Disaster resistant architecture

CHAITANYA KORRA B.ARCH 8019263319

1.Short notes on Richter
Scale level and damage:
The Richter magnitude scale (often shortened to Richter scale) was
developed to assign a single number to quantify the energy released during
an earthquake.
 The scale is a base-10 logarithmic scale.
The magnitude is defined as the logarithm of the ratio of the amplitude of
waves measured by a seismograph to an arbitrary small amplitude.
 An earthquake that measures 5.0 on the Richter scale has a shaking
amplitude 10 times larger than one that measures 4.0, and corresponds to a 31.6
times larger release of energy

Magnitude Description Mercalli intensity Average earthquake effects
Average frequency of
occurrence (estimated)
Less than 2.0 Micro I
Microearthquakes, not felt, or
felt rarely by sensitive
people. Recorded by
seismographs.[16]
Continual/several million per
year
2.0–2.9
Minor
I to II
Felt slightly by some people.
No damage to buildings.
Over one million per year
3.0–3.9 II to IV
Often felt by people, but very
rarely causes damage.
Shaking of indoor objects can
be noticeable.
Over 100,000 per year
4.0–4.9 Light IV to VI
Noticeable shaking of indoor
objects and rattling noises.
Felt by most people in the
affected area. Slightly felt
outside. Generally causes
minimal damage. Moderate to
significant damage very
unlikely. Some objects may
fall off shelves or be knocked
over.
10,000 to 15,000 per year
5.0–5.9 Moderate VI to VIII
Can cause damage of varying
severity to poorly
constructed buildings. At
most, none to slight damage
to all other buildings. Felt by
everyone. Casualties range
from none to a few.
1,000 to 1,500 per year

6.0–6.9 Strong VII to X
Damage to many
buildings in populated
areas. Earthquake-
resistant structures
survive with slight to
moderate damage.
Poorly-designed
structures receive
moderate to severe
damage. Felt in wider
areas; up to hundreds
of miles/kilometers
from the epicenter.
Damage can be
caused far from the
epicenter. Strong to
violent shaking in
epicentral area.
Death toll ranges
from none to 25,000.
100 to 150 per year

7.0–7.9 Major
VIII or greater[17]
Causes damage to most
buildings, some to partially or
completely collapse or
receive severe damage. Well-
designed structures are likely
to receive damage. Felt in
enormous areas. Death toll
ranges from none to 250,000.
10 to 20 per year
8.0–8.9
Great
Major damage to buildings,
structures likely to be
destroyed. Will cause
moderate to heavy damage to
sturdy or earthquake-
resistant buildings. Damaging
in large areas, some totally
destroyed. Felt in extremely
large regions. Death toll
ranges from 100 to 1 million.
One per year (rarely none,
two, or over two per year)
9.0–9.9
Severe damage to all or most
buildings with massive
destruction. Damage and
shaking extends to distant
locations. Permanent changes
in ground topography. Death
toll ranges from 1,000 to
several million.
One per 5 to 50 years
10.0 or greater Epic/Massive X or greater
Total devastation; damage
extends to distant areas.
Landscape and elevation
changes permanently. Death
toll usually over 100,000.
Never recorded
(unknown/may be impossible)

SOIL LIQUEFACTION
Soil liquefaction describes a phenomenon whereby a
saturated soil substantially loses strength and stiffness in response to an
applied stress, usually earthquake shaking or other sudden change in stress
condition, causing it to behave like a liquid.
In soil mechanics the term "liquefied" was first used by Hazen in reference
to the 1918 failure of the Calaveras Dam in California. He described the
mechanism of flow liquefaction of the embankment dam as follows:
If the pressure of the water in the pores is great enough to carry all the
load, it will have the effect of holding the particles apart and of producing a
condition that is practically equivalent to that of quicksand.
The initial movement of some part of the material might result in
accumulating pressure, first on one point, and then on another, successively,
as the early points of concentration were liquefied.

 The phenomenon is most often observed in saturated, loose (low density or
uncompacted), sandy soils. This is because a loose sand has a tendency to compress when
a load is applied; dense sands by contrast tend to expand in volume or 'dilate'.
 If the soil is saturated by water, a condition that often exists when the soil is below the
ground water table or sea level, then water fills the gaps between soil grains ('pore
spaces').
 In response to the soil compressing, this water increases in pressure and attempts to
flow out from the soil to zones of low pressure (usually upward towards the ground
surface).
However, if the loading is rapidly applied and large enough, or is repeated many times
(e.g. earthquake shaking, storm wave loading) such that it does not flow out in time before
the next cycle of load is applied, the water pressures may build to an extent where they
exceed the contact stresses between the grains of soil that keep them in contact with each
other.

