What is Beam?
Beams are horizontal structural members that counter vertical loads applied along the axis of the beam and resist shear force and bending moment caused by the applied load.
A beam is a structural element in which one dimension is very large than the other two, and it is subjected to a system of external forces acting at a right angle to its axis.
They are well supported on one or more ends. The beam’s effective length between two end support is termed as span.
They transfer the load applied along the beam axis to supports such as columns, walls, and foundations.
Beams are defined by their cross-section shape, equilibrium conditions, support manner, length, and construction material.
In this article, we will know the different types of beams used in construction.
Types of Beams
Based on Support Condition
Simply Supported Beam
A beam is called a simply-supported beam when both ends of this beam rest freely on supports.
As its name indicates, it is one of the simple and most essential types of a beam containing pinned support at one end and roller support at the opposite end.
It is depending upon the type of load, this beam experience both shear force and bending moment.
If both the end of a beam are fixed or built in to resist rotation, it is termed a fixed beam. This beam doesn’t allow horizontal, vertical, and rotational movement.
Reinforcements are also provided at the end connection to restrict the rotation of the beam.
All multistorey buildings consist of the fixed beams, but the way they are fixed looks different.
Over Hanging Beam
A beam whose one or both of the end parts extends beyond the supports is termed the overhanging beam.
Usually, beams on both ends are supported by columns, but an overhanging beam from one end extends beyond the support. These beams are primarily used in balconies.
This beam has greater than two supports, identified as continuous beams. Extreme left and right supports are known as end supports, and the rest are known as intermediate supports.
- A continuous beam has a lesser net bending moment than simply beam. The significant mid-span moment is reduced due to the negative moment at the ends.
- It has lesser deflection as opposed to a simply supported beam.
- It permits a greater span than simply a supported beam.
- It has a more vertical load carrying capacity for the same span as a simply supported beam.
- For the same span, the depth of the section can be lesser than the simply supported beam.
- Its analysis and design procedure is challenging.
- Mainly in the case of precast members, its construction is complex.
- It requires proper detailing of maximum bending moment and shear force occurring at supports.
- Development of secondary stresses due to temperature and time-dependent effects such as shrinkage, creep, support settlement.
- Increased shortening may result in lateral forces at the supporting column.
This beam is fixed or built-in at one end, and free at another end refers to a cantilever beam. In a cantilever beam, there is no reaction at its fixed end.
Based on cross-section shape
These beams have a rectangular cross-sectional shape widely used in reinforced concrete building construction or frame structures.
These beams experience compression at the top part and tension at the bottom portion. Therefore extra reinforcement is provided at the bottom.
Also, Read – Difference Between Singly and Doubly reinforced Beam
T – Beam
These beams resemble the shape of capital T and are primarily constructed with reinforced concrete slabs monolithically.
To enhance the compressive strength of concrete, sometimes an isolated T beam is also constructed.
Moreover, according to the applied load need inverted T beam may also be built. T -Beam helps to reduce deflection significantly and offers to select larger span as compared to rectangular beam.
L – Beam
These beams are provided around the perimeter of the structure and cast monolithically with an RCC slab. Thus it acts as an L beam rather than a rectangular beam.
You can find these beams around the building perimeter where the slab is not projected beyond the beam axis.
I – Beams
I-beam resembles the shape “I” is an essential member of steel structure. It comprises two flanges united by the web. These beams are mainly used for steel structures, bridge support frames, etc.
H- Beam resembles the shape capital “H” and is an essential member of a steel structure made of rolled steel. H- beams are usually used in commercial and residential buildings due to their excellent mechanical properties.
These beams are made of steel in the form of a truss known as a truss beam. Truss beams are mainly used for larger spaces, such as open sheds, workshop sheds, and warehouse sheds.
Based on Equilibrium Conditions
Statically determinate beam
If equilibrium conditions are enough to calculate the reaction forces due to applied load, it is known as a statically determinate beam.
In these types of beams, the number of unknown reaction forces equals the equilibrium equation’s number.
These beams are mainly used in bridges because temperature change can induce significant stresses in the bridge.
Statically Indeterminate Beam
A statically indeterminate beam is called if equilibrium conditions are insufficient to calculate the reaction forces due to applied load.
The number of unknown reaction forces in these beams does not equal the equilibrium equation’s number.
The conditions arrive when we provide extra support to the structure than required make it statically indeterminate.
Extra supports ensures stability and increase the stiffness of the structure. For example, in trusses, we provide added diagonal members to assure stability.
- Usually, stresses are lesser in indeterminate structures.
- Due to greater stiffness, less deflection in the indeterminate structure compared to the determinate structure.
- Statically indeterminate structures allow load distribution that means if any member fails in such a system, the load will be redistributed to another member, and the structure will not collapse.
A statically determinate structure is neither more satisfying nor poorer compared to the statically indeterminate system. Based on details, it may be more effective or more vulnerable.
Based on Construction Material
Reinforced Concrete Beam
These beams are made of concrete in which steel bars are arranged as reinforcement. RCC beams are an essential part of frame structure and are commonly used in building construction.
If the beam is concealed in the RCC slab, it is known as a slab beam or hidden beam or flat beam.
These beams are made of steel mainly used in industrial construction and pre-engineered Buildings.
These beams are robust, durable, and readily available allow faster construction of the structure.
These beams are made of timber and used in older days. Now the use of these beams in the construction industry has been significantly reduced.
Composite beams are consist of two or more different materials, for example, steel and concrete.
Based on Geometry
As the name indicates, these beams have a straight form, and the maximum numbers of beams in the structures are straight beams.
As the name suggests the beams that have curved profile along its length is known as the curved beam. These beams are used in curved or circular shape buildings.
These beams have tapered profiles along their length, known as tapered beams.
Based on the Method of Construction
Cast -In-Situ Concrete Beams
These types of cast on-site, for which firstly formwork is installed in the desired shape then fresh concrete is poured on it and let them dry. Then curing is done until concrete gains the desired strength.
Precast Concrete Beam
These types of beams are made on manufacturing plants under controlled conditions. So the quality of such beams is better than constructed on-site.
Precast concrete beams can be constructed in various shapes, such as T-shape, L-shaped, Double T, inverted T, etc.
Prestressed Concrete Beam
The pre-stressed concrete beam is a type of RCC beam in which internal stresses are induced before being used to resist the tensile stresses produced in concrete due to the load.
The pre-tensioned concrete beam and the post-tensioned concrete beam are the types of this beam.
According to the ACI code, these beams have more depth than regular beams, and their clear span to depth ratio is less than four.
Significant loads are transferred to the supports through compression force merging loads, and the reactions resulting in the strain distribution are no longer leaner than convention beams.
These beams are made of steel sections and are primarily used to carry heavy loads.
Lintel beams are an essential part of the structure in building construction to support the masonry over the doors, windows, and other openings.
To know more about lintel, please visit – What is Lintel? – Function & Type
Plinth Beam is an important superstructure member in building construction provided at or above the ground level, or plinth level is known as plinth beam.
To learn more about the plinth beams, please read – What is Plinth Beam? – Plinth protection, Difference Between Plinth Beam and Tie Beam
These beams connect two or more columns at any height in the structure refers to a tie beam.
These beams are constructed at ground level or grade level, known as a grade beam. To read more about grade beam – Grade Beam – Grade Beam Foundation – Construction Process, Advantage and Disadvantages