Engineer Designs Material That Will Bend, Not Break, During Quakes

June 2, 2020 By Christopher Tyree, Christopher Tyree,

It was nearing 9 p.m. on Jan. 24, and Ahmet Ozbulut was steeping a cup of black tea, part of his nightly routine.

He’d spent the day, like most since his retirement, puttering around his yard and visiting friends around Elazığ, a city of about 350,000 people in the Upper Euphrates River Valley in Eastern Turkey. The area is known for lush vineyards and an endemic grape varietal called öküzgözü, which translates to “bull’s eye.” 

Ozbulut had switched on the TV and just settled into his couch to watch the nightly news when he first noticed ripples in his tea, then heard items falling in the kitchen and bathroom. He looked up and saw the chandelier swinging like a clock pendulum.

Seven miles under his feet, a tectonic collision had occurred, sending energy racing upward through the Earth, a result of the ongoing movement between the Eurasian, African, Arabian and Anatolian plates.

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Collapsed Residential building in Turkey being destroyed by equipment and construction workers
A collapsed residential building following the earthquake in the Turkish town of Elazığ in January.

The bull’s eye was now on his hometown.

He tried to stand but the undulating floor quickly sent him back to the couch. For the next 40 terrifying seconds, Ozbulut could only hope that the tons of reinforced concrete from the second story of his home would not come crashing down.

Meanwhile, in Charlottesville

Approximately 5,800 miles and eight time zones away, Osman Ozbulut had just returned to his office with a cup of steaming coffee, which tasted good despite it being an abnormally warm January day in Charlottesville, Virginia.

The associate professor in the University of Virginia’s Department of Engineering Systems and Environment was in the middle of revisions on a scientific article for the journal Engineering Structures. The article was about steel building frames braced with shape memory alloys, which are types of smart metals that can stretch and bend but then return to their original shapes once the stress on them is gone, following a shock or aftershock from an earthquake. The midday caffeine was welcome.

Since 2012, Osman Ozbulut has been dedicated to developing innovative materials and sensing technologies at UVA Engineering, with a goal of building resilient and sustainable civil infrastructure systems. Toward achieving his goal, he has secured or been part of teams that have earned more than $2.8 million in external funding from agencies such as the National Science Foundation, the U.S. Department of Transportation and the Virginia Department of Transportation, backing 18 research projects. He was also awarded the International Young Scientist Fellowship by the National Natural Science Foundation of China.

His interest in earthquakes started at an early age. “I remember when I was in middle school, an earthquake hit my hometown, Elazığ. It wasn’t a major one, but I know what it feels like to be in an earthquake,” he said. “In 1999, one year before I entered college at Istanbul Technical University, there was a major earthquake in the western part of the country. More than 17,000 people were killed.”

Ozbulut comes from a family of engineers and thought he’d head back to Turkey after getting his master’s degree at Texas A&M University.

That mindset changed, however, after he began researching shape memory alloys. He was the first student in Texas A&M’s civil engineering department to deeply research these smart metals, and he had so much initial success that he was encouraged by his adviser to stay on for his Ph.D. He did his post-doctoral research work at Texas A&M Transportation Institute before coming in 2012 to UVA, where he set up the Resilient and Advanced Infrastructure Laboratory.

A short drive away from Ozbulut’s office, on that warm day this January, his Ph.D. candidate, Amedebrahan Asfaw, had sent Ozbulut a text message asking about the test setup of a new device they’d constructed that they hoped would dissipate seismic energy and dampen vibrations of buildings during an earthquake.

Ozbulut, left, works with Amedebrahan Asfaw, right, to prepare an earthquake damping machine
Ozbulut, left, works with Ph.D. candidate Amedebrahan Asfaw on the development of an earthquake damping device made with smart metal technology.

