Earthquake projects try to preserve history
The Ottoman mansion of Hassan Bey in the seismically active medieval centre of Rhodes, Greece, does not worry civil engineers – even though the building is faulty because its floor isn’t very well connected to the wall.
That is because scientists have already tested how it would behave in an earthquake, by using advanced computer simulations that take into account the design and composition of the building, its foundations, and the type of soil it rests on.
The tests were part of an EU-funded project, PERPETUATE, which used computer simulations to assess the risk to historical buildings from earthquakes.
Such work is important because historical buildings and archaeological sites are especially sensitive to damage from earthquakes, and risk being lost forever without special measures being taken to strengthen their structures.
Normally, the floor of the Ottoman mansion on Rhodes would have been replaced with reinforced concrete to protect it in case of an earthquake. But the PERPETUATE study showed that all that was required was to reinforce the connections between the wooden planks and the beams around the floor to add stiffness.
‘The idea is to use more traditional interventions and by considering a solution compatible with the original behaviour of the building,’ said Serena Cattari, an engineer from the Department of Civil, Environmental and Architectural Engineering at the University of Genoa, Italy, who participated in the project.
The PERPETUATE project, led by the University of Genoa, included partners from France, Greece, Slovenia, the UK and Algeria.
‘The idea is to use more traditional intervention and by considering a solution compatible with the original behaviour of the building.’
On Rhodes, the computer modelling covered not just an individual building but the entire historic district, so that scientists could get a broader understanding of how earthquakes can affect a wide area.
Researchers tested their assumptions by using so-called shaking table tests, where scale models of historic structures were placed on large moveable plates in a laboratory which were then shaken to replicate the effects of an earthquake.
Researchers at a separate project developed a device that can protect a building by helping to absorb the energy of an earthquake.
The dissipator, developed by the EU-funded NIKER project, is made of pieces of steel which can be embedded between the walls of buildings.
During an earthquake, the pieces of steel slide back and forth over one another, taking up some of the energy of the earthquake, and preventing the walls from collapsing.
A prototype version was inserted in the 17th century church of San Giuseppe dei Minimi in L’Aquila, the scene of a devastating earthquake in 2009 which killed more than 300 people.
While L’Aquila has not had any major earthquakes since 2009, the dissipator was sensitive enough to have responded to micro-tremors.
Santa Maria Paganica Church after the L'Aquila 2009 earthquake (Italy). © inabruzzo.itSanta Maria Paganica Church after the L'Aquila 2009 earthquake (Italy). © inabruzzo.it
‘They are good in strengthening connections and increasing ductility. We can obtain a greater level of energy dissipation at the device without causing cracking of the masonry,’ said Dr Dina D’Ayala, reader in the Department of Civil, Environmental and Geomatic Engineering at University College London, UK, who led the team designing the dissipator.
The NIKER consortium, coordinated by the University of Padua, Italy, is now in talks with a German company over the commercial development of one of the devices aimed at the European market, particularly Italy and Greece where seismic activity is highest.