BASIC COMPONENT OF BUILDINGS

By: Ar. Sanjib SenguptaSeptember 2016

WHAT IS BUILDINGAny structure for whatsoever purpose and of whatsoever materials constructed and every part thereof whether used as human habitation or not and includes foundation, plinth, walls, floors, roofs, chimneys, plumbing and building services, fixed platforms, verandah, balcony, cornice or projection, part of a building or anything affixed thereto or any wall enclosing or intended to enclose any land or space and signs and outdoor display structures. tents/ shamianahs / pandals, tarpaulin shelters, etc., erected for temporary and ceremonial occasions shallnot be considered as building.

WHAT IS BUILDINGHowever here we will talk about a structure with a roof and walls including all attached apparatus, equipment, and fixtures standing more or less permanently in one place. Buildings come in a variety of sizes, shapes and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, to land prices, ground conditions, specific uses and aesthetic reasons.

PURPOSE OF A BUILDING.

Buildings serve several needs of society primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical division of the human habitat (a place of comfort and safety).

TYPE OF BUILDINGSResidential house, school, hospital, or factory etc. Buildings may be load bearing masonry buildings or RCC framed structure building.

Load Bearing Masonry Building RCC framed Structure Building

1. Sub-Structure or Foundation:- The lower portion of the building, which is located below the ground/soil , is called foundation. Foundation, which is in direct contact with ground in depth, transmits the loads of the super-structure to the supporting soil. Floors below ground/soil are called basement, being below ground, wherever constructed are also part of Sub-Structure. However Padstone foundation is always over ground and normally found in hill area.

2. Super Structure:-The upper part/portion of the building above ground level with roof and walls including all attached apparatus, equipment, and fixtures

BASIC COMPONENT OF A BUILDINGAll Buildings which are built on ground are two primary basic component

WHAT ARE THE LOADS OF SUPER STRUCTURE1.Dead loads:-Are permanent or stationary loads which are transferred to structure throughout the life span. Dead load is primarily due to self-weight of structural members like walls, roofs, permanent partition walls and other fixed components of building, fixed permanent equipment, furniture and weight of different materials etc.

2. Live loads:-Are either movable or moving loads without any acceleration or impact. Live loads that do, or can, change over time. Live loads include any temporary or transient forces that act on a building or structural element. Typically, they include people, movable partitions and furniture, vehicles, and almost everything else that can be moved throughout a building.

3.Impact Loads:-Caused by vibration or impact or acceleration. Thus, impact load is equal to imposed load incremented by some percentage called impact factor or impact allowance depending upon the intensity of impact.

4. Environmental loads:-Are loads that are created naturally by the environment and include wind, snow, seismic, and lateral soil pressures.

TYPE OF SUB-STRUCTURE/FOUNDATION

Foundations are divided into two categories:

1.Shallow foundations:- Shallow foundations can be made in depths of as little as 3ft (1m) and are used for small, light buildings.

2.Deep foundations:- Deep foundations can be made at depths of 60 - 200ft (20 - 65m) and are for large, heavy buildings

SHALLOW FOUNDATIONSThese are also called spread footings or open footings. The 'open' refers to the fact that the foundations are made by first excavating all the earth till the bottom of the footing, and then constructing the footing. During the early stages of work, the entire footing is visible to the eye, and is therefore called an open foundation. The idea is that each footing takes the concentrated load of the column and spreads it out over a large area, so that the actual weight on the soil does not exceed the safe bearing capacity of the soil. There are several kinds of shallow footings: i) Individual footings/Isolated Footing, ii) Strip Footings/Spread Footing, iii), Pad Foundation, iv) Pad Stone Foundation v) Rubble Stone/trench Foundation and vi) Raft Foundation. In cold climates, shallow foundations must be protected from freezing. This is because water in the soil around the foundation can freeze and expand, thereby damaging the foundation. These foundations should be built below the frost line, which is the level in the ground above which freezing occurs. If they cannot be built below the frost line, they should be protected by insulation: normally a little heat from the building will permeate into the soil and prevent freezing.

INDIVIDUAL FOOTING/ISOLATED FOOTINGIndividual footings are one of the most simple and common types of foundations. These are used when the load of the building is carried by columns. Usually, each column will have its own footing. The footing is just a square or rectangular pad of concrete on which the column sits.

STRIP FOOTINGS/SPREAD FOOTINGS Strip footings are commonly found in load-bearing masonry construction, and act as a long strip that supports the weight of an entire wall. These are used where the building loads are carried by entire walls rather than isolated columns, such as in older buildings made of masonry. It is continuous foundation of which the length considerably exceeds the breadth. The depth of a strip foundation must be equal to or greater than the overall width of the wall. The principle design features of a strip/spread foundation/footing are based on the fact that the load is transmitted at 45 degrees from the base of the wall to the soil. The key sizes of a strip foundation for concrete cavity wall construction and timber frame cavity wall construction are similar. The size and position of the strip is directly related to the overall width of the wall. The width of the foundation must be three times the width of the supported wall Strip foundations are used where the soil is of good bearing capacity.

