# Cantilever Beam | Advantages of a Cantilever Beam | Disadvantage of the Cantilever Beam ## Cantilever Beam

A cantilever beam is a type of beam that has simply support on one side and a free end on the other side. The cantilever beam is a rigid structural member. One is a support fix, and the other is a free end.

Cantilever beams are made of reinforced concrete or steel. Maximum use of space can be made with a cantilever beam.

The cantilever beam is mostly used in the parking area, railway station, balcony of the building. This feature has greatly increased the use of a cantilever beam. Some space can be created using two cantilever beams.

## Advantages of a Cantilever Beam

1. The cantilever beam has support on one side only.
2. The cantilever beam has the same shear forces everywhere.
3. When the length of the span is greater, a cantilever beam can be used against two faces.
4. Maximum space can be used with the use of a cantilever.
5. A special part of the cantilever is useful in the elevation of the building.
6. Cantilever projection is used in building design for ducts for the sewage line.

## Disadvantage of the Cantilever Beam

1. The cantilever beam has more bending moments.
2. The cantilever beam produces uplift pressure.
3. Special care should be taken in the cantilever beam ni design.
4. Defection is increased in the cantilever beam.

## Shear Force and Bending Moment Diagram for Cantilever Beam with Point Load at the Free End L is the length shown in Fig when a point is a fixed end when point b is the free end.

For calculation of shear force.

Suppose the x-x section is the distance from a point B to x.

So the shear force on the x-x section.

Fx = + W.

The shear force at point A,

Fa = + W.

Similarly, shear force applied at point B,

Fb = + W.

Thus, the value of shear force remains the same at each point as no other load is applied to the end point to the left.

To calculate the bending moment,

To calculate the bending moment, the clock-wise moment is taken as – ve, and the anti-clockwise moment is taken as + ve.

Section x-x forward bending moment,

Mx = -w * x = – Wx

Mb = – w *0 = 0

Ma = – w * L = wl

A shear force and bending moment can be detected.

## Shear Force and Bending Moment Diagram for Cantilever Beam with U.d.l. Over the Whole Span U.d.l on the cantilever beam as shown in Fig. The load seems to be over the full length.

For calculation of shear force,

Suppose the x-x section is the distance from point b to x.

So the shear force on the x-x section,

Fx = + W * x = WX.

The shear force at point a,

Fa = + W * l = WL.

Similarly shear force applied at point b,

Fb = + W * 0 = 0.

To calculate the bending moment.

To calculate the bending moment, the clock-wise moment is taken as (-ve), and the anti-clockwise moment is taken as (+ ve).

Section x-x forward bending moment,

Mx = -(W.X)X/2 = -WX2/2,

MB =  0,

MA = -(W.L)L/2 = -WL2/2.

The graph of the bending moment diagram becomes parabolic.