Dynamic analysis and vibration control of lightweight frp footbridges considering human-structure interaction

• Autores: Christian Gallegos Calderón
• Directores de la Tesis: María Dolores Gómez Pulido (codir. tes.), José María Goicolea Ruigómez (codir. tes.)
• Lectura: En la Universidad Politécnica de Madrid ( España ) en 2022
• Idioma: español
• Tribunal Calificador de la Tesis: Manuel Aenlle López (presid.), Jaime García Palacios (secret.), Antonio Carnerero Ruiz (voc.), Javier Fernando Jiménez Alonso (voc.), Maria de los Dolores Martínez Rodrigo (voc.)
• Programa de doctorado: Programa de Doctorado en Ingeniería de Estructuras, Cimentaciones y Materiales por la Universidad Politécnica de Madrid
• Materias:
  • Física
    • Acústica
      • Vibraciones
  • Ciencias tecnológicas
    • Tecnología de la construcción
      • Puentes
      • Construcciones ligeras
      • Ingeniería de estructuras
• Enlaces
  • Tesis en acceso abierto en: Archivo Digital UPM
• Resumen

  • Fibre Reinforced Polymers (FRPs) have demonstrated to be feasible alternatives to traditional construction materials in Bridge Engineering, offering several bene fits such as high strength-to-weight ratio, low maintenance cost, dead load reduction, electromagnetic transparency, corrosion resistance, and fast installation. Due to the recent history of these materials in the construction industry, lack of a well-established standard to design FRP structures is one the major disadvantages that constrains the widespread use of composites, particularly the design against pedestrian dynamic actions. Indeed, human-induced vibration problematic remains as a subject to be properly addressed given the lightweight nature of FRPs.

    Therefore, this research aims to: (i) improve the understanding about the dynamic response of lightweight FRP footbridges subjected to pedestrian actions, and (ii) set guidance to estimate vibrations accurately on composite structures at Vibration Serviceability Limit State (VSLS). The aforementioned objectives have meant to be accomplished by carrying out four major tasks.

    First, a 10-m long FRP footbridge that ful ls requirements at Deflection Serviceability Limit State (DSLS) and Ultimate Limit State (ULS) has been designed. As a motion-based design approach has been followed, the simply supported structure, built at the Laboratory of Structures of the School of Civil Engineering - Universidad Politécnica de Madrid, presents a linear mass of only 80 kg/m.

    Second, the modal parameters of the FRP footbridge has been identifi ed, and an experimental campaign has been carried out to evaluate the in-service dynamic response of the laboratory bridge under two pedestrian actions. People bouncing and walking have been considered. Experimental results have shown excessive vertical vibrations on the structure due to higher harmonics of the pedestrian actions. Additionally, the influence of passive (standing) and active (walking) people on the fundamental vibration mode of the FRP footbridge has been assessed, obtaining that the damping of the human-structure system is increased.

    Third, the dynamic response of the FRP structure has been poorly estimated using load models that omit Human-Structure Interaction (HSI). Thus, a Mass-Spring-Damper-Actuator (MSDA) system has been adopted, to account for HSI and higher harmonics of the human action. Based on the experimental results, two load models have been identifi ed considering this system to represent: (i) a person bouncing, and (ii) a pedestrian walking. In addition, a procedure to account for Crowd-Structure Interaction (CSI) has been proposed to assess the dynamic response of simply supported structures. The flow of pedestrians walking on a footbridge has been defi ned as an equivalent time-invariant system.

    Fourth, a frequency domain approach, based on a coupled human-structure-controller system, has been proposed to design Tuned Vibration Absorbers (TVAs) for lively pedestrian structures considering HSI. Employing the proposal, a TVA has been designed, assembled and installed on the FRP footbridge to control the excessive vertical vibrations. Thus, the motion-based design approach adopted initially has been completed. Although a slight detuning of the TVA has been observed when the number of people walking on the bridge increases, the vibration control device has demonstrated an adequate performance.

    In this thesis, the approaches to assess the dynamic response of footbridges and control human-induced vibrations have been mainly discussed in terms of an ultra-lightweight FRP structure. Nevertheless, the identi ed HSI models and proposed procedures are general, since they can be applied to other lightweight pedestrian structures, regardless of the material employed for the construction.