The International Information Center for Structural Engineers

Wednesday, 20 February 2019 01:00cat

New method to evaluate building safety after seismic events

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New method to determine how safe buildings are after an earthquake-Source:EPFL New method to determine how safe buildings are after an earthquake-Source:EPFL

Researchers from EPFL (École Polytechnique Fédérale de Lausanne) in Switzerland have found a bran-new method to determine whether a building is safe after an earthquake.

Structures that have withstood a severe seismic shock may have developed internal flaws that are not readily detectable. These structural defects could result in a building's inadequacy to sustain another significant temblor. Fortunately, the scientists from Applied Computing and Mechanics Laboratory (IMAC) of EPFL have developed a system to address this issue.

Their method is based on measuring vibrations in buildings that can be utilized to facilitate current approaches capable of determining which structures are vulnerable. 

Until now, engineers are using a visual method to diagnose a building's condition developed by Italian researchers. This method has proven effective in 2 major seismic incidents in Italy occurred on 2009 and 2016, respectively. However, it requires a large amount of time (about 3 hours per building) and it cannot determine the vulnerability of buildings in a following severe earthquake.

The new approach suggests that the building should be monitored via a portable seismograph that can detect vibrations. In order to function, 3-4 sensors must be placed in different points of a structure. The method does not require data about the building's pre-earthquake condition. "Our article shows that we can leverage existing technology in new ways. We took systems that are already used to measure the condition of bridges, and applied them to the assessment of buildings damaged by an earthquake. The other novel aspect of our method is that we don't need to know the baseline – that is, pre-earthquake – condition of a building to perform the assessment." Lestuzzi, a senior research at IMAC, stated.

The data obtained are inserted in a computer model and the vulnerability of a construction is determined. Researchers stated that their results are 50-100% accurate. Off course, the results can be combined with visual assessment. Despite being in a preliminary examination, Lestuzzi suggests that the developed method should already be applied in the boundaries of earthquake-affected areas so that people can return to their residences as soon as possible.



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