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Seismic isolation

system patented in

Japan has applicability

in earthquake-proneU.S. locations.

by Clyde E. Witt

Editors note: In May I was on a natural history tour to Trini-dad and Tobago. Our guide took the opportunity to show us a

spot where an earthquake had occurred a few months earlier. Thefissure in the ground ran for more than 50 yards. The ground wasuneven and still gaped a foot wide in places. It started me thinkingabout how buildings might fare in areas of seismic activity. I askedthe experts at ProLogis for some information. CW

Aseismic isolation construction methodused in multi-storied warehouses in Ja-pan has recently won patent protectionfrom the government there.

Now industry observers here are won-dering whether the technique has appli-

cation in North America--especially in markets like SanFrancisco and Los Angeles, where earthquakes are a factof life and where land constraints make multi-story distri-bution centers economically feasible.

The technique was pioneered by ProLogis (www.pro-

logis.com), the Denver-based industrial real estate de-veloper, which has extensive operations in Japan. The

It Cant

Happen

Here

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method enables seismic isolation de-vices to be installed in buildings usingreduced amounts of excavation andconstruction material.

Multi-story warehouses are com-mon in Japan due to land constraintsthroughout the country, and protect-ing them from earthquake damagecan add significantly to the total costof construction, says Kenji Ishijima,the companys first vice president ofconstruction management in Japan.This method enables us to reducethat cost in a meaningful way, with-out compromising the structural in-tegrity of the building.

Japans multi-storieddistribution centers

Japan has the worlds second-larg-est economy. The country is denselypopulated and highly land con-strained, with nearly 70% of its land-mass mountainous and uninhabitable.Consequently, more than 80% of Ja-pans population, 10th largest in theworld, is concentrated in about 30%of the countrys coastal flatlands.

Developable land in urban areas isscarce and extremely expensive. InTokyo, for example, industrial-zonedland can sell for as much as five toeight times the premium prices forsimilarly-zoned land in such primeU.S. locations as those near the LosAngeles/ Long Beach seaports.

As a result, multi-storied distribu-tion centers are common throughout

Japan, including in Tokyo, Osaka, Na-goya and other key distribution hubs.

While the purpose of these buildingremains the same, the structures arevastly different from anything foundin the United States today.

In Japan, d istribution facilitiesrange between four and eight sto-ries and often exceed more than onemillion square feet. Dock doors lineeither side of a one-way truck cor-ridor that runs through the middle ofeach floor and connects two opposing

spiral access ramps; one for incom-ing traffic on one end and one for

outgoing on the other. Truck courtparking is restricted and trailer park-ing is limited.

The cost to develop a multi-storieddistribution facility is considerably

higher than it would be for a stan-dard one-story facility elsewhere inthe world. For example, a one mil-lion-square-foot distribution facil-ity located in Southern CaliforniasWestern Inland Empire, currentlythe hottest, priciest, most land-con-strained market for industrial realestate in the U.S., would cost be-tween $85-$95 million to develop.(This approximation includes land,hard and soft costs based on a 45%

building coverage.) In the TokyoBay Area, which could be consid-ered Japans Inland Empire, a onemillion-square-foot multi-storieddistribution center would averagebetween $200-$300 million.

Seismic safetya key factor

Japan is located in one of the mostearthquake-prone regions in the

world, experiencing more than 1,000seismic events each year. Multi-sto-

ried warehouses, though efficient,are obviously at risk for damage bythese earthquakes.

To prevent the loss of life andproperty, real estate developers in Ja-pan today are using a variety of earth-quake mitigation methods. These in-clude anti-seismic, vibration controland seismic isolation techniques.

Seismic isolation is generally con-sidered the most effective. It involvesplacing a seismic isolation device,which is composed of a rubber bear-ing, isolation cylinder and steel balls,between the foundation of the build-ing and the ground to help displacehorizontal and vertical movement

caused by an earthquake. By convert-ing strong seismic vibrations into alow speed motion, structural integrityis maintained and the risk of damageto the building, from the top floor tothe ground level, is reduced.

But seismic isolation is also themost costly approach. A single seis-mic isolation device can cost upwardsof $20,000, and a multi-storied facil-ity totaling one million square feet or

more might need between 200 and300 such devices.The design and construction tech-

nique devised by ProLogis, however,directly connects a seismic isolationdevice to a steel pipe pile, a key com-ponent in building foundations,instead of between the foundationand the ground. While this doesnot reduce the number of devicesneeded, it does reduce the size of thefoundations as well as smaller build-

ing columns and beams, which savessubstantial construction time and ma-terials costs. The company estimatesits patented construction methodsaves more than 60% on foundationcosts while achieving more than 80%seismic input absorption.

It also results in minimal post-quake repair costs and helps ensurethat building operations are main-tained, says Ishijima.

Currently, ProLogis has four indus-trial parks in Japan that were devel-

ProLogis building in

Yokohama, Japan.

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