 These contacts between grains are the means by which the weight from
buildings and overlying soil layers are transferred from the ground surface to
layers of soil or rock at greater depths. This loss of soil structure causes it to lose
all of its strength (the ability to transfer shear stress) and it may be observed to
flow like a liquid (hence 'liquefaction').
SEISMIC WAVES
Seismic waves are waves of energy that travel through the Earth's layers, and
are a result of an earthquake, explosion, or a volcano that imparts low-frequency
acoustic energy.
 Many other natural and anthropogenic sources create low amplitude waves
commonly referred to as ambient vibrations.
Seismic waves are studied by geophysicists called seismologists. Seismic wave
fields are recorded by a seismometer, hydrophone (in water), or accelerometer.

The propagation velocity of the waves depends
on density and elasticity of the medium. Velocity tends to increase with
depth, and ranges from approximately 2 to 8 km/s in the Earth's crust up
to 13 km/s in the deep mantle.
Earthquakes create various types of waves with different velocities;
when reaching seismic observatories, their different travel time help
scientists to locate the source of the earthquake hypocenter.
 In geophysics the refraction or reflection of seismic waves is used for
research into the structure of the Earth's interior, and man made
vibrations are often generated to investigate shallow, subsurface
structures

2.FOUNDATION TO BUILDING
RESISTANT TO EARTH QUAKES
FOUNDATIONS
For the purpose of making a building truly earthquake resistant, it will be necessary to
choose an appropriate foundation type for it.
 Since loads from typical low height buildings will be light, providing the re-uired bearing
area will not usually be a problem.
 The depth of footing in the soil should go below the zone of deep freezing
in cold countries and below the level of shrinkage cracks in clayey soils.
For choosing the type of footing from the earthquake angle, the soils may be grouped as
Firm and Soft avoiding the weak soil unless compacted and brought to Soft or Firm
condition.

SOIL STABILIZATION
Firm soil
In firm soil conditions, any type of footing(individual or strip type) can be used. It should
of course have a firm base of lime or cement concrete with requisite width over which the
construction of the footing may start.
 It will be desirable to connect the individual reinforced concrete column footings by
means of RC beams just below plinth level intersecting at right angles.
In soft soil, it will be desirable to use a plinth band in all walls and where necessary to
connect the individual column footings by means of plinth beams as suggested above.
 It may be mentioned that continuous rein-forced Concrete footings are considered to
be most effective from earthquake consid-erations as well as to avoid differential
settlements under normal vertical loads.

These should ordinarily be provided continuously under all the walls. Continuous footing
should be reinforced both in the top and bottom faces, width of the footing should be
wide enough to make the contact pressures uniform, and the depth of footing should be
below the lowest level of weathering.
WALLS RESISTANT TO EARTHQUAKE
 A free standing wall must be designed to be safe as a vertical cantilever.
 This requirement will be difficult to achieve in un-reinforced masonry. Therefore all
partitions inside the buildings must be held on the sides as well as top. Parapets of
must be reinforced and held to the main structural slabs or frames.
 Horizontal reinforcement in walls is required for transferring their own out-of-plane
inertia load horizontally to the shear walls.

 The walls must be effectively tied together to avoid separation at vertical joints
due to ground shaking.
 Shear walls must be present along both axes of the building.
 A shear wall must be capable of resisting all horizontal forces due to its own
mass and those transmitted to it.
 Roof or floor elements must be tied together and be capable of exhibiting
diaphragm action.
 Trusses must be anchored to the supporting walls and have an arrangement for
transferring their inertia force to the end walls.

OPENINGS
Door and window openings in walls reduce their lateral load resistance and hence, should
preferably be small and more centrally located.
Openings in any storey shall preferably have their top at the same level so that a continuous
band could be provided over them, including the lintels throughout the building.
If a window or ventilator is to be projected out, the projection shall be in reinforced masonry
or concrete and well anchored.
c) Water tanks
 Supply of drinking water is essential immediately after destructive earthquakes. Without
assured water supply, the uncontrolled fires subsequent to major earthquakes may cause
more damage than the earthquakes themselves.
 So the water supply system should be designed as seismic resistant and seismic
performance of water tanks draws special significance in the design.

