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Damage reported in a B17 aircraft during the Second World War (http://www.americanairmuseum.com/media/18738)
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This paper will explain the elementary aspects related to structural robustness. The concept of structural integrity is firstly introduced and next it is considered how it varies in time. The different kind of progressive collapses are introduced with reference to real cases. Design strategies are then explained with reference of bridges and viaduc...
Citations
... However, when it comes to bridges, research efforts in this area have been comparatively limited, even though robustness considerations are equally, if not more, crucial than in building structures. Existing studies on bridge robustness address it both qualitatively and quantitatively, including specific case studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Design strategies to enhance the robustness of bridges con be found in Refs. ...
... Design strategies to enhance the robustness of bridges con be found in Refs. [3,17]. Literature offers various studies quantifying bridge robustness through both deterministic and probabilistic approaches, some of which are collected in the forthcoming JRC technical report [18]. ...
Considerable research efforts have been dedicated to understanding the resistance of buildings against progressive collapse. However, these efforts have been relatively limited in the context of bridges, despite the equal, if not more, critical importance of robustness criteria in bridge engineering. In the context of existing bridges, it is crucial not only to assess safety, but also to evaluate robustness using reliable metrics. These metrics can aid managing authorities in prioritizing necessary interventions. Considering this, the paper applies various robustness measures to a specific type of reinforced concrete (RC) girder bridge known as half-joint bridges. As a case study, the Annone viaduct is examined, which collapsed in 2016 due to the passage of a heavy truck. A notional removal approach of critical elements to quantify structural robustness is proposed. This approach considers several load configurations, some envisioned during the design stage, and others representing abnormal loads. The study results reveal specific scenarios that may lead to potential progressive collapse and highlight the preferred metrics for this type of bridges. Ultimately, the assessment of robustness can play a key role in choosing a retrofitting solution over other intervention options for existing bridges.
... Several papers considered indirect losses by focusing on bridges, such as [5][6][7][8]. In other studies [9][10][11][12], the role of indirect losses for bridge configurations has been considered in detail. Ranjbar and Naderpour [13] proposed two sources of indirect losses: economic costs and losses due to casualties. ...
Resilience of systems to natural hazards has become an interesting concept in civil engineering and it is based on the determination of the losses due to the impacts of natural hazards. In the last decades, many contributions have focused on the assessment of losses that may occur at the time of the event, as generally assumed for earthquakes. However, this assumption may be incorrect when the interval between the time of occurrence and the time when the system functionality reaches the minimum value needs to be considered. This paper aims to propose a novel method to quantify this interval, which is called disruption time, by proposing a novel formulation of the loss model based on infrastructure redundancy. The proposed method was herein applied to a case study that considers landslides in Sri Lanka. The main goal of the paper is to propose a formulation that can be implemented in a more comprehensive framework to calculate more realistically the resilience of systems to natural hazards.
... The vulnerability of RC Gerber beams arises due to the lack of resilience and robustness. In the past, concepts like durability, resilience, and robustness (Bontempi, 2019) were not properly considered by the designers (Malerba, 2017) and (Malerba, 2018). The isostatic structure they favored ensured the absence of imposed distortions arising from settlement and thermal fluctuations, making structural analysis and optimization simpler. ...
This paper addresses the strengthening of a reinforced concrete (RC) road bridge with Gerber-type beams, prompted by the recent collapses of some Italian bridges. The study discusses the characteristics of half-joint bridges, also known as Gerber beam types. These designs, originating in the late 1800s and commonly utilized from the 1950s to the 1970s, exhibit an isostatic structure. While they are easy to design, typically featuring pairs of piers with symmetrical cantilevers and two or more suspended spans, they often suffer from weakening of the half joints (saddles), necessitating structural consolidation. Designers have proposed several solutions to strengthen this type of bridges and the approach presented in this paper focuses on cost-effectiveness and efficiency. It involves a gradual demolition of longitudinal strips on the RC slab of suspended beams, followed by the installation of new steel beams to create a mixed RC-steel system. The application of this method is illustrated in a double-pier bridge spanning the Arno River, Italy. The bridge’s rehabilitation required a complete closure of the traffic road for twelve weeks, followed by alternating traffic for twenty-four weeks. The paper discusses both the design and construction aspects of the proposed intervention, considering costs and implementation time. Furthermore, a low-cost health monitoring procedure is briefly introduced.
