Earthquake Resistant designs with exp... all the things u need to know

1. EARTHQUAKE
RESISTANT DESIGNS
Submitted by-
PRATEEK SRIVASTAVA
Guided by – AR. Madhura Yadav
Roll no - 27
S.Y. B.ARCH
SEMINAR PROJECT

2. Contents
 What is earthquake?
 Why is it deadly?
 India’s profile
 Need for earthquake resistant design.
 Important considerations for design
 Sesmic vibration control

3. What is Earthquake
 An earthquake (also known as
a quake, tremor or temblor) is the result of a
sudden release of energy in the Earth’s crust that
creates seismic waves.
 In its most general sense, the word earthquake is
used to describe any seismic event — whether
natural or caused by humans — that generates
seismic waves
 The most recent large earthquake of magnitude
9.0 or larger was a 9.0 magnitude earthquake in
Japan in 2011 (as of March 2011), and it was the
largest Japanese earthquake since records began.

4. CONTINENTL
DRIFT

6. Source: from internet

7. Fault
A fault is nothing but a crack or weak zone inside the Earth. When two blocks of rock
or two plates rub against each other along a fault, they don’t just slide smoothly.
As the tectonic forces continue to prevail, the plate margins exhibit deformation as
seen in terms of bending, compression, tension and friction. The rocks eventually
break giving rise to an earthquake, because of building of stresses beyond the
limiting elastic strength of the rock.

8. Effects of earthquakes
 Types-
 Shaking and
ground rupture
 Landslides and
avalanches
 Fires
 Soil liquefaction
 Tsunami
 Floods

10. M > 8 Great Very great
7 - 7.9 Major Great
6 - 6.9 Strong Moderate
5 - 5.9 Moderate Moderate
4 - 4.9 Light Slight
3 - 3.9 Minor Slight
M < 3 Micro
earthquake
EARTHQUAKE MAGNITUDE CLASS
USGS IMD

11. Magnitude Annual Average No.
M > 8 2
7 - 7.9 20
6 - 6.9 100
5 - 5.9 3000
4 - 4.9 15,000
3 - 3.9 >100,000
GLOBAL EARTHQUAKE
OCCURRENCE

12. Records of Worlds Largest
Earthquakes

13. Earthquake as the deadliest
Natural Disaster

14. The Vulnerability Profile - India
 59% of land mass prone to earthquakes
 40 million hectares (8%) of landmass prone to floods
 8000 Km long coastline with two cyclone seasons
 Hilly regions vulnerable to avalanches/landslides/Hailstorms/cloudburst
 68% of the total area susceptible to drought
 Different types of manmade Hazards
 Tsunami threat
 1 million houses damaged annually + human, economic, social and
other losses

15. More than 60 % area is
earthquake prone.
Zone V 12 %
Zone IV 18 %
Zone III 26 %
Zone II 44 %
Fig. courtesy: nicee

16. Casualties during past events
1004 768
8000
38 63
14000
0
2000
4000
6000
8000
10000
12000
14000
Numberofdeaths
Bhuj
Chamoli
Jabalpur
Killari
Uttarkashi
Bihar
?

17. Earthquake Do Not Kill people
Improperly Designed
Structures Do!

21. Earthquake Design Philosophy

23. Need for Earthquake Resistant
Design
 Earthquake Resistant Design is the scientific field
concerned with protecting society, the natural and
the man-made environment from earthquakes by
limiting the seismic risk to socio-economically
acceptable levels.
 Traditionally, it has been narrowly defined as the
study of the behavior of structures and geo-
structures subject to seismic loading, thus
considered as a subset of
both structural and geotechnical engineering.
 However, the tremendous costs experienced in
recent earthquakes have led to an expansion of
its scope to encompass disciplines from the wider
field of civil engineering and from the social
sciences, especially sociology, political sciences,
economics and finance.

24. Earthquake Resistant Design
 The main objectives of earthquake engineering
are:
 Foresee the potential consequences of
strong earthquakes on urban areas and civil
infrastructure.
 Design, construct and maintain structures
to perform at earthquake exposure up to the
expectations and in compliance with building
codes.
 A properly engineered structure does not
necessarily have to be extremely strong or
expensive. It has to be properly designed to
withstand the seismic effects while sustaining an
acceptable level of damage.

