The goal of NEST is to provide a contribution to the revision phase of the Italian guidelines for ‘Guidelines for risk classification and management, safety assessment and monitoring of existing bridges’ through the comparison of the approach proposed by the Italian guidelines with the multi-risk approach adopted in the technical documents in force in other countries and in particular in the United Kingdom where the problem of floods and undermining of the piles is of considerable importance. To this aim the guidelines will be applied to exemplary cases in order to identify possible criticalities and possibilities of improvement of the current document. The period at PoliMI of dr Maria Pregnolato, visiting researcher from Bristol University, will enable and facilitate this comparison
In 2020 the Italian Consiglio Superiore dei Lavori Pubblici approved the “Guidelines for the classification and management of risk, the evaluation of safety and the monitoring of existing bridges” (in Italian, “Linee guida per la classificazione e gestione del rischio, la valutazione della sicurezza ed il monitoraggio dei ponti esistenti”). These guidelines are currently adopted within an experimental phase, i.e. a preliminary revision is necessary for their final adoption, until the end of 2022.
The goal of this NEST project is to provide a contribution to the revision of the guidelines by:
- applying the proposed methodology to case studies and identify potential criticalities of the current document;
- comparing the proposed methodology to the guidelines currently in used in other countries, for example in the United Kingdom. The comparison will be conducted through comparative case studies to highlight differences in methodology and/or classification.
This project addresses the problem of managing bridges prone to natural phenomena, such as earthquakes and floods. Socur is one of the main causes of differential subsidence or, in the worst cases, the collapse of riverine bridges. This phenomenon is intensified by flood events, which are increasingly frequent and intense due to climate change. Scour at bridge piles can be particularly problematic for bridges in seismic areas, since the erosion process may lead to significant displacements and the loss of support of the deck during seismic events even of modest intensity. Considering the damages or the collapse of a bridge, the direct consequences of the costs for repair or reconstruction are added to the indirect consequences, which result from the loss of functionality of the structure and disruption of the transport network.
The management of existing bridges is therefore a significant challenge for Civil Engineering. The limitation of current methods has led to the adoption of risk-based approaches for prioritising the interventions. For bridges in seismic areas and prone to scour, a multi-risk procedure is necessary.
A procedure of this type is contained in the ‘Guidelines for risk classification and management, safety assessment and monitoring of existing bridges’ approved in Italy in 2020 by the Consiglio Superiore dei Lavori Pubblici. The adoption of this document aims to ensure the homogeneity of the classification and risk management at national level, for the assessment and monitoring of existing bridges, viaducts, and similar structures.
This project is among the first studies to apply and evaluate the new Italian Guidelines for the classification and assessment of bridges. It will provide an actual example of how the legislation can be applied for bridges in seismic areas exposed to scour risk piles, as well as identifying areas for improvement thanks to comparison with international best-practice.
Maria Pina LIMONGELLI
Pier Francesco GIORDANO
Silvia DI SANO