Lintels, Slabs, Beams and Columns
Lintel
Lintel is a horizontal member, which is placed across the openings, left in the wall for the provision of doors, windows etc. Width of the lintel is equal to the thickness of wall. Depth of the lintel varies from 100 to 150 mm.
Types of Lintels
(a) Reinforced cement concrete lintel
(b) Brick lintel.
(c) Stone lintel
(d) Timber lintel
(e) Steel lintel
(a) Rein forced cement concrete lintel
RCC Lintel has more strength, rigidity, fire resistance and are more economical. RCC Lintels are easy in construction. They can be used on any span.
(b) Steel Lintel
Steel lintel consists of rolled joints (RSJ) or channel section. They are provide where the opening is larger and weight of the load given on its is high. Steel Lintels are mostly used or super structures.
(c) Stone lintel
It consists of simple atone slab of greater thickness. Dressed stone give architectural appearance. These lintels are used in stone masonry structure of buildings.
(d) Brick lintel
Bricks lintels are built from well burnt and copper coloured bricks. They are not structurally strong. They are not for small openings, generally not exceeding 1 metre span. They are used for light loads. Arched bricks lintel imparts more thrust.
(e) Timber lintel
Hard timber, like teak is used for this type of lintel. These lintels are mostly used in the hilly areas. The ends of the timber lintel rest on the mortar base on the walls for a minimum width of 15 cm.
Slabs
The horizontal portion of a building that covers the building or each floor of the type is called slab.
Types of slab
(a) Simple RCC slab
(b) Tee-beam slab
(a) Simple RCC slab
It is suitable for covering small spans of room. It cannot with-stand heavy load. The thickness of the slab depends on the type of concrete used, the floor loads etc. If the ration of length of the room to the width of the room is less than 1.5, then two way reinforced slabs is used. If it is greater than 1.5 one way reinforced slab is used.
(b) Tee-Beam slab
Tee-beam is used for wide opening. In the tee-beam slab, the loads from the slab is transmitted to the beams and then from beam to the columns. The tee-beam act as intermediate supports and the slab is layer continuously over these beams.
Beams
A beam is a structural member which carries the horizontal load in a structure.
Important definitions (Beans)
(a) Span of the Beam:
>the horizontal distance between inner faces of the supporting wall is known as clear span.
(b) Joists
Members used to carry roofing and floors of buildings.
(c) Girders
They are the main load carrying members on to which floor beams are placed.
(d) Spandrels
Exterior beams at the floor level, used to carry part of the floor load and the load due to exterior wall.
(e) Dead load
It is the self weight of the various components of the buildings.
(f) Live load
The live load is the super Imposed load on a structure.
Types of Beams
(a) Simply supported beam
(b) Cantilever beam
(c) Rigidly fixed beam
(d) Over hanging beam
(e) Continuous beam
(a) Simply supported beam
In this type of beams, the ends of the beams are supported freely on columns or walls. In this case the moment is not induced at supports, because it allows rotation.
(b) Rigidity fixed beam
Two ends of the beam are rigidity fixed in the walls. In this case the moments are induced at the supports.
(c) Cantilever Beams
Here the beam is fixed at one end and the other end is free. In this case the moment is induced in fixed end only.
(d) Over hanging beam
The beams having its end portions extended beyond the support is called hanging beam.
(e) Continuous Beam
If the beam is supported on more than two supports, then it is known as continuous beam.
Column
It is vertical structural member that support the beams. Column transmits the load given on it to the soil below.
Types of columns
(a) Short column
(b) Long column
(c) RCC column
(d) Steel column
(a) Short column
If the effective length of a column is less than or equal to 12 times the least internal dimension, then it is called a short column.
(b) Long column
If the effective length is more than 12 times the least lateral dimension, the column is said to be a long column.
(c) RCC column
Usually RCC column are cast in situ type. They are constructed in square, rectangular, circular or hexagonal shapes. Vertical reinforcements are provided to take the major load on to the columns. Lateral stirrups are provided to keep the main reinforcement in position.
(d) Steel columns
Steel column are fabricated by using steel joists, angle and plates. Steel columns are mostly used in industrial structures. Some form of steel stanchions is I section, H section etc.