This document discusses past earthquakes in India and retrofitting techniques for masonry structures. It summarizes the 2004 Indian Ocean earthquake and tsunami, which had a magnitude of 9.1-9.3 making it one of the largest ever recorded. Over 230,000 people were killed across 14 countries by the resulting tsunamis. The document then discusses failure modes of confined masonry walls and retrofitting techniques to improve seismic resistance, including adding horizontal reinforcement, improving wall density and tie columns. Key factors for seismic resistance of confined masonry structures are also summarized.

1. PAST EARTHQUAKES IN INDIA AND
THEIR RETROFITTING
TECHNIQUES
BY
Y.BOOPATHI

2. 2004 INDIAN OCEAN EARTHQUAKE AND
TSUNAMI
 It was an undersea mega thrust earthquake that
occurred at 00:58:53 UTC on Sunday, 26
December 2004, with an epicenter off the west
coast of Sumatra , Indonesia.
 The resulting tsunami is given various
names, including the 2004 Indian Ocean
tsunami, South Asian tsunami, Indonesian
tsunami, and the Boxing Day tsunami.

5.  The earthquake was caused by subduction and triggered
a series of devastating tsunamis along the coasts of most
landmasses bordering the Indian Ocean, killing over
230,000 people in fourteen countries, and inundating
coastal communities with waves up to 30 meters (98 ft)
high.[

6.  With a magnitude of Mw 9.1–9.3, it is the third largest
earthquake ever recorded on a seismograph. The
earthquake had the longest duration of faulting ever
observed, between 8.3 and 10 minutes. It caused the
entire planet to vibrate as much as 1 centimeter (0.4
inches)
 In all, the worldwide community donated more than $14
billion (2004 US$) in humanitarian aid.

7.  The hypocentre of the main earthquake was
approximately 160 km (100 mi), in the Indian Ocean
just north of Simeulue island, off the western coast
of northern Sumatra, at a depth of 30 km (19 mi)
below mean sea level (initially reported as 10 km
(6.2 mi))

8. TECTONIC PLATES
 An estimated 1,600 kilometres (1,000 mi) of fault
surface slipped (or ruptured) about 15 metres (50 ft)
along the subduction zone where the India
Plate slides (or subducts) under the
overriding Burma Plate. The slip did not happen
instantaneously but took place in two phases over a
period of several minutes.

9.  Seismographic and acoustic data indicate that the first
phase involved a rupture about 400 kilometers (250 mi)
long and 100 kilometers (60 mi) wide, located 30
kilometers (19 mi) beneath the sea bed—the largest
rupture ever known to have been caused by an
earthquake
 A pause of about another 100 seconds took place before
the rupture continued northwards towards the Andaman
and Nicobar Islands.

10. ENERGY RELEASED
 The energy released on the Earth's surface only
(ME, which is the seismic potential for damage) by
the 2004 Indian Ocean earthquake and tsunami
was estimated at 1.1×1017 joules or 26 megatons of
TNT(Trinitrotoluene).
 This energy is equivalent to over 1500 times that of
the Hiroshima atomic bomb, but less than that
of Tsar Bomba , the largest nuclear weapon ever
detonated

11. DEATH TOLL AND CASUALTIES
 According to the U.S. Geological Survey a total of
227,898 people died.
 Indonesia was the worst affected area, with most
death toll estimates at around 170,000.

12. RETROFITTING TECHNIQUES USED IN
MASONRY STRUCTURE
 The following failure modes characteristic of
confined masonry walls:
• Shear failure mode, and
• Flexural failure mode
 Shear failure mode is characterized by distributed
diagonal cracking in the wall
 A masonry wall panel resists the effects of lateral
earthquake loads by itself while the confining
elements (tie-columns) do not play a significant
role.

13. SHEAR FAILURE OF CONFINED MASONRY
WALLS

14.  Flexural failure caused by in-plane lateral loads is
characterized by horizontal cracking in the mortar
bed joints on the tension side of the wall
 Separation of tie-columns from the wall was
observed in some cases (when toothed wall-to-
column connection was absent).

15. FLEXURAL FAILURE OF CONFINED MASONRY
WALLS

16. KEY FACTORS INFLUENCING SEISMIC
RESISTANCE
OF CONFINED MASONRY STRUCTURES
 Wall Density
 Masonry Units and Mortar
The lateral load resistance of confined
masonry walls strongly depends on the strength of
the masonry units and the mortar used
 Tie-Columns
 Tie-columns significantly influence the
ductility and stability of cracked confined masonry
walls.

17.  Horizontal Wall Reinforcement
 to provide horizontal joint reinforcement in the form of
one or two wires laid in the mortar bed joint

18.  Openings
when the opening area is less than approximately
10% of the total wall area, the wall lateral load resistance
is not significantly reduced as compared to a solid wall

20. SOME OF THE MASONRY STRUCTURE FAILURE

23. EARTHQUAKE-RESISTANT CONFINED MASONRY
CONSTRUCTION: A GUIDELINE
 Background
Confined masonry construction has typically
performed well in past earthquakes
worldwide, when built according to code
requirements. Its satisfactory earthquake
performance is due to the joint action of masonry
walls and their confining elements. Properly
designed and built confined masonry buildings are
expected to experience damage in severe
earthquakes.

24. ARCHITECTURAL GUIDELINE
BUILDING LAYOUT

25. BUILDING ASPECT RATIO

26. SYMMETRICAL WALL LAYOUT

27. CONTINUOUS WALLS UP THE BUILDING
HEIGHT

28. POSITION OF OPENINGS IN A BUILDING

29. MASONRY WALL CONSTRUCTION

30. FOUNDATION CONSTRUCTION: A) RC
PLINTH BAND AND STONE MASONRY
FOUNDATION; B) RC STRIP FOOTING

31. LINTEL BEAM RENFORCEMENT (TIE-COLUMN
REINFORCEMENT) EXCEED 1.5M

32. CONFINED MASONRY CONSTRUCTION
 Over the last 100 years, confined masonry
construction has emerged as a building technology
that offers an alternative to both unreinforced
masonry and RC frame construction
 Confined masonry construction consists of masonry
walls (made either of clay brick or concrete block
units) and horizontal and vertical RC confining
members built on all four sides of a masonry wall
panel. Vertical members, called tie-columns
orpractical columns.

33. A TYPICAL CONFINED MASONRY BUILDING

34. CONFINED MASONRY BUILDING
 The structural components of a confined masonry
building are
Masonry walls – transmit the gravity load
from the slab(s) above down to the foundation. The
walls act as bracing panels, which resist horizontal
earthquake forces. The walls must be confined by
concrete tiebeams and tie-columns to ensure
satisfactory earthquake performance.

35.  Confining elements (tie-columns and tie-beams) –provide
restraint to masonry walls and protect them from
complete disintegration even in major earthquakes.
These elements resist gravity loads and have important
role in ensuring vertical stability of a building in an
earthquake.

36.  Floor and roof slabs – transmit both gravity and lateral
loads to the walls. In an earthquake, slabs behave like
horizontal beams and are called diaphragms.
 Plinth band – transmits the load from the walls down to
the foundation. It also protects the ground floor walls from
excessive settlement in soft soil conditions.
 Foundation – transmits the loads from the structure to the
ground.

37. Thank u