After the February 6 earthquakes in Kahramanmaraş, the region is far away when it returns to normal. However, examining the collapsed buildings and revealing the causes can prevent future disasters.
Civil and civil engineers from the UK came to Turkey to investigate the damage caused by the severe earthquake that struck last month. In the study carried out by the Earthquake Engineering Field Investigation Team (EEFIT) of the UK Institute of Structural Engineers, detailed investigations are being made on why so many buildings collapsed.
Due to the 7.7 and 7.6 magnitude earthquakes that took place on February 6, more than 48 thousand people lost their lives in Turkey. Tens of thousands of buildings were destroyed and many more became unusable. EEFIT teams will examine the collapsed buildings together with their Turkish colleagues and will reveal the mistakes made in the construction of the buildings. As a result of the studies, a detailed report has not been published yet, but some findings have been shared.
Why So Many Buildings Destroyed?
Studies show that the growth of destruction is due to bad examples of construction, including large pebbles mixed into the concrete, weakening the strength of the concrete. However, experts underlined that the strength of the earthquake also caused some of the destruction, and that the magnitude of ground motion in some places went beyond the endurance limit for which the buildings were designed.
Professor Emily So, Director of the Risk Center in the Built Environment at the University of Cambridge, co-leader of the study, says: “It’s important to see the whole picture, rather than just a snapshot of a single asset or a single building,” adds: “The achievements of buildings that are still intact and performing excellently It is as important as the neighboring buildings that have been demolished.”
Concrete samples taken from a collapsed building in Adiyaman revealed that it contained stones 6 cm long. It has been determined that these stones came from a nearby river and were added to the concrete mortar. “This has some serious effects on the strength of concrete,” says Professor So.
It was also determined that the steel bars in the concrete, which should strengthen the concrete, were not protruding but flat. This means that the concrete cannot hold on to them and again weakens the structure. Although the findings show that the majority of the destroyed buildings are old, it is observed that the new buildings have also been demolished. Recalling the new building regulations introduced after the 1999 Gölcük earthquake, Professor So said, “I think it’s very important that we realize these and really test to find out why these new buildings, built in accordance with the rules, are failing in this way.”
The Nature of the Earthquake Is Also Analyzed
Co-leader of the expedition from UCL in London, Dr. Yasemin Didem Aktas said the earthquake was extremely strong and said, “Even aftershocks were as big as a reasonable-sized earthquake.” Drawing attention to the large ground shifts in earthquakes that occurred, Aktas said, “The ground shakes horizontally and vertically in an earthquake. Generally, the vertical component is much lower and negligible compared to the horizontal movement. However, very high vertical accelerations were also recorded in this event.”
In addition, it is stated that buildings were built and in some places a process called liquefaction took place. This process turns solid ground into very wet sand, resulting in buildings that rake or sink. However, buildings can be designed to be earthquake resistant.
Buildings Can Be Made To Be Earthquake Resistant
Ziggy Lubkowski, who leads the seismic team of design and engineering company Arup, which sent engineers to Turkey for research, said: “What we try to do when designing buildings is to prevent loss of life. The basic design principle is to allow some type of damage inside the building. This damage absorbs the energy of the earthquake and It allows the building to still stand upright but not collapse.”
Lubkowski says seismic isolators or energy-absorbing rubber structures can be used, which act as shock absorbers as the building sways back and forth. All these additions result in an additional 10 percent to 15 percent additional cost, depending on the nature of the building.
However, at the end of the day, the additional structural costs are not so much when compared to the hardware costs of the building. The United Nations estimates that the cost of cleanup and rebuilding from the earthquake in Turkey could exceed $100 billion. The EEFIT team will publish its detailed report in the coming weeks.