PAD FOUNDATIONPad foundations are generally rectangular or square foundation to transfer load from structure to the ground. These are provided at shallow depth and are shallow foundations.

PADSTONE FOUNDATIONPerhaps the simplest foundation is the Padstone, a single stone which both spreads the weight on the ground and raises the timber off the ground

RUBBLE STONE FOUNDATIONThe rubble trench foundation, an ancient construction approach popularized by architect Frank Lloyd Wright, is a type of foundation that uses loose stone or rubble to minimize the use of concrete and improve drainage. It is considered more environmental friendly than other types of foundation because cement manufacturing requires the use of enormous amounts of energy. However, some soil environments are not suitable for this kind of foundation; particularly expansive or poor load-bearing (< 1 ton/sf) soils. A rubble trench foundation with a concrete grade beam is not recommended for earthquake prone areas.

Rubble trench Foundation Cross section view of

rubble trench foundation

RAFT OR MAT FOUNDATIONSRaft Foundations, also called Mat Foundations, are most often used when basements are to be constructed or where the soil is week or where columns are closely spaced (which means that if individual footings are used, they may touch each other.) so that building loads are spread over a large area. Mat foundations are the types of foundation which are spread across the entire area of the building to support heavy structural loads from columns and walls. The use of mat foundation is for columns and walls foundations where the loads from the structure on columns and walls are very high. This type of foundation is used to prevent differential settlement of individual footings, thus designed as a single mat (or combined footing) of all the load bearing elements of the structure.

DEEP FOUNDATIONS1. Pile Foundations:-

Pile foundation is a type of deep foundation which is used to transfer heavy loads from the structure to a hard rock strata much deep below the ground level. Pile foundations are generally used for soils where soil conditions near the ground surface is not suitable for heavy loads. The depth of hard rock strata may be 5m to 50m (15 feet to 150 feet) deep from the ground surface. The pile foundations resists the loads from structure by skin friction and by end bearing. Pile foundations are capable of taking higher loads than spread footings. Use of pile foundations also prevents differential settlement of foundations.

Pile Foundations( Cont.---)A pile is basically a long cylinder of a strong material such as concrete or wood that is pushed into the ground so that structures can be supported on top of it.

Concrete Pile Wooden Pile

Pile foundations are used in the following situations:a) When there is a layer of weak soil at the surface. This layer cannot support the weight of the building, so the loads of the building have to bypass this layer and be transferred to the layer of stronger soil or rock that is below the weak layer.b) When a building has very heavy, concentrated loads, such as in a high rise structure.There are two types of pile foundations, i) End bearing & ii) Friction Pile, each of which works in its own way.

Pile Foundations( Cont.---)

Pile Foundations( Cont.---)End Bearing Piles:- In end bearing piles, the bottom end of the pile rests on a layer of especially strong soil or rock. The load of the building is transferred through the pile onto the strong layer. In a sense, this pile acts like a column. The key principle is that the bottom end rests on the surface which is the intersection of a weak and strong layer. The load therefore bypasses the weak layer and is safely transferred to the strong layer.

Friction Piles:-Friction piles work on a different principle. The pile transfers the load of the building to the soil across the full height of the pile, by friction. In other words, the entire surface of the pile, which is cylindrical in shape, works to transfer the forces to the soil.

To visualize how this works, imagine you are pushing a solid metal rod of say 4mm diameter into a tub of frozen ice cream. Once you have pushed it in, it is strong enough to support some load. The greater the embedment depth in the ice cream, the more load it can support. This is very similar to how a friction pile works. In a friction pile, the amount of load a pile can support is directly proportionate to its length. In practice, however, each pile resists load by a combination of end bearing and friction.

The mono pile foundation is a simple construction. The foundation consists of a single, generally large diameter steel pile/structural element with a diameter of between 3.5 and 4.5 meters embedded into the earth to support all the loads (weight, wind, etc.) of a large above- surface structure. The pile is driven some 10 to 20 meters into the seabed depending on the type of underground. This type of foundation is normally used for offshore construction

Monopile foundation

Drilled shafts is also a type of deep foundation and has action similar to pile foundations discussed above, but are high capacity cast-in-situ foundations. It is also called as caissons. It resists loads from structure through shaft resistance, toe resistance and / or combination of both of these. The construction of drilled shafts or caissons are done using an auger. This foundation can transfer column loads larger than pile foundations. It is used where depth of hard strata below ground level is location within 10m to 100m (25 feet to 300 feet).Drilled shafts or caisson foundation is not suitable when deep deposits of soft clays and loose, water-bearing granular soils exists. It is also not suitable for soils where caving formations are difficult to stabilize, soils made up of boulders, artesian aquifer exists.

