Il progetto INTERREG FIRESPILL: colmare il divario tra ricerca e pratica per favorire una migliore risposta dei servizi di emergenza transfrontalieri

Il principale obiettivo del Progetto INTERREG FIRESPILL “Promuovere una migliore reazione dei servizi di emergenza transfrontalieri” è quello di rafforzare la capacità delle organizzazioni coinvolte nella gestione delle emergenze nelle zone transfrontaliere in relazione a rischi di tipo naturale ed antropico, riducendo l’esposizione delle popolazioni all’impatto di tali fenomeni e aumentando la sicurezza delle aree italiane e croate coinvolte nel progetto migliorando la prevenzione delle emergenze ed i criteri di gestione delle stesse. Il progetto si focalizza su 4 differenti tipi di rischio (incendio, rilasci ambientali, mareggiate e terremoti) e vuole promuove la definizione di protocolli di azione congiunta tra le parti coinvolte mirati a migliorare sistemi di gestone dell’emergenza esistenti, sviluppare nuovi EMS e coinvolgere i cittadini nella percezione dei rischi. Il presente contributo illustra le principali attività svolte nel progetto FIRESPILL relativa- mente alla valutazione di strutture ed infrastrutture esistenti in acciaio relativamente al rischio sismico, ed alle attività di miglioramento della consapevolezza dei cittadini nei confronti del rischio sismico.

Many structures and infrastructures currently in service in Europe are exposed to seismic risks, accelerate degradation and safety issues because they were designed following guidelines and regulations that didn’t adequately keep in count dynamic solicitations and increasing traffic loadings and loading frequency. Furthermore, in the contemporary society, time is essential and therefore there is continuous demand for time-optimization and speeding processes. With the aim to improve awareness of citizens and communities to the topic of seismic risk assessment and mit- igation, within the framework of the INTERREG FIRESPILL Project - Fostering Improved Reaction of Crossborder Emergency Services a wide range of bridges has been investigated to evaluate the condition state and its implications on seismic risk rating. In the following sections some relevant results related to the portion of bridges with steel superstructure are detailed, that can significantly suffer when subject to corrosion due to environmental agents. In addition, relevant activities related to seismic risk awareness of citizens in the area of the project have been carried out with dissemination activities and with the design of a survey aimed at understanding the level of risk perception of population in relation to main societal features.

Risk rating of existing steel bridges

Within this context, the activities of the FIRESPILL project were focused in analyzing the state of condition of representative bridge case studies. In detail, a qualitative risk assessment was carried out following the recent Guideline of the Italian Ministry of Infrastructure on the Classification of existing bridges, their risk rating, monitoring, and retrofitting design.

Methodology

Specifically, the Guidelines show how the classification of the risk based on the computation of the so-called Class of Attention (CoA) is placed in a general multilevel approach which from the simple census of the bridges reaches the determination of a Class of Attention based on which, in the cases foreseen by the methodology itself, to the security check.

The proposed multilevel approach envisages expeditious evaluations extended to a territorial level, which are justified by the large number of infrastructures present, such as the census, inspec- tions and classification, and punctual evaluations, of greater complexity, concentrated on single buildings. In particular, from an initial analysis performed on the entire existing infrastructural assets through the construction of a reasoned census based on the retrieval of the greatest number of information possible and on the performance of visual inspections (initial and special) to detect defects on bridge elements, the class of attention to be attributed to each bridge is defined and, therefore, the degree of complexity and the type of further investigations that may be required, suitably graded and optimized.

The assessment of the attention class, which includes Level 2 of the Guidelines, consists in the simplistic and expeditious estimation of the relevant risk factors for the bridges in question considering their peculiarities and those of the contexts in which they are generally located, and which are structural and foundational risk, seismic risk, hydro-geological risk (hydraulic and landslide). These are initially analyzed separately in terms of the main factors of hazard, vulnerability and exposure, and are then combined into a single general classification of the attention class.

These factors are in turn determined by considering the main parameters that influence them and are divided into "primary parameters", which have greater importance for the purpose of classification, and "secondary parameters". The determination of the factors and therefore of the attention class, is performed using an approach for "classes and logical operators", i.e. grouping each main and secondary parameter into classes and combining the classes with each other through logical flows.

The primary and secondary parameters are determined by processing the data collected through the census (level 0) and the visual inspections (level 1). Depending on the value of the primary parameters, 5 classes are identified: low, medium-low, medium, medium-high, high. These are defined with specific criteria and range of variation and are then corrected according to the secondary parameters.

Visual surveys have been carried out with the use of by-bridge inspection platforms, as well as by feet and with drones. The visual inspections are aimed at verifying in the first hypothesis the reliability of the data collected in the census and at gathering further information regarding the actual geometric and structural characteristics of the work in question and of the construction site and at evaluating, albeit in a quick and summary manner, the degree of conservation and the main degradation phenomena present in the structures.

They provide a "photograph" and a description as objective as possible of the actual conditions of the asset and the relief of the main degradation phenomena present. Visual inspections require the examination of both the extrados and the intrados of the bridge in each of their elements to have complete and adequate visibility, where appropriate.

Case studies

The abovementioned approach has been applied to a bridge stock composed by 31 structures for a total number of 161 spans. Among these, 7 bridges are belonging to the “steel-concrete” girder type, for a total number of 33 spans. Figure 1 shows some views of the investigated bridges.

...Continua a leggere nel PDF in allegato.

L'intera memoria è in lingua inglese.

La presente relazione è stata presentata in occasione del XXIX Congresso CTA, svoltosi a Milano il 26 e 27 settembre 2024.