(Finance) – Strengthening historic buildings with innovative anti-seismic technologies and advanced sensor solutions with minimal visual impact. This is what has been achieved within the framework of the REPAIR projectwhich was attended by AENEAS, the company EdilCAM Systems and the University of Cassino and Southern Lazio, Sapienza and Roma Tre (the latter in the role of coordinator), thanks to the funding of the Lazio Region within the Cultural Heritage Technology District (DTC). The new technologies – validated on the ENEA shaking tables – will make the buildings suitable to resist more than twice the accelerations of the 2016 earthquake.
In the first phase of the project – explains ENEA in a note – the researchers used stone elements taken from the rubble of buildings that collapsed following the 2016 earthquake to replicate typical walls of historic buildings in the villages of central Italy, both in terms of the wall texture and the characteristics of the mortar. The prototype wall, without reinforcements, was then tested on the vibrating tables of the ENEA Casaccia Research Center where the same shocks as the 2016 and 2017 Central Italy earthquakes were reproduced.
The walls were later repaired and reinforced with two innovative solutions developed within the project: the first involved small keyholes integrated into the exposed brickwork to ensure the correct “pull” and retention of the walls; the second solution instead involved the application of metal strips between the mortar and the stones, totally invisible from the outside. Both solutions were integrated with the insertion of an innovative monitoring system based on fiber optic sensors, created and installed by ENEA and the University of Roma Tre, to monitor the steel strips – and therefore the structural ‘health’ of the building – and minimize the visual impact, while ensuring reliability and durability.
The integrated system installed on the walls it was subjected to the same violent accelerations of the earthquakes that hit our country about 8 years ago: while the wall without reinforcements reached a level of damage similar to the Collapse Limit State (CSL) for a peak acceleration value at the base equal to 0.5 g, or half the gravitational acceleration, the reinforced one demonstrated a resistance capacity twice that of the unreinforced condition.
The analysis of the results obtained from the two configurations has highlighted the‘effectiveness of the new anti-seismic solution, confirming that this can be the path to take to strengthen the historic stone buildings of central Italy, combining the safety and conservation of ancient stone houses.
The vibrating tables located at the ENEA Casaccia Research Center – we read in the note – are among the largest in Europe and at the forefront in the instrumentation and analysis of vibration data acquired in seismic tests. Able to move in six spatial dimensions (three directions of movement and three rotations), they represent a unique infrastructure available to the Country System for the experimentation of the most mature technologies for applications in civil and industrial engineering, construction and cultural heritage. In 2007 the Analysis and Modeling Laboratory for Critical Infrastructures and Essential Services, where the shaking tables are located, was the first seismic engineering laboratory in the world to equip itself with a 3D motion capture system, still the most advanced of its kind in Italy, capable of measuring the displacement in 3D space of hundreds of points of the object subjected to seismic tests, with an accuracy of less than a tenth of a mm and with a sampling frequency of up to 2000 Hz. Since 2017, the laboratory has been further strengthened thanks to the implementation of a new advanced processing technique derived from the magnified motion method, which amplifies, making them visible to the naked eye, even the smallest movements of objects, allowing the most vulnerable parts, at risk of breakage or collapse, to be identified.