The seismic retrofit of the existing building heritage represents an urgent issue to be faced and innovative solutions which allow to overcome renovation barriers are needed. In this scenario, pin-supported (PS) walls represent an eligible solution, enabling linearization of the deformation of the frame along its height and inhibiting soft storey collapse mechanisms. The PS wall can be connected to the existing building from outside, thereby avoiding disruption to occupants or their relocation, which are acknowledged as the main barriers to the renovation nowadays. Suitability of PS wall solutions in the seismic retrofit of the existing building stock has been investigated herein, particularly in the case of existing reinforced concrete (RC) buildings, preliminarily focusing on 2D RC frames. The paper shows the weaknesses and strengths of the PS wall solution in relation to the specific features of the considered buildings. An analytical closed-form formulation is proposed and applied as a preliminary tool to evaluate the load distribution in the existing frame and in the PS wall after the retrofit considering the first mode of vibration of the retrofitted system. The results show that, in some conditions, the application of PS walls may be detrimental to the structural response. Along with the evaluation of the effectiveness of the retrofit solution, the proposed formulation allows a preliminary design of the retrofit system. Finally, a series of finite element model analyses have been carried out for validation purposes showing a good agreement between the proposed analytical formulation and the numerical results.

The effects of deterioration strongly impact the expected future service life and the structural performances of existing reinforced concrete structures. Currently, straightforward methodologies are required to include such effects in the assessment and renovation of the RC buildings’ heritage. A simplified protocol enabling the detection, evaluation, and modelling of corrosion effects is presented in this paper. The protocol provides the guidance for the design and management of the on-site diagnostic campaign, aimed at identifying a possible corrosion risk scenario. Then, equivalent damage parameters describing corrosion effects in the structural models can be calibrated. Structural performances over time can be assessed to predict the structural residual life, maintenance management criteria and timing, and major indications on the feasibility of the retrofit intervention, or the unavoidable need of demolition. The application of the proposed protocol to some case studies emphasises the effectiveness of the procedure for detecting possible activated corrosion processes and for supporting engineers in their decision-making process and choice of renovation strategy.

In recent years hinged walls have been implemented as a retrofit technique for existing RC buildings. To investigate the effectiveness of the proposed solution on different frame typologies, non-linear 2D pushover analyses have been carried out. Two main configurations were adopted, representing an inner frame with weak beams and strong columns and a side frame with strong beams and weak columns, respectively. The study shows that some computational aspects are of fundamental importance in providing reliable results, namely: the dead load distribution on the beams and the moment-axial force interaction in the columns. The hinged wall technique proves to be an effective retrofit solution only if conceived properly for each structural typology; whilst in some cases it may be detrimental when applied in the traditional way. Some new configurations are herein proposed based on new connection layouts in order to be suitable for the different typologies of existing RC frames.

When is demolition mandatory? To date there is a lack of specific tools and protocols enabling a rigorous scientific assessment of the deterioration level of existing structures, guiding the choice between the real possibility of renovation or the unavoidable need of demolition. In the present paper, an attempt is made to develop a protocol suitable to assess the actual capacity of existing structures and predict their future behaviour based on inspection and diagnosis of the building. The potential benefit of such a tool is to help detecting the best intervention strategy making the renovation process more sustainable and efficient. Toward this perspective, a critical analysis and comparison of literature models on the residual capacity of structural elements has already been carried out by the authors. The assessment of the preservation state is herein further extended to the overall structural level, by proposing a new approach relating the performance of deteriorated elements over time to the behaviour of the whole structural system.