Fatigue assessment of a railway bridge detail using dynamic analysis and probabilistic fracture mechanics

This paper presents a generic methodology for the use of PFM within the context of bridge loading for the fatigue design and assessment of steel railway bridges and provides detailed guidance on how to use the proposed methodology in order to carry out a PFM-based fatigue assessment. The problem is set in a probabilistic context to take into account material, loading as well as modeling uncertainties. Guidance is given on how to calibrate a constant amplitude PFM analysis against an S-N curve. Finally, as a case study, a cracked welded bridge detail is considered and its time-dependent fatigue reliability is established © 2012 Taylor & Francis Group

Dynamic Effects of Turbulent Crosswind on the Serviceability State of Vibrations of a Slender Arch Bridge Including Wind-Vehicle-Bridge Interaction

The use of high-performance materials in bridges is leading to structures that are more susceptible to wind- and traffic-induced vibrations due to the reduction in the weight and the increment of the slenderness in the deck. Bridges can experience considerable vibration due to both moving vehicles and wind actions that affect the comfort of the bridge users and the driving safety. This work explored the driving safety and comfort in a very slender arch bridge under turbulent wind and vehicle actions, as well as the comfort of pedestrians. A fully coupled wind–vehicle–bridge interaction model based on the direct integration of the system of dynamics was developed. In this model, the turbulent crosswind is represented by means of aerodynamic forces acting on the vehicle and the bridge. The vehicle is modeled as a multibody system that interacts with the bridge by means of moving contacts that also simulate road-surface irregularities. A user element is presented with generality and implemented using a general-purpose finite-element software package to incorporate the aeroelastic components of the wind forces, which allows modeling and solving of the wind–vehicle–bridge interaction in the time domain without the need for using the modal superposition technique. An extensive computational analysis program is performed on the basis of a wide range of turbulent crosswind speeds. The results show that bridge vibration is significantly affected by the crosswind in terms of peak acceleration and frequency content when the crosswind intensity is significant. The crosswind has more effect on the ride comfort of the vehicle in the lateral direction and, consequently, on its safety in terms of overturning accidents

Human error impact in structural safety of a reinforced concrete bridge

The economic and social losses due to increasing bridges collapse over the years have underlined the importance of the development of more robust bridge structural systems when exposed to harmful events, such as natural hazards, human-made hazards and human errors. Natural and human-made hazards are usually explicitly addressed in the numerous works available in the literature, but when it comes to human errors, very few studies can be found. It is worth mentioning that human errors have been identified as one of the main causes of bridges failure. Consequently, the main goal of this paper is the assessment of human errors impact on the robustness and safety of a prestressed reinforced concrete bridge through a probabilistic-based approach. Uncertainties concerning the numerical model, material strength, geometry and loading condition are used as key input parameters for the probabilistic assessment. Considering the structural system performance in its early days (i.e., virgin reliability index) the human error impact in structural safety is measured according to the structural system performance reduction given different errors with different magnitudes. Therefore, the structural system ability to maintain acceptable levels of performance, given such errors, is assessed.FEDER funds through the Competitivity Factors Operational Programme (COMPETE) and by national funds through the Foundation for Science and Technology (FCT) within the scope of project POCI 01 0145 FEDER 007633; (ii) national funds through FCT - Foundation for Science and Technology, under grant agreement “PD/BD/143003/2018” attributed to the 1st author; and (iii) FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/202