Defining structural robustness under seismic and simultaneous actions:an application to precast RC buildings

The increasing complexity of urban systems is making robustness a crucial requirement for structural design. The paper deals with the concept of robustness of civil structures against extreme events. After a brief literature survey, a novel point of view to robustness assessment is proposed, fitting the most accepted robustness definition. The proposed approach is discussed and compared with other methodologies for quantifying structural robustness. Thus, the methodology is developed and applied to an existing precast industrial building case study, assumed to be prone to seismic and wind hazards. In particular, the case study is assumed to be located in Emilia, Italy, where a significant earthquake occurred in 2012, causing relevant damage to gravity load designed industrial buildings. Three structural options are discussed, namely a simple supported beam–column connection (gravity load designed solution) and two pinned connections (seismic designed solution), where only one of them satisfies the current structural code requirements. The results are discussed in terms of robustness quantification, by means of a robustness matrix. The authors envisage that this approach can be effectively adopted for portfolios of existing structures, to prioritize retrofitting interventions, aimed at maximizing the overall risk mitigation with limited economic resources. © 2015 Springer Science+Business Media Dordrech

Defining a Digital Strategy in a BIM Environment to Manage Existing Reinforced Concrete Bridges in the Context of Italian Regulation

Regulatory activity concerning the management of existing bridges has recently been affected by updates, for instance, in Italy, which calls for a speedy and pragmatic approach based on new technologies such as building information modeling (BIM), when dealing with the survey and risk classification as well as the evaluation and monitoring of structural safety. This paper focuses on the development and integration of a digital solution, based principally on the specific framework developed by the authors, which supports BIM modeling and information management activities, in the structural setting under investigation, through the use of several technologies and tools, namely BIM-authoring, CDE platform and visual programming, in addition to programming in Python. Starting from the organization of a specific BIM object library and the initial data, inserted by means of a custom-made input environment, it was possible to reproduce digital models of bridges in accordance with specific information requirements following the new Level of Information Need setting. The applicability of the proposal is tested on two judiciously chosen real-life cases with different characteristics. Through this implementation, a series of advantages emerge, including expediting traditional procedures for BIM modeling, accessibility and traceability of information— which are constantly updated to support the monitoring of structural safety over time—and the decision-making process related to the bridge management context

Open BIM Standards: A Review of the Processes for Managing Existing Structures in the Pre- and Post-Earthquake Phases

The problem of managing existing structures before and after seismic events has led to the development of many di erent strategies across the lobe. These aim to mitigate the catastrophic e ects of earthquakes on the occupants of a building, as well as improve the management of the emergency that inevitably ensues. This paper explores the use of an openBIM approach to resolve the issues referred to above, which is possible because of two new standards: Industry Foundation Classes and Information Delivery Manuals. A review of the most popular strategies adopted in both the pre- and post-earthquake phases is conducted using a process map. This organizes the relevant steps and processes into tasks, and additionally identifies the points at which information is produced and exchanged and the party responsible for doing so. Also described is how BIM models can be utilized in essential pre- and post-earthquake activities, as well as current benefits and ongoing developments intended to improve the processes themselves

Application of openBIM for the Management of Existing Railway Infrastructure: Case Study of the Cancello - Benevento Railway Line

In the field of infrastructure, the development and application of the openBIM (open Building Information Modeling) approach and related standards (principally Industry Foundation Classes) remain limited with regard to processes in O&M (Operation and Maintenance) phases, as well as the broader context of AM (Asset Management). This article deals with the activities carried out as part of a pilot project based on the need to manage the operation and assess the condition and value of existing infrastructure along the Cancello–Benevento railway line. The principal goal was to systematize information by digitalizing the infrastructure, in order to enable the assessment of possible performance gaps (compared to national railway standards) in the event of integration within the national infrastructure. In compliance with the project requirements, a digitalization strategy was designed for the definition of surveying activities and the implementation of openBIM systems for the development of an object library and a federated digital model, structured within the collaborative platform that was used, and allowing management, maintenance, and subsequent financial evaluation in the broader context of asset management. The project involved the collaboration of railway operators, a university, and a software company that implemented innovative concepts concerning IFC (specifically, IFC4x2 was used) through the development of dedicated software solutions. The digital solution we proposed enabled the use of digital models as access keys to survey and maintenance information (ERP platforms used by the railway operators) that was available in real time. This project was nominated at the buildingSMART awards 2021 and was one of three finalists in the “Asset Management Using openBIM” category

Advanced analysis and modeling of strategic infrastructures subjected to extreme loads

