LINTELS definition A lintel is a horizontal member
LINTELS
definition “A lintel is a horizontal member which is placed across an opening to support the portion of the structure above it”. ØFunction of an lintel is same as that of arch and beam. ØBut when compared to them construction of lintels is very simple. ØHere no special centering form work is required as in case of arches.
Following Are The Function Of Lintel Beams: • Lintel supports the walls above the openings like doors, windows etc. • Lintels provide a safeguard of the windows and doors. • Lintel withstands the imposed loads coming from above bricks or block including the roofing members. • The lintel is used to transfer all imposed loads to the side walls. • Sometimes lintels are used as decorative architecture element.
Characteristics of lintels ØThe ends of lintels are built into the masonry and thus the load carried by lintels is transferred to the masonry. ØLintels are generally classified based upon the materials being used. ØAt present, RCC lintels are widely used.
Lintel construction precautions The distance up to which it is inserted in the supporting wall, should be minimum of the following 3 considerations. Ø 100 mm ØHeight of the lintel ØOne-tenth to one-twelfth of the span of lintel.
Types of lintels ØWood or timber lintels ØStone lintels ØBrick lintels ØSteel lintels ØReinforced cement concrete lintels or RCC lintels
Wood or timber lintels ØThese are the pieces of timber which is placed across the opening. ØTimber lintels are the oldest types of lintels. ØIn most of the hilly areas timber lintels are used. Reason for this is easy availability of the wood. ØA single piece of wood can be used as a lintel ØRelatively costly, structurally weak and vulnerable to fire. ØEasily decay, if not properly taken care.
ØA built-up sections may be formed and can be used as lintels. ØBolts are provided in built-up sections. ØIf the timber lintels are strengthened by providing mild-steel plates at their top and bottom, they are called FLITCHED LINTELS.
Features of wooden lintels ØA bearing of about 150 -200 mm should be provided. ØThe ends of the lintels should be placed on mortar so as to create level and firm bearing. ØThe width of lintel should be equal to the thickness of the opening. ØThe depth of lintel should be min of 80 mm. ØSound and hard timber like teak wood should be used. ØWooden lintels are comparatively weak.
Stone lintels ØThese lintels are the slabs of stones placed across the openings. ØThey may be formed of single piece or more than one piece. Disadvantages of Stone Lintels: ØThe stone possess less tensile strength. ØDepth of stone should be at least 1/10 th length of opening. ØStones cracks when subjected to vibratory loads. ØIt is difficult to obtain good stone of required size.
brick lintel ØThese lintels consists of bricks which are generally placed on end or edge. ØBricks used should be hard and durable. ØTemporary wood support is provided during the construction. ØBricks having frogs are more suitable. ØIt is generally weak, hence used for smaller spans up to 1 m. ØTo increase the strength reinforcement may be provided.
Steel lintels ØProvided at large opening and where the superimposed loads are heavy. ØIt consists of steel angles and rolled steel joists. ØThe former is used for smaller loads and latter is used for heavier loads. ØEither used singly or in combination of two or three units. ØJoint with bolts. ØThese lintels are embedded in concrete to protect steel corrosion.
Reinforced cement concrete lintels ØThese lintels consists of reinforced cement concrete. ØPractically they have replaced all other types of lintels. Advantages of RCC lintels ØThey are fire proof ØStrong ØDurable ØEconomical ØEasy to construct
Method of construction of rcc lintels ØThe usual concrete mix for RCC lintel is 1: 2: 4. ØEven plain concrete lintels can be used. But should be used for openings less than 800 mm. ØSince concrete is weak in tension, steel is used to take the tensile loads. ØThe amount of reinforcement required depends on: v. Span of lintel v. Width of opening v. Total load to be supported by the lintel.
ØRCC lintels may be Pre-Cast or Cast-in-situ. Advantages of Pre-Cast lintels ØPre-Cast lintels are more economical for spans up to 2 m. ØThey are economical as same moulds can be used to prepare number of lintels. ØThey increase the speed of the construction. ØThey allow sufficient time for curing before fixing. ØTheir top should be marked with paint or tar. This helps in proper placing of lintels.
ØFor Cast-in-situ RCC lintels: v. Centering is prepared v. Reinforcement is placed v. Concreting is done as usual. ØCommonly used lintels. ØDepth of lintel depend on span. ØA flexible DPC should be provided to avoid moisture penetration.
CHAJJA: • A chajja is the projecting or overhanging eaves or cover of a roof, usually supported on large carved brackets. • Usually protects from external sunlight. • Also protects from rainwater entering into the building. • It also serves as aesthetic decoration with little design on it from architectural point of view.
Balcony • A balcony is a platform projecting from the wall of a building, supported by columns or brackets, and enclosed with a balustrade usually above the ground floor. • It act as an external place beside from usable carpet area. • It also act as an door to environment. • It helps in maintaining proper circulation in the building
Canopy A canopy is an overhead roof or else a structure over which a fabric or metal covering is attached, able to provide shade or shelter from weather conditions such as sun, hail, snow and rain. • It provide an elegance beauty to structure • It maybe a temporary offset or structure provided in the building for special reason.
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