Beam Structure: Definition and Types

Beam structures are an important type of structural element that construction professionals and some types of engineers must be familiar with. These structures play a prominent role in how weight is transferred and ensures that a building's foundation is firmly planted in the ground. The most common types of beam structures include over-hanging, fixed, trussed, continuous and simply supported beams. In this article, we'll explore what a beam structure is, why it's important to understand these structures and the most common types of beams used by construction workers and engineers.

What is beam structure?

A beam structure, sometimes simply referred to as a beam, is a type of structure used in construction and engineering to provide a safe and efficient load path that effectively distributes weight throughout the foundation of a building. These beams support the load by resisting being bent under the load's pressure. Beams resist this force in a lateral way as the force is applied to the axis.

In most situations, the load distribution pattern includes a slab, beam, column and foundation. This means that the beam is inserted below the foundation and column to provide more comprehensive support throughout the structure. The primary purposes of beam structure include:

• Offsetting shear forces and/or beam momentum

• Resisting loads

• Distributing loads in a uniform fashion

• Uniting the structure together

In a beam structure, there are a few different reinforcements that are used depending on the type of building being built and the purpose of the beam. The most commonly used reinforcements include:

• Main bars: This type of reinforcement is used to carry loads.

• Support bars: A support bar is a reinforcement that is set in the top part of the beam and works to hold the beam's stirrups in place.

• Stirrups: This type of reinforcement is used to offset the shear force or shear stresses of the structure.

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Why it's important to understand beam structure

Understanding beam structure is essential in construction and structural engineering because these beams are a primary way in which the building bears its weight. Beams ensure that there is a stable load path at the foundation of the building so that the weight of the building's roofs, ceilings and floors are properly supported. Construction and engineer professionals must understand the type of beam that is most appropriate for a structure and how to effectively install beams to ensure the structure being built is able to withstand its own force.

For example, if a building is of a larger stature, heavier and larger beams will likely need to be used to effectively support the load. Smaller structures require smaller beams, as they tend to have a lighter load and do not need as much support. Choosing the wrong type of beam can result in the structure not being stable enough to withstand its own load and could be detrimental in terms of the building's longevity and safety.

Understanding beams requires knowledge of statics of engineering and fundamental physics. This understanding allows construction and engineering professionals to identify the loads that will affect the beam and choose the correct size, shape and material of the needed beam effectively.

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Types of beam structure

There are a few primary types of beams used in construction and engineering. These beams are typically classified based on their length, equilibrium and cross-section and include:

Continuous beams

A continuous beam is one that has two or more supports that reinforce the beam. These supports are used under and between the beams and are typically vertical in nature. Continuous beams are thought to be more economical when compared to other beam types.

Simply supported beams

Simply supported beams are those that have supports at both end of the beam. These are most frequently utilized in general construction and are very versatile in terms of the types of structures that they can be used with. A simply support beam has no moment resistant at the support area and is placed in a way that allows for free rotation at the ends on columns or walls.

Fixed beams

A fixed beam is one that is fixed on both ends of the beam with supports. This type of beam does not allow for bending moment production and will not have any vertical movement or rotation. Fixed beams are most frequently used in trusses and similar structures.

Overhanging beams

An overhanging beam is one that is supported at two different areas, typically at one end and in the middle of the beam, but does not have a support at the other end of the beam, leaving it hanging. This type of beam extends beyond the walls or columns and the overhanging section of the beam is unsupported. An overhanging beam is a combination of a simply supported beam and a cantilever beam.

Cantilever beam

A cantilever beam is one that is free-hanging at one end of the beam and fixed at the other. This type of beam is capable of carrying loads with both bending moment and sheer stress and is typically used when building bridge trusses or similar structures. The end that is fixed is typically attached to a column or wall. The tension zone of a cantilever beam is found at the top of the beam with the compression at the bottom of the beam.

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Construction careers that require beam structure knowledge

There are several construction occupations that require knowledge of beam structures. These occupations include:

• Structural engineer

• Civil engineer

• Architect

• Building information modeling (BIM) coordinator

• BIM manager

• Building services engineer

• Building surveyor

• Computer-aided design (CAD) operative

• Civil engineering technician

• Construction manager

• Design manager

• Estimator

• Materials engineer

• Project manager

• Mason

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Each of these careers works with the structure of a building in some capacity. Some of these positions require in-depth knowledge of beam structures, while others only require a fundamental understanding of how beams work.

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