 Codes of practice realize that it is uneconomic to design a structure to remain elastic
during a severe earthquake and therefore generally allows some inelastic behaviour.
 The reduction in design forces specified by various codes on account of inelastic behaviour
or ductility is significantly smaller for elevated tank structure compared to building
structure.
 The tanks located in a fault region are found to be vulnerable under near fault pulses with a
large duration compared to the natural period of tank.
 The post evaluation study on the failure of elevated water tank shows that there are
significant seismic deficiencies to critical elements, including steel columns, diagonal braces
and horizontal struts.
The frame support of elevated water tank should have an adequate strength to resist axial
loads, moment and shear force due to lateral loads.

 These forces depend upon total weight of the structure, which varies with the amount of
water present in the tank container.
Supporting structure, especially the staging of an elevated water tank does not have much
redundancy.
This lack of redundancy is extremely serious in circular shaft type staging where lateral
stability depends only on the shaft.
 The slender staging resulting from low design forces are unfavourable for seismic areas.

3.HISTORICAL EXPERIENCE OF A
CITY THAT HAS SUFFERED EARTH
QUAKE IN INDIA
 The magnitude 7.7 earthquake that struck Gujarat, India at 03:16 UT
(08:46 local time) on January 26, 2001 killed approximately 20'000
people and devastated a large number of villages and towns over a wide
area of western Gujarat.
 Unlike many earthquakes that have tended to affect particular types
of structures more severely , this earthquake had a profound effect on
structures of all types, from ancient to modern, from traditional
masonry to contemporary reinforced concrete. (Unesco Report)

The 2001 Gujarat earthquake occurred on January 26, 2001, India's 51st Republic Day, at
08:46 AM local time (3:16 UTC) and lasted for over two minutes.
 The epicentre was about 9 km south-southwest of the village
of Chobari in Bhachau Taluka of Kutch District of Gujarat, India.
 The earthquake reached a magnitude of between 7.6 and 7.7 on the moment magnitude
scale and had a maximum felt intensity of X (Intense) on theMercalli intensity scale.
 The quake killed around 20,000 people (including 18 in South eastern Pakistan), injured
another 167,000 and destroyed nearly 400,000 homes.
This was an intraplate earthquake, one that occurred at a distance from an active plate
boundary, so the area was not well prepared.
 The shock waves spread 700 km. 21 districts were affected and 600,000 people left
homeless.

4.NATURAL HAZARDS THAT EFFECT
BUILDINGS IN DIFFERENT GEGRAPHICAL
SITUATIONSNORTH AMERICA
 Windstorms, hurricanes and tornadoes are the most frequent type of disaster affecting the
greatest number of people and causing the highest total economic costs in North America.
 The region suffers the greatest economic loss from natural disasters: In 2005, Hurricane
Katrina caused $125 billion in economic loss.
OCEANIA & JAPAN
 Earthquakes and Tsunamis account for the highest number of deaths.
 Between 1996 and 2005, this region recorded the lowest incidence of disasters for any
region and hazard type, except for volcanic eruptions. The region also has the lowest
economic losses and absolute number of people killed and affected by all disaster types.
 Japan’s location in one of the world’s most active crustal zones puts its cities at risk of
many natural hazards, including earthquakes, storms and floods.
 Low-lying small island states within the region face major challenges due to sea-level rise
caused by climate change.

TRANSITIONAL COUNTRIES
 Some of the countries in East and Central Europe have difficult topographies and are located
in areas that place them at risk to natural and human-induced disasters.
 Many countries are landlocked, sit on or are surrounded by steep mountains that are
frequently disturbed by seismic activity, heavy rains, avalanches, landslides and earthquakes.
DEVELOPING COUNTRIES
 Developing countries have experienced the fastest rate of increase in the incidence of natural
and human-made disasters over the last three decades.
Cities in developing countries suffer disproportionately from the impacts of natural disasters.
This is a function of the inability of authorities to manage pre- and post-disaster situations.
The result is that natural disasters tend to claim more lives than in developed countries.
 98 per cent of the 211 million people affected by natural disasters between 1991 and 2000
resided in developing countries.

One factor accounting for the magnified impact of natural disasters in developing countries is
underdevelopment:
This makes it impossible for citizens to adhere to building regulations and also for authorities to
enforce them.
14 per cent of the urban population of developing countries live in low-elevation coastal zones,
while 54 per cent of these zones are urban.
 The high-level of urbanization in this low-elevation zones vis-à-vis the entire developing world
(44 per cent) presents major challenges, given the low capacity and weak infrastructure to deal
with rising sea levels.
LATIN AMERICA & THE CARIBBEAN
 Earthquakes, hurricanes, tropical storms and floods are the main natural hazards in this
region. During the three decades leading up to the 21st century, there were 32 disasters in the
region, accounting for about 7,500 deaths per year, on average.
 The economic loss arising from these disasters varies between $700 million and $3.3 billion.
 The Caribbean is more exposed to risk of disasters than South America, measured in terms of
occurrence per thousand square kilometres. The Caribbean is 10.1 against 0.3 for South America.

