The urgent need to take a significant step-change towards the development of a systematic and comprehensive National Plan for the Safety evaluation, Risk Reduction and Maintenance/Repairing of the Italian existing reinforced concrete buildings and bridges - designed and constructed in the 20th century often with a currently longer-than-originally-designed life span - has become particularly evident after the recent catastrophic earthquakes (L'Aquila 2009, Emilia 2012, Central Italy, 2016).
On one hand the level of performance expectations/requirements/objectives, implemented through structural detailing, design methodology, quality control and assurance, for new structures and infrastructures has been continuously improving in the past decades, making existing/older structures inherently obsolete and potentially less adequate in terms of safety and overall expected performance. On the other hand, the natural aging and possible deterioration of the mechanical characteristics of the material (mild steel, prestressed steel, concrete, adherence/bond between the two), including effects of concrete carbonatation, steel ossidation and corrosion, as well as fatigue issues, requires specific and special approaches to assess the condition of the structure as well as to plan medium-to-long term maintenance/repairing/retrofit interventions.
This project intends to build on the most recent international developments (e.g. New Zealand, US, Japan, Europe) in the area of vulnerability, safety and condition assessment of existing buildings and bridges to develop a first set of specific Guidelines in order to quantitatively assess - through a mechanical (analytical) and semi-probabilistic approach - the Residual Capacity and Safety of Damaged (by earthquake events) and/or Deteriorated Reinforced Concrete Buildings and Bridges.
The key innovative features of the research projects are:
1. Development of a practical analytical approach for the evaluation of the Residual Capacity and Safety of existing Damaged/Deteriorated buildings and Bridges.
The traditional theory adopted to design and analyse (section level and/or component and system level) the behaviour of reinforced concrete structures (under monotonic or cyclic, static or dynamic, loading) assumes fully bonded conditions between steel rebars and concrete and intact material in terms of stress-strain relationship.
This approach is adopted in any Engineering School at either Undergraduate and Graduate level and is the basis for any national and international codes
The challenge of this project is to develop a rational and simplified-enough approach, to be used on a daily basis by practicing engineers, to analyse and thus design the retrofit/repair intervention damaged/deteriorated structures.
2. Evaluation of the Safety Margin of an existing Structure within a semi-probabilistic approach
Two rather complex research questions which the project intends to tackle and answer are:
a) what is - and how can it be evaluated - the level of safety (under static or earthquake loading) of an existing structure (building and/or bridges) in its current conditions (e.g. aged/deteriorated or damaged by an earthquake) when compared to the original as-built design and to a new structure (new Building Standard or % NBS).
b) when considering the life-time of the structure, how is this safety margin and risk changing and what should be the remedial/repairing interventions to re-establish the safety/risk to a targeted objectives?
The two above-mentioned questions are becoming more and more critical, at both national and international level, prompting a comprehensive and collaborative approach to tackle the problem and provide easy-to-use tools and procedures for their implementation in Italian-European code-provisions (which are based on semi-probabilistic approach and material-based safety-reduction factor) as well as adaptation to other (US, Japan, NZ) approaches (which are typically based on global capacity reduction factor)
3. Non-conventional Dissemination of Knowledge to stakeholders/end-users
Given the complexity of the problem, this project aim at providing some technical and scientific evidence-based guidelines as a sound basis for a multi-criteria decision-making cost-performance approach for the selection of alternative retrofit/repair strategies of deteriorated/damaged buildings and bridges.
In order to reach the decision makers, a specific communication campaign needs to be implemented to go beyond the traditional academic venues and channels.
In addition to the typical academic channels for the dissemination of research results, i.e. conference papers/ presentations, international peer review journals, theses and research reports, focus will be given to the direct dissemination to the wider technical community of end-users, via seminars to practitioner engineers and architects, invited lectures to institutes or groups, paper into non-academic magazines of wider dissemination within the construction industry.
Informal discussion and thematic workshops will be also organized through the project to involve various local and central territorial authorities, fostering the dissemination of the research-output directly within the market/end-user environment ("Terza Missione") and promoting the enhancement of a synergy between academia/researchers, stakeholders/end-users and high-level decision makers.