Jose Maria Goicolea

A key challenge in 3D finite element models of coupled railway vehicle–bridge dynamics is the rigorous definition of kinematic constraints and the development of an efficient, robust solution. This paper presents a novel approach that can be implemented in general finite element software using constraint equations tailored to wheel–rail contact behavior, essential for analyzing lateral vehicle–bridge interactions. The method employs absolute coordinates to describe the motion of nodes defining the track position and orientation for each wheelset, without assuming infinitesimal displacements or rotations. This general formulation enables realistic simulations of extreme scenarios involving large lateral movements caused by strong winds or earthquakes. The proposed wheel–rail contact model is first validated against published results, and a 3D numerical example demonstrates the method’s performance and capabilities.

This work focuses on the dynamic analysis of road bridges under large microsimulated traffic flows, contributing an efficient dynamic analysis framework for future fatigue, comfort or driving safety studies in which realistic interactions between vehicles are considered. Different strategies to define the loading vector in the governing dynamic equations are presented for bridges discretized with beam and shell elements. The proposed interpolation techniques for beam-like models include a recursive binary search and a novel vectorized strategy based on shape functions expanded to the entire length of the deck. These are applied to a short simply supported bridge and a very long cable-stayed bridge under traffic flows generated with a cellular automata microsimulation model. The strategies presented here reduce the computational time required in conventional load interpolation algorithms, particularly in long bridges subject to dense traffic flows. Finally, the binary search algorithm is applied to the study of bridge decks discretized with shell elements under microsimulated traffic, demonstrating that high vehicle densities increase the contribution of the transverse vibration of the slab and the potential discomfort of pedestrians.

El uso de tableros multicelulares de Polímero Reforzado con Fibra de Vidrio (GFRP por sus siglas en inglés) en la rehabilitación y construcción de puentes ha aumentado en los últimos 30 años por varios motivos, como: el bajo costo de mantenimiento, rápida instalación, resistencia a la corrosión, y alta relación resistencia-peso. Debido a la naturaleza ortotrópa de los tableros de GFRP y la compleja geometría de su sección transversal, el análisis dinámico de puentes que incluyan este tipo de elementos puede representar un problema computacional costoso. Por lo tanto, este artículo estudia la respuesta dinámica de un puente carretero de GFRP-acero cuando se modela el tablero multicelular de GFRP como una placa ortótropa. Para ello, se desarrolla un modelo de elementos finitos del puente híbrido, y se realiza un análisis de sensibilidad para investigar la influencia de las propiedades mecánicas del elemento ortótropo en el comportamiento del puente. La rugosidad del pavimento, el grado de acción compuesta entre el tablero y los largueros, el modelo dinámico multicuerpo de un camión, y la interacción vehículo-puente se tienen en cuenta en el análisis. Los resultados indican que las propiedades más relevantes de la placa ortótropa en la respuesta de la estructura son el módulo de elasticidad en la dirección longitudinal, el módulo de elasticidad en la dirección transversal, y el módulo de cortante. De igual manera, se determina que lograr una acción compuesta total y evitar el deterioro de la vía son aspectos importantes para reducir la respuesta del puente híbrido.

Due to the high strength-to-weight ratio of fibre reinforced polymers (FRPs), human-induced vibration problematic remains as a subject to be fully comprehended in order to extend the use of composites in Bridge Engineering. Thus, this paper studies an ultra-lightweight FRP footbridge, which presents excessive vertical vibrations when the fourth harmonic of a walking pedestrian is synchronised with the structure’s fundamental frequency. Focusing on the vertical bending mode, at 7.66 Hz, the bridge dynamic behaviour was assessed under the action of a single pedestrian crossing the facility at a step frequency of 1.9 Hz. As an over prediction of the footbridge response was computed using a moving force (MF) model available in a design guideline, a mass-spring-damper-actuator (MSDA) system was adopted to depict a walker. Hence, Human-Structure Interaction (HSI) phenomenon was considered. Employing the experimental results, parameters of the MSDA system were identified, leading to a HSI model that considers the first fourth harmonics of a walking human. Additionally, a parametric analysis was carried out, determining that the damping ratio of the human body and the load factor associated to the fourth harmonic are the most relevant parameters on the estimation of the response. The identified HSI model may be used as a first approximation to accurately predict the dynamic response of ultra-lightweight composite structures and should be extended to account for crowd-induced loads.