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Q: What are the various types of beams?

What are the different types of support and loading on a beam explain in brief?

 

Types of the Beams

(I) Hinged or Pinned support: The essential feature of a pinned support is to prevent translation at the end of a beam but does not prevent rotation. Thus, an end carrying hinged or pinned support cannot move in the vertical or horizontal direction but, it can rotate around the hinged.

A pin or thin support is capable of developing a reaction force with horizontal and vertical components ( R_x and R_y ), but cannot develop a moment reaction.

Hence it can resist force acting in any direction of a plane but cannot resist rotation.

Fig.1: Hinged or Pinned support

(ii) Roller support or Link support: A roller support is capable of resisting force only in one specified line of action.

Fig.2: Roller support or Link support

The link is shown in Fig.2(a) can resist force only along with direction AB.

Roller in Fig.2(b) can resist force only in the vertical direction. Whereas roller in Fig.2(c) can resist forces acting perpendicular to line CD.

It should be noted that roller support is capable of resisting a force in either direction (i.e. upward and downward) i.e. a beam is not allowed to lift off from support.

Knife-edge support: The function of knife-edge support is similar to roller support. It is also capable of resisting force in only one specified line of action, but here beam can be lifted up or it may leave the support.

Fig.3: Knife-edge support

(iv) Fixed support: Fixed support is a support that resists translation of beam as well as rotation of the beam.

Fig.4: Fixed support

Support reaction is the force that is offered by the support, against the loads acting on the beam. The support reaction for various types of supports is shown below.

(i)  Hinged or pinned support:

(ii) Roller support:

(iii) Knife edge support

(iv) Fixed support

 

Note: Number of reaction at any support = Number of restricted motion.

Example: As hinged support can resist force acting at any direction in a given plane, therefore it has two components of that reaction force (R_x and R_y ) .

The beam is classified into different categories depending upon the types of support as below :

(i) Simply supported beam: Simply supported beam is a beam that is supported at its two ends by either two roller support or two hinge support or one roller and one hinged support.

Fig.(a) : Simply supported beam

(ii) Overhanging beam: An overhanging beam is a beam, simply supported at any two-point within the span of the beam but it also projects beyond one or both the support.

Fig.(b): Overhanging beam

(iii) Cantilever beam: Cantilever beam is a beam that is fixed at one end and free at the other. A fixed support beam can neither translate nor rotate, whereas at the free end it may do both.

Fig.(c) : Cantilever beam

(iv) Fixed-beam: When both ends of the beam are built-in or fixed, such beam is called a fixed beam.

Fig.(d) : Fixed beam

(v) Continuous beam: It is a beam that expands over more than two supports.

Fig.(e) : Continuous beam

(vi) Propped cantilever beam: A cantilever beam that has support between the fixed end and the free end is called propped cantilever beam.

Fig.(f) : Propped cantilever beam