• Cumulative losses resulting from natural disasters, from 1970 to 1999, represented 4 per
cent of the gross domestic product (GDP) of South America and 43 per cent for the Caribbean.
This suggests that, in economic terms, smaller countries are more vulnerable to natural
disasters.
• In Latin America and the Caribbean, 8 per cent of the population live in the low-elevation
coastal zones. Bahamas, Surinam, Guyana and Belize rank among the top 10 in the world that
have the highest proportion of their urban population living in the coastal zone.
• In most of the Caribbean, 50 per cent of the population live within 2km of the coast. This, with
the urbanization patterns and processes in low-income areas, have, in part, contributed to
making the Caribbean highly vulnerable to rises in sea levels and extreme weather conditions.

ASIA
 More than any other region of the world, Asia has the greatest number of disasters
associated with avalanches, or landslides, earthquakes or tsunamis, floods, windstorms
and industrial accidents. The number of people affected is
also high, as is economic loss.
 Flooding is the most frequent natural hazard affecting the largest number of people and
causing the greatest economic losses.
 Between 1996 and 2005, a total 472 floods resulted in 42,570 deaths, affected 1.3 billion
people and cause economic loss of $129 billion.
 Tsunamis and earthquakes caused the greatest mortality, with the 2004 Indian Ocean
Tsunami accounting for some 230,000 deaths in which the province of Aceh lost capital
stock worth 97 per cent of its GDP.

MIDDLE EAST & NORTH AFRICA
These regions suffer from desertification, drought, flash floods, earthquakes and
landsides: Algeria and Morocco (North Africa) are subject to earthquakes: Yemen (Middle
East) experiences floods.
The desert exposes the areas to droughts and extreme water shortages: the projected
water availability per person for the next two decades is 500 cubic metres; the current
world average per capita is 7,000 cubic metres.
SUB-SAHARAN AFRICA
Flooding is the most common form of natural disaster in Africa and results in the highest
mortality.
Earthquakes, floods and storms cause the greatest economic loss, and drought affects
the most people.
Economic loss to disasters is low for Africa, compared to other world regions but is high
as a proportion of GDP.
From 1996 to 2005, more people were killed or affected by volcanic eruptions in Africa
than in any other region, despite the low incidence of volcanic eruption events.

FIRE SAFETY IN HIGH RISE
BUILDINGS
In high buildings exists because of the increased number of storeys and because exit stairs do
not normally increase in width as they descend, Stair shafts also represent one of the primary
means by which smoke moves vertically. Additionally, the time it takes an occupant to descend a
stairway increases with the height of the building, thus increasing the potential for smoke exposure.
 The basic issue is that the building egress system must provide sufficient evacuation time
before smoke reaches lethal levels, and thus harms those occupants still remaining in the building.
department can still reach only 6 or 7 floors in a building. Thus exterior rescue and
firefighting is restricted to the lower floors. With a fire above the reach of ladders, firefighters
must move vertically inside the building and launch an interior attack at the same time that
occupants are descending the stairs. This can result in delays in reaching and attacking a fire
and to increased contamination of stair shafts if doors to exit stairs must be left open to run
hoses.

 Movement in high buildings. Stack effect increases with increasing height of building.
Wind velocity and direction also affect the course of a fire. They are significantly less of a
problem in lower buildings.
Egress Systems – The potential for crowding and slow movement in exit stairs
Fire Department Access – Even with modern aerial apparatus, the fire
The Forces of Nature – Stack effect and winds have a major impact on smoke
 The occupant and fuel densities increase within a given building footprint. Despite
horizontal fire barriers, fire tends to move upward, thus potentially adding more fuel and
affecting more occupants.
Increased Density of Occupant and Fuel Load – By adding floors to a building,

conduit run vertically through high-rise buildings. As well, fire protection water supplies
must also be provided from either the top or bottom of the building both with associated
problems.
As a result of these vertical utilities, other fire problems can occur such as cables to
fire systems being damaged by fire on one level and affecting many other floors.
Complex Vertical Utility Services – A complex series of pipes, ducts, cables and alone
structures.
 Typically, they are situated above shopping malls or other commercial Integrated Fire Problems –
High-rise apartment buildings are no longer stand-occupancies, above atrium buildings containing,
for example, offices, or above subway systems.
 Each occupancy has its own unique fire safety problems and coupled with those in
a high-rise apartment building, the problems require special engineered solutions to ensure
occupant safety.
Each of these unique features presents a special problem to be resolved before a designer can
achieve a fire-safe high-rise design. While the Codes provide generalized solutions to many of the
problems, architects must be aware of the problems and the need for unique solutions based on
sound fire safety engineering.

