A novel numerical methodology is presented to solve the dynamic response of railway bridges under the passage of running trains, considering soil–structure interaction. It is advantageous compared to alternative approaches because it permits, (i) consideration of complex geometries for the bridge and foundations, (ii) simulation of stratified soils, and, (iii) solving the train-bridge dynamic problem at minimal computational cost. The approach uses sub-structuring to split the problem into two coupled interaction problems: the soil–foundation, and the soil–foundation–bridge systems. In the former, the foundation and surrounding soil are discretized with Finite Elements (FE), and padded with Perfectly Match Layers to avoid boundary reflections. Considering this domain, the equivalent frequency dependent dynamic stiffness and damping characteristics of the soil–foundation system are computed. For the second sub-system, the dynamic response of the structure under railway traffic is computed using a FE model with spring and dashpot elements at the support locations, which have the equivalent properties determined using the first sub-system. This soil–foundation–bridge model is solved using complex modal superposition, considering the equivalent dynamic stiffness and damping of the soil–foundation corresponding to each natural frequency. The proposed approach is then validated using both experimental measurements and an alternative Finite Element–Boundary Element (FE–BE) methodology. A strong match is found and the results discussed.

No abstract

Chapter 10 2017); Jean et al. (2004)). These models assume the problem is continuous in the track direction and as such not well suited to modelling transition zones, etc.At the earlier stage, when attempting to identify line sections where vibration is likely to cause problems in nearby buildings, simplified scoping models are often used. This is because they are faster running and allow engineers to assess long lengths of track quickly, in absence of detailed design information.Empirical approaches to estimate soil and building vibrations due to a train passage have been proposed by the Federal Railroad Administration (FRA) and the Federal Transit Administration (FTA) of the U.S. Department of Transportation (Hanson et al. (2005, 2006). The simplifications considered in these procedures have been verified by the numerical model presented by Verbraken et al. (2011).Alternatively, some scoping models have been recently proposed. Connolly et al. (2014a,b) presented a scoping tool, called Scoperail, to instantly compute vibrations due to train passages. A machine learning approach to obtain free-field vibrations was developed using numerically records for a wide range of train speeds and soil types. These soil vibrations were coupled with empirical factors in order to predict in-door noise and structural vibrations due to high speed trains. A hybrid model has been proposed by Triepaischajonsak and Thompson (2015), that combined a detailed vehicle-track model formulated in the time domain with a layered ground model operating in the frequency domain, based on the formulation outlined by Kausel and Roësset (1981). Then, forces acting on the ground were obtained from the train-track model and later used to calculate ground free-field vibrations. Kuo et al. (2016) developed a hybrid model where the source and propagation mechanisms were decoupled. The model combined experimental tests and numerical predictions considering the definitions proposed in Hanson et al. (2005Hanson et al. ( , 2006. Kouroussis et al. (2017) developed a hybrid experimental-numerical model to predict vibrations from urban railway traffic. The level of vibration was calculated by combining the force density obtained from a numerical train-track model with the mobility function measured through an experimental approach.Research has also been performed to investigate the propagation of free-field vibration into buildings. Auersch (2010) studied building responses using a simple soil-wall-floor model based on an empirical transfer fuction obtained from the characteristics of the structure. The soil was modelled using a spring and a viscous damper to evaluate the effects of soil-structure interaction. François et al. ( 2007) analysed building induced vibrations by employing simplified methods that ignore soil-structure interaction (SSI), but take into account the relative stiffness between the building and the soil. Later, Hussein et al. (2013) proposed a sub-modelling method to couple a 3D train-track-soil model with a 2D frame building. López-Mend...

El Giraldillo es una escultura de bronce del siglo XVI, de gran valor artístico, histórico y simbólico, que corona la torre de la Giralda de la Catedral de Sevilla haciendo la función de veleta. Entre 1999 y 2005, el Instituto Andaluz de Patrimonio Histórico (IAPH) se encargó de llevar a cabo un intenso proyecto de restauración integral del Giraldillo que culminó con su reposición sobre la torre de la Giralda. Dada la inaccesibilidad tras su reposición y su carácter mecánico como veleta, resulta conveniente disponer permanentemente de información acerca de su comportamiento mecánico y de su estado de conservación. Así, en octubre de 2005 se inicia el proyecto ¿Seguimiento instrumental y análisis del comportamiento mecánico y físico del Giraldillo¿, financiado por el IAPH. Este proyecto supone la puesta en marcha de un complejo y singular sistema de monitorización por cuanto supone su especial ubicación, sus características y su finalidad. Este sistema permite obtener registros temporales de diversas magnitudes mecánicas y físicas de interés para el estudio de la conservación del Giraldillo, y asimismo se realiza un procesado de estos registros enfocado a la detección de daños estructurales basándose en la identificación y monitorización de diversos parámetros relacionados con la respuesta dinámica de la estructura ante la acción del viento. En este artículo se realiza una descripción del sistema de instrumentación instalado y del proceso de gestión y análisis de los datos obtenidos. Se presentarán también algunos de los resultados más significativos alcanzados durante los dos primeros años de funcionamiento del sistema.