WORLD NEWS | Buildings in Turkey provide design guidance for future earthquake-resistant buildings

Virginia, April 5 (Dialogue) On February 6, 2023, earthquakes in Turkey and Syria damaged more than 100,000 structures, collapsed more than 10,000, and killed more than 50,000 people. These earthquakes also tested advanced construction techniques that minimize damage and maintain building functionality after earthquakes.

According to local news reports, several hospitals built with such technology, known as a seismic isolation system, suffered little damage from the quake, even as surrounding buildings suffered significant damage.

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Adana City Hospital was built to record ground shaking and building responses. According to the company that designed the isolation system, vibrations in the building have been reduced by 75% compared to neighboring buildings due to the isolation system. The system keeps buildings running after earthquakes.

Engineers aren’t surprised that hospitals equipped with seismic isolation systems survived with minimal damage, but through my work as a civil engineer I keep hearing people in Turkey and abroad ask why more buildings don’t use these more Smart engineering.

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A year after the 1999 Izmit, Turkey, earthquake that killed more than 17,000 people, I moved to Istanbul to pursue a bachelor’s degree in civil engineering. I immigrated to the US in 2005 for postgraduate study, and since then I have been working on advanced technologies and materials to ensure buildings can be quickly restored and rebuilt after strong earthquakes.

Although we’ve seen the effectiveness of seismic protection technologies during past major earthquakes, these technologies have only been installed in a fraction of the places where they could be useful.

Earthquake Resistant Building Technology

Engineers can control a structure’s response to earthquakes in a number of ways.

Traditional methods rely on having certain components of a building, such as columns or beams, absorb seismic energy. However, this approach can lead to the accumulation of damage to these structural features, rendering the building uninhabitable.

Seismic systems, such as seismic isolators and seismic dampers, minimize the seismic energy entering these columns or beams by absorbing or diverting it. As a result, buildings experience less movement and damage, and are more likely to remain functional after an earthquake.

Seismic isolation systems begin by preventing seismic energy from entering buildings by using devices made of rubber or steel plates coated with friction-generating materials that slide against each other to minimize the effects of earthquakes. These isolators are installed between the building’s foundation and the building itself. Alternatively, earthquake dampers installed on each floor of a building could absorb seismic energy, much like the way shock absorbers work in a car, and convert it into heat to minimize damage.

Both seismic isolation systems and seismic dampers can help buildings achieve “functional restoration”—a performance goal in which buildings are constructed to prevent damage and reuse. Designing such structures not only saves people and buildings, but also prevents earthquakes from causing community and economic collapse.

While functional restoration is an emerging idea for building earthquake-resistant structures, modern building codes around the world state that, at a minimum, structures must take steps to prevent the building from collapsing—known as life safety objectives. Buildings following life safety objectives are designed to withstand damage in a controlled manner to keep the building standing and protect those inside.

While these buildings may not collapse, it may not be safe to use them after an earthquake. While this is not the same as functional restoration, thousands of lives could be saved if more buildings were built in Turkey and Syria to meet life safety thresholds.

The situation in Türkiye

Most of the damage in Turkey occurred in non-ductile concrete buildings constructed according to the pre-1998 Turkish building codes. The ductile concrete building elements required by new building codes are more flexible, thanks to steel reinforcement in key locations. They can accommodate building movements caused by earthquakes. Older non-ductile buildings often have poorly placed reinforcement and are susceptible to sudden collapse of building columns.

Likewise, many so-called soft-story buildings were damaged in these earthquakes. A soft story is a story that is more susceptible to lateral seismic forces than other stories in a multi-story building. The first floors of these buildings—often used for commercial purposes such as retail, garage or office space—tend to have more open areas and fewer structural components, such as beams and columns, making them prone to collapse.

These types of structures can be found all over the world, including in densely populated, earthquake-prone areas such as Istanbul, San Francisco, Los Angeles and Vancouver—all of which lie near active fault lines.

Buildings designed to older codes can be reinforced to meet life safety performance thresholds. However, these upgrades can cost a lot of money, and enforcing them, especially for private buildings, requires carefully planned policies.

learn a lesson

While buildings designed for life safety goals can protect thousands of lives, the February 2011 earthquake in Christchurch, New Zealand, revealed the limitations of modern seismic codes centered on this design goal alone. Buildings designed for life safety suffered so much damage that thousands of buildings had to be demolished after the earthquake.

It was also the earthquake that led engineers to focus on “functional restoration” and the wider implementation of anti-seismic technologies. The additional cost of this earthquake protection technology is usually less than 5% of the initial construction cost, which is insignificant compared with the cost of the social and economic damage caused by a large earthquake. Also, getting lower insurance premiums may recoup most of the initial cost.

Total economic damage after the Christchurch earthquake was estimated at $32 billion, not accounting for inflation, of which $24 billion was construction costs. The most recent earthquake in Turkey is estimated to have caused damages of more than $84 billion and counting.

The earthquake in Turkey showed that earthquake protection technology works. To avoid severe economic and social consequences, local authorities can update regulations and codes for designing new buildings to allow post-earthquake reoccupancy and functional restoration. In addition, policies, fiscal incentives, and tax breaks that promote enhanced building design can improve seismic safety more broadly. (dialogue)

(This is an unedited and auto-generated story from a Syndicated News feed, the content body may not have been modified or edited by LatestLY staff)