Basic Components of a Building

7/27/2019 Basic Components of a Building

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BASIC COMPONENTS OF A BUILDING

A BUILDING HAS THREE BASIC PARTS :

(i) Sub-structure or foundation,(ii) Plinth, and(iii) Super-structure.Sub-structure or Foundation is the lower portion of the building usually located

below the ground level, which transmits the loads of super-structure to the supporting

soil.

Super-structure is that part of the structure which is above ground level, and which

serves the purpose of its intended use.

Plinth is therefore defined as the portion of the structure between the surface of the

surrounding ground and surface of the floor, immediately above the ground. The level of

the floor is usually known as the plinth level. The built-up covered area measured at the

floor level is known as plinth area.

A building has the following components :

1. Foundations2. Plinth3. Masonry units : walls and columns4. Floor structures5. Doors, windows and other openings6. Sills, lintels, arches and weather shades.7. Vertical transportation structures, such as stars, lifts, ramps, etc.8. Roofs9. Building finishesThe basic functional requirements of these components will now be discussed in

the following paragraph :

1. Foundations : The basic function of a foundation is to transmit the dead loads,live loads and other loads to the subsoil on which it rests in such a way that.(a)Settlements are within permissible limits, without causing cracks in the

super-structure.

(b)Soil does not fail in shear.2. Plinth : The plinth height depends upon various factors such as need of

architectural treatment to a building, highest flood level of area, adjoining


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ground nature etc. As per the bye laws, the minimum height of the plinth

should not be 45 cm.

3. Masonry units : Walls, columns etc. : Masonry unit may be defined as theconstruction of building units bonded together with mortar. The building units

commonly known as masonry may be stones, bricks or precast blocks.

walls are the most essential components of a building. The primary function ofthe wall is to enclose or dived space of the building to make it more functional

and useful. Walls may be either load bearing or non-load bearing. Wall may be

of several types, such as cavity walls partition walls dwarf walls, retaining

walls.

4. Floor structures : The main function of a floor is to provide support foroccupants, furniture and equipments of a building and the function of

providing different floor is too divided the building in to different levels for the

purpose of creating more accommodation within the limited space.

The floor of a building immediately above the ground is known as ground

floor. All other floors which are above the ground floor are is knows as the

upper floors. Every floor has two components : (i) the sub floor, which is a

structural components to impart strength and stability to support the super

imposed loads and (ii) floor covering or flooring of suitable floor finish.

5. Doors, Windows, and Other Openings : A door is a movable barrier providein the opening of a wall to provide access to various spaces of a building and

their size and number should be properly determined as per the requirements.

6. Sills, Lintels and Weather Shades : window sills are provided between thebottom of window frame and wall below to protect the top of wall from wear

and tear. The openings are provided in the wall of a building to accommodate

doors and windows The actual frame of a door or window is not strong enough

to support the weight of the wall above all openings and is similar in character

to a beam. Weather shades on chhajjas are generally combined with lintels of

windows to protect them from the weather elements such as sun, rain, frost etc.

7. Vertical Transportation Structures : These consist of stair, lamp, ladders,lifts and escalators etc. to afford access between various floor. Out of these,

stairs are most common. A stair may be defined as series of steps suitably

arranged for a purpose of connecting different floors of a building. Stairs may

be constructed of different material such as timber, stone, reinforced concrete

or steel.


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8. Roof structures : A roof is the uppermost part of a building whose mainfunction is to enclose the space and to protect the same from the effects of

weather elements such as rain, sun, wind, heat, snow etc. A good roof is just as

essential as a safe foundation. Just as a floor, a roof consist of two components,

and at the same time they provide decorative effects. Finishes of several types

such as pointing, plastering, painting distempering, varnishing and polishing,

white washing etc. are applied on walls.

FOUNDATION

As described before, the part of structure which is above ground level is

called as superstructure and the part of structure which is below ground level ,is called as

substructure.

Foundation is the part of structure , which receives load of superstructure and

transmits it to lower and firmer strata safely without causing excessive settlement or

stresses or any damage to superstructure .

It is very difficult and costly to costly to carry out any repairs to foundation after

it is constructed. Also foundation failure is a safety hazard for many years. Hence, it is

essential to understand basic principles of foundations.

Definition and Purpose of Foundation :

It is the part of structure below ground level, which is directly in contact with

subsoil to receive load of superstructure and to transmit it to firm strata below safely.

