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Rigid or Cable Type? Engineering Criteria for Seismic Bracing Selection
What are the differences between rigid and cable-type seismic bracing systems?
Learn the engineering criteria for selecting the right seismic bracing system in detail.
Why Is Seismic Bracing Selection So Critical?
The behavior of mechanical systems during an earthquake is often overlooked, yet it directly affects overall structural safety. Pipework, air ducts, and mechanical equipment are subjected not only to vertical loads but also to multi-directional horizontal forces during seismic events.
To control these forces, seismic bracing systems are generally classified into two main categories:
- Rigid seismic bracing systems
- Cable (wire) type seismic bracing systems
A frequently asked question on site and during design stages is:
“Which one is better?”
However, the correct question should be:
“Which system is engineering-wise correct for this specific project?”
What Are Rigid and Cable-Type Seismic Bracing Systems?
Rigid Seismic Bracing Systems
Rigid systems consist of steel profiles, rigid connection elements, and fixed geometries designed to limit displacement. They are preferred in applications requiring high load capacity and low movement tolerance.
Cable-Type (Wire) Seismic Bracing Systems
Cable-type systems are composed of steel cables, tensioning components, and anchors. Thanks to their flexible structure, they offer the advantage of accommodating multi-directional forces.
Both systems are safe when properly designed; however, selecting the wrong system for the wrong application can result in serious risks.
1- Structural System and Building Type
When Are Rigid Systems Advantageous?
- In steel structures
- In projects with rigid structural systems
- In installations with low displacement tolerance
Rigid bracing systems transfer loads directly and in a controlled manner to the supporting structure.
When Are Cable-Type Systems Advantageous?
- In reinforced concrete structures
- In high-rise buildings
- In structures where the load-bearing system behaves differently in multiple directions
Cable systems can better adapt to the natural movement of the structure.
2- Installation Type and Load Characteristics
Installations Suitable for Rigid Systems
- Large-diameter piping
- Heavy mechanical equipment
- Fire protection systems
In such applications, uncontrolled movement is unacceptable.
Installations Suitable for Cable-Type Systems
- Light to medium-weight systems
- Long-span ductwork
- Installations exposed to multi-directional forces
Cable systems are used not only to resist loads but also to guide and manage movement.
3- Displacement and Movement Control
The Most Critical Engineering Criterion
During an earthquake, a certain amount of movement in mechanical systems is normal. What truly matters is ensuring that this movement is:
- Predictable
- Limited
- Non-damaging to the structure
In Rigid Systems
- Displacement is minimal
- The system behaves more stiffly
- Incorrect design may increase brittleness
In Cable-Type Systems
- Displacement occurs in a controlled manner
- Energy dissipation capacity is higher
- Incorrect tensioning may lead to serious performance loss
4- Installation Tolerances and Site Conditions
Installation Realities of Rigid Systems
- High precision in measurement and alignment is required
- Strict compliance with the design is necessary
- On-site modification tolerance is limited
Installation Realities of Cable-Type Systems
- Greater installation flexibility
- Better accommodation of site tolerances
- Tension adjustment is critical
Therefore, site conditions must always be considered during system selection.
5- Engineering Calculations and Compliance with Standards
For both systems, making a selection without proper engineering calculations is one of the most critical mistakes.
Calculations for Rigid Systems
- Section strength verification
- Buckling checks
- Connection stiffness analysis
Calculations for Cable-Type Systems
- Cable tensile capacity
- Tensioning angles
- Anchor load calculations
What truly matters is not the type of system, but the accuracy of the calculations.
Why Is the Question “Which Is Safer?” Incorrect?
This commonly asked question is technically incomplete because:
- A rigid system used in the wrong application may create excessive stiffness
- A cable system used incorrectly may result in uncontrolled movement
The correct system is the one determined based on the specific project, structure, and installation requirements.
Choosing the Right System with Darhan’s Engineering Approach
Darhan evaluates the engineering scenario first, rather than focusing solely on products, when selecting rigid or cable-type seismic bracing systems.
Within this approach:
- The seismic behavior of the structure is analyzed
- Installation loads and movement requirements are defined
- Hybrid solutions are applied when necessary
The goal is not to impose a single solution, but to deliver the most appropriate system for each project.
Conclusion: The Right Question, the Right System, the Right Engineering
The question “Rigid or cable type?” only gains meaning when evaluated through proper engineering criteria. Safety in seismic bracing systems does not arise from:
- The product type
but from - Calculations, design, and correct implementation
A properly selected seismic bracing system:
- Controls installation behavior during earthquakes
- Ensures compatibility between structure and mechanical systems
- Provides long-term safety and performance
For this reason, seismic bracing selection should be based on engineering principles, not habits.