types of beams and loads

R.c.c structural members

Nowadays, plain and R.C.C. structural members like foundations, various types of Beams, columns, Lintels, Roof and Roof slabs, etc., are widely used in the construction of all types of buildings.

advantages

R.C.C. structural members are highly durable, strong, economical, quickness in construction with improved appearance. Also, different types of finishes can be given to concrete.

R.C.C. Beams

Beam: Beam is a horizontal member of a structure, carrying transverse loads. The beam is rectangular in cross-section. Beams carry the floor slab or the Roof slab. R.C.C., Pre-stressed concrete and steel I sections are used as beams to support the slabs.

The beams transfer all the loads ( Dead load and live loads ) including their self-weight to the columns or wall. The loads from the columns or walls are transmitted to the foundation. From the foundation, the load are safely transferred to the soil.

R.C.C. Beam: R.C.C. Beam is subjected to bending moments and shear. Due to the vertical external load, bending compresses the top fibre of the beam and elongates the bottom fibres. The strength of an R.C.C. beam depends on the composite action of concrete and steel.

Concrete is strong in compression and weak in tension.

Main Reinforcement: Reinforcement main steel bars are embedded in the tension zone to give tensile strength.

Concrete takes all the compressive stresses and the main steel bars take all the tensile stresses.

Stirrups: Vertical shear bars called stirrups are provided to withstand shearing forces

definitions

Loads acting on a structure and the all types of beams

1. Dead load
2. Live load

Dead load

Dead load is the self-weight of the various components of a building.

Live load

Live load is the external superimposed load on a structure. Live loads may be

1. Uniformly distributed load
2. Uniformly varying load
3. Concentrated load

Horizontal or Sloping Beams

Beams may be mostly horizontal or sloping like roof beams.

Span

The distance between the two supports of a beam is called the span of the beam.

Clear span

It is the clear horizontal distance between the two supports of a beam.

Effective span of a beam

It is the horizontal distance between the centre of one support to the centre of the next support. For design purposes, the effective pan is always considered.

types of beams

based on support

1. Simply supported beam
2. Fixed beam
3. Cantilever beam
4. Continuous beam
5. Overhanging beam

simply supported beam

It is a beam supported freely at the two ends on walls or columns. In actual practice, no beam rests freely on the supports ( walls or columns ) without fixing on the supports.

The moment is not induced at the supports, since it allows rotation. Hence, no beam is practically simply supported.

fixed beam

In this beam, both the ends of the beam are rigidly fixed to the supports (walls or columns). Also, main reinforcement bars and stirrups (in the form of rectangular rings) are provided.

Here, Bending is constrained at the supports. A moment is induced at the supports since it will not allow rotation.

cantilever beam

When a beam is fixed in a wall or column at one end and the other end is free, it’s called a cantilever beam. It has a tension zone on the top side and a compression zone on the bottom side.

Uses: It is used to support slabs projecting outside the wall/column.

Example: Portico, Balcony, etc.

continuous beam

A continuous beam is supported on more than two supports this beam is more economical for any span length. This beam is commonly and most used compare to all types of beams.

overhanging beam

In overhanging beam, its end extends beyond the wall or column support. Overhanging the beam is the unsupported portion of the beam. It may be one side or both sides of the support.

based on reinforcement

Types of beams based on reinforcement are

1. Singly Reinforcement Beam
2. Doubly Reinforcement Beam

singly reinforcement beam

If the main reinforcement steel bars are provided only on one side of the beam, it is known as a singly reinforcement beam.

doubly reinforcement beam

If the main reinforcement steel bars are provided with both at the top and bottom (tension and compression zones) of the beam, it is known as a doubly reinforcement beam.

Concrete covers: Main bars are placed uniformly along the perimeter of the column leaving the required covers. The concrete cover is the distance between the outer surface of the member and the nearest point of reinforcement. It may be the end cover or bottom cover.

loadings on beam

Types of beams loading is

1. Concentrated load
2. Uniformly Distributed Loads (U.D.L.)
3. Uniformly Varying Loads (U.V.L.)
4. Arbitrary loading

Concentrated load

A concentrated load is, single point load is acting on the beam on particular area. wheather, centre or etc,.

Example; Secondary beam, cross wall, column

Uniformly Distributed Loads (U.D.L.)

A uniformly distributed load is, the load is acting on the beam on the entire length in evenly.

Example; wall load

Uniformly Varying Loads (U.V.L.)

A uniformly varying load is, the load is acting on the beam on the entire length in inclined.

Example; inclined roof

Arbitrary loading

A arbitrary load is, the load is acting on the beam on the entire length in not evenly.

steel beams

Steel beams are generally rolled steel I-section.

I-section may be split and rejoined by welding and used for beams with large spans and light loads.

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