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Infrastructure plays a key role in society. Recent collapses of bridges have underlined their importance for road functionality, causing disruptions to commuters and emergency vehicles. Major issues arise on rural roads, where the lack of redundancy leads to the isolation of entire communities. Actual approaches to assess the resilience of countryside roads rely on the availability of specific datasets, limiting their practical application; this issue is typically related to traffic data. This research aims to propose innovative algorithms to assess the road network’s vulnerability in rural areas, including a novel traffic data collection process and its calibration. The aggregate metric is called Detour-Impact Index (DII) and compares user costs before and after a disruptive event. The method uses traditional network-impact metrics in combination with a new algorithm that allows us to gather quantitative traffic data starting from qualitative information. User travel time showed good agreement between the proposed procedure and traditional web-based methods. Furthermore, the paper provides user delay costs functions accounting for traffic composition, trip purposes, vehicle operative costs, nonlinear volume–capacity relation, and average daily traffic. A significant aspect is the adaptability of this framework, as it is designed to be coupled with existing approaches. The method is demonstrated on a case study in Tuscany (Italy)., The first, third and sixth authors acknowledge that, this work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT Foundation for Science and Technology within the scope of the project POCI-01-0145- FEDER-007633. This work was supported by the FCT Foundation for Science and Technology under Grant SFRH/ BD/145478/2019.

The use of reinforced concrete (r.c.) in industrial plants presents new challenge in the design of gas containments. The r.c. has advantages in terms of costs, shape optimization and monolithicity, although its permeability to gas and vapor is a critical issue. The concrete has well-known performances for water containment (as dams or reservoir) but not for the vapor tightness, due to the natural porosity and physiological cracking due to shrinkage and low traction strength. Special additives can mitigate the problem of the natural cracking that is physiologic for non-prestressed concrete; nevertheless, coatings can solve this problem. The internal coating can produce proper insulation from vapor and gas, but it is difficult to survey and to repair. The external coating is characterized by opposite advantages. In this paper the effectiveness of four different type of the external coatings on the vapor tightness of concrete boxes is analyzed. The experimental test is developed considering small-scale boxes (a cube of 1,20 m side) with a thickness of about 10 cm. Four specimens of cubic concrete boxes made in vibro-compressed concrete are coated with four different layers. The tightness test is carried out by the application of an internal pressure given by blown nitrogen. The tests highlight the level of tightness of each treatment and highlights strength and drawbacks of each coating.

The current development of Liquid Natural Gas (LNG) storage site requires a thorough analysis of concrete behaviour under cryogenic temperatures. Indeed, this kind of infrastructure is based on a set of tanks that presents several layers. The first one is the cryogenic steel tank that directly contains the LNG. An outer concrete box represents the external layer and usually between these two layers there is a thermal insulating material. A leak from the steel tank can apply a tremendous thermal gradient to the concrete external layer. Thus, the study of concrete behaviour in this situation is important and few studies are available for concrete characterized by lightweight clay aggregate. In this experimental work, the variation of the modulus of elasticity of lightweight clay aggregate concrete, due to temperature gradients have been analyzed and discussed. A set of concrete cubes has been immersed in liquid nitrogen to reach -180°C, then they have been tested under compressive stress measuring both stress and strains. Correlations between elastic properties and temperatures are proposed.

Several relevant collapses of historical urban walls happened in Tuscany in the last ten years, due to rainfalls. The wide extension of the walls, with difficulties of proper monitoring, joined with lack of maintenance, contributed to the failures. This recalled the attention on their vulnerability, in view to ensure a proper safety level and appropriate cultural heritage protection. In this paper, a method of extensive and quick structural survey to identify the mechanical characteristics of an historical urban wall path is proposed. It is based on geographic method of management of the territory (GIS database, satellite data). The data are obtained throughout a discretization of the walls in a wide set of vertical sections. A reduced subset of sections is directly surveyed, while the others are indirectly identified via numerical procedure, with the help of GIS data. A specific form to take note of the most relevant features is edited. The method is tested on the entire perimeter of the Middle Age walls of Volterra (2,6 km), affected by two relevant collapses in 2014. The procedure of survey is conceived to perform structural analysis to evaluate the vulnerability to landslides and earthquake risks, in view to determine restoration strategies and consolidation or monitoring programs.