25. IMPORTANT CONSIDERATIONS TO MAKE A
BUILDING EARTHQUAKE RESISTANT
1. Configuration
2. Ductility
3. Quality control
4. Base Isolation
5. Passive Energy Dissipating Devices
6. Active Control Systems

26. A terminally ill patient , however
effective the medication, may
eventually die.
Similarly, a badly configured building Cannot
be engineered for an improved performance
beyond a certain limit.
1. Configuration

28. Regular Configuration
 Regular configuration is seismically ideal. These
configurations have low heights to base ratio,
symmetrical plane, uniform section and elevation
and thus have balanced resistance.
These configurations would
have maximum torsional
resistance due to location
of shear walls and
bracings. Uniform floor
heights, short spans and
direct load path play a
significant role in seismic
resistance of the building.

29. Irregular Configuration
Buildings with irregular configuration
Buildings with abrupt changes in lateral
resistance
Buildings with abrupt changes in
lateral stiffness

30. Re-entrant corner

31. Discontinuity in diaphragm Stiffness
Discontinuity in Diaphragm Stiffness
FLEXIBLE
DIAPHRAGM
R I G I D
D I A P H R A G M
O P E N
Vertical Components of Seismic Resisting System

32. Out of plane Offsets
Shear
Wall
Out-of-Plane Offset
in Shear Wall
Shear
walls
Non-parallel
system

34. ELEVATION IRREGULARITIES
1) Soft-Storey/Pan-caked 2) Set-backs 3) Connections

35. Pancaking
Soft storey

36. ELEVATION IRREGULARITIES
4) Pounding 5) Breaks in
Columns
or Beams
6) Staggered
Levels
7) In-fills

37. Open ground storey building (soft storey)

39. Right or Wrong…?

40. Short column effect

42. Ductility
Let us first understand how different materials behave.
Consider white chalk used to write on blackboards and steel pins with solid
heads used to hold sheets of paper together. Yes… a chalk breaks easily!!
On the contrary, a steel pin allows it to be bent back-and-forth. Engineers define
the property that allows steel pins to bend back-and-forth by large amounts, as
ductility; chalk is a brittle material.

43. The currently adopted performance criteria in the earthquake codes are
the following:
i. The structure should resist moderate intensity of earthquake shaking
without structural damage.
ii. The structure should be able to resist exceptionally large intensity of
earthquake shaking without collapse.

44. The strength of brittle construction
materials, like masonry and concrete,
is highly sensitive to the
1. quality of construction materials
2. workmanship
3. supervision
4. construction methods

45. Quality control
special care is needed in construction to ensure
that the elements meant to be ductile are indeed
provided with features that give adequate
ductility.
Thus, strict adherence to prescribed standards of
construction materials and construction processes
is essential in assuring an earthquake-resistant
building.

46. Elements of good quality control.
1.Regular testing of construction
materials at qualified laboratories (at site
or away)
2. Periodic training of workmen at
professional training houses, and
3. On-site evaluation of the technical
work
Prepared by CT.Lakshmanan

47. Seismic vibration control
 After the seismic waves enter
a superstructure, there are a number of ways
to control them in order to soothe their
damaging effect and improve the building's
seismic performance, for instance:
 to dissipate the wave energy inside
a superstructure with properly
engineered dampers.
 to disperse the wave energy between a
wider range of frequencies
 to absorb the resonant portions of the whole
wave frequencies band with the help of so
called mass dampers

48. Oldest Technique
 However, there is quite another approach: partial
suppression of the seismic energy flow into
the superstructure known as seismic or base
isolation.
 For this, some pads are inserted into or under all
major load-carrying elements in the base of the
building which should substantially decouple a
superstructure from its substructure resting on a
shaking ground.
 The first evidence of earthquake protection by
using the principle of base isolation was
discovered in Pasargadae, a city in ancient
Persia, now Iran: it goes back to 6th century
BCE. Below, there are some samples of seismic
vibration control technologies of today.

49. Mausoleum of Cyrus,
the oldest
base isolated
structure in the world

50. Dry –stone walls control
Dry-stone walls of Machu Picchu Temple of the
Sun, Peru

51. Dry-stone walls control
 People of Inca civilization were masters of the
polished 'dry-stone walls', called ashlar, where
blocks of stone were cut to fit together tightly
without any mortar. The Incas were among the
best stonemasons the world has ever seen, and
many junctions in their masonry were so perfect
that even blades of grass could not fit between
the stones.
 Peru is a highly seismic land, and for centuries
the mortar-free construction proved to be
apparently more earthquake-resistant than using
mortar. The stones of the dry-stone walls built by
the Incas could move slightly and resettle without
the walls collapsing, a passive structural
control technique employing both the principle of
energy dissipation and that of
suppressing resonant amplifications.

