civil engineering basics in projects

What is Beam? What are main Types of Beams

Today we will discuss about what is beam and  types of beams. Beam is a horizontal structure member used to carry vertical load, shear load and sometime horizontal load. It is the major component of building structures. It mainly use in construction of bridges, trusses, and other structures which carry vertical load. Beams may be define as:

Any structure member which cross section is much smaller compare to its length and undergoes lateral load, known as beam.

In other words beam is a horizontal bar witch undergoes lateral load or couple which tends to bend it or a horizontal bar undergoes bending stress known as beam.

According to its requirement, different beams use in different conditions like fix beam, cantilever beam etc. 

Types of beams:

Beams are classified as follow. 

 According to end support:

1. Simply Supported Beam:

As the name implies, simply supported beam is supported at both end. One end of the beam is supported by hinge support and other one by roller support. This support allow to horizontal movement of beam. It beam type undergoes both shear stress and bending moment.

2. Continuous Beams:

When we talk about types of beams we cannot forgot continuous beam. This beam is similar to simply supported beam except more than two support are used on it. One end of it is supported by hinged support and other one is roller support. One or more supports are use between these beams. It is used in long concrete bridges where length of bridge is too large. 

3. Overhanging Beams:

Overhanging beam is combination of simply supported beam and cantilever beam. One or both of end overhang of this beam. This beam is supported by roller support between two ends. This type of beam has heritage properties of cantilever and simply supported beam.

4. Cantilever Beams:

Cantilever beams a structure member of which one end is fixed and other is free. This is one of the famous type of beam use in trusses, bridges and other structure member. This beam carry load over the span which undergoes both shear stress and bending moment.

5. Fixed beams:

This beam is fixed from both ends. It does not allow vertical movement and rotation of the beam. It is only under shear stress and no moment produces in this beams. It is used in trusses, and other structure.

According to cross section:

A beam may have different cross section. The most common cross section of beam are as follow.

1. I beam:

This beam types have I cross section as shown in figure. It has high resistance of bending. 

2. T beam:

It has T cross section as shown in figure.

According to equilibrium condition:

1. Statically determinate beam:

A beam is called determinate beam if it can be analyze by the basic equilibrium condition. The support reaction can be found by using basic equilibrium condition. These conditions are

Summation of all horizontal forces is zero.

Summation of all vertical forces is zero.

Summation of all moments is zero.

Example: Simply supported beam, Cantilever beam etc.

2. Statically indeterminate beam:

If the beam cannot be analysis by using basic equilibrium condition, known as statically indeterminate beam. The end reaction find out by using basic equilibrium condition with combination of other conditions like strain energy method, virtual work method etc.

Example: Continuous beam, fixed beam

According to Geometry:

1. Straight beam

2. Curved beam

3. Tapper beam

Today we have discussed article What is Beam and types of beams. If you have any query regarding this article ask by commenting below. 

TYPES OF SUPPORTS Roller Supports Roller supports are free to rotate and translate along the surface upon which the roller rests. The surface may be horizontal, vertical or slopped at any angle. Roller supports are commonly located at one end of long bridges in the form of bearing pads. This support allows bridge structure to expand and contract with temperature changes and without this expansion the forces can fracture the supports at the banks. This support cannot provide resistance to lateral forces. Roller support is also used in frame cranes in heavy industries as shown in figure, the support can move towards left, right and rotate by resisting vertical loads thus a heavy load can be shifted from one place to another horizontally.

Hinge Supports The hinge support is capable of resisting forces acting in any direction of the plane. This support does not provide any resistance to rotation. The horizontal and vertical component of reaction can be determined using equation of equilibrium. Hinge support may also be used in three hinged arched bridges at the banks supports while at the center internal hinge is introduced. It is also used in doors to produce only rotation in a door. Hinge support reduces sensitivity to earthquake. FIXED SUPPORT Fixed support can resist vertical and horizontal forces as well as moment since they restrain both rotation and translation. They are also known as rigid support For the stability of a structure there should be one fixed support. A flagpole at concrete base is common example of fixed support In RCC structures the steel reinforcement of a beam is embedded in a column to produce a fixed support as shown in above image. Similarly all the riveted and welded joints in steel structure are the examples of fixed supports Riveted connection are not very much common now a days due to the introduction of bolted joints. PINNED SUPPORTS A pinned support is same as hinged support. It can resist both vertical and horizontal forces but not a moment. It allows the structural member to rotate, but not to translate in any direction. Many connections are assumed to be pinned connections even though they might resist a small amount of moment in reality. It is also true that a pinned connection could allow rotation in only one direction; providing resistance to rotation in any other direction. In human body knee is the best example of hinged support as it allows rotation in only one direction and resists lateral movements. Ideal pinned and fixed supports are rarely found in practice, but beams supported on walls or simply connected to other steel beams are regarded as pinned. The distribution of moments and shear forces is influenced by the support condition. INTERNAL HINGE Interior hinges are often used to join flexural members at points other than supports. For example in above fig two halves of an arch is joined with the help of internal hinge. In some cases it is intentionally introduced so that excess load breaks this weak zone rather than damaging other structural elements as shown in above image.