A Computational Analysis of the Friction Pendulum Base Isolation System
Open Access
- Author:
- Heid, Matthew Joseph
- Area of Honors:
- Mechanical Engineering (Behrend)
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Oladipo Onipede Jr., Thesis Supervisor
Amir Khalilollahi, Thesis Honors Advisor - Keywords:
- Friction Pendulum Bearing
Seismic Base Isolation
Matlab Simulink
Coulomb Damping - Abstract:
- Each year, earthquakes occur globally and at times cause serious damage to buildings, bridges, and other structures. As a result, seismic base isolation devices have been developed to dampen vibration caused by seismic activity and prevent serious structural damage by changing the stiffness of the structure. One type of isolation device is the friction pendulum bearing. The curved sliding surfaces of the friction pendulum bearing are one of the defining features of the friction pendulum. The friction between the sliding surfaces of the pendulum provides the necessary damping while the curved surface alters the natural frequency of the structure. However, the effect of each of the design parameters on the isolation system response is not well understood. These design parameters include the radius of curvature, coefficient of friction, the mass of the structure being supported, and the design displacement for the pendulum. A one dimensional mathematical model is developed to further understand how these parameters affect the response. To simplify the modeling, an energy approach is utilized to create an equivalent spring and viscous damper system that will mimic the friction pendulum bearing system response with coulomb damping. From the model, several important conclusions can be made including the realization that the effective spring constant is a function of not only the radius of curvature but the coefficient of friction. Also, the natural frequency of the isolation system is independent from the mass of the supporting structure. The understanding of the design parameters can then be utilized to optimally design a friction pendulum bearing isolation system for a specific application that will minimize the shearing displacement of the structure during an earthquake.