Pinned support

Definition

A pinned support is a type of structural support that allows rotation but prevents translation in any direction. This means that while the structure can rotate around the pinned point, it cannot move horizontally or vertically. Pinned supports are essential for maintaining the stability of beams and frames under various loading conditions, allowing for the transfer of forces while accommodating movement due to bending and other factors.

5 Must Know Facts For Your Next Test

1. Pinned supports are commonly used in bridge and building designs, where they allow for necessary movement due to thermal expansion and contraction.
2. In structural analysis, pinned supports are represented as a single point where the beam connects, often denoted with a specific symbol in diagrams.
3. The reactions at a pinned support typically include two components: one vertical and one horizontal, accommodating different loading scenarios.
4. Unlike fixed supports, pinned supports do not resist moment, which means that bending moments can occur in beams connected to them.
5. Understanding how pinned supports function is crucial for determining the overall behavior of structures under different load conditions, especially in statically determinate structures.

Review Questions

• How do pinned supports differ from fixed supports in terms of their role in structural stability?
  • Pinned supports differ from fixed supports primarily in their ability to allow rotation. While pinned supports restrict translation but permit rotation at the connection point, fixed supports restrict both translation and rotation. This distinction is crucial because it affects how forces and moments are distributed throughout a structure. Understanding these differences helps engineers determine appropriate support types based on the intended design and loading conditions.
• Evaluate the importance of pinned supports in the design of cantilever beams and their ability to handle various loading scenarios.
  • Pinned supports are vital in the design of cantilever beams as they provide necessary stability while allowing some freedom of movement. This flexibility helps cantilever beams manage loads effectively by enabling rotation without translating. When loads are applied, the reaction forces at the pinned support help distribute stresses and maintain equilibrium. The use of pinned supports also allows engineers to account for factors like thermal expansion, ensuring the structural integrity remains intact under varying conditions.
• Analyze how understanding pinned supports can influence decisions made during the structural analysis process.
  • Understanding pinned supports significantly influences decision-making during structural analysis as it determines how forces are transferred through a structure. Engineers must consider the reaction forces at these supports when modeling structures to ensure they can withstand applied loads without failing. Knowledge of how pinned supports permit rotation without moment resistance allows for accurate predictions of deflections and stress distributions. This understanding ultimately guides choices about materials, support types, and overall design strategies to achieve safety and functionality.

Related terms

Fixed support:

A fixed support is a type of support that restrains both translation and rotation, providing complete stability to a structure.

Cantilever beam: A cantilever beam is a beam that is anchored at one end while the other end is free, often relying on pinned supports to maintain equilibrium.

Reaction force: A reaction force is the force exerted by a support or connection in response to loads applied to a structure, crucial for analyzing structural stability.