They had attached cables made with shape memory alloys, in this case twisted strands of nickel and titanium, to specially designed steel plates. Their theory was that the overall design, called a “damping device,” would prove to be a cost-effective approach for resilient buildings; the device could be attached to the support structures of a building and absorb the destructive energy of earthquakes, then return to its original shape and hold the building in its normal position instead of being heavily damaged.

Asfaw was preparing for the first big test of this novel device.

Shortly after the text from Asfaw, and about 35 minutes after the quake struck his hometown, Ozbulut received a call from a friend asking how his parents were doing. Ozbulut hadn’t been paying attention to the news, so he initially thought the question was odd. Then his friend said the city Ozbulut’s parents lived in had experienced a significant earthquake with a magnitude of 6.8 on the Richter Scale.

Ozbulut hung up and immediately began trying to call his father.

An Experiment – and a Pipe

If shape memory alloys sound like something dreamed up in a lab in a Marvel Comic book, that’s because they kind of were. In 1958, metallurgist William Buehler was working at the Naval Ordnance Laboratory in Maryland to build a better nose cone for the U.S. Navy’s Polaris ballistic missile that could stand up to the extremes of reentry into Earth’s atmosphere. He tried more than 60 new alloys, but eventually found a nickel-titanium version that showed promising results under impact and heat. He called the combination NITINOL (Nickel Titanium Naval Ordnance Laboratory).

He later realized the alloy’s unique damping effect when one afternoon he accidently dropped a piece of the cold metal on the floor, where it made an unexpected thud. He then purposely dropped the other, hotter, pieces of the metal alloy on the floor, where they produced a higher-pitched ringing tone. He knew something was up with how the molecules that make up the alloy responded to temperature.

Asfaw tightens the smart metal alloy strands in an earthquake damping device
Asfaw tightens the smart metal alloy strands in his earthquake damping device prior to testing.

Buehler continued his research through the early 1960s, and eventually fabricated a piece of the alloy that he’d stretched and bent into a type of metallic accordion that could fold and unfold at room temperature without breaking. In 1961, he sent his lab assistant to a divisional meeting with the piece of flexible metal as part of a show-and-tell.

During the meeting, the novel material was passed around the conference room, where it ended up in Dr. David Muzzey’s hands. Muzzey, the Naval Ordnance Laboratory’s associate technical director, was a pipe smoker. What happened next is still considered by some to be one of the coolest accidental scientific discoveries of modern times. Muzzey fired up his pipe lighter and applied heat to the metal alloy. To the amazement of everyone in the room, the accordion-twisted metal immediately snapped back to its original, rigid, flat form.

Since that discovery, NITINOL’s unusual properties have been further studied; starting in the 1980s, the alloy has been used to build everything from underwire bras to flexible spectacles, heart stents and even parts of the Mars Rover. Ozbulut’s and Asfaw’s damper system is the first shape memory alloy-based device that has the potential to be easily and cheaply fabricated to protect buildings from earthquakes in the future.

A Deadly Toll

Sounds of panicked people reverberated through the cold, night air as Ahmet Ozbulut emerged from his home in Turkey. Dust from collapsed buildings wafted through the darkened streets. With a sense of relief, he noticed most everything was still intact in his home, but many of his neighbors were not so lucky. At least five homes nearby were heavily damaged.

The earthquake that night killed 41 people, injured more than 1,600 and left more than 10,000 people homeless, just as the winter was bearing down on the region. Approximately 550 buildings in the city collapsed during the quake, and an additional 6,270 were severely damaged, many of those uninhabitable and needing to be demolished.

White tents set up in Elazığ for earthquake victims
More than 10,000 people in the city and area around Elazığ were permanently displaced by January’s earthquake.

Standing outside surveying the destruction around him, Ozbulut’s cell phone began to ring. It was his son, Osman Ozbulut, calling from Charlottesville.

“We spoke for only a couple of minutes, but I was relieved to hear that he and my other family members were safe,” Osman Ozbulut said. His mother had been visiting his sisters in Turkey’s capital, Ankara, far outside the destruction zone.

