23 Types of Beams Used in Construction (With Classification)
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Beams are integral to most structural construction projects, from bridges, highrises, highway overpasses, to homes. These central building components provide support in several ways, depending on the type, material, size, shape, and use, for example. Understanding the basics of beams, including which type is best for a project, can help professionals in careers like construction, engineering, and architecture.
In this article, we define beams, explore the many types of beams, and list each of them under their designated classifications, including the type of support, material, cross-section, geometry, and construction.
What is a beam?
There are many types of beams, which are horizontal features, often called structural members. Builders use beams to help bear vertical loads, sheer forces, and rotation or moments. Contractors use beams to make floors, ceilings, roofs, and bridges.
Understanding the physics involved in building and other engineering concepts can be important to ensure the structural integrity of projects and the safety of the public that uses them.
What are the different types of beams?
When deciding which types of beams can support the tremendous weight and stress imposed by the structural elements above it, professionals typically look at several conditions related to support. Engineers choose a beam based on how well it can resist the required load determined by project parameters.
Beam types constitute specific classifications according to the load they support, the beam's material makeup, the cross-section shape, its geometry, equilibrium, and construction. When a beam falls under two classes, professionals often assign a classification based on a beam's prominent feature or distinction from other beams.
Beams classified by type of support
The type of support for beams refers to how and what a builder uses to reinforce or attach the beam to other structures. Builders can attach supports at the ends, middle, or anywhere along a beam's horizontal line. There are four common types of support:
Fixed supports: A fixed support is rigid and prevents the beam from rotating or moving horizontally or vertically. An example is a beam attached directly to a wall.
Pinned supports: Pinned or hinged supports allow a beam to rotate or pivot but not move vertically or horizontally. Bridges and trusses often require pinned supports.
Roller supports: Roller supports can resist vertical loads, but they can't resist horizontal force, so they typically require a second support like a hinge support. Roller supports are common on one end of long bridges, as they can resist extreme temperature changes that can cause expansion and contraction of girders or beams.
Simple supports: Simple supports can't resist horizontal loads but can resist vertical forces. For example, a beam placed on another structure like a concrete column only has the support from the vertical force of the columns, which is why builders rarely use these supports.
Examples of beams classified by one of these support types include:
Simply supported beams
These beams have no restrictions against horizontal movement as they simply rest on two supports, like concrete columns. Simple support systems often use roller and pinned supports on both ends, so they still allow for horizontal movement. Also called free support beams, professionals can use these beams to build earthquake-resistant buildings and suspension bridges.
This structural element extends horizontally and has one end that contractors fix to the rest of the structure, while its other end is free. Builders often attach these beams to a secure wall. They use cantilever beams in the construction of certain types of bridges, bay windows, and balconies.
These beams have over two points of fixed support and are typically longer than other beams. Because they have multiple support areas, they offer more stability if one support fails. Professionals can use these beams for bridges, rooftop extensions, and multi-floor buildings, especially in earthquake-prone areas.
Fixed-end or built-in beams are beams contractors fix at both ends so they can't move vertically, horizontally, or rotate. This provides extreme stability for the structure. Professionals often use fixed-end beams for buildings, bridges, raised walkways, trusses, and column-like structures.
Builders attach overhanging beams at two immobile support points, leaving at least one end hanging past its support structure. Professionals can use overhanging beams for balconies and roof extensions, for residential homes, apartment buildings, and hotels. Architects often use overhanging beams to create unique artistic elements.
Double overhanging beam
A double overhanging beam has both ends extending past its fixed support point. The support area is typically in the middle of the beam, like a support wall. Professionals may use these beams where a higher floor extends past a lower one, like in enclosed balconies or buildings with glass floors.
Beams classified by material
Beams come in a variety of materials, each with different strengths, flexibility, and durability. For instance, steel is typically stronger than wood, but wood can be more pliable. Understanding a material and its structural characteristics can be important when choosing the right beam. Here are several examples:
Steel beams are one of the strongest beams, so you often see them in large commercial projects, like apartment complexes and shopping malls. Apart from withstanding heavy loads, these beams rarely corrode, so they can typically withstand extreme weather like temperatures, wind, and rain. This unique characteristic is also what makes them good for underwater projects, like offshore drilling or bridges.
