Research related to vibrations from high speed railway traffic

We discuss here recent results from several research programmes related to dynamic aspects and vibrations induced by high speed railway traffic, developed at the computational mechanics group, within the “Escuela de Ingenieros de Caminos” of the Technical University of Madrid. The first part of this work concerns the dynamic response of railway bridges and structures under high speed traffic. The study of vertical dynamic effects in bridges has lead recently to improved understanding and practical design concepts, embodied in the new engineering codes [1,2,3,4,5]. Some special and seldom considered features of the dynamic response are also discussed. In the second part we present some results for lateral dynamic effects. These have not been so widely studied as the vertical vibrations, however they may pose significant problems for bridges. Finally, in the third part we discuss recent results of ongoing research for the mechanical response of slab track and ballast track, focusing on the vertical vibration of the track and the associated dynamic traffic loads

Ciudades inteligentes: Requerimientos, desafíos y algunas claves para su diseño y transformación

El artículo describe cuáles son los requerimientos para que una ciudad pueda ser considerada como “inteligente”, para lo que es necesario que aborde de una forma holística y eficiente los grandes desafíos que tienen las ciudades y que lo haga utilizando las técnicas más avanzadas disponibles en cada momento. También describe los cuatro retos a los que deberán enfrentarse las ciudades en el futuro, que son el aumento de competencia entre ellas derivado de la globalización, el incremento de la tensión social por la creciente concentración de la riqueza, los desafíos derivados del cambio climático y la necesidad de acrecentar la resiliencia frente a fallos tecnológicos o bien producidos por fenómenos extremales de origen climático. Por último, describe cuáles deben ser las estrategias de las ciudades para hacer frente a los desafíos derivados del calentamiento global

Dynamic effect of high speed railway traffic loads on the ballast track settlement

The traditional ballast track structures are still being used in high speed railways lines with success, however technical problems or performance features have led to non-ballast track solution in some cases. A considerable maintenance work is needed for ballasted tracks due to the track deterioration. Therefore it is very important to understand the mechanism of track deterioration and to predict the track settlement or track irregularity growth rate in order to reduce track maintenance costs and enable new track structures to be designed. The objective of this work is to develop the most adequate and efficient models for calculation of dynamic traffic load effects on railways track infrastructure, and then evaluate the dynamic effect on the ballast track settlement, using a ballast track settlement prediction model, which consists of the vehicle/track dynamic model previously selected and a track settlement law. The calculations are based on dynamic finite element models with direct time integration, contact between wheel and rail and interaction with railway cars. A initial irregularity profile is used in the prediction model. The track settlement law is considered to be a function of number of loading cycles and the magnitude of the loading, which represents the long-term behavior of ballast settlement. The results obtained include the track irregularity growth and the contact force in the final interaction of numerical simulatio

América y la dignidad del hombre.

Sin resume

El indigenismo desdeñado.

Sin resume

Unofficial description of loads and masses of high speed train in Spanish network AVE S-103 (Siemens ICE3 Velaro)

Unofficial simplified mechanical description of AVE S-103 - ICE3 Velaro E high speed train. Includes Geometru, suspension, masses and inertias, and axle loads

A robust numerical framework for the analysis of material failure of fibre reinforced soft tissue

In this work, robustness and stability of continuum damage models applied to material failure in soft tissues are addressed. In the implicit damage models equipped with softening, the presence of negative eigenvalues in the tangent elemental matrix degrades the condition number of the global matrix, leading to a reduction of the computational performance of the numerical model. Two strategies have been adapted from literature to improve the aforementioned computational performance degradation: the IMPL-EX integration scheme [Oliver,2006], which renders the elemental matrix contribution definite positive, and arclength-type continuation methods [Carrera,1994], which allow to capture the unstable softening branch in brittle ruptures. The IMPL-EX integration scheme has as a major drawback the need to use small time steps to keep numerical error below an acceptable value. A convergence study, limiting the maximum allowed increment of internal variables in the damage model, is presented. Finally, numerical simulation of failure problems with fibre reinforced materials illustrates the performance of the adopted methodology

Nuevas Investigaciones en la Dinámica de puentes de ferrocarril de alta velocidad

1. Moticacion Nuevos puentes 2. Efectos Dinámicos (¿Puentes Seguros?) 3. Requisitos de Servicio (¿Traco Seguro?) 4. Modelos y Normas (¿Cómo saberlo?) Modelos de Cálculo Normas Técnicas 5. Observaciones finale

Safety-related issues for high-speed railway bridges

Railway bridges have specific requirements related to safety, which often are critical aspects of design. In this paper the main phenomena are reviewed, namely vertical dynamic effects for impact effect of moving loads and resonance in high-speed, service limit states which affect the safety of running traffic, and lateral dynamic effects