Seismic Bearing Capture Assembly for Impact Mitigation
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Solution Overview
Problem
Conventional seismic isolation devices and mitigation strategies are inadequate for addressing the unique damage risks posed by large-scale events such as explosions and direct airplane strikes on structures, including nuclear power plants, as they do not effectively differentiate between the distinct reactions caused by earthquakes and impact events.
Innovation Solution
The implementation of lateral dampening devices and seismic bearings with specialized configurations, including restorative and reactive members, capture assemblies, and energy-absorbing materials, to selectively mitigate damage from both earthquakes and aircraft impacts by differentiating between the displacement profiles of these events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional seismic isolation devices are used, then seismic protection is provided, but protection against impact events such as aircraft strikes is inadequate
Solution Approach 1:
The seismic bearing incorporates a capture assembly with movable components (outer shaft, hook) that transition from a non-engaged state during earthquakes to an engaged state during impact events. This dynamic reconfiguration allows the device to adapt its mechanical properties based on the type of event, providing impact protection only when needed while maintaining seismic isolation functionality.
Solution Approach 2:
The capture assembly changes the stiffness and damping parameters of the seismic bearing system based on displacement magnitude and rate. During earthquakes with smaller displacements, the bearing operates in its conventional flexible mode. During impact events with large sudden displacements, the capture assembly engages, dramatically increasing the system's stiffness and energy absorption capacity.
2Reliability
If seismic bearings with capture assemblies are implemented, then impact event protection is enhanced, but device complexity increases
Solution Approach 1:
The capture assembly is nested within the seismic bearing structure, with the outer shaft fitting within the bearing housing and the hook mechanism integrated into the core post assembly. This nested configuration minimizes additional space requirements and reduces the visual and structural complexity compared to a completely separate impact protection system.
Solution Approach 2:
The outer shaft and hook act as intermediary components that mediate between the seismic bearing and the foundation. Rather than directly modifying the entire bearing structure, these intermediary elements selectively engage to provide impact protection, simplifying the overall design by isolating the complexity to specific functional components.
3Reliability
If lateral dampening devices are added, then aircraft strike protection is improved, but ease of operation and maintenance decreases
Solution Approach 1:
The capture assembly is designed to engage automatically based on displacement conditions without requiring external control systems, sensors, or power sources. The mechanical engagement of the hook with the stationary hoop occurs passively when displacement thresholds are exceeded, eliminating the need for complex control mechanisms that would complicate operation and maintenance.
Solution Approach 2:
The capture assembly is integrated with the existing seismic bearing components rather than being a completely separate system. The outer shaft, hook, and stationary hoop work in conjunction with the conventional bearing elements, allowing for combined maintenance procedures and reducing the operational burden of managing separate impact protection systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These systems effectively reduce structural damage from both seismic events and aircraft strikes by absorbing and dissipating energy specifically during impact events, while maintaining conventional seismic isolation functionality during earthquakes, thus providing enhanced protection for critical infrastructure like nuclear reactor containment buildings.
Implementation Method 1
The restorative member may include a spring
Implementation Method 2
an energy-absorbing and restorative core post
Data Source
AI summary
Systems mitigate structural damage by selectively engaging energy-absorbing structures only during impact events, including aircraft impacts. Systems include lateral dampening devices and/ or seismic bearings between a structure and its foundation. Lateral dampening devices include a restorative member and/ or reactive member configured to rigidly join the structure and the foundation and dampen reactive movement after the structure moves toward the foundation during an impact event. Seismic bearings include a top plate connected to the structure, a bottom plate connected to the foundation, and a resistive core between the top plate that dampens relative movement between the structure and the foundation. Seismic bearings may include a capture assembly that rigidly joins and dampens reactive movement between the structure and the foundation during an impact event. The structure may further include a ledge into which the top plate seats and dampens reactive movement between the structure and the foundation during an impact event.