... On the other side, structural redundancy is defined by the ASCE standard for Mitigation of Disproportionate Collapse Potential in Buildings and Other Structures, as the availability of alternative load paths that would allow for a load to be transferred from the point(s) of application to the point(s) of resistance in the event of structural compromise of the primary load path by a hazard scenario [4]. Before this, the definition of redundancy was built up to consider the different characteristics of structural systems [5][6][7][8][9]. In this regard, ref. [5] describes the progressive collapse of bridges in the several aspects of analysis and design. ...
... Moreover, disproportionate collapses have been discussed in [6], with particular attention to the terminology and procedures. The redundancy of bridges configurations has been described in [7][8][9]. In particular, ref. [7] considered the role of redundancy and robustness in the design and evaluation of European and North American bridges. ...
Infrastructures are fundamental links in sustainable communities, and they need to remain at a level of functionality during and after natural events. In particular, assessing the seismic resilience of infrastructures has become an interesting topic in earthquake engineering. The estimation of indirect losses due to seismic events is still a topic under discussion, especially for infrastructures. In this regard, the paper focused on including the level of redundancy inside an analytical formulation of the seismic resilience (SR). The main idea is to explore the possibility of alternative infrastructures that allow the circulation of services and people when the flow on the original infrastructure is interrupted or reduced. This goal is fundamental for preserving the resilience for sustainable communities. Therefore, the proposed formulation consists of considering the reduction in losses when the infrastructure is redundant by introducing the concept of the level of redundancy. In particular, indirect costs were herein defined with a new formulation that includes the level of redundancy inside the calculation of SR. The paper presented a case study that implements the formulation with the aim to demonstrate the efficiency of the proposed methodology. Several levels of infrastructural redundancy have been applied in the calculation of the SR of an infrastructure subjected to an ensemble of 100 seismic motions in order to scope the role of redundancy in improving the SR of the system.
... Bridges are important structures that provide a continuous path or way over a river, valley, watercourse or other obstacle . Bridges are also considered to be one of the most important urban infrastructures in the development of smart city projects (Bontempi, 2019). They provide road and rail transportation facilities, connecting different parts of cities by crossing physical barriers in special topographical conditions (Brown et al., 2010). ...
In the present study, we have developed a novel hybrid Machine Learning (ML) based model namely B-IBk which is a combination of Bagging (B) ensemble and Instance-based K-nearest neighbors (IBk) predictor, for quick and accurate prediction of vertical deflection of steel-concrete composite bridges. In the models’ study, we have used five easily determined input parameters: cross-sectional shape, length of concrete beam (m), number of exploitation years, height of main girder (m), and distance between the main girders (m) to obtain output parameter: maximum vertical deflection (mm). For the development of models, direct measurement data of 80 steel-concrete composite bridges located at different places in Vietnam was collected and used as input and output parameters. Standard statistical evaluation indicators namely Mean Absolute Error (MAE), Correlation Coefficient (R), Root Mean Square Error (RMSE) were used to validate and compare the models’ performance. Results indicated that performance of the novel hybrid model B-IBk is very good (R = 0.908) for the prediction of Y of steel-concrete composite Bridge and better than single IBk model (R = 0.875) on testing dataset. Therefore, the developed novel model B-IBk is a promising tool for the accurate prediction of Y of Steel-Concrete Composite Bridges.
... Over the years, structural properties previously combined under the term redundancy have taken separate definitions to distinguish between the different characteristics of structural systems (Ghosn and Moses 1998;Starossek 2006;Starossek and Haberland 2010;Anitori et al. 2013;Ghosn et al. 2014;Bontempi 2019). Specifically, the forthcoming ASCE standard for Mitigation of Disproportionate Collapse Potential in Buildings and Other Structures (Dusenberry et al. 2022) defines redundancy as the availability of alternative load paths that would allow for a load to be transferred from the point(s) of application to the point(s) of resistance in the event of structural compromise of the primary load path by a hazard scenario. ...