Concrete beams can handle powerful stressors and enormous loads. They're suitable for larger-scale, weight-bearing construction. You often see them used for bridges, highways, dams, parking garages, stadiums, and piers, where increased support is essential.
Timber beams can be a variety of woods and each has specific strengths, colours, hardness, permeability, and durability, for example. Oak, Douglas fir, red maple, redwood, eastern white pine, and yellow birch are some examples. Builders may also choose a wood based on esthetics for exposed beams.
Fabricators make composite beams with two or more materials with different flexibility properties. This adds more strength and rigidness to the beam. Reinforced concrete and steel are the composite beams most commonly used by constructors because they're reliably sturdy and suitable for large weight-bearing structures.
Beams classified by cross-section
A beam's cross-section shape can affect how it performs. Every cross-section shape has distinct pros and cons, depending on the type of construction required. Here are some examples:
Looking at the cross-section of these beams, they form a rectangle. They're the most common beam in construction. While rectangular beams receive most of their reinforcement from bottom tension, they can also resist compression.
Contractors also call these beams rolled steel joists, universal beams, and H-beams, although H-beams are wider, longer, and heavier. These beams, which resemble the letter "I," have a central rectangular section, sandwiched by two flat crossbars or flanges, which allows them to resist incredible loads. I-beams are typically steel, concrete, aluminum, or fiberglass and used for bridges, commercial plants, and multi-level buildings.
T-beams look like a "T" and can be more cost effective and flexible than other support beams because they're one piece of steel with a reinforced concrete slab. It can curve slightly, which helps soften any deflection. Contractors use T-beams for commercial buildings, roof framework, and highways.
L-beams or angle beams resemble an "L" or right angle. Their design makes them especially strong because they can prevent bending while resisting shear stress. Professionals often use these beams in the construction of building corners and stairways.
Contractors sometimes call U-beams or C-beams parallel channel flange beams because of their double flange. Contractors typically attach them to a wall or other supporting surface. They may also weld them back-to-back to create a reinforced I-beam, to support floor joists, or general framework.
Beams classified by geometry
A beam's shape determines its geometry, which can affect the way contractors use it. Certain shapes naturally offer more strength than others. For example, the strongest shape is an arc or curve because it can disperse weight. Here are some examples:
Straight beam: A straight beam is a broader term for any beam that's straight with no cross-sections. Manufacturers make these beams from steel, composite, wood, or concrete.
Curved beam: These beams often feature two support points for stability. Professionals use curved beams for structures like arches, gazebos, and buildings with circular rooms or towers.
Tapered beam: Tapered or slant beams feature two ends with varying widths. Builders use them when framing a roof, or in more ornate structures like churches with exposed rafters.
Beams classified by equilibrium
Engineers categorize beams by their equilibrium conditions to estimate how much force they can withstand. Contractors classify beams under this category based on their state of balance. Some examples include:
Statically determinate beam: Statics, equations for equilibrium, can determine any reactions and internal forces. These beams are suitable for buildings and structures that may experience varying levels of stress, like bridges.
Statically indeterminate beam: Statically indeterminate beams are more stable because they typically have more supports than required, ensuring the complete stability of a structure.
Beams classified by construction
How a manufacturer casts a beam during fabrication can determine its classification. Casting involves pouring a liquid material into a shaped mould and letting it solidify. Here are several examples:
Cast in situ concrete beam: Contractors use these beams to ensure custom conditions. They make them onsite by pouring concrete into a mould and allowing it to cure.
Precast concrete beam: Professionals make precast concrete beams in a factory and transport them to the construction site. They rigorously test and treat them before shipping to ensure quality.
Pre-stressed concrete beams: Fabricators test and apply force to pre-stressed concrete beams before they cast them. This can help ensure their strength and quality for large, heavy-load construction projects.
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