This paper proposes a stochastic life-cycle assessment (LCA) as a general stochastic formulation to quantify the environmental impact of an engineering system. The assessment is performed i...

This work arises from the evidences of recent collapses of historical urban walls. These events, mainly occurred after severe rainfalls, recalled the attention on the vulnerability of these...

Unreinforced masonry (URM) buildings make up a significant portion of the built environment, with hollow clay being the predominant choice for the units. The capacity of URM buildings is a ...

Constructions ageing is a relevant problem in developed country like Italy. In particular, in case of existing masonry buildings, retrofitting interventions aimed at improving structural and thermal performances represents an obvious need. At the same time, sustainability awareness of buildings life-cycle has grown in the last years. Consequently, the whole life-cycle of constructions should be analyzed and assessed during the design of retrofitting interventions. In order to take into account these aspects new design and planning methods are necessary. This paper presents an integrated approach to evaluate structural and thermal retrofitting strategies for masonry walls. Economic and ecological costs of each examined retrofitting solution are compared, taking into account thermal and seismic capacity demand of the construction site. Given the economic cost, a set of retrofitting solutions for masonry panels have been mapped with a couple of parameters (structural strength Vs thermal insulation). An analogous mapping, considering the ecological cost due to equivalent CO2 production, have been performed. A methodology to find the best solution among a set of retrofitting solutions is presented, depending on the location of the building and its seismic and thermal characteristics. Examples, based on six retrofitting techniques located in four different sites in Italy, are analyzed to explain the effectiveness and the feasibility of the proposed method. The comparison between ecological and economical cost allowed to highlight the characteristics of the different interventions. Thermal performance proved to be more important in cold weather conditions while structural retrofitting is preferable in high seismic risk areas.

In this paper, the use of Fast Falling Weight Deflectometer (Fast-FWD) is analyzed as a non-destructive and quick test procedure to evaluate the efficiency of short-span bridges. The Fast-FWD is an instrument that can produce a broadband dynamic force up to an impact value of 120 KN: The impact is constant and replicable, providing accurate action measures of bridge stiffness in a truly short period (30 ms). In this paper, a single-span reinforced concrete bridge is investigated, using the Fast-FWD. The considered bridge, approximately 12.0 m long and 15.5 m wide, was in critical condition. The bridge is in a suburban principal road near to the City of Cagliari in Sardinia (Italy), with an Annual Average Daily Traffic of 13,500 vehicles/day, and was suddenly closed, creating serious problems for urban mobility. In these conditions, the investigation through other standard techniques is time-consuming and labor intensive. For this reason, it is important to introduce methods that can be rapid, accurate and cost-efficient. In this paper, bridge stiffness values obtained during the in situ experimental campaign were compared with finite element models values. The Fast-FWD has the potential to provide engineering information that can help us to better understand bridge condition, in a rapid and cost-effective procedure.

Risk management plays a crucial role in the stakeholders’ decision making because it is directly related to safety, serviceability and economy. There is now a growing concern about how to relocate known risks into an acceptance threshold: this implies the evaluation of several options obtained from hazard scenarios considering the related consequences. In parallel, practitioners usually rely on standard tools for risk assessment, and on structural codes to compute performances. Although this approach is currently widely implemented, this research shows that hazardous situations can arise in properly designed infrastructures, due to errors in management. This paper deals with such issue, also highlighting a gap in current codes that could contribute to losses caused by unforeseen failure modes. In this study, a preliminary FMEA assessment was performed to identify the failure modes that required a deeper quantitative analysis. In a second step, a quantitative analysis was implemented, using a modular methodology that combines reliability theory with a risk-based approach. The results evidenced that a wider analysis focused on the identification of vulnerable areas shall be considered in every stage of the asset management. Furthermore, the dynamic of this process is regulated by the established safety level concerning possible damages to people, production sites and commercial activities., This work was partly financed by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT Foundation for Science and Technology within the scope of the project POCI01-0145-FEDER-007633. This work was supported by the FCT Foundation for Science and Technology under Grant SFRH/BD/145478/2019. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 769255.

