Understanding Fixed Beams and Their Alternative Names

A beam is a structural element primarily designed to carry loads applied laterally to the beam's axis. Beams are classified based on their support conditions, which significantly influence their behavior under load.

One type of beam is known as a fixed beam. Fixed beams are also referred to by another specific term. Let's explore the properties and names associated with this type of beam.

What is a Fixed Beam?

A fixed beam is a beam that is supported in such a way that both ends are restrained against rotation and translation. This means that at the support points, the beam cannot move vertically or horizontally, and it cannot rotate. This type of support provides maximum rigidity compared to simply supported or cantilever beams.

Key characteristics of a fixed beam:

• Restrained against rotation at both ends.
• Restrained against translation (vertical and horizontal movement) at both ends.
• Also known as a built-in beam.

Alternative Name for Fixed Beam

The question asks for another name for a fixed beam. Among the given options, the term that specifically refers to a fixed beam is Encaster beam.

The word "encaster" means to fix firmly or build in. Thus, an encaster beam is one that is fixed or built-in at its supports, which perfectly describes a fixed beam.

Comparing Beam Types

Understanding the difference between various beam types helps clarify the definition of a fixed beam:

As seen in the table, a fixed beam, also known as an encaster beam, has both ends fixed, preventing both rotation and translation.

Statement Analysis

Let's look at the options provided:

• Constressed beam: This is not a standard term for a beam type based on support conditions.
• Spandrel beam: A spandrel beam is a beam that forms part of the exterior wall of a building, typically supporting floors or roofs above. It's a functional description, not a support condition type.
• Encaster beam: As discussed, this is another name for a fixed beam, meaning 'built-in' or 'fixed'.
• Constricted beam: This term is not standard terminology for a beam type based on support conditions.

Based on standard structural engineering terminology, 'Encaster beam' is the correct alternative name for a fixed beam.

Revision Table: Beam Terminology

Additional Information: Beam Support Conditions

The way a beam is supported dictates its behavior under load and how internal forces (shear force, bending moment) are distributed.

Common types of beam supports and their constraints:

• Fixed Support (Built-in Support): Prevents translation in all directions (usually vertical and horizontal) and prevents rotation. It resists forces in multiple directions and a moment. This is what fixes the end of a fixed beam or cantilever beam.
• Pinned Support (Hinged Support): Prevents translation in all directions (usually vertical and horizontal) but allows rotation. It resists forces in multiple directions but no moment. Used in simply supported beams.
• Roller Support: Prevents translation in only one direction (usually vertical) but allows translation in another direction (usually horizontal) and allows rotation. It resists a force in one direction. Used in simply supported beams to allow for thermal expansion.

Understanding these support types is crucial for analyzing stresses, strains, and deflections in beams.