A mobile tool for teaching advanced dynamic analysis = Una aplicación móvil para el aprendizaje del análisis dinámico avanzado

Díaz, Iván M.; Palacios, Jaime; Soria, José Manuel Nieto; Renedo, Carlos M.C.

doi:10.20868/abe.2019.1.3885

Cited by 2 publications

(1 citation statement)

References 11 publications

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“…The preliminary experimental tests consisted of measuring with a mobile phone the lateral accelerations of the footbridge at the centre of the main span. These data were used to determine the modal characteristics of the structure as a first approach [66]. The tests were carried out using a Xiaomi Redmi Note 4 mobile phone.…”

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confidence: 99%

Assessment of the lateral vibration serviceability limit state of slender footbridges including the postlock-in behaviour

Cuevas¹

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The lateral vibrations of slender footbridges caused by walking pedestrians have been the subject of many studies over the last few decades. However, despite the large amount of research, a common design guidance has not been set yet. The phenomenon of experiencing excessive lateral accelerations (generally known as the lock-in effect) occurs in low-damped structures with natural frequencies in the range 0.4-1.3 Hz when the number of pedestrians on the footbridge is above a certain "critical number". The lock-in behaviour is characterised by a sudden increase in the amplitude of vibrations, usually associated with resonant loads but that can also be explained by the phenomenon of interaction between pedestrians and the structure. Pedestrians are biomechanical systems that generate ground reaction forces while walking, due to the acceleration or deceleration of their centre of mass. The lateral force is the consequence of the action of keeping the body balance during walking and can be affected by the ground stability. As people perceive the floor vibration, they modify their gait in order to avoid losing balance. People interact with the structure, generating the auto-induced force in the natural frequency of the footbridge, with independence of the pedestrian frequency. This phenomenon, known as human-structure interaction (HSI), is widely accepted as the main cause of the sudden onset of high amplitudes of vibration. However, the current design recommendations do not include an expression for the auto-induced component of the pedestrian action and, as a consequence, it is not possible to evaluate the footbridge comfort once the lock-in effect has developed.

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confidence: 99%

Assessment of the lateral vibration serviceability limit state of slender footbridges including the postlock-in behaviour

Cuevas¹

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Interactive lecture notes for structural dynamic analysis in frequency domain = Apuntes de clase interactivos para el análisis de la dinámica estructural en el dominio de la frecuencia

et al. 2019

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Dynamic and experimental analysis of structures are two of the most abstract and complex disciplines in structural engineering, because of its awkward mathematical and physical background and due to the multidisciplinary knowledge needed to go over the whole analysis (from the acquisition of measures up to the final interpretation of results). In particular, Fourier analysis (frequency domain analysis) in discrete time, which is routinely used in the dynamic analysis, is not usually well-understood and even is not well computed in discrete time. Frequently, students lose motivation trying to decrypt difficult mathematical developments, which do not let them to interpret properly complex concepts which are extremely important for current analysis in discrete time such as: Fourier transforms, aliasing, leakage, filtering, windowing, etc. For this reason, the authors has implemented a new teaching tools based on the numerical experiments and interactive learning that transform the learning experience into a more pleasant process than in the pass. In this way, recently-developed tools as “MATLAB Live Editor” allows professors to create interactive lecture notes, which students can easily follow, modify and simultaneously run during classes, developing its own intuitive interpretation of the knowledge. This tool is been successfully employing to teach dynamic analysis of structures in frequency domain with excellent feedback from the students.ResumenEl análisis experimental y dinámico de estructuras son dos de las disciplinas más complejas y abstractas de la ingeniería estructural debido a la complejidad de los fundamentos que se manejan y al conocimiento multidisciplinar necesario para llevar a cabo el proceso completo de análisis (desde la toma de datos hasta la interpretación final de los resultados). En particular, el análisis de Fourier (análisis en el dominio de la frecuencia), el cual se usa continuamente en el análisis dinámico, no siempre se entiende adecuadamente e incluso no se aplica correctamente en el dominio discreto. Con frecuencia los estudiantes pierden la motivación intentando comprender los desarrollos matemáticos asociados, lo que no les permite interpretar adecuadamente conceptos más complejos y a la vez importantes como: la transformada de Fourier, “aliasing”, “leakage”, filtrado, ventanas de ponderación, etc. Por ello, los autores han implementado una nueva herramienta basada en la experimentación numérica y en el aprendizaje interactivo, haciendo del mismo un proceso más llevadero que en el pasado. Así, herramientas recientes como “MATLAB live Editor” permiten que los profesores creen clases interactivas que los estudiantes pueden de forma sencilla, seguir, modificar y ejecutar durante las clases, desarrollando un conocimiento más intuitivo del problema. Los autores están empleando esta herramienta exitosamente en el análisis dinámico de estructuras en el dominio de la frecuencia con muy buenos comentarios por parte de los estudiantes.

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A mobile tool for teaching advanced dynamic analysis = Una aplicación móvil para el aprendizaje del análisis dinámico avanzado

Cited by 2 publications

References 11 publications

Assessment of the lateral vibration serviceability limit state of slender footbridges including the postlock-in behaviour

Assessment of the lateral vibration serviceability limit state of slender footbridges including the postlock-in behaviour

Interactive lecture notes for structural dynamic analysis in frequency domain = Apuntes de clase interactivos para el análisis de la dinámica estructural en el dominio de la frecuencia

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