Assessing seismic risk of structures in only 2 hours
01.02.2012TÜV Rheinland Hellas
Blocks of flats in Turkey: they were all constructed by the same company, based on the same study, but only one of the 5 collapsed. Resonance occurred when the natural frequencies of the structure and the soil coincided due to a relatively weak earthquake…
A high-tech method of assessing seismic risk of structures in very little time (no more than 2 hours) and at a low cost (2-3 euro/m2) is now available in Greece, protecting the security of our lives and investments in our homes.
Living in an earthquake-prone country like Greece, how safe do we really feel in our homes, in public buildings, in our workplace? How much do we worry about the possibility of an earthquake? How safe are the buildings in which we spend most of our day?
Each structure has an “identity” which is determined by a number of elements, such as: the quality of its construction materials, its mechanical properties, possible damage caused by previous earthquakes or natural causes. The soil where the structure stands also has an “identity”, determined by its properties, its structure, its texture etc. Mechanical resonance can cause damage or even the complete destruction of a building.
Using an innovative method, EQ-Fast “reads” these two “identities” (the natural frequencies of the structure and soil), and with the help of a special software tool, which takes into account data from each geographic region, it compares and analyzes all relevant information, assesses the possibility of mechanical resonance in case of an earthquake and even estimates the possible damage as related to the total value of the property.
The implementation of this method is a quite simple procedure, since it only involves a portable computer and a special device for measuring natural frequencies. The device is placed preferably on the floor of the last story of the building. It is non-destructive and it is used to measure the building’s natural frequency. Then, it is placed on the soil where the building stands or within a certain radius around it (in case the actual soil underneath the building cannot be accessed) in order to measure the soil’s natural frequency.
An experienced civil engineer makes all necessary measurements in the building and detects all visible damages. EQ-Fast processes this information, along with the rest of the data, and analyzes it based on the strictest criteria established by Eurocode 8 in order to make a detailed report which serves as a certificate.
Based on this certificate, buildings are classified in classes A, B, C or D, depending on how well they are expected perform in case of seismic activity with a certain intensity. The actual rates which determine the structural integrity of a building are: the damage ratio (DR), the mean damage ratio (MDR), an index representing a 90% chance of damage, the structure’s reliability index etc.
The time required for assessing the seismic risk of a structure is 2 hours and the report can be delivered as quickly as in one working day.
This innovative idea is supported by TUV Rheinland which, once again, breaks new ground by proposing EQ-Fast.
TUV Rheinland is the largest provider of product certification services in the world. Its workforce includes 18.000 scientists and it has over 300 locations in 70 countries.