR) is the ratio of the total usable floor area of a building to
the plot area. In simple words, FSI is the maximum amount of permissible area
that can be used for construction in the given plot of land. It is also termed
as floor space ratio.
Floor space index can be further defined as the maximum area to construct on a piece of land or a plot. It varies from one city or even locality to another.
Importance
of Floor Space Index
- The
floor space index plays a significant role in controlling urban
density.
- FSI
value directly limits the number of buildings within a land or plot, and
any use of land exceeding FSI value can create unwanted pressure on the
city.
- Unauthorized
and illegal construction will increase in the absence of FSI rules.
- The
floor space index also impacts the land value in an area.
- Proper utilization of FSI rules in building
plans will
help in early approvals of building permits and NOCs.
Factors
Affecting Floor Space Index Value
FSI/FAR value is determined by the
local municipal corporations. The permissible floor space index ratio value
depends upon:
- Population
density
- Size
of the plot
- Availability
of open spaces
- Availability
of power, water, sewer lines
- Building
type
- Environmental
impact of the project
- Preparedness in the event of a natural
disaster
Calculation
of Floor Space Index
The floor area ratio is used to
calculate the total built-up area for a plot and calculate the number of floors
the building can have.
FSI is Total built-up area= FSI ✕ Area of plot
Example: To
calculate the total built-up area, one needs to know the type of building that
is being planned to construct. Generally, different buildings have different
FSI regardless of the location.
If the area of plot being used for a
project is 800 sq ft and the FSI determined for that particular city/locality
is 1.5, then the built-up area that can be constructed will be 1200 sq ft
(500×1.5). The maximum space available on the ground floor is 800 sq ft and the
remaining built-up area of 400 sq ft can be constructed on the first floor.
Thus, considering the plot area and the floor space index applicable in that
particular locality, a developer would be permitted to construct a one-story
building.
Advantages
of Floor Space Index
The floor area ratio has the
following advantages in a city or a place where construction is progressing at
a fast pace.
- FSI
maintains the ratio of open space to built-up space.
- It
controls the skyline of the city.
- It
ensures development in urban areas.
- It
ensures efficient use of resources in the city.
- It
eliminates illegal and unauthorized construction.
- It
helps government authorities in the proper planning of the city.
- It
ensures the proper layout of the city.
- It controls pollution.
What is
Premium Floor Space Index?
The premium floor space index is an
extra floor space index ratio allocated by the government by paying the premium
fee by the developer. To avail premium floor space index ratio, the width of
the road adjacent to the land must be at least 30 feet. The premium floor space
index ratio value varies, as shown in the table below:
|
Road width |
Premium FSI |
|
30-40 ft |
20% |
|
40-60 ft |
30% |
|
Over 60 ft |
40% |
Exceptions
to Floor Space Index
The following shall not be counted
for computation of floor space index:
- The
open area under a building constructed on stilts and specifically used as
parking space.
- Parking
space open to the sky.
- Ramps
running towards the parking area.
- Building
projection to the extent of 0.6 m.
- Area covered by fountains, septic tank,
manholes, water
tank,
and overhead tank.
- Stair-cabin, ramp-cabin, lift cabin with
machine room constructed on the terrace.
FAQs
Define floor space index or floor
area ratio?
The floor space
index (FSI) or floor area ratio (FAR) is the ratio of the total usable floor
area of a building to the plot area. In simple words, FSI is the maximum amount
of permissible area that can be used for construction in the given plot of
land. It can be further defined as the maximum area to construct in a piece of
land or a plot.
What are the factors which affect
floor space index value?
The
permissible floor space index ratio value depends upon:
1. Population density
2. Size of the plot
3. Availability of open spaces
4. Availability of power, water, sewer lines
5. Building type
6. Environmental impact of the project
7. Preparedness in the event of a natural disaster
What is the formula to calculate
Floor area ratio?
The floor
area ratio is used to calculate the total built-up area for a plot and
calculate the number of floors the building can have.
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