Types of Support Forms for Seismic Bracing Systems

Seismic bracing systems are critical for ensuring the stability and safety of buildings and industrial installations during earthquakes. These systems prevent structural damage by absorbing and redirecting seismic forces. One important aspect of designing seismic bracing is understanding the different types of support forms, which can be classified based on force direction, installation structure, functionality, and other special considerations.

1. Classification by Core Force Direction

The primary function of seismic braces is to resist forces during earthquakes. Based on the direction of the forces they are designed to resist, braces can be categorized as:

• Axial (Tensile/Compressive) Braces: These braces are designed to resist forces along their length, either in tension or compression. Common examples include diagonal rod braces and steel pipe braces.

• Shear Braces: These braces resist lateral shear forces between structural elements, such as floor beams and columns. They often use plate or cross-bracing systems.

• Moment-Resisting Braces: Designed to resist bending moments, these braces connect structural members rigidly to prevent rotation, often used in frame structures.

2. Classification by Installation Structure and Functional Features

Seismic braces can also be classified according to how they are installed and their functional characteristics:

• Single-Pole or Single-Rod Braces: Simple in design, they connect two points directly to transfer seismic loads. Ideal for small-scale installations or light equipment.

• Double-Angle or Multi-Angle Braces: Used in larger structures where multiple load paths are required. Their angled configuration enhances stability and distributes seismic forces more evenly.

• Hanger-Type Braces: Suspended from above, often used in piping or duct systems. They prevent vertical displacement during seismic events.

• Adjustable or Telescopic Braces: These allow for length adjustments during installation and accommodate slight movements due to thermal expansion or structural settlement.

3. Special or Unconventional Support Forms

Some seismic bracing systems are designed for unique scenarios or specialized requirements:

• Spring or Vibration-Isolated Braces: Incorporate damping elements to reduce vibrations, protecting sensitive equipment in laboratories, hospitals, or data centers.

• Base-Isolated Supports: Include flexible or sliding joints at the foundation to decouple the supported system from ground motion.

• Cross-Laminated or Multi-Layered Braces: Combine multiple materials or layers to achieve higher energy absorption and structural resilience.

Conclusion

Understanding the different types of support forms for seismic bracing is essential for structural engineers, architects, and facility managers. Classification by force direction, installation and functional features, and special forms provides a comprehensive framework to select the right solution for a given project. Properly designed seismic braces not only protect structures but also safeguard human lives and critical equipment during earthquakes.