Types of Beams in Civil Engineering
Any civil structure, particularly a building, needs beams for support. They transfer the weight bearing on the entire structure to columns and support it. Within structures, beams are horizontally aligned and capable of withstanding vertical forces, shear forces, and bending moments. Through their respective ends, the forces acting across them are transmitted onto columns, walls, and then foundations.
There are many different types of beams used in civil engineering constructions, and the type that is selected depends on the functional specifications that must be satisfied. They can be grouped according to the following standards:
Based on Support Types
Simply Supported Beams:
One of the most significant forms of beams is simply supported beams, which are also straightforward beams. Both of its ends are supported, with one pinned to a fulcrum and the other supported by rollers or fixed to something else. Additionally, there is freedom for both ends to rotate. Beams that are simply supported can withstand bending and shearing loads. When roller supports are utilised at one of its ends, it may also experience a translational moment. A simply supported beam’s ability to bend and shear is dependent on the sort of loading it is subjected to.
A beam type known as a cantilever beam is one that is fastened at one end and free at the other. Simply described, a cantilever beam is a beam that has one end fixed and hangs freely in the air. These beams are subject to loads that are transported to the supporting end, where they are resisted by fixed-end moments and shear stress. Because the fixed end of a fixed beam cannot move or rotate, the free end is typically used in structures like towers, bridges, and parking lots.
Because fixed beams are fixed at both ends, there is no room for rotation at either of these points. Typically, fixed beams are defined as having no ability to spin at their ends. To prevent any rotation, the ends of these sorts of beams are secured with the use of reinforcements. In the majority of high-rise structures, permanent beams that are rigidly coupled to intermediate columns or beams are present.
A continuous beam is a beam that has more than two supports and can be viewed as a collection of beams that are just linked together. The deflection is smaller than a simply supported beam, despite the fact that it can be conceptualised as a simply supported beam with one or more intermediary supports as well. As opposed to simply supported beams, bridge designs typically have more than one span because the maximum positive bending moment throughout its length is lower.
When a regular beam is strengthened with a truss frame, a trussed beam is created. Due to the need for sufficient open space and greater spans in warehouse and workshop shed construction, trussed frames are typically used in these types of buildings.
Overhanging and Double Overhanging Beam:
A simply supported beam with one end that extends farther up to a certain length and hangs freely in the air might be envisioned as an overhanging beam. The beam’s end that is attached to the support is either pinned or fastened. Both of the supporting points in the beam experience an additional bending moment as a result of the overhanging portion. These are typically used in residential building construction for balconies or overhanging shades. The overhang varies in length from 40 to 120 cm.
The double overhanging beam has an extended length on both of its sides, much like the overhanging beam does. A twin overhanging beam’s supports each have a rotating moment and may also be supported by rollers.
Based on Materials
Steel beams are made of a strong, resilient material that can withstand tension. Molten steel is poured into moulds of various sizes and shapes to create them. These beams are used to build industrial structures like bridges, workshops, ropeways, and furnaces.
Reinforced Concrete Beam:
Reinforced concrete beams are one of the most significant and often utilised forms of beams in modern construction. They largely aid in resisting transverse external stresses over the length of the beam, such as torsion, bending moments, and shear forces. Steel reinforcement carries the tensile loads because it is strong in tension, but concrete aids in resisting compressive forces since it is strong in compression.
To support the wooden roof trusses of wooden houses, timber beams are used in tandem with wooden posts and columns in a wooden frame structure. On both sides of a wooden truss, timber beams are typically placed horizontally in between two columns.
Two distinct types of materials are used to create composite beams. To function as a single entity, the two materials are either fused or connected together.
Based on Cross-sectional shapes
When a load is applied to a rectangular beam, the top and bottom of its rectangular cross-section experience compression forces, while the middle is subject to tensile forces. Steel reinforcements are typically placed in greater quantities at the bottom than at the top of a rectangular beam because tension operates at the bottom of the beam. They are among the beams that are most frequently used when high-rise buildings and small residential structures are being built.
An I-beam is a beam with two flanges at the top and bottom and a central web. It is often composed of steel. I-beams experience substantially less deflection than rectangular beams. In addition to being formed of concrete and fibreglass, they are also utilised to build multi-story buildings and industrial structures.
T-beams are cast as a single piece with slabs and have the shape of a ‘T’. Due to their cohesive nature, the slabs bend in the longitudinal direction of the beam. T-beams can be used more successfully for construction in bigger dimensions than rectangular beams because of their lower deflection.
The L-beam, which is shaped like an “L,” is a structural element that is added to a slab’s corner or perimeter. L-beams are sometimes known as end beams with only one side supporting slabs. L-beams are typically found at building corners where the roof slab does not protrude, as well as at corners near stairwells and elevator openings.
Based on Equilibrium
Statically Determinate Beam:
Simple static equilibrium equations can be used to compute the forces operating on statically determinate beams. In other words, the number of equilibrium equations and the number of unknown forces are equal. Because temperature changes cause significant stresses in bridge structures, statically determinate beams are frequently used in bridge construction.
Statically Indeterminate Beam:
The forces acting on statically indeterminate beams cannot be calculated using straightforward static equilibrium equations. It is necessary to employ constraint equations because there are more unknowns than can be expressed by simple equations. For comparable loads, deflection and stresses in statically indeterminate beams are less than those in indeterminate beams. Additionally, even if one component of a statically indeterminate structure fails, the entire structure won’t collapse. This is mostly a result of the structure’s load being distributed to different areas.
Based on Geometry
One of the most frequently used beams in building construction is straight beams, which are beams with a straight surface.
Buildings with circular or curved shapes frequently use curved beams, which are beams with a curved profile.
Tapered beams are beams with a tapered form.
Based on Construction Methodology
Concrete Beams Cast in Place:
Concrete Beams in Place are those that are created and cured on the spot. Fresh concrete is poured into pre-made moulds of predetermined sizes to produce the beams, which are then compacted vibratory.
Beam of Precast Concrete:
Precast concrete beams are created in controlled environments at plants that are located away from the construction site. To ensure optimal strength, ideal conditions are offered for the casting of these beams. To prevent any faults in the beams, the casting and curing processes carried out at factories are closely supervised and examined for optimum quality. To get them to the construction sites, careful transportation is required.
Beam of Pre-stressed Concrete:
Pre-stressed concrete beams are, as their name implies, prestressed before casting. Prior to pouring concrete into the casts, the tension wires in the beams are first installed in formwork and pre-tensioned using hydraulic jacks. With this pre-stressing technique, even in their eased state, beams can continue to be under compression as opposed to tension.
Lintel beams, which are placed above doors, windows, and ventilation frames, are smaller than other beams. These beams allow the wall below them to bear the weight of the doors and windows through the wall’s sides.