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6 Types of Beam Mechanics

Hi guys this is Civil Experience Blog and in this article, You will be learning about various types of beams mechanics used in civil engineering construction work based on different condition.

Types of Beam

    Beam Definition

    Beam is a structural member of a system having external loads at right angles to its axis

    There are basically 6 types of beams used in mechanics. Beams used for finding out reactions on support are assumed to be massless and the support, if pinned or roller, are frictionless. 

    Simply Supported Beam

    Starting from the simplest of the beams

    The simply supported beam rests on a pin and roller support. Pin support allows rotation and roller support allow rotation and lateral movement

    The deflected shape of the beam in 2D would look something like this on loading. 

    Simply Supported Beam

    Simply Supported Beam has got 3 unknown reactions which are vertical reactions at both the support and a horizontal reaction at pin support. We have 3 equilibrium equations in which a resummation of forces in the vertical direction is zero, the summation of forces in the horizontal direction is zero and the moment about any of the support is zero, to find the 3 reactions. 

    Hence it is called a statically determinate beam

    Overhanging Beam

    Next, we are looking at an overhanging beam in which some portion of the beam extends from the support from one side. 

    The deflected shape of the beam on uniform loading between supports would look something like this, in which both the supports will allow rotation of the beam. 

    Overhanging Beam

    If the overhang is from both ends then the beam is supposed to be called, double overhang and the deflected shape on uniform loading would look something like this. 

    double overhang beam

    These arrangements are also statically determined with 3 unknowns and 3 equilibrium equations

    Also Read: Hidden Beams

    Fixed Beam

    Next is a Fixed beam, which has fixed or rigid supports from both ends. 

    Deflected shape due to uniform loading will look something like this in which fixed supports will not rotate

    Fixed Beam

    Fixed support gives all 3 reactions which are horizontal, vertical and moment at both supports hence a total of 6 unknowns

    These unknowns cannot be found by 3 equilibrium equations 

    Hence the arrangement is called statically indeterminate

    Cantilever Beam

    Next, we will see a cantilever beam, which is fixed on one side and free on the other side. 

    Deflected shape due to loading will look something like this. 

    Cantilever Beam

    This beam has got only 3 unknowns hence they can be found by equilibrium equations making this beam statically determinate

    Propped Cantilever Beam

    Next, we will see a propped cantilever beam which is nothing but a cantilever beam with Roller support at the other end. 

    The deflected shape due to loading on the propped cantilever will look something like this. 

    Propped Cantilever Beam

    As the total number of unknown reactions are 4, 3 from fixed support and one from the roller, it will be termed as a statically indeterminate beam

    But what if I tell you that a propped cantilever can be made statically determinate? This can be possible by introducing an internal hinge or pin. The internal hinge allows free rotation hence moment at that point is zero. 

    Beams to the left and right of the internal hinge can be treated like 2 separate beams for calculations. Deflections due to uniformly distributed loading this case would look something like this. 

    Propped Cantilever Beam

    The slope abruptly changes on each side of the hinge. In the real world, a shear connection between 2 beams can be assumed as an internal hinge.

    Continuous Beam

    Next comes a continuous beam that has 2 or more 2 spans. The support at the ends may be fixed, pinned or rolled. The ends can be overhanging or supported. 

    Deflected shape of the continuous beam unloading will look something like this. 

    Continuous Beam

    The point to be noted here is that the intermediate support will not allow rotation of the beam hence there will be some amount of bending moment present at that support. As the unknown reactions in a continuous beam are more than 3, the reactions cannot be statically determined

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    FAQ 1: what is Beam Definition?

    Beam is a structural member of a system having external loads at right angles to its axis

    FAQ 2: Simply Supported Beam

    The simply supported beam rests on a pin and roller support. Pin support allows rotation and roller support allow rotation and lateral movement. statically determinate beam.

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