Fixed support

Definition

A fixed support is a type of boundary condition in structural engineering that restrains a structure at a specific point, preventing both translational and rotational movement. This means the structure cannot move up, down, or sideways, and it cannot rotate about the support point, effectively anchoring it in place. The presence of a fixed support has significant implications for analyzing forces, moments, and deflections within a structure.

5 Must Know Facts For Your Next Test

1. Fixed supports can exert reaction forces in both vertical and horizontal directions as well as moment reactions to maintain equilibrium.
2. In analyzing structures, fixed supports simplify calculations because they provide stable boundary conditions that limit potential movements.
3. Structures with fixed supports tend to experience higher internal forces and moments compared to those with simpler supports like pin or roller supports.
4. When calculating deflections in beams with fixed supports, the constraints must be considered, as they lead to zero deflection at the support points.
5. The use of fixed supports is essential in design considerations for frames and columns, ensuring stability under various load conditions.

Review Questions

• How do fixed supports influence the analysis of reaction forces and internal moments within a structure?
  • Fixed supports significantly affect the analysis of reaction forces and internal moments because they prevent both translational and rotational movement at the point of support. This leads to the development of reaction forces in vertical and horizontal directions as well as moment reactions that must be accounted for when performing static equilibrium equations. Consequently, engineers must calculate these reactions accurately to ensure stability and safety in the overall structural design.
• Compare and contrast fixed supports with pin supports in terms of their impact on structural behavior.
  • Fixed supports provide complete restraint against translation and rotation, resulting in higher internal forces and moments within the structure compared to pin supports, which allow rotational movement but restrict translation. This difference means that structures with fixed supports often require more careful analysis due to the increased complexity in internal force distribution. Pin supports offer more flexibility, allowing structures to experience some movement under load without inducing high internal stresses.
• Evaluate the role of fixed supports in determining beam deflection and overall structural integrity under various loading conditions.
  • Fixed supports play a critical role in determining beam deflection and overall structural integrity by imposing constraints that directly influence how a beam reacts to applied loads. When analyzing deflection, the fixed nature of these supports means that deflection at the support points is constrained to zero, affecting the beam's bending behavior and load distribution along its length. This consideration is crucial when designing beams for specific applications, as failing to account for the effects of fixed supports can lead to inadequate designs that may compromise structural integrity under expected loading conditions.

Related terms

Reaction Forces:

Forces that develop at supports or connections in response to loads applied to a structure, necessary for maintaining equilibrium.

Moment of Inertia: A measure of an object's resistance to changes in its rotation, which is crucial for analyzing bending in beams.

Pin Support: A type of support that allows rotation but prevents translational movement in any direction, offering less restraint than a fixed support.