... While the research on progressive building collapse is quite extensive [6][7][8][9][10] this cannot be said for bridge structures [1,[11][12][13][14][15][16][17], in which case most studies deal with actual cases and few with experimental, numerical or theoretical studies. In this field there is still a long way to go in the study of bridge structural behaviour after a local failure [18] as well as compiling practical recommendations for robust designs and existing bridge monitoring. ...
Many of the steel bridge collapses occur in truss-type bridges. This is, in fact, the focus of this study involving an assessment of the robustness of this type of structures based on an actual bridge that the authors had extensively monitored and controlled. Robustness was assessed by means of computer simulations of various Damage Scenarios (DSs) to analyse the structural bridge capacity to efficiently activate Alternative Load Paths (ALPs). The computational models have been previously validated with the results of load tests on the bridge and a laboratory test on a full-scale bridge span. The DSs have considered a series of non-simultaneous failures in different elements. The results indicate that the structure is capable of not triggering a disproportionate collapse after each of the DSs with the help of the efficient activation of ALPs that required the contribution of other elements with extra-strength capacity as well as from the superstructure and the joints working under bending moments. The results were used as the basis for practical recommendations for: i) the design of new steel bridges and the retrofit of existing ones and ii) monitoring the structure for the optimal position of sensors to predict local failures that could spread to the rest of the bridge.
... Ghali and Tadros [6], Wang and Zhou [18], Jiang et al. [19]) or the analysis of real cases (e.g. Starossek [10], Bontempi [20], Deng et al. [1]), including truss bridges [21][22][23][24][25][26][27][28][29] with an unique experimental test [29]. In truss bridges, from a theoretical viewpoint [21,23,27], it has been shown that a failure in any element can trigger partial or total bridge collapse, so that there is a need for further studies to analyze the real behavior of these bridges to serve as the basis of future theoretical and numerical developments. ...
This study aimed to experimentally and computationally analyse the robustness of riveted steel bridges based on truss-type structures and to define practical recommendations for early detection of local failures before they cause progressive structural collapse. This paper describes a unique case of a 21m full-scale bridge span tested under laboratory conditions with an extensive monitoring system to evaluate structural behaviour and robustness as damage or failure progressed in its elements. A computational analysis was also included to examine other possible causes not included in the experiment. The results proved the structural redundancy of this type of truss structure based on different Alternative Load Paths (ALPs) and gave rise to a series of practical structural health recommendations to identify early failures and avoid progressive or sudden bridge collapse. The study carried out and the recommendations it produced are now being applied in three similar bridge case studies.
... Regarding the collapse, it can be defined to occur when: (a) there is "run-away" behavior (a structural behavior in which the time response or the load response diagrams are unconfined by certain boundary limits [18]) observed in the vertical displacement time history of the nodes around the removed column, or (b) the vertical relative drift between the beam-column nodes (D V ) located around the removed column reaches the value of 15-20% [19]. The latter is calculated starting from the vertical displacement of the node at the top of the removed column δ V and the length of the beam to which the node belongs L b : ...
A quantitative procedure for the robustness and progressive collapse assessment of reinforced concrete (RC) frames under blast load scenarios is presented. This procedure is supported by multilevel numerical models, including nonlinear numerical analyses of the structural response of both local (i.e., response of the single structural element to the blast load) and global levels (i.e., response of the structural system to the blast-induced damage). Furthermore, the procedure is applied to a 2D RC frame structure. The novelty of the proposed procedure is that the global robustness is evaluated by the so-called “damage-presumption approach” where the considered damages are defined both in typology and extension depending on the blast scenario occurring at the local level. The dedicated local response analysis of a specified blast scenario leads to the proper definition of the so-called “blast-scenario dependent robustness curves”.
... Bontempi [5] explains the aspects related to structural robustness. Bontempi first introduces the concept of structural integrity and then considers how it varies in time, accounting for the different kinds of progressive collapses (Fig. 8). ...
... Cypress Street Viaduct collapse[5] ...
The collapse of the Polcevera Viaduct at Genoa, Italy, demonstrated that good designs are not sufficient to guarantee long lives for bridges. Bridges should be monitored continuously for the detection of damage and deficiencies and for planning timely maintenance programs. This Journal dedicated a special issue to the monitoring and evaluation of existing bridges. The papers selected and published are introduced in this foreword.