Foundation of a building is designed to perform following functions :

1. It should carry loads safely : The soil strata, on which foundation is to rest,should be strong enough to safely bear the loads imposed on it.

2. Settlement of structure should be uniform and within permissible limits :Due to loads imposed on foundation, structure is likely to settle. Foundation is

designed so that, settlement is as uniform as possible throughout and is within

permissible limits.

3. Differential settlement should be less : If a part of foundation settles morethan the other part then, the difference between the two settlements is called as

Differential settlement.


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SUPERSTRUCTURE

The methods used for the construction of superstructures depend on various

factors such as loading patterns, purpose, area covered, economy or cost criteria, stability,

expected life span of the structure, sub-soil conditions, availability of materials etc.

There are mainly three types of superstructure:

(A)Load bearing wall construction. (B) Framed structures. (C) Composite structures.[A] Load bearing wall construction: In load bearing wall construction, the entire

load of the superstructures is transmitted through wall to the firm soil below the


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ground. Thus, the walls are supported on continuous foundations that are resting on

hard strata (soil). Usually, this type of construction is adopted at places where a hard

stratum is available at shallow depths. This type of construction can be adopted

maximum up to four storeyes but usually two storeyes are constructed. If the number

of storeyes is increased, the dead load and thickness and size of foundation increase.

All these factors not only reduce the carpet area but also increase the cost. This typeof construction cannot be used for multistoried construction is it poses many practical

difficulties in construction.

In this type of construction, the structural element such as beams, trusses, etc. rest

directly on the walls. The floors rest on the walls. A typical load bearing structure is

shown in Fig.2.19

(B)Framed structures: Framed structures comprises of a frame made up of beamsand columns. Beams are the horizontal members of the frame. All the loads on a

floor as well as those of walls as columns. Columns rest on the footing or

foundation on hard soil below the ground. Thus, the loads of the structures are

transmitted through the columns to the foundation.

Beams are provided at floor levels. The columns may be erected on separate

foundation or on the combined or raft foundation. In general, the partition walls orthe external walls room rest on beams. The cost of structure frame is about 30% of

the total cost of construction. Fig 2.20 shows details of frame structures.


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The different materials that are used for construction of a frame are timber, steel,

reinforced cement concrete (R.C.C).

(C)Composite structures: When the superstructure is composed of load bearing aswell as framed construction, it is known as composite structure. In this type and

the intermediate support are in the forms of columns. Thus, the floors and the

roofs are supported by load bearing walls as well as the inner columns. Composite

structures are preferred for buildings, which are not multistoried and have larger

spans such as workshop, warehouses. Composite structures, thus, has of framed

and load bearing structure. Fig.2.21 shows all essential details of this type of

construction.

COMPARISON OF LOAD BEARING AND FRAMED STRUCTURES

The load bearing and framed structures can be compared considering the various

aspects in building planning and construction such as, sub-soil conditions, floor space,

time required for construction, height of structures, economy, flexibility in planning, etc.

(i) Sub-soil conditions : The load bearing structures can be constructedwhere the hard soil is available at shallow depths; otherwise the cost of

construction increases on account of deep foundations. Thus, on black

cotton soil or reclaimed soil, load bearing structures prove to be

uneconomical . However, on the same soil, the framed structure proves to

be economical and the safe, too.


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(ii)Floor space : The external as well as internal wall load bearing structureare thicker as compared to be thickness of wall of framed structures.

Therefore, less floor area is available for use in load bearing structure.

(iii) Height : The load bearing structures can be built at the most uptofour storeyes, but the framed structures are suitable for any number of

floors.

(iv) Time of construction : For the same number of storeyes, the loadbearing construction require more time. In case of framed structure,

different construction activities can be carried out simultaneously and

hence there is reduction in the time require for the completion of framed

construction as compared to load bearing structure.

Further, if prefabricated building element such as floor panels,

beams, etc. are used in the framed structure then the time for construction

reduces.

(v) Economy : In general, load bearing structure works out to be cheaperupto 2 storeyes, whereas framed structure becomes necessary and

economical for multi storeyed construction.

(vi) Flexibility in planning : In case of framed structure, the panel wallcan be shifted and new work place can be created, which is not possible for

the load bearing structures.

(vii) Resistance to vibrations : The load bearing structures aresusceptible to vibrations due to machines and earthquakes; whereas the

framed structure can be designed to withstand these vibrations effectively.

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Basic Components of a Building