A long-span suspension bridge is a complex structural system that interacts with the surrounding environment and the users. The environmental actions and the corresponding loads (wind, temperature, rain, earthquake, etc.) together with the live loads (railway traffic, highway traffic), have a strong influence on the dynamic response of the bridge, and can significantly influence the structural behavior and alter its geometry, thus limiting the serviceability performance even up to a partial closure. This article will present some general considerations and operative aspects of the activities related to the analysis and design of such a complex structural system. Specific reference is made to the dependability assessment and the performance requirements of the whole system, while focus is given on methods for handling the completeness and the uncertainty in the assessment of the load scenarios. Aiming at the serviceability assessment, a method based on the combined application of genetic algorithms and a finite element method (FEM) investigation is proposed and applied

Purpose The purpose of this paper is two-fold: first, it highlights the importance of the presence of active teaching experiences in architecture courses. Such experiences can lead to an improvement in the teaching of technical disciplines, such as structural engineering. Second, it purports to demonstrate the relation and interaction between the active teaching strategy here presented and the learning outcomes required by the study programme. Design/methodology/approach The paper reports an active didactic experience (addressed to students of architecture and performed at Politecnico di Milano, Italy, and Université catholique de Louvain, Belgium), from its conception to its development in the classroom with the students. The experience is reported by discussing the three main steps of which an active didactic experience should be composed: the stimulus, the practice and the discussion. Findings The experience seeks to find innovative methods to stimulate the study of structural engineering by students of architecture. Through this experience, based on the study of a square silicon pot mat, students are able to learn concepts related to the mechanics of structures. In addition, students find in their experience direct connections with structures of considerable architectural importance, such as the structure of the New National Gallery by Mies van der Rohe. Originality/value This experience is original in two aspects. First of all, the introduction of an active didactic experience to improve courses that are generally structured in a passive way. Second, in an era where the importance of numerical technology is growing, this experience goes in a different direction by choosing a low-tech but no less interesting approach.

Structures of strategic importance, such as bridges, require careful planning in terms of reliability, durability and safety, qualities which must be guaranteed throughout the entire life cycle of the structure. However, due to the ageing of materials and to aggressive environmental actions which cause deterioration, the response of these structures, just like others, changes over time, resulting in a loss of performance.Yet it is important to maintain a satisfactory level of performance in a bridge throughout its service. To ensure such a performance it is important to apply properly planned maintenance strategies. Appropriate maintenance strategies require knowledge of the process of deterioration and the consequent damages to be expected in order to schedule proper maintenance procedures. It would be fundamental to define a selective maintenance plan which may involve only some parts of the structure, thus allowing bridge viability even during the maintenance activity.This paper proposes the study of strategies of selective maintenance for a steel bridge immersed in an aggressive environment, starting from the simulation of each individual member. Simulation of deterioration is obtained through the application of an appropriate damage law implemented with a Monte Carlo methodology, while the time prediction of occurrence of the deterioration is obtained through the application of a Markovian probabilistic approach. The results of the Markovian approach were the starting point for choosing strategies of selective maintenance, as the Markov process allowed the identification, in probabilistic terms, of the structure members with the highest risk of collapse and the timing for achieving levels of damage related to the possible collapse of compromised members. This timing was used to identify possible intervals of maintenance. Proposed scenarios are compared with each other both in terms of associated risk, and in terms of lifecycle cost effectiveness.

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Fundamental 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.

The behavior of structural systems can change during their service lives due to unexpected loadings, environmental effects, and deterioration processes. In order to optimize maintenance interventions, the life-cycle of a structure has to be properly assessed.Structural Health Monitoring (SHM) using collected experimental data provides a method for assessing the structural behavior over time. Since the cost related to SHM is substantial, sometime monitoring is limited in space and time.The modeling of the structural behavior based on few experimental data is characterized by uncertainty both in the choice of the appropriate model (epistemic uncertainty) and in parameters estimation (aleatory uncertainty).This paper provides an original procedure to support decisions in the presence of epistemic uncertainty. The procedure provides the development of a credibility index able to catch, between two possible models, which is the most reliable to describe the evaluation of parameters of interest.Considering as a case-study the occurrence of a foundation settlement in an arch bridge, the efficacy of the model proposed has been assessed. The approach can be applied to investigate the behavior of other aspects of the life-cycle assessment: the evolution of structural resistance, the failure time of an element or of the whole system.