I metodi dell'intelligenza artificiale nell'analisi e nella progettazione dei ponti sospesi

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I metodi dell'intelligenza artificiale nell'analisi e nella progettazione dei ponti sospesi

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Modélisations des structures: Une science (in)exacte

The paper deals with the process of structural modeling interpreted as a mathematical-numerical representation. The author, through a diagram of representation inspired by the reflections of Prof. Arielli (IUAV, Venice, Italy) on the process of representation, it tries to show how a real structure, even simple, can have different numerical representations. (Paper is in French)

Motiver et développer le sens critique des étudiants par les méthodes d'apprentissage actives

Teaching technical subjects in a school of architecture is not easy. The paper summarises a series of lectures given by the author where the problem of structural instability is introduced through the observation and study of the behavior of a real object. Through these lectures, the author also wants to stimulate the critical thinking and creativity of the students. (Paper is in French)

A Multiclass Simulation-Based Dynamic Traffic Assignment Model for Mixed Traffic Flow of Connected and Autonomous Vehicles and Human-Driven Vehicles

One of the potential capabilities of Connected and Autonomous Vehicles (CAVs) is that they can have different route choice behavior and driving behavior compared to human Driven Vehicles (HDVs). This will lead to mixed traffic flow with multiple classes of route choice behavior. Therefore, it is crucial to solve the multiclass Traffic Assignment Problem (TAP) in mixed traffic of CAVs and HDVs. Few studies have tried to solve this problem; however, most used analytical solutions, which are challenging to implement in real and large networks (especially in dynamic cases). Also, studies in implementing simulation-based methods have not considered all of CAVs' potential capabilities. On the other hand, several different (conflicting) assumptions are made about the CAV's route choice behavior in these studies. So, providing a tool that can solve the multiclass TAP of mixed traffic under different assumptions can help researchers to understand the impacts of CAVs better. To fill these gaps, this study provides an open-source solution framework of the multiclass simulation-based traffic assignment problem for mixed traffic of CAVs and HDVs. This model assumes that CAVs follow system optimal principles with rerouting capability, while HDVs follow user equilibrium principles. Moreover, this model can capture the impacts of CAVs on road capacity by considering distinct driving behavioral models in both micro and meso scales traffic simulation. This proposed model is tested in two case studies which shows that as the penetration rate of CAVs increases, the total travel time of all vehicles decreases

Comparison of Speed-Density Models in the Age of Connected and Automated Vehicles

peer reviewedFundamental diagrams (FDs) present the relationship between flow, speed, and density, and give some valuable information about traffic features such as capacity, congested and uncongested situations, and so forth. On the other hand, high accuracy speed-density models can produce more efficient FDs. Although numerous speed-density models are presented in the literature, there are very few models for connected and autonomous vehicles (CAVs). One of the recent spend-density models that takes into account the penetration rate of CAVs is provided by Lu et al. However, the estimation power of this model has not been tested against other speed-density models, and it has not been applied to high-speed networks such as freeways. Thus, this paper made a comparison between the Lu speed-density model and a well-known speed-density model (Papageorgiou) in freeway and grid networks. Different CAV behaviors (aggressive, normal, and conservative) are evaluated in this comparison. The comparison has been made between two speed-density models using the mean absolute percentage error (MAPE) and a t-test. The MAPE and t-test results show that differences between the two speed-density models are not significant in two case studies and that Lu is a powerful speed-density model to estimate speed compared with a well-known speed-density model. For the sake of comparing the above-mentioned models, this paper investigates the impact of CAVs on capacity based on FDs. The results suggest that the magnitude of the impacts of CAVs on road capacity (capacity increment percentage) which are obtained from two speed-density models are very close to each other. Also, the extent to which CAVs affect road capacity is highly dependent on their behavior

Modélisation des structures : Une science (in)exacte

Au cours d’une leçon de “mécanique des matériaux et de la facture”, le professeur Giulio Maier (professeur émérite de l’université Politecnico di Milano), nous donna une magnifque défnition de l’ingénierie des structures. Une défnition si belle que je décidai de la transcrire dans mon cahier. Vingt ans après, je la connais encore par cœur et je la cite souvent à mes étudiants. « L’ingénierie des structures est un art. L’art de savoir analyser les structures en appliquant une mathé- matique qui n’est pas encore en mesure de nous fournir des solutions exactes, l’art de pouvoir utiliser des matériaux que nous ne connaissons pas encore parfaitement, l’art de prendre en considération des charges que nous ne serons jamais capables de prévoir. Le tout avec une simplicité qui doit rester un mystère pour le grand public. » Du point de vue de l’ingénieur et du chercheur que je suis, la défnition est à mon sens belle mais surtout vraie. Vraie dans sa deuxième partie, parce qu’un ingénieur vraiment doué est capable de réduire le comportement d’une structure à quelques concepts très simples. Une opération qui, à première vue, pourrait sembler banale mais qui ne l’est pas. En effet, un bon ingénieur tout en étant parfaitement conscient des incertitudes qui caractérisent sa profession, doit néanmoins être capable d’éliminer de ses raisonnements toutes les informations, théories et problèmes n’ayant rien à voir avec l’étude du problème structurel en question pour se concentrer sur les mécanismes véritablement importants. Vraie dans sa première partie, parce que l’ingénierie des structures (contrairement à ce qu’en pense la plupart des personnes) n’est pas une science exacte. Dans le cadre de ces réflexions que je suis en train de rédiger, je souhaite m’attarder justement sur la première partie de la défnition et l’associer à l’activité de modélisation des structures, une activité qui aujourd’hui revêt une importance signifcative dans l’ingénierie des structures

Teoria dell’elasticità e meccanica computazionale

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Influence of degradation at the base of a support post in a collapse of an old guardrail: A forensic analysis

After a violent crash that took place at the entrance of the road on a bridge, the guardrail installed as protection collapsed and the vehicle left the roadway. As at the base of a number of guardrail posts, a situation of severe corrosion was found evident, its influence on the resistance and on the mode of collapse of the guardrail was explored. To this purpose, the information about the state of the place collected immediately after the accident and the plastic deformations observed on the deformed guardrail contributed decisively to reconstructing the dynamics of the impact. Later, using the same assumptions and the same methods of calculation used to assess the strength of the guardrail in a condition of degradation, the impact of a similar guardrail in perfect structural conditions was simulated. The comparison between the two analyses indicated the limited influence of corrosion on the guardrail in question and on the dynamics of the accident that had occurred. © 2014 Elsevier Ltd