DETAILED DESCRIPTION First, with reference to FIG.
1, a building structure is indicated generally at 10.
The structure illustrated has four generally vertically extending columns 12, 14, 16, and 18.
In addition, there are a number of floors formed by horizontal beams 20, 22, 24, and 26.
As indicated in this figure, the horizontal beams 22.
1, 22.
3, 24.
1, 24.
3, etc.
, extend in an east-west direction in an X-Z plane; and the beams 22.
2, 22.
4, 24.
2, 24.
4, etc.
, extend in a north-south direction in a Y-Z plane.
The structure as shown is provided with a passive control such as the chevron bracing beams 30, 32.
When the building 10 is subjected to a wind such as a westerly wind indicated by the arrow 34, the building will deflect towards the east.
The wind will input energy into the building, the additional energy being stored within the bending columns, etc.
When the velocity of the wind 34 decreases, this energy will be released to restore the building to its normal shape.
As can be seen from the structure sketched in FIG.
1, all of the deformation to the building occurs in the X-Z plane, which deformation can be resisted by the chevron bracing beams 30, 32.
When the building 10 is subjected to an earthquake, there will be horizontal movement of the ground in X and Y directions (which may be east-west, and north-south, respectively).
In addition, there will be ground waves which are indicated by the sinusoidal waves X and Z in FIG.
1.
Because of these motions, during an earthquake the building will be subjected to at least five degrees of movement; namely, movement in the X-Y-Z directions, and rotational movement about the X and Y axes, and perhaps rotational movement about the Z axis.
In most earthquakes, the excitation and most other dynamic loadings are typically random.
This can best be seen from FIG.
2 which is the E1 Centro Earthquake Response Time History.
The building 10, when subjected to such an earthquake, will be deflected and tends to vibrate.
The vibration of such a building tends to be destructive
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Vibration and Earthquake Isolation 