Recent terrorist acts have contributed to change the design approach to critical infrastructures; in fact, malicious disruptions, blasts, or impacts have unfortunately become part of the possible load scenarios that could act on constructed facilities during their life spans. Hence, a sustainable design aims to ensure the satisfactory performance of the structure during its entire lifetime considering all the possible critical actions, which the structure could be subjected to, including severe dynamic load conditions. The evaluation of the actions on the structure in case of such events is fundamental but represents a critical concern, since uncertainty related to loads definition is often quite high, especially for blast actions. Furthermore, structural response in case of such severe dynamic actions represents a critical issue, since both mechanical properties of materials and dynamic behavior of structural elements under severe dynamic loads can be very different from that exhibited under static actions. Moreover, numerical procedures used to simulate high dynamic loading conditions on structures can suffer of lack of accuracy, due to the rate and the intensity of deformations occurring on structural elements. Hence specific investigations become necessary for all these concerns. In particular, the present work addresses the assessment and design of strategic structures which are to be subjected to multiple hazards during its lifetime, including severe dynamic events, especially blast. At this aim, the most critical issues related to the assessment and design of strategic infrastructures potentially subjected to high dynamic conditions, are discussed and analyzed. Given the uncertainty involved in characterizing the load conditions, it seems inevitable to address the design based on a probabilistic framework. The design can be addressed by limiting the probability of failure below a certain de-minimis risk level that is deemed acceptable by the society. Inevitably, evaluation of the probability of failure requires taking into account possible actions or hazards that the structure could be subjected to; in other words, it needs to be evaluated based on a multi-hazard approach. In details, a multi-hazard framework is proposed and implemented for a strategic reinforced concrete buildings subjected to both seismic and blast hazard. The methodology is described in Chapter I and applied to a case study. Then, a deep investigation is presented on mechanical properties of construction materials in case of dynamic loading conditions. In particular, the strain rate sensitiveness of such material is investigated through a wide experimental activity conducted at Dynamat Laboatory at University of Lugano, Switzerland. In details, results of research activities are presented for: • concrete, in Chapter II, • steel for concrete internal reinforcement, in Chapter III, • Neapolitan yellow tuff, a natural stone widely used in Neapolitan area for masonry structures, Chapter IV, • GFRP (glass fiber reinforced polymer), in Chapter V. A further critical issue related to numerical simulations in case of high dynamic loading conditions on structures. In fact, to address dynamic loading conditions on structural elements, a variety of numerical methods have been recently proposed in the literature; the objective is to address advanced mechanical problems, such as those involving rapid deformations, high intensity forces, large displacement fields. In many of these cases, in fact, classical finite element methods (FEM) suffer from mesh distortion, numerical spurious errors and, above all, mesh sensitiveness. Hence, to overcome such issues, a number of numerical methods, belonging to the family of the so-called meshless techniques, have been widely investigated and applied. The objective of employing these methods is to avoid the introduction of a mesh for the continuum, preferring a particle discretization, with the goal of obtaining an easier treatment of large and rapid displacements. Recently, a number of researchers have tried to extend meshless methods also to solid mechanics problems. Among the several meshless numerical methods proposed, particle methods and in particular Smoothed Particle Hydrodynamics (SPH) has been widely implemented and investigated. A revision of the most common SPH methods is presented in Chapter VI and a rigorous analysis of the error is conducted, focusing on 1D problems. A novel second-order accurate formulation is also proposed for 2D and 3D applications. A further issue is addressed in Chapter VII and is related to protection interventions to be introduced in structural design to minimize disruptive effects in case of malicious blast actions and guarantee the safety of the occupants. In particular, a GFRP porous barrier is developed as fencing structure to prevent malicious disruptions, provide a standoff distance in case of blast actions, and reduce the consequences of an impact. The proposed barrier provides protection through two contributions. First, its geometrical and mechanical characteristics ensure protection against intrusions and blast loads. Second, its shape provides a disruption of the blast shock wave, adding additional protection for structures and facilities located beyond it. The efficacy of the proposed barrier under blast loads is presented by showing the results of the blast tests conducted on full-size specimens with a focus on the reduction of the blast shock wave induced by the barrier. A simplified model is also proposed to predict the reduction of the blast pressure due to the porous barrier, providing a procedure to design the geometrical characteristics of the barrier

Linking disaster resilience and urban sustainability: a glocal approach for future cities

Resilience and sustainability are two primary objectives for future cities. The violent consequences of extreme natural events and the environmental, social and economic burden of contemporary cities make the concepts of resilience and sustainability extremely relevant. In this paper we analyze the different definitions of resilience and sustainability applied to urban systems and propose a synthesis, based on similarities between the two concepts. According to the proposed approach, catastrophic events and the following transformations occurring in urban systems represent a moment in city lifecycle to be read through the complex sustainability framework. Hence, resilience is seen as a requirement for urban system sustainability. In addition, resilience should be evaluated not only for single cities, with their physical and social systems, but also on a global scale, taking account of the complex and dynamic relationships, connecting each other contemporary cities

Resilience to extreme events as a requirement for sustainability of future cities

Le città rappresentano oggi il fulcro delle trasformazioni umane, sistemi estremamente complessi e sofisticati, ma al contempo vulnerabili. Oggi, infatti, eventi estremi, di origine naturale od antropica, minacciano più che mai le città, laddove elevatissima è l’esposizione della società contemporanea. Il governo delle città e del territorio, ovunque nel mondo, passa attraverso la mitigazione e la gestione dei rischi, agendo attraverso il governo sia dell’ambiente fisico che sociale delle città. La città infatti può essere interpretata come un sistema complesso di relazioni dinamiche tra il suo ambiente fisico costituito dalle infrastrutture, dagli spazi, dalle reti (comunicazione, trasporto, energia) dalla natura esterna, ed il suo ambiente sociale, costituito dalle comunità e dalle relazioni sociali che le governano. La gestione dei rischi e dei disastri è quindi un passaggio obbligato nell’attuale concezione del governo del territorio, che muove proprio dal sistema fisico e dal sistema sociale delle città