Earthquake absorbers

Press, 3 February 1982, Page 17

Earthquake absorbers

By

REG GRATTON,

Reuter,

from Kuala Lumpur

Scientists working with natural rubber have developed a new form of earthquake protection for multistorey buildings that they believe could save .thousands of lives and millions of dollars.

The principle is simple: put buildings in earthquakeprone areas on rubber springs to isolate the structure from the quake vibrations.

Malaysia, the world’s largest producer of natural rubber, will this month play host •to the first international conference devoted to explaining how this relatively cheap form of protection works and why its developers believe it is superior to conventional building strengthening.

“We have now reached the stage in its development where we are confident enough to air the results in public,” says Des Derhain, senior principal scientist of the Malaysian Rubber Producers Research Association. The four-day conference,

sponsored by the Malaysian Rubber Research and Development Board and the United Nations Industrial Development Organisation, is aimed in particular at selling the idea to architects and civil engineers, the specialists whose lobby is needed to revise government building codes based on existing methods. “It is becoming increasingly difficult to construct buildings to withstand large earthquakes and the present method is simply to strengthen the structure," says Mr Derham, who has been working with the board on research.

The stronger the building, the more the force of the quake is transmitted from the ground, effectively causing greater damage to what’s

inside, according to Mr Derham. “You would never think of bolting an engine directly to the car chassis; you put it on rubber springs to prevent its vibrations getting through to the car. We can now do that with buildings,” he says. It was not until recently that bearings using highquality rubber could be made to accept the large movements in severe earthquakes. Groups of scientists started working on the idea independently about six years ago in France, Greece, New Zealand, Malaysia, Britain, and the United States. They recently formed the International Society for Seismic protection to pro-

mote this use of natural rubber. Initial research has been based on new buildings but the scientists are now studying the possibilities for existing structures, Mr Derham says. It would be cheaper to replace existing foundations with rubber springs than to strengthen it using conventional methods.

The rubber spring itself looks like a huge multidecker sandwich with steel leaves fitted between rubber blocks about 60cm square and 30cm thick.

The spring is a development from rubber buffers already used on some bridges and buildings for vibration isolation. These have

been used in London, for instance, for buildings over underground railway stations. “It was not until we understood how rubber behaved in these conditions that we were able to develop a material with the right dampening characteristics and stability for earthquake protection,” Mr Derham says. The research and development board worked with scientists at Berkeley University in California to perfect the design. Malaysian rubber researchers have been working on high technology use for natural rubber for some time, particularly in engineering, and are hopeful that this breakthrough will lead to other applications.