b) Flood prone coastal areas
Flood hazard area: the area (whether or not mapped) encompassing land lower than the flood hazard
level. The area relates to that part of the allotment on which a building stands or is to be erected.
Piers, posts, columns and piles used to elevate buildings to the required elevation must take account
of-
(a) the potential erosion action due to flood; and
(b) the potential debris actions.
Slabs must have adequate strength to resist the design actions even if the supporting soil under the slab
is undermined by erosion.
The openings must meet the following criteria-
(i) doors and windows must not be counted as openings but openings can be installed in doors and
windows
(ii) there must be a minimum of two openings on different sides of each enclosed area
(iii) the total net area of all openings must be at least 1% of the enclosed area
(iv) openings must permit a 75 mm sphere to pass through; and
(v) any opening covers must not impede the flow of water

5. (a)STORM SURGE
A storm surge is an offshore rise of water associated with a low pressure weather
system, typically tropical cyclones and strong extratropical cyclones.
 Storm surges are caused primarily by high winds pushing on the ocean's surface. The
wind causes the water to pile up higher than the ordinary sea level.
 Low pressure at the centre of a weather system also has a small secondary effect, as
can the bathymetry of the body of water.
 It is this combined effect of low pressure and persistent wind over a shallow water
body which is the most common cause of storm surge flooding problems.
 The term "storm surge" in casual (non-scientific) use is storm tide; that is, it refers
to the rise of water associated with the storm, plus tide, wave run-up, and freshwater
flooding.

"Tidal surge" is incorrect since there is no such thing. When referring to storm surge height, it is
important to clarify the usage, as well as the reference point.
The National Hurricane Center defines storm surge as water height above predicted astronomical
tide level, and storm tide as water height above NGVD-29. Most casualties during a tropical cyclone
occur during the storm surge.
In areas where there is a significant difference between low tide and high tide, storm surges are
particularly damaging when they occur at the time of a high tide. In these cases, this increases the
difficulty of predicting the magnitude of a storm surge since it requires weather forecasts to be
accurate to within a few hours. Storm surges can be produced by extratropical cyclones, such as
the Night of the Big Wind of 1839 and the Storm of the Century (1993), but the most extreme storm
surge events typically occur as a result of tropical cyclones. Factors that determine the surge heights
for land falling tropical cyclones include the speed, intensity, size of the radius of maximum winds
(RMW), radius of the wind fields, angle of the track relative to the coastline, the physical
characteristics of the coastline and the bathymetry of the water offshore. The SLOSH (Sea, Lake, and
Overland Surges from Hurricanes) model is used to simulate surge from tropical
cyclones. Additionally, there is an extratropical storm surge model that is used to predict those
effects

(b). STRONG EARTHQUAKE AND
RUPTURE OF SOIL
Earthquake intensity varies. Some are so minor that they can only be felt at the
epicentre. Other earthquakes are so strong that it shakes hundreds of thousands of
square miles.
The worst damage is usually done near the epicentre, which is the place above the
earthquake’s underground centre, or focus. Scientists are able to locate the epicentre
using information from seismographs at different locations.`
6.0–6.9 Strong
Damage to many buildings in populated areas. Earthquake-resistant structures survive
with slight to moderate damage. Poorly-designed structures receive moderate to severe
damage. Felt in wider areas; up to hundreds of miles/ kilometres from the epicentre.
Damage can be caused far from the epicentre. Strong to violent shaking in epicentral
area. Death toll ranges from none to 25,000.

7.0–7.9 Major
Causes damage to most buildings, some to partially or completely collapse or receive
severe damage. Well-designed structures are likely to receive damage.
8.0–9.9 Great
Severe damage to all or most buildings with massive destruction. Damage and shaking
extends to distant locations. Permanent changes in ground topography.
10.0 or greater Epic/Massive
Total devastation; damage extends to distant areas. Landscape and elevation changes
permanently. Death toll usually over 100,000.
MANITUDE OF EARTHQAKE

(C). EARTHQUAKE DAMPING
TECHNIQUES IN TALL BUILDINGS
• There are many earthquake damping techniques used in building high-rise structures in
earthquake-prone areas.
• The two damping techniques studied were cross-bracing and tuned mass dampers.
• Two large "popsicle skyscrapers" were built to see the effects of dampers on skyscrapers
when there is an earthquake.
CROSS-BRACED BUILDING