Recent collapses due to hydrogeological soil instability caused by extreme climate events recall the attention on a large-scale monitoring of the road infrastructures, particularly bridges and viaducts. Several studies focus the attention on both hydraulic and structural issues. In-depth systematic investigations do not suit this purpose because of time and cost investments usually carried out from local authorities. Increasing needs of available fast, low cost and reliable methods to investigate the performance of the road and bridges pushed towards new applications. The use of Fast-Falling Weight Deflectometer, conceived for airport pavements, is here applied as a non-destructive test to evaluate the stiffness of the deck and embankment of a bridge. The- Fast Falling Weight Deflectometer can produce a broadband, constant and replicable dynamic force, providing data in real time. An experimental campaign is here described on a case study of single span bridge.

This paper deals with analytical models of retaining walls interacting with soil, whose mechanical properties are influenced by penetrating moisture. Specifically, urban masonry walls are here considered. The proposed simplified procedure takes rainfalls as the intensity measure dependent on rain duration and return period. Growing levels of imbibition of the soil behind the wall determine a de-crease of the strength parameters of the soil. A geometry of the section at each step of imbibition is analyzed considering a set of soil layers with modified properties over time. The method is applied to a section of the Volterra historical urban walls named “Sperone” which was affected by a relevant collapse occurred in March 2014: a back analysis of the soil-structure section is also proposed to re-place the collapse.

Recycling concrete construction waste is a promising way towards sustainable construction. Indeed, replacing natural aggregates with recycled aggregates obtained from concrete waste lowers the environmental impact of concrete constructions and improves natural resource conservation. This paper reports on an experimental study on mechanical and durability properties of concretes casted with recycled aggregates obtained from two different parent concretes, belonging to two structural elements of the old Cagliari stadium. The effects of parent concretes on coarse recycled aggregates and on new structural concretes produced with different replacement percentages of these recycled aggregates are investigated. Mechanical properties (compressive strength, modulus of elasticity, and splitting tensile strength) and durability properties (water absorption, freeze thaw, and chloride penetration resistance) are experimentally evaluated and analyzed as fundamental features to assess structural concrete behavior. The results show that the mechanical performance of recycled concrete is not related to the parent concrete characteristics. Furthermore, the resistance to pressured water penetration is not reduced by the presence of recycled aggregates, and instead, it happens for the chloride penetration resistance. The resistance to frost&ndash, thawing seems not related to the recycled aggregates replacement percentage, while an influence of the parent concrete has been assessed.

Sustainability awareness of buildings life-cycle represents one of the most important engineering challenge. This is more important in developed country like Italy in which buildings age and importance can be huge. Consequently, the whole life-cycle of constructions should be analyzed and assessed during the design of retrofitting interventions. This works reports on the application of an integrated approach to evaluate structural and thermal retrofitting strategies for masonry walls. Ecological (equivalent CO2) and economic costs of each examined retrofitting solution are evaluated and compared. In this way the structural and thermal capacity of the masonry walls is represented by an iso-cost mapping. The environmental demand considering both thermal and seismic load of the construction site is represented by an equivalent function that is used to find the optimal retrofitting solution for each considered cost.

The heavy rainfalls occurring in Italy in the last few years focused the attention on the vulnerability of the land and the related infrastructures. Critical situations involving losses of human life and deterioration or failure of relevant structures are frequent. These events were due to: (1) improper land-use; (2) aging of infrastructures, (3) insufficient maintenance and protection; (4) climate changes causing rainstorms similar to tropical events. The failure of small bridges in road networks plays a key role in this sense. The present paper aims to analyse the behaviour of small bridges during rainfalls or floods. In particular, the recent case of Livorno is analysed. The Italian territory has about 460.000 small bridges, mostly designed without the support of technical codes or a proper interaction between the hydraulic and structural aspects. A large part of them can be submerged by water flows during rainfalls and pushed by unexpected actions. The failure scenarios allow identifying the hydraulic and structural vulnerabilities through a specific survey. A classification of small bridges on the basis of submergibility indexes is eventually proposed.