Drilled Shafts or Caisson Foundation

SUPER STRUCTURE Generally consist of i) Plinth, ii) Plinth Beam, iii) DPC, iv) Plinth protection v) Floors, vi) Column, vii) Walls, viii) Openings Doors/Windows/Ventilators, ix) Sill, x) Lintel, xi) Beam, xii) Roof. xiii) Parapet, xiv) Staircase, xv)Mumty, xvi) Lift machine

PlinthPlinth is a part of the super-structure, defined as the portion of the structure between the surface of the surrounding ground and surface of the floor, immediately above the ground. The distance between the surface of the surrounding ground and surface of the floor, immediately above the ground is called plinth height, which should be of minimum 450 mm, negotiable by steps or ramp. 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.

Plinth beamBeam laid above the foundation i.e. at plinth level, and braces the plinth level is called plinth beam. Plinth beam is an important part of a structure which transfer loads to the adjacent columns. The void between the foundation and plinth level is filled with compacted soil. Brick or stone masonry is usually constructed below the plinth beam. This beam is normally provided in framed structure for proper framing of structure and disbursing the live loads as well as dead loads of super structure. It is also known as a tie beam and is made so that the columns do not split due to load coming from above. Some times this beam known as plinth band is provided in load bearing masonry structure also. In principle plinth (or tie) beams between pads are only required if-- i) Differential settlement or rotation of individual pads (such as in poor ground conditions or big differences in applied pressures between adjacent pads) is expected. ii) To maintain the plinth plane proper ii) The beams are needed to support walls or floating ground floor slabs. & iii) The foundations are at different levels- such as a building built on the side of a hill.

Damp Proof Course i.e. DPC A damp-proof course (DPC) is a barrier through the structure by capillary action such as through a phenomenon known as rising damp. Rising damp is the effect of water rising from the ground into property. The damp proof course may be horizontal or vertical. Damp proofing in construction is a type of moisture control applied to building walls and floors to prevent moisture from passing into the interior spaces.. A DPC layer is usually laid below all masonry walls, regardless if the wall is a load bearing wall or a partition wall. For DPC above ground level with wall thickness generally not exceeding 40cm, any one of the type of materials mentioned below may be used. Cement concrete is however commonly adopted material for DPC at plinth level, 38 to 50mm thick layer of cement concrete M15 (1:2:4 mix) serves the purpose under normal conditions. An effective damp proofing material should have the following properties;

Damp Proof Course i.e. DPC ( Cont.---)• It should be impervious.• It should be strong and durable, and should be capable of

withstanding both dead as well as live loads without damage.• It should be dimensionally stable.• It should be free from deliquescent salts like sulphates, chlorides

and nitrates.The materials commonly used to check dampness can be divided into the following three categories:

Flexible Materials: Materials like bitumen felts (which may be hessian based or fibre/glass fibre based), plastic sheeting (polythene sheets) etc.Semi-rigid Materials: Materials like mastic, asphalt, or combination of materials or layers.Rigid Materials: Materials like first class bricks, stones, slate, cement concrete etc.

Plinth protectionPlinth protection is the additional length or strengthening provided in the lowest portion of a beam or the lower portion of a foundation/floor by providing additional thickness/height. In short: plinth is base of structure, it transmit weight of structure to the soil. The plinth usually rests directly on the ground, the plinth exists to negotiate between a structure and the ground. Some Soils has Chemicals inside and minerals that can deteriorate the strongest reinforced Concrete structure, so a protection layer is a must to extend the age of the structure. Many times plinth have to deal with external agencies like water, roots of trees, termites, etc this can affects the life of plinth and makes it weaker so it’s essential to protect plinth from such agencies, therefore plinth protection is necessary

FloorsA floor is the walking surface of a room. The levels of a building are often referred to as floors although a more proper term is story or storey. Floors typically consist of a subfloor for support and a floor covering used to give a good walking surface.

ColumnA column or pillar is a vertical structural element that takes the load of beam slab etc. and transfers the load to the earth independently is called column. Columns are frequently used to support beams or arches on which the upper parts of walls or ceilings rest.

WallsWalls are the vertical elements and fundamental part of the superstructure of a building which enclose the space within it and which may also divide that space. A wall is a structure that defines an area, carries a load, provides shelter and security. There are many kinds of walls: External walls, Internal walls, partition walls Defensive walls in fortification, Retaining walls, Boundary walls, Load bearing walls, Non load bearing walls, Curtain walls etc.

