In recent years, innovative Non-Destructive Testing (NDT) techniques, applicable for the assessment of existing civil structures, have become available for in situ analysis on Reinforced Concrete (RC) and masonry structures, but they are still not established for regular inspections, especially after seismic events. The damage assessment of RC buildings after seismic events is a very relevant issue in Italy, where most of the structures built in the last 50 years are RC structures. Furthermore, there is also a growing interest in being able to monitor structural health aspects by storing them on the building’s digital twin. For these reasons, it is necessary to develop an affordable and ready-to-use NDT procedure that provides more accurate indications on the real state of damage of reinforced concrete buildings after seismic events and to integrate these data into an interoperable digital twin for automated, optimized building performance monitoring, management, and preventive maintenance. To this end, a case study was conducted on a building in the Marche region in Italy, damaged by the 2016 earthquake. Non-destructive tests were performed and inserted into the LIS platform for the creation of a digital twin of the building. This platform seamlessly manages, visualizes, and analyzes the collected data and integrates various sensor nodes deployed throughout the building. The paper also presents a methodology to simplify the work of the test operator and make the entire process of knowledge of the building faster and more sustainable through a QR-code interface.

Assessing the condition of concrete in place is an important part of building safety verification programmes. For the study of existing concrete structures, it is important to know the strength of different elements. The assessment of the compressive strength of structures can be carried out by destructive coring tests in varying quantities and calibrated indirect methods, combining destructive coring with non- or semi-destructive techniques. When planning ultrasonic indirect measurements, it must be taken into account that in inhabited houses the columns are covered with plaster that often cannot be easily removed and restored (even more so if, in addition to being a protective covering, it also has a decorative function): indirect measurements can be performed, but it is necessary to evaluate the impact of the presence of plaster. An analytical model has been developed to predict the surface wave propagation velocities in concrete columns, both with and without a plaster covering. The aim is to support the interpretation of time-of-flight measurements in indirect ultrasonic testing.

Structural diagnostics of buildings require optimization of investigation methods to minimize invasiveness, save time, and reduce costs. In this view, non-destructive tests, such as ultrasonic and sonic tests, are essential tools. However, it is crucial to reduce and properly locate the more laborious and/or destructive tests, to enhance the diagnostic campaign efficiency, particularly if buildings are in use, to ensure the occupants' well-being. While direct ultrasonic measurements provide precise data, they often require more invasive procedures and provide punctual information. In contrast, sonic tests, which can be performed using reflection techniques, require only surface access and are less invasive, providing valuable information when compared with direct ultrasonic data. In the framework of the MULTICLIMACT project, sonic and ultrasonic tests were conducted on some columns: the results were compared with each other, to validate the proposed methodology.