This paper proposes a general physics-based probabilistic demand model for the reliability analysis of reinforced concrete (RC) beams under blast loading. The formulation of the proposed demand model builds on a computationally convenient representation of the governing physical laws from structural dynamics and adds a correction term and a model error. Specifically, the proposed demand model starts with predictions from a generalized single-degree-of-freedom (SDOF) representation of the RC beam, derived from the conservation law of energy; the correction term removes the implicit bias and improves the accuracy of the model, and the model error captures the remaining uncertainty in model predictions. Unknown model parameters are included in the correction term and the model error. Once formulated, the probabilistic model is calibrated with data from experimental tests or high-fidelity computational models. The inclusion of the governing physical laws in the proposed model avoids a strong dependence of the model on the specific data used for the model calibration. The paper uses Bayesian inference that combines predictions from the generalized SDOF representation with experimental data and any prior information to estimate the unknown model parameters. The paper then uses the proposed demand model in a formulation to estimate the reliability of RC beams under blast loading. Finally, the paper illustrates the novel contributions by estimating the reliability of an RC beam under blast loading for three damage levels. As part of the reliability analyses, the paper also identifies the dominant sources of uncertainty in estimating the failure probability.

This paper proposes a quick and simplified method to describe masonry vaults in global seismic analyses of buildings. An equivalent macro-element constituted by a set of six trusses, two for each transverse, longitudinal and diagonal direction, is introduced. The equivalent trusses, whose stiffness is calculated by fully modeled vaults of different geometry, mechanical properties and boundary conditions, simulate the vault in both global analysis and local analysis, such as kinematic or rocking approaches. A parametric study was carried out to investigate the influence of geometrical characteristics and mechanical features on the equivalent stiffness values. The method was numerically validated by performing modal and transient analysis on a three naves-church in the elastic range. Vibration modes and displacement time-histories were compared showing satisfying agreement between the complete and the simplified models. This procedure is particularly useful in engineering practice because it allows to assess, in a simplified way, the effectiveness of strengthening interventions for reducing horizontal relative displacements between vault supports.

Recent failures in road networks highlight their vulnerability towards natural hazards, particularly to extreme weather events. This paper proposes a method to evaluate the safety of road networks in case of collapse of one or more bridges. In addition, relevant consequences in terms of safety of human life, direct and indirect cost are crucial aspects to consider. The framework described here is based on the knowledge of road and river network, of the individual bridges and of the traffic data. However, this approach can be generalized in case of interruption of road network due to other causes. An algorithm has been developed to extract traffic data from Google and elaborate it throughout a procedure based on the application of the USA Highway Capacity Manual. This consents to have a quantitative definition of the road traffic directly from the users and to get updated traffic data. The maps are processed throughout a GIS software and, thanks to the application of a routing algorithm and proper constraints, it is possible to evaluate the effects of the interruption of one or more bridges. The consequences are evaluated in terms of drivers’ delay and time cost. This provides useful information about priority of intervention with the aim of proposing to stakeholders a suitable instrument for disaster prevention and management.

Probabilistic models for the concentrated leak erosion of earthen water retaining structures are presented. The models predict the values of the critical shear stress, the coefficient of erosion and the pipe radius enlargement, starting from other measurable soil properties and the geometrical dimensions of the embankment. The models account for both the non-cohesive and cohesive contributions to the erosion behavior. A Bayesian approach is used for the treatment of the unknown parameters. An importance sampling simulation is adopted to calibrate the models and estimate the posterior distribution of the unknown model parameters using laboratory and in situ experimental data. The new proposed probabilistic model for the pipe radius is then used to develop fragility curves that capture the pipe enlargement as a function of time for a given earth dam.

A methodology to quantitatively assess the improvement of seismic and energy performance of masonry buildings through retrofitting interventions is here proposed. The approach is developed at mesoscale level, considering entire facades with openings and taking into account Life Cycle Assessment (LCA). The costs of retrofitting interventions that couple effects of seismic and thermal improvement (called integrated interventions/approaches) are different whether only the construction phase or the entire life cycle of the building is considered. Therefore, it is necessary to estimate at what extent it is correct to neglect LCA in the analysis of integrated approaches. In this paper, the analysis of three masonry facades is performed with and without LCA. Traditional (insulating panels, diatons, ferro-cement) and more innovative interventions (carbon and glass fiber reinforced polymer composites) are considered. For the comparison, isocost and isoperformance curves, which determine both the economic (Euros) and environmental costs (kg CO2eq) for each intervention, are discussed. The comparison shows the necessity of always considering LCA for a reliable assessment: some retrofitting interventions are the most expensive in the construction phase but they result the most convenient in economic terms and in the amount of CO2eq emissions.

