02-06-2012, 04:35 PM
GENERAL CONCEPTS OF EARTHQUAKE RESISTANT DESIGN
GENERAL CONCEPTS OF EARTHQUAKE.pdf (Size: 365.91 KB / Downloads: 295)
INTRODUCTION
Experience in past earthquakes has demonstrated
that many common buildings
and typical methods of construction lack
basic resistance to earthquake forces. In
most cases this resistance can be achieved
by following simple, inexpensive principles
of good building construction practice.
Adherence to these simple rules will
not prevent all damage in moderate or large
earthquakes, but life threatening collapses
should be prevented, and damage limited
to repairable proportions. These principles
fall into several broad categories:
CATEGORIES OF BUILDINGS
For categorising the buildings with the
purpose of achieving seismic resistance at
economical cost, three parameters turn out
to be significant:
(i) Seismic intensity zone where the
building is located,
(ii) How important the building is, and
(iii) How stiff is the foundation soil.
A combination of these parameters will
determine the extent of appropriate seismic
strengthening of the building.
Importance of building
The importance of the building should be a
factor in grading it for strengthening
purposes,and the following buildings are
suggested as specially important:
IMPORTANT Hospitals, clinics, communication
buildings, fire and police stations,
water supply facilities, cinemas, theatres
and meeting halls, schools, dormitories,
cultural treasures such as museums,
monuments and temples, etc.
Combination of parameters
For defining the categories of buildings for
seismic strengthening purposes, four categories
I to IV are defined in Table 3.1. in
which category I will require maximum
strengthening and category IV the least inputs.
The general planning and designing
principles are, however, equally applicable
to them.
Fire resistance
It is not unusual during earthquakes that
due to snapping of electrical fittings short
circuiting takes place, or gas pipes may
develop leaks and catch fire. Fire could also
be started due to kerosene lamps and
kitchen fires. The fire hazard sometimes
could even be more serious than the earthquake
damage. The buildings should therefore
preferably be constructed of fire resistant
materials.