Types of Loads Generated by Different Circus Acts
Circus acts involve diverse movements and equipment that place various types of loads on rigging systems. Understanding these loads is essential for ensuring performer safety and the integrity of rigging setups. Loads in circus rigging can be categorized as static loads, dynamic loads, impact loads, and cyclical loads. These are influenced by the nature of the performance, the equipment used, and the physical movements of the performer.
1. Static Loads
Static loads occur when the weight applied to the rigging system is constant and unchanging. These are the simplest to calculate and occur in situations where there is no movement. Despite their simplicity, static loads form the baseline for rigging requirements.
Examples:
• Aerialist in Rest Position: When a performer is hanging stationary in a harness or on aerial silks, their weight applies a static load. For example, a 60 kg performer generates a static load of about 588 N.
• Trapeze Setup at Rest: The weight of the trapeze bar, ropes, and any attached equipment applies a static load to the rigging points.
Considerations:
Static loads are straightforward to manage but must account for additional factors such as:
• Equipment weight
• Potential load-sharing among multiple rigging points
• Tension angles that can amplify forces
2. Dynamic Loads
Dynamic loads are generated when there is movement, such as swinging, bouncing, or falling. These loads fluctuate due to the changes in acceleration and deceleration, often exceeding the static load by several times. Rigging systems for dynamic loads require a higher safety margin to account for these fluctuations.
Examples:
• Swinging Trapeze Acts: As a performer swings, the tension in the ropes increases due to centrifugal force. At the lowest point of the swing, the load is highest due to the combination of the performer’s weight and the acceleration of the swing.
• Aerial Hoops or Lyra: Dynamic movements, such as spins or inversions, generate varying forces as the performer shifts their center of gravity and changes direction.
Considerations:
• The peak load occurs during rapid changes in motion, such as transitions from upward to downward movement.
• Rigging points and equipment must be rated to handle the maximum expected load during these transitions.
3. Impact Loads
Impact loads are short, sharp forces that occur when a moving object or performer is abruptly stopped. These are the most challenging forces to manage, as they can spike to many times the performer’s weight within milliseconds. Impact loads are common in acts involving drops or catches.
Examples:
• Aerial Silks Drops: When an aerialist executes a controlled drop, the force at the point where the drop is arrested can exceed five times their static weight. For example, a 70 kg performer (static load ~686 N) executing a 3-meter drop may generate impact forces exceeding 3,000 N, depending on the stopping distance.
• Catching Trapeze Artists: When a trapeze artist is caught mid-air, the combined weight of the flyer and catcher generates a significant impact load on the rigging.
Considerations:
• Elasticity in the rigging system, such as dynamic ropes or stretchable fabrics, can help absorb impact forces, reducing the load on anchor points.
• Equipment must have a high safety factor to handle unpredictable spikes in load.
4. Cyclical Loads
Cyclical loads are forces that are applied repeatedly over time due to repetitive movements or use. These loads can cause material fatigue, even if the forces are within the equipment’s rated capacity. Cyclical loading is particularly relevant for touring circuses, where rigging systems are set up and dismantled frequently.
Examples:
• Continuous Swinging Acts: Repeated swinging of a trapeze bar or aerial hoop applies cyclical stress to ropes, cables, and anchor points.
• Repeated Performer Movements: In acts like rope climbing or aerial straps, the performer’s continuous movements generate fluctuating loads on the rigging.
Considerations:
• Regular inspections are required to identify wear and tear caused by cyclical loading.
• Ropes and cables must be replaced periodically to prevent failure due to material fatigue.
5. Lateral Loads
Lateral loads occur when forces are applied horizontally, as opposed to vertically. These are less common in circus rigging but can arise in certain scenarios, such as when performers swing sideways or when wind affects outdoor rigging setups.
Examples:
• Swinging Pendulum Acts: Acts involving pendulum-like swings generate lateral forces at the anchor points.
• Outdoor Performances: Wind acting on props, performers, or rigging equipment introduces lateral forces that must be accounted for.
Considerations:
• Anchor points must be reinforced to handle multidirectional loads.
• Additional stabilization, such as guy lines or counterweights, may be required for outdoor setups.
6. Combined Loads
Many circus acts generate a combination of static, dynamic, impact, and lateral loads simultaneously. This combination complicates the rigging design, as all potential forces must be accounted for in the system’s overall capacity.
Examples:
• Multi-Performer Acts: When multiple aerialists perform on the same rigging system, the forces combine. For instance, if two performers execute drops simultaneously, their impact loads are additive, doubling the force on the anchor points.
• Prop-Integrated Acts: Props like suspended cages, chandeliers, or swinging poles add their own weight and dynamic forces to the rigging system.
Considerations:
• Load distribution across multiple anchor points is essential to prevent overloading any single point.
• Rigging equipment must have a sufficiently high safety factor to handle the worst-case scenario.
Load Types by Specific Circus Acts
| Act | Primary Load | Forces Generated |
| Silks | Impact/Dynamic | High forces during drops; dynamic fluctuations during spins and climbs |
Swinging Trapeze | Dynamic/Centrifugal | Increased rope tension at the lowest swing point; lateral forces during horizontal motion |
Static Trapeze | Static | Minimal forces; constant weight of performer and equipment |
High Wire Walking | Static/Dynamic | Minimal load fluctuations; concentrated weight on wire due to small contact area. Fall load should performer slip, fall and catch wire. |
Flying Trapeze (Catch Act) | Dynamic/Impact/Combined | Significant impact loads during catches; combined weight of flyer and catcher |
Aerial Hoop (Lyra) | Dynamic/Impact | Forces vary with performer movement; high impact during drops or rapid changes in position |
Duo Straps | Dynamic/Combined | Two performers sharing rigging generate combined static and dynamic loads |
Conclusion
Circus rigging is a complex interplay of forces that vary dramatically depending on the type of act. Each performance introduces unique challenges, from the predictable static loads of stationary acts to the unpredictable impact forces of aerial drops. By understanding these different types of loads, riggers can design systems that ensure the safety and success of every performance, allowing circus artists to push the boundaries of human ability while captivating audiences worldwide.
See Also: Safety Factors