Structural elements are the fundamental parts of a building. They are rigidly connected to provide support and stability, ensuring the building can safely withstand loads and external forces.
These elements, beams, columns, walls, slabs, and foundations, are designed to transfer safely and economically loads from one part of the structure to another.
Read More: Structural Design: The Best Literature Review for Engineers
Table of Contents
Read More: Engineering Disciplines: A Complete Guide
Beams as Structural Elements
Beams are a generic name for a structural member used for spanning, sustaining lateral loading, and developing internal resisting force actions of bending and shear.
Depending on its particular task in a structural system, a beam may be further described as a joist, rafter, purlin, girder, header, or lintel; however, it is classified as a beam for its fundamental behavior.
Read More: Theory of Structure You Must Know Right Now
Types of Beams as Structural Elements
Types of beams: Simple supported, cantilevered beam, overhanging beam, and restrained or fixed-end beam.
The following are the types of beams based on the support condition:
- Simple supported beam: This type of beam consists of a single-span beam with supports at each end, offering only vertical force resistance. Because the supports do not provide restraint to the rotation of the beam ends, the beam takes the simple curved form of deformation.
- A cantilever beam: This type of beam consists of a single-span beam with only one end support. For stability of the beam, this support must be a rotation-resisting support, called a fixed support or a moment-resisting support.
- Overhanging beam: This is a type of beam which supported at two or more points with an extension beyond the supports.
- Restrained or fixed-end beam: This is a single-span beam with both ends fixed against rotation.
Read More: Structural Engineer | All You Need To Know
Load and Support Conditions
Members that serve as beams exist in various situations and sustain many loads. The most common types of loading conditions are explained below:
Uniformly Distributed Load
Concentrated Load
Nonuniformly Distributed Load
- Uniformly Distributed Load: The dead weight of the beam itself is constituted as a load that is distributed evenly along the beam length. This is a common loading called a uniformly distributed load, or simply a uniform load.
- Concentrated Load: The second most common load is one in which the force is delivered to the beam at a single location, effectively as though it were concentrated at a point. In framing systems, beams that support the ends of other beams sustain concentrated loads consisting of the end reactions of the supported beams.
- Nonuniformly Distributed Load: Complexities of the building form or construction sometimes result in distributed loads on beams that are not uniform in magnitude along the beam length.
As with other structural elements, beams often sustain combinations of loads rather than a single load. For a given design situation, the structural engineer has to investigate the behavior of the beam for several loading combinations.
Read More: Structural Design Basis: General Guidelines You Need To Know
Beam Actions
The behavior of beams involves various actions that may need consideration in structural investigation for design.
The following are the major considerations:
- Flexure or Bending: Bending is a primary beam function involving the need for some resistance to internal moment at most cross sections of the beam.
- Shear: Shear as a result of the direct load effects is the other primary beam function.
- Rotation and Deflection: Beam deformation is manifested as angular change and deflection. The angular change (rotation) may be visualized as the movement of vertical plane sections or of tangents to the curved beam profile. Deflection is the distance of dislocation of points in the beam from their previous, unloaded positions.
- Lateral Buckling: If a beam lacks lateral stiffness and is not braced, it may buckle sideways due to the column-like action of the compression side (top) of the beam. The chief determinants of this action are the lateral bending stiffness of the beam section and the stiffness of the beam material. The usual solution is bracing; if not, moment resistance is reduced.
- Torsional (Rotational) Buckling: If the beam lacks torsional resistance and is not adequately braced, it may be rolled over by the loads or at its end by the support force. As with lateral buckling, bracing is the best solution, or the load capacity must be reduced.
- Torsional Moment: Beams may experience a twisting effect (called torsion) due to the direct effects of loading. This may be caused by loading not aligned with the beam’s vertical axis (eccentric loading) or by moment transfer from attached framing. This is not the same as torsional buckling, although the effect is similar, consisting of a rolling over of the beam.
- Bearing: If a beam is supported by direct bearing on a support, the support force must be developed as a vertical compression on the beam end and as a contact-bearing pressure on the support.
Read More: What is Civil Engineering? | History, Functions, and More
Structural Analysis of a Beam
The structural analysis of a beam involves determining internal forces (shear, moment, axial), reactions, and deformations under applied loads.
Reactions
Beam Reactions
For statically determinate beams, the first step in the structural analysis of a beam is the determination of the effects of the supports on the beam, called the reactions.
For the simplest definition, the reactions are a set of vertical forces that respond directly to the vertical loads on the beam, constituting with the loads a system of coplanar, parallel forces.
This system yields a solution by consideration of static equilibrium if there are not more than two unknowns (corresponding to the number of conditions for equilibrium of a parallel force system.
Shear
The Shear force and Bending moment diagram
Shear force is the internal force acting perpendicular to the beam’s longitudinal axis, causing a “sliding” effect.
It is crucial for determining beam strength and designing reinforcements (e.g., stirrups in concrete beams or web stiffeners in steel beams).
Bending Moment
Bending moment in a beam is the effort required by the beam for consideration of complete equilibrium at all points in the beam, figure above.
Furthermore, the bending moment causes a beam to bend under applied loads. Bending moment is important for structural engineers to determine beam strength, deflection, and reinforcement required (for concrete beams).
Read More:
- Engineering Ethics All Engineers Should Know Right Now
- Types of Glasses for Construction You Need To Know In 2025
- What is the Function of Buildings? The Quick Guide
- Best CAD Software for Architects | All You Need to Know
- 21 Types of Engineering You Need To Know
- What is Research Methodology? The Ultimate Engineer’s Guide
- Unit Operations for Wastewater Treatment: The Complete Guide
Wrapping Up
As discussed above, structural elements are a combination of beams, columns, slabs, foundation, and walls rigidly connected to form a monolithic frame.
Each member must be capable of resisting the forces acting on it, so the determination of these forces is an essential part of the design process.
Furthermore, Beams are structural elements that primarily resist loads applied laterally to their axis, supporting the weight of floors, roofs, or walls.
I think you enjoyed reading this blog post. If you liked this article, please join us on Telegram. You can also find us on Pinterest, Twitter, and Facebook.
Thank you!
Frequently Asked Questions (FAQs)
Briefly explain the Structural Elements.
Structural elements are the fundamental parts of a building. They are rigidly connected to provide support and stability, ensuring the building can withstand loads and external forces safely and economically.
Mention elements designed to transfer loads from one part to another.
Elements such as beams, columns, walls, slabs, and foundations are designed by a structural engineer to transfer loads from one part of the structure to another.
What is Bending Moment?
Bending moment in a beam is the effort required by the beam for consideration of complete equilibrium at all points in the beam.
What is a Beam?
Beams are horizontal members used to carry loads from the floor to columns or walls.
What is the aim of Structural Design?
Structural design aims to ensure that, with an acceptably high probability, a structure will remain fully functional during its intended life.
What are the types of beams based on support conditions?
Types of beams based on support conditions are: a simply supported beam, a cantilever beam, an overhanging beam, and a restrained or fixed-end beam.