52. Base isolators
Prepared by CT.Lakshmanan

53. Basic example

55. Lead rubber bearing
 Lead Rubber Bearing or LRB is a type of base
isolation employing a heavy damping. It was invented by Bill
Robinson, a New Zealander.[24]
 Heavy damping mechanism incorporated in vibration
control technologies and, particularly, in base isolation devices, is
often considered a valuable source of suppressing vibrations thus
enhancing a building's seismic performance.
 However, for the rather pliant systems such as base isolated
structures, with a relatively low bearing stiffness but with a high
damping, the so-called "damping force" may turn out the main
pushing force at a strong earthquake.
 The bearing is made of rubber with a lead core.
 Many buildings and bridges, both in New Zealand and elsewhere,
are protected with lead dampers and lead and rubber bearings.
 Te Papa Tongarewa, the national museum of New Zealand
 New Zealand Parliament Buildings
 Both have been fitted with the bearings.
 Both are in Wellington, which sits on an active earthquake fault.

56. Te Papa Tongarewa,
the national
museum of New
Zealand
New Zealand
Parliament
Buildings

57. Simple roller bearing
 Simple roller bearing is
a base isolation device
which is intended for
protection of various
building and non-building
structures against
potentially damaging lateral
impacts of strong
earthquakes.
 This metallic bearing
support may be adapted,
with certain precautions, as
a seismic isolator to
skyscrapers and buildings
on soft ground. Recently, it
has been employed under
the name of Metallic Roller
Bearing for a housing
complex (17 stories)

58. Tuned mass damper
 Typically, the tuned mass dampers are huge
concrete blocks mounted in skyscrapers or other
structures and moved in opposition to
the resonance frequency oscillations of the
structures by means of some sort of spring
mechanism.
 Taipei 101 skyscraper needs to
withstand typhoon winds and
earthquake tremors common in its area of the
Asia-Pacific. For this purpose, a steel pendulum
weighing 660 metric tons that serves as a tuned
mass damper was designed and installed atop
the structure. Suspended from the 92nd to the
88th floor, the pendulums sways to decrease
resonant amplifications of lateral displacements
in the building caused by earthquakes and
strong gusts.

59. Tuned
Mass
Dampers

60. Taipei101

62. Building
Elevation
Control

63. Transamerica
Pyramid
Building,
San Francisco,
USA

64. Building elevation control
 Building elevation control is a valuable source of vibration
control of seismic loading. Pyramid-shaped skyscrapers
continue to attract attention of architects and engineers
because such structures promise a better stability against
earthquakes and winds. The elevation configuration can
prevent buildings' resonant amplifications because a properly
configured building disperses the shear wave energy between
a wide range of frequencies.
 Earthquake or wind quieting ability of the elevation
configuration is provided by a specific pattern of
multiple reflections and transmissions of vertically propagating
shear waves, which are generated by breakdowns into
homogeneity of story layers, and a taper. Any abrupt changes
of the propagating waves velocity result in a
considerable dispersion of the wave energy between a wide
ranges of frequencies thus preventing the resonant
displacement amplifications in the building.
 A tapered profile of a building is not a compulsory feature of this
method of structural control. A similar resonance preventing
effect can be also obtained by a proper tapering of other
characteristics of a building structure, namely,
its mass and stiffness. As a result, the building elevation

65. Building during
Earthquake

66. CROSS-BRACING
 The vertical structural system of a
building consists of columns,
beams and bracing, and functions
to transfer seismic forces to the
ground. Engineers have several
options when building the vertical
structure. They often build walls
using braced frames, which rely
on trusses to resist sideways
motion. Cross-bracing, which
uses two diagonal members in an
X-shape, is a popular way to build
wall trusses. Instead of braced
frames or in addition to them,
engineers may use shear walls --
vertical walls that stiffen the
structural frame of a building and
help resist rocking forces.
Engineers often place them on
walls with no openings, such as
those around elevator shafts or

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