Pivoting Arm Spring Seismic Control System
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Solution Overview
Problem
Conventional seismic design approaches, such as strength-based designs, often result in structural damage during earthquakes, leading to high repair costs and potential collapse, while active and semi-active control systems face power supply issues during severe earthquakes, making passive control systems more attractive but requiring effective energy dissipation and vibration reduction strategies.
Innovation Solution
A novel passive response control system for steel buildings that utilizes a specific arrangement of pivoting arms and springs to modify building response to ground shaking, reducing accelerations and base reactions without requiring external power, combined with analytical models for optimal damper placement and stiffness distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strength-based seismic design is used to increase structural strength and ductility, then the structure can withstand earthquake loads, but the structure suffers significant structural damage and requires expensive repairs or demolition
Solution Approach 1:
The invention converts harmful seismic energy into beneficial heat energy through friction dampers. The friction dampers are designed to dissipate earthquake energy through controlled frictional sliding, transforming the destructive kinetic energy of seismic events into harmless thermal energy, thereby protecting the main structure from damage
Solution Approach 2:
The friction dampers serve as intermediary elements between the seismic loads and the main structural system. These dampers absorb and dissipate earthquake energy through frictional mechanisms, acting as a buffer that protects the primary structure from direct exposure to damaging seismic forces
2Reliability
If active control systems with electrohydraulic or electromechanical actuators are used to supply control forces, then structure response is reduced, but large external power source is required which may fail during severe earthquakes
Solution Approach 1:
The friction dampers are self-service devices that automatically dissipate seismic energy without requiring external power sources. The frictional sliding mechanism is activated by the seismic motion itself, converting the kinetic energy of the earthquake directly into heat, eliminating the need for electrical systems that could fail during power outages
3Use of energy by moving object
If semi-active control systems are used to adjust control forces with small external power source, then power consumption is reduced, but the system still requires power source which may fail during earthquakes
Solution Approach 1:
The friction dampers operate as purely passive, self-service devices that require no external power input at any stage. The frictional mechanism is inherently activated by relative motion between structural components during seismic events, ensuring continuous operation without reliance on batteries or other power sources that could fail
4Loss of energy
If passive control systems with energy dissipators are used to convert mechanical energy to heat energy, then seismic energy is dissipated, but the system requires effective energy dissipation strategies and optimal placement
Solution Approach 1:
The friction dampers are strategically placed at specific locations within the structural system where they can most effectively dissipate seismic energy. The local quality of the frictional sliding mechanism is optimized at these critical points to maximize energy dissipation while maintaining overall system simplicity
Solution Approach 2:
The friction force parameters of the dampers are carefully calibrated to match the expected seismic loading conditions. By adjusting the friction coefficients and normal forces in the dampers, the system is optimized to dissipate the appropriate amount of seismic energy across different earthquake intensities
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 system effectively reduces seismic-induced accelerations and base reactions, enhancing structural safety and reducing repair costs by dissipating seismic energy without power dependence, and the analytical models ensure optimal distribution of damping and stiffness for improved performance.
Implementation Method 1
Friction dampers which dissipate energy by converting it into heat
Implementation Method 2
Passive control systems are systems that do not require any external power source to function since they utilize the motion of the structure to develop the control forces
Data Source
AI summary
A new passive control building arrangement is provided for improving the seismic response of structures. The proposed control arrangement was incorporated to a 1/20 scale model of a steel structure. The SAP2000 software program was used to develop an analytical model of the constructed scale model. After using a series of experimental data to calibrate the analytical model, valuable information of the dynamic properties of the arrangement was obtained. Different configurations with distinct parameters of the control arrangement were analyzed in the program to evaluate the variables that affect the dynamic properties of the model. It was determined that the geometric configuration of the arrangement and the spring stiffness value of a spring used in the arrangement affect considerably the dynamic properties. Simulated earthquake tests were performed in two proposed alternatives of the control arrangement to evaluate their effectiveness in improving the seismic response of the scale model. It was observed that the control arrangement can effectively reduce the accelerations and base reactions of the model.