TUNED MASS DAMPING
A tuned mass damper is a large pendulum
located at the top of the building which helps the
building from swaying during an earthquake.
Taipei 101 has a tuned mass damper in it

(d). SELECTION OF APPROPRIATE MATERIAL
FOR QUAKE PROOFING OF BUILDINGS
Proofed earthquake building material
•Brickwork resists earthquake effects in a way that's different to modern materials. That's a bit of an
issue because engineers who are not used to dealing with brickwork say `get rid of it, it's dangerous'
but you can strengthen it by putting in ties and strengthening structural elements to alter the mode of
response in a building.
•Brickwork could be strengthened with ties and new carbon grouting in cuts run up a wall – work which
could be done in a way that was not easily visible.
•Steel frames, stairways or lift shafts could be used to strengthen building interiors.
•Heavy ornamentation and old chimneys could be removed and replaced with lightweight materials.
Buildings could also be strengthened significantly by wrapping columns with carbon fibre.
•A German composite construction company developed a proofed earthquake-safe supported core
material - based on internal beam/frame constructions. The same principle allows construction of
hurricane-safe houses.

(e)SEISMIC RETROFITTING
Seismic retrofitting is the modification of existing structures to make them more
resistant to seismic activity, ground motion, or soil failure due to earthquakes. With
better understanding of seismic demand on structures and with our recent
experiences with large earthquakes near urban centers, the need of seismic
retrofitting is well acknowledged
Addition of post
cast shear walls

SEISMIC RETROFITTING
•A Seismic Retrofit provides existing structures with more resistance to seismic activity due to
earthquakes.
• In buildings, this process typically includes strengthening weak connections found in roof to wall
connections, continuity ties, shear walls and the roof diaphragm.
METHODS OF SEISMIC RETROFITTING
•Conventional strengthening methods
•Traditional methods of seismic refitting
•Retrofit of structures using innovative materials
•Base isolation
•Supplemental energy dissipation & structural
control

6.Epicentre of earthquake
The epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point
where an earthquake or underground explosion originates.
•In the case of earthquakes, the
epicentre is directly above the point
where the fault begins to rupture,
and in most cases, it is the area of
greatest damage.
• However, in larger events, the
length of the fault rupture is much
longer, and damage can be spread
across the rupture zone.
By measuring the time difference on any seismograph as well as the distance on a travel-time graph at
which the P-wave and S-wave have the same separation, geologists can calculate the distance to the
earthquake's epicentre. This distance is called the epicentral distance.

SOIL CHARACTERISTICS
AND EFFECTS
The two most important geologic characteristics that affect levels of ground shaking during an earthquake are:
•The softness of the ground at a site, and
•The total thickness of sediments above hard bedrock.
The softer and thicker the soil, the greater the shaking or amplification of waves produced by an earthquake.
Ground Softness
Seismic waves travel faster through hard rock than through softer rock and sediments.
As the waves pass from harder to softer rocks, the waves slow down and their amplitude increases. Thus
shaking tends to be stronger at sites with softer surface layers, where seismic waves move more slowly.
Ground motion above an unconsolidated landfill or soft soils can be more than 10 times stronger than at
neighbouring sites on rock for small ground motions.
The effect of the underlying soil on the local amplification is called the site effect.

Behaviour of non structural elements in
the event of earthquake :
Non structural damage is caused in two ways. The component may be directly affected by
ground motion transmitted by the main structure of the building and be subject to
accelerations and consequent inertial forces in a similar way to the building structure.
Alternatively or in addition the non structural component may be affected by movement or
distortion in the structural elements that support or abut the elements.
These two causes can be summarized as acceleration or drift related damage
Non structural items may be located unattached on structure, in which case they will
receive the accelerations and motion of their support.
Depending on the item, it may reproduce the building motion, it may amplify it, or it may
reduce it by sliding or rocking.

7.Construction details of elevated water
tanks in earthquake regions
Supply of drinking water is essential immediately after destructive earthquakes. Without assured
water supply, the uncontrolled fires subsequent to major earthquakes may cause more damage
than the earthquakes themselves.
 So the water supply system should be designed as seismic resistant and seismic performance of
water tanks draws special significance in the design.
 Codes of practice realize that it is uneconomic to design a structure to remain elastic during a
severe earthquake and therefore generally allows some inelastic behaviour.
 The reduction in design forces specified by various codes on account of inelastic behaviour or
ductility is significantly smaller for elevated tank structure compared to building structure.
 The tanks located in a fault region are found to be vulnerable under near fault pulses with a large
duration compared to the natural period of tank.

