Pinned support

Definition

A pinned support is a type of structural support that allows rotation but prevents translation in any direction. This means it can resist vertical and horizontal forces while allowing the connected member to rotate freely. Pinned supports are crucial in analyzing structures since they contribute to equilibrium, influence load distribution, and impact the overall stability of frameworks.

5 Must Know Facts For Your Next Test

1. Pinned supports can provide two reaction forces: one vertical and one horizontal, but they do not resist moments.
2. These supports are commonly found in beams, trusses, and frames, ensuring that loads can be transferred effectively.
3. In free-body diagrams, the pinned support is typically represented by a circle or triangle, indicating the points where reactions occur.
4. When analyzing structures with pinned supports, it's essential to consider how loads will affect stability and whether the structure will remain in static equilibrium.
5. The design of pinned supports must account for potential movements due to loads, which is vital in preventing structural failure.

Review Questions

• How do pinned supports contribute to maintaining equilibrium in structures?
  • Pinned supports help maintain equilibrium by providing two reaction forces that counteract applied loads while allowing rotation. This balance ensures that the structure does not translate or topple under force. When analyzing static conditions, these supports play a vital role in ensuring that all forces acting on the structure are accounted for and balanced, which is essential for stability.
• In what ways does a pinned support differ from other types of supports when analyzing a truss structure?
  • Unlike fixed supports that resist both translation and rotation, pinned supports allow rotation but resist translation. This difference affects how forces are distributed throughout a truss. When using methods like joints or sections for analysis, recognizing these characteristics is crucial as it influences how the internal forces are calculated and how loads will be transferred through the truss members.
• Evaluate the implications of improper design or placement of pinned supports in a structural framework.
  • Improper design or placement of pinned supports can lead to significant structural issues such as excessive deformation, unexpected failures, or even collapse. If pinned supports do not effectively counteract applied loads or are incorrectly located, it could result in unbalanced forces within the framework. Additionally, inadequate consideration of rotational allowances may introduce vulnerabilities, emphasizing the importance of precise engineering and analysis in structural design.

Related terms

Reaction Forces: Forces developed at supports or connections in a structure to maintain equilibrium under applied loads.

Equilibrium: A state in which the sum of forces and moments acting on a body is zero, resulting in no motion.

Static Determinacy: A condition in a structure where the number of unknown reaction forces is equal to the number of equations of equilibrium available.