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Building Design With Resiliency

Published: April 18, 2016

Damaged building after earthquake
PHOTO COURTESY OF VESNA TERZIC

What was that? Did the building just sway? If it did without falling down, thank the expertise of structural engineers like Vesna Terzic, an expert on resiliency and a member of the Department of Civil Engineering and Construction Engineering Management Department at CSULB.

Resiliency is the ability of a structure to provide continuous operation immediately following an earthquake.

“To me, resiliency means preserving a building’s functionality,” said Terzic, who joined CSULB in 2014. “For the communities to be resilient, it is necessary to minimize a building’s inoperability following an earthquake event. The buildings may have some minor damage that can be easily patched and repaired while the occupants continue their normal lives. I don’t mean no damage at all. That’s not impossible but it is too expensive.”

Buildings have a lot to be resilient about. “When a building rises anywhere in the world, today’s engineers look at all possible hazards,” said Terzic, who earned her Ph.D. from UC Berkeley in 2009. “In California, earthquakes govern designs. If a building can resist earthquakes, it will resist all the other hazards. For other regions such as New York City, for example, winds govern design.”

Resilient design protects more than occupants lives. Structural engineers are concerned with designing and building a skeleton that will carry building content, occupants, and all nonstructural components such as partition walls, outside glazing, mechanical and electrical equipment.

“In the case of a big hazard event, the building is expected to undergo substantial damage that will interrupt building’s functionality but the building should not collapse and there should be no casualties,” said Terzic. “With a resilient design we are moving the boundaries. New ideas of resilient design look at the building as a whole, including all structural and non-structural components. It is not only that we don’t want anybody in the building to die, we also want to protect all non-structural components that the building’s functionality depend on. For example, a building’s functionality depends on mechanical and electrical equipment. Through resilient design of a building we can protect them to assure continuous functionality.”

Different nations have different ways of addressing resiliency.

“The Japanese experience big earthquakes more often than the West. It is an everyday reality for them,” Terzic explained. “For them, earthquake is beyond the research level. They are fast to adopt research into practice. They are quick to adopt new technologies resulting in more resilient building inventory. There is amazing research going on in the U.S. But when it comes to moving research into practice, the U.S. is slower. Our building inventory is not as resilient as Japan’s. Currently, there is a strong push in the U.S. to speed up the move of research into practice.”

Government tax breaks play a role in stipulating resilient building design. The U.S. was more concerned with preparing a response to earthquakes than in preventing earthquake damage and was typically spending more money on preparedness than prevention, according to Terzic.

“Sure, America really needs to be prepared to effectively respond to earthquakes when it comes to the inventory of older buildings,” she said, “but for the buildings that will rise over the next 50 years, prevention will be the key. I already see a shift from preparedness to prevention as lot more money is being currently spent on prevention than in the past.”

Vesna Terzic
PHOTO COURTESY OF VESNA TERZIC
Vesna Terzic

Resilience is green. When modern “smart” buildings are created, there is an emphasis on their sustainable or “green” aspects, Terzic said.

“The idea of sustainable is the use of green materials and green technologies within the buildings. There is less concern about the ability of a building’s skeleton to protect them against an earthquake when it comes,” she said. “The framework of sustainability needs resiliency as a final touch. All the green things built into new structures will be damaged, unfortunately. I am hoping that sustainability and resilience will go hand-in-hand to assure building’s sustainability following an earthquake event.”

There is a role for resilience in retrofitting existing buildings and when engineers design the retrofit solution for a building, they do it to the code. But code does not assure resiliency, she noted.

“When you’re doing retrofit, you are not designing it for the same intensity of the ground shaking as you would consider for a new building,” she said. “Retrofitting is meant to prepare the building for a shorter building life than for the new building, for example a retrofitted building may be expected to be there for another 20 years and a new building for 50 years. The chances of having a big earthquake in those 20 years is smaller than in the case of a new building and that’s why the retrofits are designed for smaller earthquakes. To me, this looks like a scary game.”

Terzic pointed to the 6.3 quake that struck New Zealand in February 2011.

“The U.S. and New Zealand have similar building codes. When the earthquake came, some retrofitted buildings fell down,” she said. “The prospect of new quakes is all a matter of probability or chance of an earthquake occurring within a certain time frame. However, there is a new trend toward planning for the possible, not the probable. Is it possible that there will be a big earthquake? Yes. Is it probable? No.”

Sometimes Terzic feels cursed by knowing what she knows about resiliency.

“For everyone else, it is easy to walk around without knowing what buildings will survive. When I look at a building, I have a feeling about the consequences to come with the next big earthquake,” she said. “It’s not easy walking around knowing what I know. It may come in handy when I shop for a home someday. I would consider a more resilient house over a nicer-looking one.”