The pagoda at the Horyu-ji temple in Japan is a testament to architectural design that was ahead of its time. Built in 607 AD, the 122-foot-tall structure is still standing, now one of the world’s oldest wooden buildings at 1,410 years old.
It’s also an enduring symbol of forward-thinking engineering concepts that are applied today in protecting large structures against earthquakes. Horyu-ji’s pagoda is a monument to stability in a land of seismic instability; it has stayed upright despite nearly 50 earthquakes of magnitude 7.0-plus having struck Japan during the building’s lifespan.
Japanese builders used a shinbashira — a large column within a shaft in the building’s center — to act as a shock absorber and buffer between the floors.
This same technology is used today in the form of tuned mass dampers, also known as harmonic absorbers, which help reduce vibrations from an earthquake. Dampers can come in steel, liquid or concrete and are housed in numerous large buildings, skyscrapers and bridges in the United States and around the world.
Like automobiles driven on a bumpy road, buildings in wind and seismic regions are a dynamic problem. Who would ever buy or manufacture a car without shock absorbers? The dynamic laws of physics are the same for each.
Besides damper technology, other remarkable examples of ancient construction methods still holding up against earthquakes abound in iconic structures around the world.
In China, some of its oldest buildings, including the Forbidden City, have withstood earthquakes thanks to an ancient building technique called dougong, which dates back over 2,000 years. Dougong is a series of interlocking wooden brackets used to support overhanging roofs, a signature of Chinese architecture. This method distributes weight more evenly.
The oft-photographed Wooden Pagoda in Shanxi province, designed with dougong, was built in 1056 along a seismic belt and has withstood many earthquakes. Today, architects are employing dougong for retro-aesthetic and structural reasons; one of those examples being the China Art Museum in Shanghai.
Peru’s Machu Picchu, an Inca citadel sitting on a mountain 7,970 feet above sea level, is another monument to earthquake-protection ingenuity with ties to today’s technology.
In an earthquake-prone region, Incan workers devised a system similar to Legos, with the stones fitting together without mortar. That inspired California-based architects to explore creating a similar design.
Large structures without extra building protection like dampers may have imperiled structural integrity when the earth shakes violently. The current building codes in the U.S. and worldwide only require that new buildings be designed for collapse prevention. They do not require what is referred to as “performance-based designs” that would make the buildings perform much better in an earthquake.
Some people think that if they move into a brand new building that meets all the modern building codes, their building will perform well during earthquakes.
This is simply not true.
Douglas P. Taylor is the CEO of Taylor Devices, which manufactures seismic dampers that protect structures during such events as earthquakes and high winds. He is inventor or co-inventor of 34 patents in the fields of energy management, hydraulics and shock isolation. In 2015, he was inducted into the Space Technology Hall of Fame by NASA and the Space Foundation.
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