Japan Architects Push Boundaries in Tech and Design for Earthquake Resistant Construction Methods

19 Jan, 2021 –

Japan Real Estate
Japan Properties

In Japan, planning for natural disasters is a serious business. For good reason. Over the past decade, the island nation has weathered about 20% of the world’s “strong” earthquakes (magnitude 6 or greater) as well as multiple tropical storms a year. The worst of these events can be utterly devastating: The 2011 Tohoku earthquake, which triggered a massive tsunami and a meltdown at the Fukushima Dai-Ichi nuclear power plant, killed more than 15,000 people. And climate change is making major disasters more frequent. The global number of incidents jumped to 7,348 over the past 20 years from 4,212 in the previous two decades, a recent United Nations report found — affecting 4.2 billion people and incurring an economic toll of $2.97 trillion.

So it’s understandable that Japan’s already considerable investment in mitigating natural disasters is ramping up, via public-sector funding, seismic engineering and advances in artificial intelligence. In December, the government adopted a new five-year, 15 trillion yen ($144.4 billion) plan to accelerate its anti-disaster preparations. Measures aimed at mitigating the risks of predicted massive earthquakes — as well as wind and flood damage — range from upgrading roads, schools and airports to a supercomputer for predicting rainfall. The plan, which includes 123 disaster reduction projects, was adopted after the government judged an existing three-year emergency project insufficient to protect lives and property.

Architects and engineers are pushing the boundaries of technology and design to reduce damage. Factors that set the country’s disaster-proofing industry apart include its kenchikushi  — licensed architect-engineers who can be held liable for building defects for a period of 10 years — and its legislative framework. “By gradually amending building laws in response to successive earthquakes and socioeconomic and demographic changes,” a 2018 World Bank report noted, Japan has created a built environment “that is among the safest and most disaster resilient in the world.”

Tokyo Skytree — the world’s tallest broadcasting tower at 634 meters and one of the city’s major tourist attractions since it opened to the public in 2012 — is one famous example of the country’s efforts. Wind is the toughest weather condition for high-rise buildings, said Atsuo Konishi, a senior structural engineer at Nikken Sekkei Ltd. who helped to create Skytree. So Konishi and his colleagues designed a steel truss tower that allows strong winds to simply pass through the gaps. 

Skytree also has a unique vibration-control system: A 375-meter-tall concrete core column at its center that is connected to the tower’s outer frame by a series of flexible “dampers” but structurally independent of it. The column moves with a time lag and reduces the vibration of the entire building by up to 50% during an earthquake and 30% in strong winds. A more common system is seismic isolation, in which a building’s foundations include layers of steel and rubber that act as a shock absorber. The technique has been used in Japan since the early 1980s and is now employed in thousands of buildings there and abroad, including Apple Inc.’s Silicon Valley headquarters. 

In newer buildings, some firms are experimenting with unconventional materials. Maeda Corp. is building a 13-story Tokyo office building using a lattice of wood and steel, designed to improve the building’s resistance to earthquakes. “Wood is rarely used as an earthquake-resistant element inside a steel-frame building,” said Yoshitaka Watanabe, Maeda’s chief engineer, but because steel can withstand pulling forces while wood withstands compressive forces, each material compensates for the other’s shortcomings.  The use of timber reduces the environmental impact of construction and incorporating steel will delay collapse in case of fire, allowing more time for evacuation, said Akira Wada, professor of Engineering at Tokyo Institute of Technology. 

Artificial intelligence is also starting to play a part in safer building design. Typhoon simulation software can predict wind loads and speeds in two to three days, a process that may currently require months of data collection and wind-tunnel tests. “The calculation accuracy of the software is as good as wind tunnel tests,” said Hideyuki Tanaka, group leader of the natural and biological environmental engineering department at Takenaka Corp., the architectural engineering company that is developing the software. Architects will be able to factor the data into design elements such as a building’s shape and the thickness of window glass. 

For all Japan’s advances in anti-disaster planning, significant gaps remain. Flood risk management is still a work in progress, an issue highlighted by the record-breaking rains that killed 84 people last July. Evacuation is often especially difficult for frail, elderly people, a particular problem for the country’s aging population. And of course there’s Covid-19. While there was no cluster at evacuation facilities during July’s floods, local media reported that more than 1,500 people remained in waterlogged houses and cars as a result of fears about the risks of infection at evacuation centers, in some cases for several weeks. 

One possible solution is building disaster-proof shelters within the home. Inspired by Nordic designs, Nagoya-based architect Naoko Ito’s log shelter is designed to increase the durability of the entire house while securing a safer place for its residents without the need to evacuate. However only a few examples of her design have been built so far. Japan’s risk management has further to go. But as natural disasters become more frequent, other countries may want to examine its approach.  

“We need to plan, during the design phase, a structure that can withstand disasters,” said Mayumi Sakamoto, a professor at the University of Hyogo Graduate School specializing in Disaster Risk Management. “By embedding disaster preparation facilities during the construction phase, the city will become even more resilient.”

(Source – Bloomberg, Pic – Construction / “Hideya HAMANO“)

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