Page 88 - Vertical City

88 The vertical city

ture can absorb the energy transmitted by its deforma-
tion, which is more effective as the structure is high and
flexible.

Buildings of less than 20 stories are also those that
are the least resistant to earthquakes.

High towers, less vulnerable to seismic activity, are
now equipped with various types of damping devices
to respond to the effects of wind, and also to avoid the
queasiness provoked by the variation in the acceleration
of horizontal movement.

The guy stays that equip the towers of the small
vertical city (Chapter V) simultaneously enable resis-
tance to the wind loads in an economical manner, while
at the same time providing the necessary damping and
the absorption of seismic energy by the flexibility of the
height of the tower.

Finally, it is also possible to foresee holes at various
heights of the towers to substantially reduce wind loads.

Resistance to fire and malevolence

The worldwide trauma provoked by the collapse of
twin towers of the World Trade Center in New York
City, September 11, 2001, brings us from that moment
on to consideration of security criteria applicable to all
high-rise structures.