Abstract
The project aims to develop a methodology for predicting the effects of the evolution of different forms of degradation in existing ordinary and prestressed reinforced concrete elements. The topic has strong relevance at the National and International level, from both social and economical points of view, because it has significant implications in terms of structural safety. Furthermore, the project is of high scientific relevance both in terms of topics and of the adopted methodological approach. One of the original aspects of the proposed methodology is due to the integration of experimental tests and numerical modelling at different levels, performed adopting numerical identification techniques based on inverse analysis and genetic algorithms for the calibration of the main parameters of the mechanical models. The proposed models are based on the results of the experimental tests and numerical simulations carried out within the framework of the project, through the definition and calibration of physical-mechanical relationships. Due to the adopted approach, these models could also be updated in the future, based on the results of others experimental tests. Finally, the models could be generalized including other forms of degradation apart from those studied during the project by means of additional calibration phases, as new data will become available. In detail, the project will tackle three forms of degradation, particularly relevant for existing reinforced concrete elements, for which reliable predictive models, in terms of time evolution and effects on the structural response, are not available in the literature: 1. Corrosions of post-tensioning strands; 2. Degradation of concrete with particular reference to alkali-silica reaction; 3. Degradation of strengthening systems applied to deteriorated elements. These phenomena are relevant for a large percentage of existing structures and infrastructures, because they were not well known at the time of their construction. These three types of degradation, which are associated to the three main research lines of the project, will be studied with a unified approach, defining for each of them different degrees of investigation and different scales for experimental testing and numerical modelling. In the first stage of the project, relevant environmental and degradation scenarios for reinforced concrete and prestressed reinforced concrete structural elements will be defined, allowing to define the conditions to reproduce during the experimental tests, considering the relationship between laboratory and field conditions. Subsequently, all the investigations will be first focused on the material level and then performed at the structural level considering single elements, also taking into account the interaction between different types of degradations.
Results achieved
The activities carried out within the project, with the aim of predicting the degradation of strengthening systems applied to reinforced concrete elements, enabled a targeted analysis at both the material and structural levels. At the material level, tests were performed on small-scale specimens, while at the structural level, strengthened beam elements were examined and subsequently subjected to accelerated artificial ageing. The results obtained from the analysis of different types of concrete, including already deteriorated concrete recovered from the demolition of an existing bridge, showed an overall limited degradation of the strengthening systems when exposed to aggressive environments, such as freeze–thaw cycles or saline conditions. Flexural tests performed on beam elements confirmed the predictions obtained from the material-level tests, extending them to the structural scale and allowing a realistic assessment of the evolution of degradation when strengthening systems are applied to existing bridges and infrastructure.Project details
Unibo Team Leader: Marco Savoia
Unibo involved Department/s:
Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali
Coordinator:
Università Iuav di Venezia(Italy)
Total Unibo Contribution: Euro (EUR) 38.078,00
Project Duration in months: 24
Start Date:
28/09/2023
End Date:
28/02/2026
