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 linearly along the plane. Pinned supports are essential in understanding how structures behave under loads, as they create a connection point that can balance forces while allowing for movement that helps distribute loads efficiently.

5 Must Know Facts For Your Next Test

1. Pinned supports are crucial in bridge design, where they allow for movement due to temperature changes and other factors while maintaining stability.
2. The reactions at a pinned support can be represented in free body diagrams as two forces: one vertical and one horizontal.
3. Pinned supports do not provide any resistance to moments, which means they allow the connected structure to rotate freely about the pin.
4. In analyzing structures, determining the location and magnitude of forces at pinned supports is key to ensuring structural integrity.
5. Pinned supports are often represented as circles in free body diagrams, making it easier to visualize the constraints they impose on structures.

Review Questions

• How does a pinned support differ from a fixed support in terms of movement and structural constraints?
  • A pinned support allows for rotation while preventing translational movement, meaning it can adapt to angular changes without limiting linear motion. In contrast, a fixed support does not permit any movement; it restrains both translation and rotation, providing maximum stability. Understanding these differences is vital when analyzing structures under various loading conditions.
• Explain the role of pinned supports in distributing loads within a structure and how this is represented in free body diagrams.
  • Pinned supports play a key role in distributing loads by allowing rotation at the connection point while preventing linear displacement. This flexibility helps maintain equilibrium under various forces. In free body diagrams, the reactions at pinned supports are illustrated as two perpendicular forces, which simplify calculations for analyzing how the structure handles applied loads.
• Evaluate how the behavior of a structure changes when pinned supports are replaced with fixed supports and what implications this has for structural design.
  • Replacing pinned supports with fixed supports significantly alters how a structure behaves under loads. Fixed supports prevent all movement, leading to greater internal stresses due to constrained deformations. This change necessitates different design considerations, such as accounting for increased bending moments and shear forces, which can impact material selection and overall stability. Understanding these dynamics is essential for creating resilient structures that can withstand various environmental conditions.

Related terms

roller support:

A roller support allows for horizontal movement while preventing vertical movement, providing another type of constraint in structural analysis.

fixed support: A fixed support restrains both translation and rotation, providing maximum stability to structures but limiting their ability to adapt to applied loads.

reaction force: A reaction force is the force that a support exerts to maintain equilibrium, counteracting applied loads on the structure.