Phase control for semi-active applications: inertial mass dampers and base isolation systems

• Autores: Christian A. Barrera Vargas
• Directores de la Tesis: Jaime Higinio García Palacios (codir. tes.), Iván Muñoz Díaz (codir. tes.)
• Lectura: En la Universidad Politécnica de Madrid ( España ) en 2024
• Idioma: inglés
• Tribunal Calificador de la Tesis: Antolín Lorenzana Ibán (presid.), Carlos Zanuy Sánchez (secret.), Ady Aviram (voc.), Jorge Pérez Aracil (voc.), Emiliano Pereira González (voc.)
• Programa de doctorado: Programa de Doctorado en Ingeniería de Estructuras, Cimentaciones y Materiales por la Universidad Politécnica de Madrid
• Calificación: Sobresaliente Cum Laude
• Materias:
  • Física
    • Física de fluidos
      • Dinámica de fluidos magnéticos
  • Ciencias tecnológicas
    • Tecnología de los ordenadores
      • Dispositivos de control
    • Tecnología de la construcción
      • Resistencia de estructuras
• Enlaces
  • Tesis en acceso abierto en: Archivo Digital UPM
• Resumen

  • The new challenges of civil engineering are focused on the development of sustainable structures and the need to reduce the carbon footprint. Under these circumstances, structures will be more slender and prone to vibration problems, which give rise to the presence of local failures or collapse situations. On the one hand, these vibrations may be due to the action of a pedestrian or group of pedestrians walking with possible resonance effects if the passing frequency, or any of its higher harmonics, is close to the natural frequency of the structure; this effect is more likely to occur in the case of lightweight structures with low mass/stiffness ratio. On the other hand, wind and earthquakes action generate vibrations on the structure. The particularity of this type of load lies in the uncertainty that exists in the dynamic characteristics of the excitation and how it can affect the structure. Without a correct evaluation of this effect, the design behavior may deviate from reality. The most common solution to control the vibration problems consists of increasing the stiffness of the structure with two main objectives: i) to increase the fundamental frequency of the structure avoiding resonance effects, and ii) to guarantee the lateral stability of the structure and reduce maximum drift caused by wind or earthquake actions. An alternative to avoid stiffness increase in the structure is the use of passive control devices, such as Tuned Mass Dampers (TMDs) and seismic base isolators. These devices do not require additional energy for their correct operation, developing adequate behavior when they are correctly tuned or designed. However, if the modal properties of the structure change over time or other uncertainty factors are present, the passive control systems may become detuned, and their performance may be far from the expected one. In order to alleviate the detuning or saturation problems of passive devices, semi-active devices can be used to upgrade capacities. The system maintains its passive nature with low energy demand and real-time adaptative capacities as an alternative to active control systems, where unstable behaviors may occur and high energy demand for functioning is required. In this thesis, the use of a Magnetorheological Damper added to a passive TMDs and to a Friction Pendulum System (FPS) isolator is explored. For both implementations, a phase control law is considered; that is, the damper activates or deactivates depending on the relative position (or acceleration) and the velocity sign. The practical implementation is quite simple since it can be implemented by using two accelerometers, one on the structure and the other on the device, and structural models are not needed for the implementation. The practical implementation has been tested through experimental tests carried out on a very lightweight footbridge in which human-structure-controller interaction phenomena have been considered for the design of a Semi-active Tuned Mass Damper (STMD). Additionally, realistic simulations have been undergone for friction pendulum isolators equipped with MR dampers, named as Semi-active Friction Pendulum System (SFPS). Therefore, the advantages of including semi-active dampers within the passive devices have been demonstrated in terms of performance improvements and/or reduction of the control device. This thesis dealt with the challenge of optimizing the design of semi-active devices, which encompass both inertial controllers and isolator devices. The functional principle of the devices is based on phase control using an On-Off strategy, a continuous fixed gain control, and a variable gain control, which automatically selected its value in real time to avoid overdemand on the semi-active damper associated with the continuous fixed gain. Hence, the proposed semi-active systems controlled by phase control-based strategies enhance the passive devices in terms of effectiveness and reducing the device size.