Seismic upgrading of RC wide beam–column joints using steel jackets

This study is devoted to experimentally investigate the seismic behaviour of reinforced concrete (RC) wide beam–column joints equipped with a steel jacketing seismic strengthening solution. To this end, three identical full-scale specimens have been tested under cyclic loading, one in the as-built condition and two after the application of the strengthening solutions. Details of selected solutions are described in the paper along with the experimental results which confirm how the application of simple and feasible steel interventions can effectively improve the seismic capacity of wide beam–column connections in RC frames, especially in terms of lateral load carrying capacity and energy dissipation

Durability enhancement of half-joints in RC bridges through external prestressed tendons: The Musmeci Bridge's case study

This paper numerically investigates the effect of post-tension interventions to strengthen the deteriorated half-joints of the Musmeci Bridge in Potenza (Italy), with the primary objective of increasing the ultimate load-bearing capacity and monitoring the secondary effects in terms of preventing or limiting cracking patterns. Bearing this in mind, the study aims to investigate the role of the reinforcement detailing, of the post-tension stress and of the corroding time in the presence of chlorides, outlining the intervention ability to improve the structure's durability. To this end, nonlinear finite element models are provided with chloride ions diffusion analysis to investigate corrosion initiation and progress in reinforced concrete elements and account for deterioration due to two scenarios (45 and 95 years). Results show the significant impact of reinforcement layout as the presence of inclined bars increases the ultimate load by about 86 %. The ultimate load improvement is in the range 50–55 % when the intervention is carried out after 45 years while it is equal to about 30–35 % if a period of 95 years is last since the construction. This latter highlights the significant influence of the intervention timeliness on structural durability

Key mechanisms of the seismic behaviour of external rc wide beam–column joints

Background: Reinforced concrete beam-column connections provided with wide beams are widely used in the European residential building stock. Several seismic codes indicate some limitation to be applied to this kind of reinforced concrete buildings due to their reduced performances with respect to those provided with conventional beams. Objective: The paper is focused on improving the knowledge of wide beam-column joints, highlighting the key degradation mechanisms affecting them, mainly related to slip phenomena of beam rebars, especially the rebars placed outside the column width. Methods: The behavior of wide beam-column joints has been evaluated by means of both experimental tests under cyclic loading and accurate nonlinear finite element analyses. The FE models predicted satisfactorily experimental results, thus enabling to carry out additional numerical analyses aimed at checking the effect of the longitudinal reinforcement amount in the beam member. Results: Experimental results show that wide beam-column joints conforming to the Italian seismic code do not exhibit a sufficiently ductile behavior due to damage in the non-confined concrete region, where beam rebars external to the joint core are anchored. Numerical simulations allowed to monitor bond slip of beam rebars as a function of the applied global displacement, showing differences between bars placed inside and outside the column width. Conclusion: Numerical simulations showed that different behavior is expected in case additional beam rebars are placed either inside or outside column width. In the first case, higher peak load and ductility values can be achieved, provided that the amount of beam reinforcement is not high enough to shift damage towards the column or cause high shear stress to the joint core and its consequent fragile failure

Durability of gerber saddles in RC bridges: Analyses and applications (Musmeci Bridge, Italy)

Guaranteeing adequate safety levels in critical infrastructures such as bridges is essential to modern societies and their vital services. Bridges with reinforced concrete structures are subject to deterioration, especially due to corrosion effects. Gerber saddles are among the key components of bridges which are especially exposed to environmental actions due to their position and reduced possibility of inspection. In this paper, a framework for the durability analysis of these components is proposed, considering the simultaneous presence of permanent loads and environmental actions under the form of chloride ions. Nonlinear numerical simulations adopting the finite element code ATENA are performed, accounting for chloride ingress analyses. The presence of cracks (due to applied loads and/or design/construction defects) which may speed-up corrosion propagation, steel reinforcement loss, cracking and spalling, and their effects on the load-bearing capacity is considered. This framework has been applied to the Gerber saddles of a prominent reinforced concrete (RC) bridge, namely the Musmeci bridge in Potenza, Italy. Durability analyses made it possible to evaluate the saddles’ strength capacity (i) at the time of construction, (ii) after forty-five years since the construction, and (iii) at an extended time of fifty years. The results show that corrosion can influence both the ultimate load capacity and the collapse mechanism

The Italian guidelines on risk classification and management of bridges: Applications and remarks on large scale risk assessments

Bridges are essential for guaranteeing the functioning of transportation systems since their failure can cause serious threats to the safety, well-being and economy of modern communities, especially in emergency conditions. Following recent bridge failures, among which include the Morandi bridge in 2018, specific guidelines on risk classification and management, safety assessment and monitoring of existing bridges have been issued in Italy by the Minister of Infrastructure as a mandatory code. They pay particular attention to the evaluation of the residual life span of critical transportation infrastructure dating back to the 1950s and 1960s of the last century. Being a newly issued tool, the Guidelines need to be applied and tested in order to find possible drawbacks and to point out the main factors influencing their results. Therefore, in this study, after a short description of the Italian Guidelines, pointing out some differences with other approaches adopted worldwide, some advantages and disadvantages are discussed by an application to a bridge stock located in the Basilicata region (Italy). Data needed to apply the Guidelines are gathered by a purposely set up procedure that exploits existing databases on road infrastructure (OpenStreetMap) complemented by additional data retrieved by means of public image repositories (Google Street View). By accounting for the qualitative nature of the risk classification results obtained by applying the lower analysis levels of the Guidelines, a prioritization method is proposed for ranking bridges for higher assessment levels and possible interventions, as well as consequent funds allocation. The application shows that the Guidelines’ approach tends to provide conservative results. In fact, even in case of bridges with low degradation levels, the final risk classification induces actions undertaken for preliminary or detailed assessment; thus, normal operation (with periodic inspections) would not be possible anymore