The paper deals with the behavior of restrained rocking blocks under seismic actions. Structural or non-structural masonry or r.c. elements, such as building facades or pre-cast panels subjected to out-of-plane modes, may be assimilated to rocking blocks restrained by horizontal springs. Horizontal restraints can represent flexible floors or steel anchorages or any anti-seismic device designed to impede overturning probability. Their effect could improve, in most cases, the dynamic response of blocks in terms of reduction of rotation amplitude. Nevertheless, this effectiveness could vanish or, surprisingly, affect the response in negative way, resulting in overturning when low values of stiffness or one-sided motion in particular conditions are assumed. Two cases of horizontal restraints are analyzed: (1) concentrated restraint as single spring and (2) smeared restraint as spring bed with constant or linearly variable stiffness. The single stabilizing or destabilizing terms of the formulation are here analyzed and commented, providing practical evaluations to obtain enhancement of response in static and dynamic perspective. A numerical example of a masonry facade with non-linear boundary conditions has been provided highlighting how the choice of stiffness values affects the oscillatory motion and rebound effects. Finally, unit stiffness for masonry/concrete walls and retrofitting techniques, such as steel tie-rods, has been calculated.

This special issue of the International Journal of Structural Glass and Advanced Materials Research contains new contributions and the extended version of some selected papers presented in the 6th International Workshop on Design in Civil and Environmental Engineering (DCEE2017) held at the University of Cagliari during November 9 - 10 - 11, 2017. Previous conferences of this series have been successfully held in Rome (2016), Taiwan (2015), Lyngby (2014), Worcester (2013), Dajeon (2011).

This paper deals with the need of extending results of deterministic rocking analyses to stochastic analyses on restrained masonry façades in one-sided motion. The purpose is to define the level of improvement achieved with any anti-seismic device of a given stiffness and strength, in terms of reduction of probability of exceedance of a certain limit state. The most efficient intensity measures (IMs) are identified for three masonry façades of churches in free and restrained conditions. A reliability analysis is carried out by considering over 70 earthquakes, of which 50 recorded during the recent 2016–2017 Central Italy Earthquake. Four limit states are taken into account: rocking initiation, limited rocking, moderate rocking and near-collapse condition. The yielding limit state is considered for the analysis with anti-seismic devices. Univariate and bivariate fragility curves (FCs) are compared in free and restrained configurations, to discuss the reduction of probability of exceedance depending on 15 intensity measures. The results show that the best IMs are velocity-based parameters, in particular the Fajfar Index and Peak Ground Velocity, together with Peak Ground Acceleration. In one-sided motion without restraints, the higher the compression stiffness of the sidewalls, the more unstable the wall is in probabilistic terms. Practical curves show, for each IM, the reduction of probability of exceedance obtained thanks to assumed horizontal restraints. These help to understand, in a stochastic perspective, to what extent the anti-seismic device can be beneficial or detrimental (in case of amplifications of motion) for given earthquake intensities. The comparison of univariate and bivariate FCs confirms the superiority of bivariate FCs. Indeed, often the univariate curves sensitively underestimate the probability of exceedance, especially for low-medium intensity earthquakes, and are not able to offer any information regarding the influence of other IMs, The authors thank the sponsorship of the Italian Department of Civil Protection, in the framework of the RELUIS Project - Masonry Structures (2018) and Eng. Fabio Solarino for helping in the calculations., info:eu-repo/semantics/publishedVersion

The retrofitting of existing masonry buildings is now a crucial problem for Europe. Indeed, structural safety and energy efficiency should represent the target of any renovation. The proposal of a new synthetic performance parameter is presented and discussed. Following this approach, in this paper, after a review of the main studies available in the literature, a proposal of a new performance parameter approach is presented and discussed. It is capable of taking into account both the structural and thermal aspects of masonry retrofitting. An emblematic set of reinforcements and energy improvements for masonry walls is examined. An example, generalized formulas, and a simultaneous evaluation of the role of multiple structural and thermal parameters on masonry buildings are proposed, with a view to optimize several categories of costs related to the intervention.