 The post evaluation study on the failure of elevated water tank shows that there are
significant seismic deficiencies to critical elements, including steel columns, diagonal braces and
horizontal struts.
The frame support of elevated water tank should have an adequate strength to resist axial
loads, moment and shear force due to lateral loads.
 These forces depend upon total weight of the structure, which varies with the amount of
water present in the tank container.
Supporting structure, especially the staging of an elevated water tank does not have much
redundancy.
This lack of redundancy is extremely serious in circular shaft type staging where lateral
stability depends only on the shaft.
 The slender staging resulting from low design forces are unfavourable for seismic areas.

b) Staircases in apartments
The staircases connect the successive levels or stories of a structure and thus contribute
to its lateral stiffness.
If the lateral – load – resisting frame is relatively flexible such as in low- rise frame
structures and the location of staircase in plan affects significantly the tensional rigidity
and response, it may be proper to include staircase in the structural model.
In this way the effect of participation of staircase on seismic effect can be modelled as :
(i) Inclined truss member
(ii) Inclined beam member
Only monolithic connections of the staircase and its supporting beams to the rest of
structure are included in the model as the nodes between the elements.

8.Indian land map divided into
different earthquake zones

Zone 5
Zone 5 covers the areas with the highest risks zone that suffers earthquakes. The IS code
assigns zone factor of 0.36 for Zone 5. Structural designers use this factor for earthquake
resistant design of structures in Zone 5. The zone factor of 0.36 is indicative of effective (zero
period) peak horizontal ground accelerations of 0.36 g (36% of gravity) that may be generated
during MCE level earthquake in this zone. It is referred to as the Very High Damage Risk Zone.
The state of Kashmir , the western and central Himalayas, the North-East Indian region and
the Rann of Kutch fall in this zone.
Generally, the areas having trap or basaltic rock are prone to earthquakes.
Zone 4
This zone is called the High Damage Risk Zone and covers areas liable to MSK VIII. The IS code
assigns zone factor of 0.24 for Zone 4. The Indo- Gangetic basin and the capital of the country
(Delhi), Jammu and Kashmir fall in Zone 4. In Maharashtra Patan area( Koyananager) also in
zone 4.

Zone 3
The Andaman and Nicobar Islands, parts of Kashmir, Western Himalayas fall under this zone.
This zone is classified as Moderate Damage Risk Zone which is liable to MSK VII. and also 7.8
The IS code assigns zone factor of 0.16 for Zone 3.
Zone 2
This region is liable to MSK VI or less and is classified as the Low Damage Risk Zone. The IS
code assigns zone factor of 0.10 (maximum horizontal acceleration that can be experienced
by a structure in this zone is 10% of gravitational acceleration) for Zone 2.
Zone 1
Least active zone

9.The social and
economical consequences
of earthquakeEXAMPLE IN INDIA
The major economic consequences of earthquakes result from damage to elements of the built
environment that are essential to the operation of the economic activities in the impacted region.
 Some economic sectors are by their nature more vulnerable than others.
 Some sectors will even find an increase in their activity because of demands placed on them by
the disaster. Some activities will be winners while others will be losers.
There may be both winners and losers in a particular sector. Factors that will cause businesses
to lose include the direct damage they entail to their facilities because of their location in the area
that was stricken.
Other factors include their dependency on damaged or destroyed support systems of transport
and communication for workers, customers, supplies, shipments, water, electricity, gas,
telephone, and other services.
ECONOMICAL CONSEQUENCES

Businesses that may benefit are ones for which there is an increased demand for their
products or services for relief, clearing and removing debris, repair and restoration, and
reconstruction.
 In total, to an extent depending on flows of external assistance from other regions and local
accumulation of resources, the regional economy may experience an increase rather than a
decrease in income.
 Whether or not a business loses will be greatly influenced in addition to its sector, by the
extent to which the managers have planned, taken precautionary preparations, and necessary
measures to mitigate the impact of a seismic event.
In Japan:
Short term - People were evacuated and emergency rations provided.
Rescue teams searched for survivors for 10 days.
Long term - Many people moved away from the area permanently.
Jobs were created in the construction industry as part of a rebuilding programme.