Post-earthquake rehabilitation of healthcare buildings: The case study of the mirandola hospital

Recent earthquakes in Italy and other countries have shown the fragility of hospital complexes which resulted in many cases unusable due to structural and non-structural damage. Depending on the extent of damage, unusable hospitals were reopened after some weeks/months, or affected by long rehabilitation intervention or demolished. In order to allow for a prompt resumption of the social activities of the local communities, the usability evaluation carried out in the immediate aftermath of a seismic event is a crucial step to address the short-term countermeasures and to obtain a gross estimate of the economic losses. After the first weeks, it is often necessary a more detailed assessment which allows for a more accurate evaluation of damage and, more importantly, about the reparability of the structure along with the study of feasible intervention strategies. This latter activity needs detailed analyses based on increased knowledge of the structure. Keeping in mind the objectives of detailed post-earthquake assessment and reparability evaluations, the Santa Maria Bianca hospital of Mirandola, damaged by the Emilia 2012 earthquake, has been analyzed as a case study. Analyses were devoted to defining an upgrading strategy to match the code serviceability limit states (damage limitation and occupancy). The selected strategy included solutions to carry out most of the work from outside, to limit the downtime of the building as well as reconstruction of demolished non-structural elements. Further analyses were made in order to check the effects of the upgrading strategy under the seismic actions recorded during the 2012 Emilia earthquake. These analyses highlighted that even the upgraded hospital building could not be able to remain operational after a new seismic event having the same intensity as the 2012 event, underlining the need of more stringent design criteria for strategic structures like hospitals that are requested to provide healthcare services even more when strong earthquakes occur

FIRE PLANNING OF URBAN-RURAL INTERFACE IN OPEN SOURCE GIS ENVIRONMENT: CASE STUDY OF THE APULIA REGION (SOUTHERN ITALY)

Abstract. Fires represent one of main challenges of the last decades as global changes are causing an increase in economic and environmental damages. Indeed, just in 2017, more than 10,000 km2 of land were burned in Europe, causing significant damage to both the natural heritage (25% of burned areas were part of Natura 2000 protected areas) and the economy with estimated losses around 10 billion euros. In addition, every year there are losses of human life that make even more necessary new strategies of action and monitoring. Therefore, an efficient management of forecasting, prevention, active fight and post fire phases, is essential to make the territories less vulnerable and reduce the impacts on human lives. But these steps require an integrated approach of different tools in order to make faster and more efficient the different operations. In this context, the study illustrates the expeditious and standardized methodologies in open source GIS environment proposed in a research project with the Civil Protection of Apulia Region in order to implement a vulnerability index to improve operations in forecasting, emergency management in real-near time and post-event analysis in urban-rural interface. All the techniques and methodologies proposed were based on the use of QGIS software as it is a highly user friendly software that can be easily used even by non-specialized technicians. Moreover, the methodologies have been validated through a direct comparison with the tools currently in use in Civil Protection Department of Apulia Region

Level 3 Assessment of Highway Girder Deck Bridges according to the Italian Guidelines: Influence of Transverse Load Distribution

The Italian Ministry of Infrastructure and Transportation adopted the guidelines on risk classification and management, safety assessment and monitoring of existing bridges through the Decree No. 578 dated 17 December 2020. This document must be used by all managing entities to prevent damage due to a lack of maintenance to these crucial components of the infrastructure system. The approach of the guidelines for existing bridges is developed across six levels, ranging from Level 0 to Level 5. The research work presented in this article is focused on Level 3, which pertains to preliminary assessments conducted on existing bridges. Through an automated procedure, the preliminary verification is performed by comparing bending and shear stress generated by traffic load schemes extracted from previous standards with the ones based on the current code. These loads are applied to a series of girder deck models, selected through a statistical study conducted on a database of bridges. Performance indices are derived from the comparison to evaluate the adequacy of previously designed and constructed structures by applying the load models specified in the current regulations for designing new bridges. The analysis results highlight a performance gap, which varies depending on the standard code at hand

Analysis of the Effect of Soil Erosion in Abandoned Agricultural Areas: The Case of NE Area of Basilicata Region (Southern Italy)

Land abandonment is among the most complex la nd use change processes driven by a multiplicity of anthropogenic and natural factors, such as agricultural over-exploitation, implementation of agricultural policies, socio-economic and climatic aspects. Therefore, it is necessary to deepen the effects of land abandonment based on methodologies that are as multidisciplinary as possible. Environmental and social problems related to abandonment include soil erosion and environmental degradation. Approaches combining GIS (Geographic Information System), remote sensing, and image analysis techniques allow for assessments and predictions based on integrating theoretical models with advanced geospatial and geostatistical models. One of the most widely used models for soil erosion estimation is the Revised Universal Soil Loss Equation (RUSLE). The present work developed a model using remote sensing and GIS tools to investigate some factors of the RUSLE equation to evaluate the adverse effects of soil erosion in areas covered by arable crops and subsequently abandoned. To identify potentially degraded areas, two factors of the RUSLE were related: the C Factor describing the vegetation cover of the soil and the A Factor representing the amount of potential soil erosion. Through statistical correlation analysis with the RUSLE factors, based on the deviations from the average erosion values and mapping of the areas of vegetation degradation relating to arable land, the areas identified and mapped are susceptible to soil degradation