Compact sections

Definition

Compact sections refer to structural members that have a uniform cross-sectional shape and sufficient stiffness to resist buckling under compressive loads. This term is crucial in seismic design as it directly influences how braced frames behave during earthquakes, particularly in terms of stability and strength under lateral forces.

5 Must Know Facts For Your Next Test

1. Compact sections are designed to avoid buckling when subjected to compressive forces, making them essential in the seismic design of braced frames.
2. These sections help ensure that the braced frames can maintain their structural integrity during significant lateral loads caused by earthquakes.
3. The AISC (American Institute of Steel Construction) provides guidelines on what qualifies as a compact section based on its dimensions and material properties.
4. In seismic design, compact sections improve the performance of structures by enhancing energy dissipation during an earthquake, thus reducing potential damage.
5. Inadequate consideration of section compactness can lead to unexpected failures in braced frames, underscoring the importance of selecting appropriate cross-sectional shapes.

Review Questions

• How do compact sections influence the performance of braced frames during seismic events?
  • Compact sections significantly enhance the performance of braced frames during seismic events by providing adequate stiffness and resistance to buckling. This means that when lateral forces are applied, such as those experienced during an earthquake, the structural integrity is maintained. The ability to resist these forces without losing load-carrying capacity ensures that the braced frame remains stable and effective in dissipating energy, thus protecting the overall structure from damage.
• What role does the AISC play in defining compact sections and their significance in seismic design?
  • The AISC provides specific guidelines for defining compact sections based on their geometry and material properties, which are crucial for ensuring safety and performance in seismic design. These standards dictate how certain cross-sectional shapes can be classified as compact and outline the necessary conditions for their use in braced frames. By following these guidelines, engineers can ensure that structures are designed with appropriate members that can effectively resist lateral forces during earthquakes.
• Evaluate the implications of using non-compact sections in the design of braced frames for earthquake resistance.
  • Using non-compact sections in the design of braced frames can lead to serious implications for earthquake resistance. Non-compact sections are more susceptible to buckling under compressive loads, which could result in structural failure during a seismic event. This could compromise the overall stability and safety of the building. Inadequate performance under lateral forces may lead to significant damage or collapse, emphasizing the need for proper section selection and adherence to established guidelines like those from AISC.

Related terms

Braced frames: Structural systems that use diagonal braces to provide lateral stability, helping to resist forces such as those generated by earthquakes.

Buckling:

The sudden failure of a structural member under compressive load, which leads to a loss of load-carrying capacity.

Lateral forces: Forces that act horizontally on a structure, such as wind or seismic activity, requiring special design considerations for stability.