Ozbulut then texted Asfaw, who at this point was deeply engaged in testing the device. “I told him that he may not have heard, but there was an earthquake in my hometown. And I told him, ‘Let’s make a contribution to the engineering community with this test.’”

A short while later, Asfaw texted back the early results of the testing. The device was performing better than expected.

“To be honest, I was having mixed emotions in that moment,” Ozbulut said. “But it was nice to see that the test went very well and that this system, which isn’t very expensive to develop, could be incorporated into future buildings to make them more resilient.”

Preventing Damage Before It Happens

There is a lot of activity going on under our feet every day as the continents we live on drift over the Earth’s mantle. About every minute somewhere in the world, they stick, building up pressure until the rock cracks, causing an earthquake. On average, roughly 1,400 earthquakes happen every day, and about 275 of them are strong enough to be felt.

Sometimes they are so significant they cause widespread destruction. There is also no way to predict when they will come or how extreme they might be. A case in point: In 2010, earthquakes killed as many as 320,000 people globally, while last year they claimed only 288 lives.

Studies show that 75% of deaths in earthquakes can be attributed to poorly built structures that collapse. In many cases, the buildings weren’t constructed according to codes that usually consider seismic activity.

With new technologies, Ozbulut said, communities could have the capability to do more than just prevent buildings from collapsing in earthquakes.

“Buildings constructed with current seismic design codes are expected to protect occupants and avoid collapse, but it is expected that the structures will suffer significant damage. Basically, the building will take the punch, but will allow us to get out alive,” Ozbulut said. “With the damage and losses communities have been experiencing following natural hazard events, there is a push toward moving beyond the current design paradigm and addressing continued functionality after a hazard event.”

This is the driving reason why Asfaw and Ozbulut have been focused on using shape memory alloys in the development of a system to keep buildings habitable after earthquakes. Their device is designed to be easily installed onto the existing support structures of buildings so that earthquake energy is dissipated.

“The current seismic design philosophy is about creating buildings that don’t collapse, but that may take severe structural damage or be deformed and leaning. This requires either demolishing the buildings or replacing huge sections of building components, which can be costly,” Ozbulut said. “In the case of our device, the shape metal alloy will not only diminish damage, it will self-center the structure, allowing the building to be occupied immediately after an earthquake.”

Promising Results

The night before the earthquake in Turkey, and before his big testing day, Asfaw hadn’t been able to sleep. A year of research, computer simulations and fabrication were leading up to the first test of the damper system he and Ozbulut designed and fabricated. He was anxious about how the testing would go.

Early the next morning, Asfaw transported the UVA blue- and orange-painted damper to the lab at the Virginia Transportation Research Council, which is located on Grounds a short way from Ozbulut’s and Asfaw’s offices at UVA Engineering. The lab is the only place nearby that has a large-scale tension and compression testing machine of the strength needed to most accurately test a device of that size.

Gritting his teeth, Asfaw used a monkey wrench to tighten a couple of the shape memory alloy cables attached to the steel plates, before hoisting the heavy device with a forklift and placing it into the jaws of the testing apparatus. He then set up lasers to measure how well the shape memory alloy cables absorbed the pressure as the testing apparatus put the damper through a rigorous deformation.

Asfaw inspecting his earthquake machine
Asfaw checks on his earthquake damping device during the successful testing at UVA Engineering.

After the testing apparatus stopped exerting its destructive pressure, the shape memory alloy cables snapped themselves and the attached steel plates back into their original places.

When the testing was complete, Asfaw texted Ozbulut a snapshot of the results while also saying he was sorry about what happened in Turkey.

“But at the same time, here is a promising device that can be implemented in the future to minimize earthquake damage,” Asfaw said. “And he was very happy with that result as well. It’s hard to express how I was feeling with words at that time. I was really very excited that day. I felt like I was able to accomplish something important that can save lives and provide people with a safe place to live.”