The effect of irregularities due to the non-uniform distribution of material properties on structural elements of a significant real case is here investigated. Mechanical tests performed on a typical Italian reinforced concrete (r.c.) school building built in the 1960s showed irregularity in the distribution of compression strength in columns, even though the construction is featured by substantially symmetric distribution of the frames. Extreme scenarios in the distribution of irregularities in compression strength of concrete columns are analyzed, with the hypothesis of rigid or deformable slabs. The seismic analysis showed the influence of the response due to the irregular distributions of concrete strength. A proposal of equivalent “material eccentricity” is shown to account for the mentioned irregularity. Furthermore, the practical solution of reinforcement to mitigate the effects of irregularities is also described. It consists of couple of external r.c. walls stiffened by r.c. buttresses added to the building, connected by transverse slabs. An extensive reduction of material eccentricity is achieved, together with a relevant improvement in seismic capacity.

This contribution comes from the investigations carried out on recent flooding events occurred in Italian suburban areas. Those events, regarding minor roads, cause unexpected failure modes of exis...

Seismic assessment and rehabilitation of Monumental Buildings constitute an important issue in many regions around the world to preserve cultural heritage. On the contrary, many recent earthquakes have demonstrated the high vulnerability of this type of structures. The high nonlinear masonry behaviour requires ad hoc refined finite element numerical models, whose complexity and computational costs are generally unsuitable for practical applications. For these reasons, several authors proposed simplified numerical strategies to be used in engineering practice. However, most of these alternative methods are oversimplified being based on the assumption of in-plane behaviour of masonry walls. Moreover, they cannot be used for modelling the monumental structures for which the interaction between plane and out-plane behaviour governs the structural response. Recently, an innovative discrete-modelling approach for the simulation of both in-plane and out of-plane response of masonry structures was proposed and applied to study several typologies of historic structures. In this paper the latter model is applied with reference to a real case study, and numerically compared with an advanced finite element modelling. The method is applied to the St.Venerio church in Reggiolo (Italy), damaged during the 2012 Emilia-Romagna earthquake and numerically investigated in the literature.

The present paper deals with the influence of material variability on the seismic vulnerability assessment of reinforced concrete buildings. Existing r.c. buildings are affected by a strong dispersion of material strengths of both the base materials. This influences the seismic response in linear and nonlinear static analysis. For this reason, it is useful to define a geometrical parameter called “material eccentricity”. As a reference model, an analysis of a two storey building is presented with a symmetrical plan but asymmetrical material distribution. Furthermore, an analysis of two real buildings with a similar issue is performed. Experimental data generate random material distributions to carry out a probabilistic analysis. By rotating the vector that defines the position of the center of strength it is possible to describe a strength domain that is characterized by equipotential lines in terms of the Risk Index. Material eccentricity is related to the Ultimate Shear of non-linear static analyses. This relevant uncertainty, referred to as the variation of the center of strength, is not considered in the current European and Italian Standards. The “material eccentricity” therefore reveals itself to be a relevant parameter to considering how material variability affects such a variation.

The ‘Triple R’ approach on the restoration of dry stone walls, using recognizable, reversible and respectful constructive techniques is here illustrated. A set of restoration procedures are explained and applied to a UNESCO World Heritage site in Al-Baleed (Salalah, Sultanate of Oman) in the ‘Land of Frankincense’. The procedures were adapted in an innovative way to take into account the climate features of the Indian Ocean area (specifically, the effects of the monsoon season). All the restoration procedures aimed at conserving the site’s original architectural features by using only suitable stones and materials found on-site. Specific procedures have been adopted to consolidate walls, gates, foundations and sloping surfaces. Simple on-site mechanical tests and evaluation methods have been developed for a quick assessment of the safety level of the restored walls to ease future archaeological excavations. The application is related to a waterfront side of the ancient city built around the ninth ...