Earthquakes: Walls twice as resistant with innovative Italian-made seismic reinforcements

A typical hystorical building of the Italian Apennine zones, reinforced with innovative, easily applied, low-cost Italian-made solutions, resisted earthquake accelerations twice as strong as those of the most violent earthquakes that hit central Italy in 2016. This is what emerges from the results of the shaking tables tests conducted at the ENEA Casaccia Research Center on a U-shaped tuff masonry structure provided with asymmetric openings and sustaining a timber roof, with the purpose of identifying the best and least invasive tecniques for strenghtening the buildings without having to vacate them.

The tests, conducted by the Roma Tre University and ENEA, with the support of the company Fibre Net  as part of the project COBRA, funded by the Regione Lazio, were carried out on the three walls, one central and two lateral, which had previously been damaged last November during a series of tests simulating the increasing intensity of the earthquakes occurred in Nocera Umbra (1997), L’Aquila (2009), Emilia (2012) e Norcia (2016).

Figure 1 I Stone and tuff walls strenghtened with Kerakoll technology and positioned on the shaking table during the 2016 tests. The bright spots are reflecting markers of the motion Capture 3DVision System

In order to assess the increased seismic capacity, two out of three walls were fixed and strenghtened with reinforced mortar comprising glass fiber meshes, a minimally invasive, low cost, structural strenghtening system applicabile without having to vacate the buildings.

“The walls strenghtened with fiber glass meshes withstood earthquakes amplifying the level of intensity of ground motions up to 220%, double the most violent  earthhquakes of 2016, while the unreinforced wall was badly damaged already at a 120% intensity level, that of the ground motions of the earthquake occurred two years ago”, Gerardo De Canio, Head of the ENEA Laboratory of Technologies for a Sustainable Innovation, pointed out. “In order to counteract overturning- De Canio went on- a steel bar was applied to this last wall, the so called “chain” so as to allow the structure to reach the” ultimate limit state”, associated with collapse, to demonstrate the efficacy of the intervention”.

Figure 2 3DVision System of data acquisition and remote sharing of experimental tests

“The innovation, entirely developed in Italy, consists in a composite material applicable,  together with the traditional refurbishment of buildings,  on the external walls ”, Gianmarco De Felice, of the Rome University Roma Tre, coordinator of the project, said. “Composite materials -De Felice went on- are already in use in the aviation and automobile sectors but not in the building sector. That’s why we hope that the outcomes will pioneer innovation also in this important field”.

“Our shake tables-De Canio concluded- can move in all six degrees of freedom (three translations and three rotations) and represent a unique infrastructure in Italy for testing mature technologies, ranging from construction to Cultural Heritage applications with innovative diagnostic, data acquisition and repository techniques.

Group 2: Sequence of the reinforcement intervention ON/OG the U-shaped masonry structure using Fibrenet technology . Note the green

The entire sequence of experimental tests, which had been conducted last year using a Kerakoll technology, is part of the institutional activities ENEA conducts in support to SMEs, organizations,professional associations and universities for experimental tests and verification of the intervention techniques, aimed at the seismic improvement  and the structural strenghtening of the building stock as well as the conservation of Cultural Heritage, as part of the challenge of disseminating a seismic safety culture, innovation and a sustainable development.

Data obtained during the tests were “captured” through a 3D motion capture and shared thanks to the virtual platform DySCo, designed and implemented by ENEA; in this way, in addition to the partners of the project, experts, operators in the sector and representatives of the most prestigious italian and international research organizations,  including the Universities of Taipei, Miami, Sheffield, Pavia e Perugia, the  MIT - Massachusetts Institute of Technology in Boston, the Smithsonian Institute, the  National Gallery of Art in Washington, the LCNEC in Lisbon and the Order of Engineers, were able to virtually attend and actively participate via live streaming.

 

Figura 3: The U-shaped masonry structure during verification of the reinforcementThe bright spots are reflecting markers of the 3DVision motion capture system.	Figura 4 The U-shaped masonry structure shows a crack on the upper left side where the containement mesh can be seen; on the right a chain, indicated by an arrow	Figura 5 3DVision System of displacement data acquisition and remote sharing of experimental tests

For more information please contact:

Gerardo De Canio, ENEA – Laboratory of Technologies for a Sustainable  Innovation,  gerardo.decanio@enea.it

 

Link to the video, free for reproduction:

• Seismic tests on a shake table on a masonry model strenghtened with reinforced mortar comprising glass fiber meshes https://www.youtube.com/watch?v=wHW8_klk-q8

 

• It measures real time openings of cracks  via Motion Capture 3D system during seismic tests on the shake table https://www.youtube.com/watch?v=WJCkeQ96F_Q

 

Additional videos are available on demand