Rotary Force Limiter with Flexural Yield Plates
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Solution Overview
Problem
Commercial and industrial storage rack systems are vulnerable to damage and goods displacement during earthquakes due to uncontrolled racking motion, which existing diagonal ties attempt to mitigate but may lead to catastrophic failure under high peak loads.
Innovation Solution
A control structure with a rocker frame assembly and rotary units that utilize flexural members to absorb seismic forces by flexing elastically or plastically, maintaining a constant resistive yield force and limiting peak accelerations and displacements, while preventing membrane forces from developing within the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If diagonal ties are used to reduce lengthwise racking, then rack rigidity is improved, but peak loads increase causing catastrophic failure
Solution Approach 1:
The patent changes the mechanical parameters of the diagonal ties by introducing rotary joints that allow controlled rotation. This transforms the ties from rigid elements to flexible elements that can rotate to accommodate seismic movements, thereby reducing peak loads while maintaining rack stability during earthquakes.
Solution Approach 2:
The patent introduces dynamic behavior to the diagonal ties through rotary joints that enable rotation during seismic events. This dynamic capability allows the ties to adapt to changing load directions and magnitudes, converting static rigid structures into dynamic systems that can dissipate energy through controlled rotation.
2Stability of the object's composition
If diagonal ties are tensioned to brace against racking, then lateral stability is improved, but energy absorption capacity is reduced
Solution Approach 1:
The patent converts the harmful effect of seismic energy into beneficial work by allowing the diagonal ties to rotate and absorb energy through controlled motion. The rotary joints enable the ties to transform seismic energy into rotational kinetic energy and heat, dissipating energy that would otherwise cause catastrophic failure.
Solution Approach 2:
The patent changes the mechanical state of the diagonal ties from purely tensile to tensile-with-rotation, enabling them to perform work during seismic events. This parameter change allows the ties to absorb energy through rotational motion while maintaining lateral stability during normal operation.
3Stability of the object's composition
If rigid diagonal ties are used to prevent racking, then structural rigidity is improved, but ductility and energy dissipation are reduced
Solution Approach 1:
The patent introduces dynamic rotation capability to the diagonal ties, transforming them from rigid static elements to dynamic elements that can rotate during seismic events. This enables the structure to maintain rigidity during normal conditions while achieving ductility and energy dissipation during earthquakes through controlled rotational motion.
Solution Approach 2:
The patent creates a composite mechanical system combining rigid diagonal ties with flexible rotary joints. This composite approach allows the structure to exhibit both rigidity (from the ties) and ductility (from the rotating joints), achieving both structural stability and seismic energy dissipation simultaneously.
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
The control structure effectively limits forces and dissipates energy within storage racks and buildings during seismic events, reducing the risk of catastrophic failure and maintaining structural integrity by allowing controlled flexure and energy absorption.
Implementation Method 1
flexing elastically or plastically
Implementation Method 2
flexing elastically or plastically
Implementation Method 3
absorb seismic forces by flexing elastically or plastically, maintaining a constant resistive yield force and limiting peak accelerations and displacements
Data Source
AI summary
A control structure comprising a pivotably based rocker frame assembly integral with rotary yield units able to produce a constant resistive yield force through high elasto-plastic displacements and high ductilities. Located within and distributed about the rotary yield units are flexural yield plates with particular boundary conditions enabling them to elasto-plastically flex to high cycling elasto-plastic displacements and high displacement and curvature ductilities, while maintaining a constant resistive yield force. The constant resistive yield force produced by the replaceable rotary units enables the control structure to resist and endure extreme seismic events (base motion input) with a constant resistive yield force, while plastic curvatures within the yield zones of the flexural plates of the rotary units are maintained well within their capacity; and forces within the control structure, within its supporting foundations, and within masses or other structures it is seismically supportive of are controlled and limited.