MadSci Network: Engineering
Query:

Re: What materials are used to prevent damage to infrastructure in earthquakes?

Date: Tue Mar 16 20:45:37 1999
Posted By: Jim Stana, , Mechanical Design/Analysis Manager, Lockheed Martin Orlando
Area of science: Engineering
ID: 920695049.Eg
Message:

There are no particular types of materials chosen for earthquake proof 
structures and highways.  The design of the structure must take into the 
account the extreme vibrations caused by the earthquake.  These start out 
usually as a strong vertical pulse followed by a period of strong side to 
side motions of the earth.

The design of the structure in question must take take into account the 
stresses and deflections (movements) created by the motion of the earth.  
This is often done today by modeling the building or highway on a computer 
as a series of finite elements and watching what happens to each of the 
elements when the motion is simulated.

If the structure is flexible enough and the motions not too extreme, the 
materials in the structure will bend but not break.  This might still be 
disconcerting for the occupants, but it will not pose a danger.  In 
California, any building over several stories is required to have a ground 
motion recorder in the building.  As a graduate student at Caltech in the 
70's, I remember looking up the displacement records for the Alcoa Building 
in downtown Los Angeles and being amazed that the top of the building 
swayed several feet in the last strong earthquake there. 

Stiff buildings, like un-reinforced concrete buildings, seem to fare the 
worse.  Concrete is ok in compressive loading where it is being squeezed 
together, but develops cracks and falls apart when pulled in tension like 
what might happen in an earthquake.

You might want to pay a visit to the Caltech Mechanical Engineering 
Department, which specializes in earthquake engineering.  You might be able 
to get more details on their research and what materials are more commonly 
used or avoided.




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