Curtain wall:- Is a system for outer covering of a building in which the outer walls are non-structural, but merely keep the weather out and the occupants in. The curtain wall being non-structural it can be made of a material other than conventional brick and concrete. Curtain-wall systems are typically designed with extruded aluminum members infilled with glass, which provides benefits such as daylighting. However, parameters related to solar gain control such as thermal comfort and visual comfort are more difficult to control when using highly glazed curtain walls. Other common infills include: stone veneer, metal panels, louvers, and operable windows or vents.

Walls(Cont.---)

Walls(Cont.---)The curtain wall facade does not carry any dead load from the building other than its own dead load. 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, sway induced by wind and seismic forces acting on the building, and its own dead load forces. Curtain walls, differ from store-front systems, are designed to span multiple floors, & take into consideration design requirements such as: thermal expansion & contraction; building sway & movement; water diversion; thermal efficiency for cost-effective heating, cooling, and lighting in the building.

Openings What does opening mean in a building. A gap, hole, breach, or aperture in the wall of a building for ingress and egress and for admission of light and air.Types of Openings in Buildings1. Doors:-An openable barrier secured in an opening left in a wall for the purpose of ingress and egress to/from the structure. It basically consists of two parts, namely, frame and shutter. The door shutter is held in position by the door frame which in turn is fixed in the opening of the wall by some suitable means.2. Windows:-: An opening especially in the wall of a building for admission of light and air. It also basically consists of two parts, namely, frame and shutter. The window shutter is also held in position by the door frame which in turn is fixed in the opening of the wall by some suitable means. Generally window bottom shall have sill.3. Ventilators:-An opening or aperture smaller than window, in the wall and above lintel level for ventilating a room or other space.

Window Sill:-The horizontal member at the base of a window opening. Window frame sits on the window sill of the wall opening.

Lintel:- A structural horizontal block that spans the space or opening between two vertical supports and serves to carry the weight of the wall above it . A lintel can be a load-bearing building component, a decorative architectural element, a combined ornamented structural item. It is often found over portals, doors, windows & fireplaces. A horizontal supporting member, installed above an opening such as a window or a door.

BEAM A beam is a horizontal or inclined structural element/member spanning a distance between one or more supports, and carrying vertical loads across (transverse to) its longitudinal axis that is capable of withstanding load primarily by resisting against bending. A beam is a laterally loaded member, whose cross-sectional dimensions are small as compared to its length. Six basic types of beams are: (1) Fixed, (2) Simple supported, (3) Continuous, supported at more than two points, (4) Over hanging, double over hanging, (5) Cantilever, supported at one end with the other end overhanging and free, (6) Truss.

BEAM (Cont.--)The other types of beam are i.) Flat beam—a beam whose width is larger than depth. ii.) Upstand/inverted beam--a beam that projects above floor level, iii.) Concealed/Hidden beam is defined as the beam whose depth is equal to the thickness of the slab. Truss:-essentially a triangulated system of straight interconnected structural elements. The most common use of it is in buildings, where support to roofs, the floors and internal loading such as services and suspended ceilings, are readily provided. The main reasons for using trusses are:-i)Long span, ii) Lightweight, iii) Reduced deflection (compared to plain members), Opportunity to support considerable loads.

Upstand BeamFlat

Beam

Roof/TerraceA roof is part of a building envelope. It is the covering on the uppermost part of a building or shelter which provides protection from weather, notably rain, snow, heat, wind and sunlight. The characteristics of a roof are dependent upon the purpose of the building that it covers, the available roofing materials and the local traditions of construction and wider concepts of architectural design and practice and may also be governed by local or national legislation. A roof may also provide additional usable space, for roof/terrace garden , installation of water tank, solar panel/ heater etc. Roof can be flat roof or slope roof.

PARAPETParapet is a barrier at the edge of a roof, terrace, balcony, walkway or other structure.

STAIRCASEA staircase/stairway is a construction designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps. Stairs may be straight, round, spiral, dog legged or may consist of two or more straight pieces connected at angles. In buildings, stairs is a term applied to a complete flight of steps between two floors. A stair flight is a run of stairs or steps between landings. A staircase or stairway is one or more flights of stairs leading from one floor to another, and includes landings, newel posts, handrails, balustrades and additional parts. A stairwell is a compartment /shaft extending vertically through a building in which stairs are placed.

Mumty is a colloquial ward which denote the covering of stair well at minimum 2.1 m above the last landing of the staircase at roof level.

MUMTY

A Lift machine room (sometimes known as elevator machine room or lift motor room) is a room that house elevator drives and controllers. This room projects above roof level.

Lift Machine Room

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