Codes and costs may trump engineering in building construction.
The recent earthquake near the Turkish-Syrian border has killed, at the time of writing, over 41,000 individuals and has collapsed over 6,000 buildings in Turkey alone. Turkey is a known region for serious seismic events and has endured significant earthquakes.
Turkish building codes from 2007, heavily revised in 2018, specify earthquake-resistant construction, and the city of Istanbul completed a $500 million project in 2015 to prepare that large city for a seismic event. While multiple and unconfirmed reports show that lax construction techniques and corruption resulted in many substandard buildings, the region contains many old, before-code structures.
The Turkish civil engineering sector is highly advanced and capable, so it seems unlikely that fault for this disaster will be found in the design process. Tighter enforcement of building codes plus enhanced disaster preparedness systems, as have been implemented in Istanbul, are logical paths forward in the aftermath of this disaster.
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Episode Transcript:
We’ve all seen the images from the February 6th earthquake in Turkey and Syria. As of now, the death toll is estimated at over 41,000. The quake carried a moment magnitude of 7.8, although this figure has been commonly reported by the mass media as a Richter scale measurement.
In fact, two earthquakes occurred, nine hours apart and within 60 miles of each other in Kahramanmaraş Province near the Turkish-Syrian border. It’s the worst earthquake in Turkey since 1939, and the deadliest globally since the 2010 Haiti earthquake. Deaths caused by collapsed buildings were widespread, with as many as 6,000 residential and commercial buildings collapsed in Turkey alone.
While it’s too soon to conduct a full engineering analysis of the construction methods and modes of collapse in those buildings, as-yet-unconfirmed allegations of shoddy workmanship and lax oversight of deviations from standard design practice are widespread in global media.
But how does an architect or civil engineer design for earthquake preparations?
A conceptually simple but highly effective strategy is called base isolation. The concept is to design supports for the building structure that pass primary loads vertically to the foundation, but which tolerate shearing forces by displacing laterally under earthquake conditions. Rubber isolation blocks, springs, bearings and low-coefficient of friction pads can keep amplitudes in structures within design limits, to protect both the building and the people inside.
Fire is a major threat in the immediate aftermath of seismic events, and natural gas piping is commonly equipped with earthquake isolation valves in seismically active areas. Multiple technologies exist to prevent widespread collapse as seen in this recent disaster, and Turkey itself embarked on a 10-year project between 2004 and 2015 called the Istanbul Seismic Risk Mitigation Project.
This $550 million project improved that large city’s capacity for disaster emergency management, and improved measures for enforcing building codes and land-use regulations within the metropolitan area. National building codes in Turkey have been regularly updated to reflect seismic risk, with a major revision occurring in 2018, replacing the 2007 standards. The extensive revision added new standards for high-rise, seismically isolated, cold formed steel and wooden buildings.
With the success of the Istanbul project, combined with modern building codes, the root cause analysis of this disaster suggests two possibilities: old, pre-code buildings and/or lax regulatory enforcement.
Turkey has a large, state-of-the-art civil engineering industry, and has built modern, highly complex projects such as the recently completed Çanakkale bridge over the Dardanelles Straight, the longest suspension bridge in the world. Forensic investigation of the collapse of major buildings during the earthquake will determine where fault lies, and the civil engineering community worldwide will be watching to see if standards, enforcement or both are tightened during the lengthy rebuilding process.