Long-term impacts
Disease may spread. People may have to be re-housed, sometimes in refugee camps.
SOCIAL
CONSEQUENCES
Short-term (immediate) impacts
People may be killed or injured. Homes may be destroyed. Transport and communication
links may be disrupted. Water pipes may burst and water supplies may be contaminated.
EXAMPLE FOR EARTHQUAKE RELIEF AND
REHABILITATION IN INDIA :
A major earthquake devastated vast areas of Gujarat on 26 January, 2001, killing more
than 20,000 people and rendering millions homeless. A total of 35 million people are
affected. The impact of the earthquake is expected to worsen as there is a severe
drought situation in the State

Proposing to develop reconstruction and rehabilitation activities in communities most
affected by the earthquake as follows:
Disaster resistant housing
Village infrastructure
Livelihood provisioning and security
Establishment and support of community organisations and self help group
Strengthening of local delivery institutions and disaster preparedness
A relief coordination office was set up at the BAPS Headquarters in Ahmedabad to
coordinate all rescues, relief and rehabilitation work.
 Thousands of BAPS volunteers were called for duty.
 Within 40 minutes, BAPS rescue teams were removing rubble to rescue victims in
Ahmedabad, Bhuj and the Morbi sub-districts.
 Within 75 minutes, BAPS centre in Bhuj, which was damaged by the earthquake,
became a sanctuary for hundreds of homeless people. A relief kitchen was set up and by
lunch time, the centre had served hot meals to 3,000 people.

Relief kitchens started preparing hot meals in Ahmedabad for victims and relatives, and rescue
workers, doctors, nurses and paramedics working in affected areas and also at the Civil and VS
hospitals.
BAPS erected large and small tents, and marquees to shelters thousands of homeless victims
from the freezing winter nights. Mattresses and blankets were provided, toilet and bathrooms
facilities arranged and hot meals were served. Secure cloakroom facilities to store belongings
were set up.

10. Safety measures to be adopted in
building design against fire threats
FIRE SAFETY
 In high buildings exists because of the increased number of storeys and because exit stairs
do not normally increase in width as they descend, Stair shafts also represent one of the primary
means by which smoke moves vertically. Additionally, the time it takes an occupant to descend a
stairway increases with the height of the building, thus increasing the potential for smoke exposure.
 The basic issue is that the building egress system must provide sufficient evacuation time
before smoke reaches lethal levels, and thus harms those occupants still remaining in the
building.
 Department can still reach only 6 or 7 floors in a building. Thus exterior rescue and fire
fighting is restricted to the lower floors. With a fire above the reach of ladders, fire-fighters must
move vertically inside the building and launch an interior attack at the same time that occupants are
descending the stairs. This can result in delays in reaching and attacking a fire and to increased
contamination of stair shafts if doors to exit stairs must be left open to run hoses.

As well, fire protection water supplies must also be provided from either the top or
bottom of the building both with associated problems.
As a result of these vertical utilities, other fire problems can occur such as cables to
fire systems being damaged by fire on one level and affecting many other floors.
Typically, they are situated above shopping malls or other commercial Integrated Fire
Problems – High-rise apartment buildings are no longer stand-occupancies, above atrium
buildings containing, for example, offices, or above subway systems.
 Each occupancy has its own unique fire safety problems and coupled with those in
a high-rise apartment building, the problems require special engineered solutions to ensure
occupant safety.
Each of these unique features presents a special problem to be resolved before a designer
can achieve a fire-safe high-rise design. While the Codes provide generalized solutions to many
of the problems, architects must be aware of the problems and the need for unique solutions
based on sound fire safety engineering.

b) FOUNDATION TO BUILDING RESISTANT TO EARTH
QUAKES
FOUNDATIONS
For the purpose of making a building truly earthquake resistant, it will be necessary to
choose an appropriate foundation type for it.
 Since loads from typical low height buildings will be light, providing the re-uired bearing
area will not usually be a problem.
 The depth of footing in the soil should go below the zone of deep freezing
 In cold countries and below the level of shrinkage cracks in clayey soils.
 For choosing the type of footing from the earthquake angle, the soils may be grouped as
Firm and Soft avoiding the weak soil unless compacted and brought to Soft or Firm
condition.

OPENINGS
Door and window openings in walls reduce their lateral load resistance and
hence, should preferably be small and more centrally located.
Openings in any storey shall preferably have their top at the same level so that
a continuous band could be provided over them, including the lintels throughout
the building.
If a window or ventilator is to be projected out, the projection shall be in
reinforced masonry or concrete and well anchored.
If an opening is tall from bottom to almost top of a storey, thus dividing the
wall into two portions, these portions shall be reinforced with horizontal
reinforcement of 6 mm diameter bars at not more than 450 mm intervals, one on
inner and one on outer face, properly tied to vertical steel at jambs, corners or
junction of walls, where used.
The use of arches to span over the openings is a source of weakness and shall
be avoided. Otherwise, steel ties should be provided.

Disaster resistant architecture

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