The document outlines the importance of rehabilitation and seismic retrofitting in buildings to mitigate the impact of earthquakes, which are increasingly destructive due to poor construction practices, particularly in developing countries. It discusses various causes of building failures and deterioration, methods for retrofitting and strengthening structures, and guidelines for the selection of materials and techniques. The need for adequate training and policy implementation for effective retrofitting practices is emphasized to improve earthquake resistance in existing buildings.

1. REHABILITATION AND SEISMIC
RETROFITTING
DR. K.M. SONI
CHIEF ENGINEER
WEST ZONE I, CPWD, MUMBAI
1

2. EARTHQUAKES
• EARTHQUAKES DO NOT KILL BUT IT IS
THE BUILDINGS WHICH KILL
• NEARLY 5,00,000 EARTHQUAKES OCCUR
EVERY YEAR
• ABOUT 1,00,000 ARE FELT
• Minor earthquakes occur nearly
constantly around the world in places like
California and Alaska in the U.S., as well
as in Mexico, Guatemala, Chile, Peru,
Indonesia, Iran, China, Pakistan, Portugal,
Turkey, New Zealand, Greece, Italy, India
and Japan, but earthquakes can occur
almost anywhere.
2

3. CASUALTIES
• LARGE NUMBER OF CASUALTIES
OCCUR IN DEVEOPING COUNTRIES.
REASONS MAY BE;
– INADEQUATE DESIGN
– POOR CONSTRUCTION AND
MAINTENANCE
– LACK OF RESOURCES
– INADEQUATE KNOWLEDGE
– INADEQUATE AWARENESS
– INADEQUATE TRAINING
– INADEQUATE SAFETY IMPLEMENTATION
3

4. HAITI’S E/Q, 12.1.2010; DEATHS-3,16,000; MAGNITUDE:7
4http://haitiearthquake.web.unc.edu/

5. TANGSHAN, CHINA, 27.7.1976;
DEATHS-242,769; MAG. 7.5
5travel.smart-guide.net/wp-content/uploads/2010/11/The-Tangshan-

6. SUMATRA E/Q, 26.12.2004
DEATHS;2,27,898
MAG. 9.1
6
http://indonesiabackpacker.com/sumatra-earthquakes/

7. Haiyuan, china
e/q 16.12.1920
Deaths; 2,00,000
Mag. 7.8
7
http://forum.china.org.cn/redirect.php?tid=13090&goto=lastpost

8. Kanto, e/q, Japan; 1.9.1923
Deaths-1,42,800
Magnitude: 7.9
8
http://webra.cas.sc.edu/hvri/feature/sep2013_dom.a
spx

9. Pakistan e/q, 18.10.2005
Deaths; 86000
Mag-7.6
9
www.golder.com/in/modules.php?name=Newsletters&op=viewarticle&sp_i
d=109&page_id=1100&article_id=65

10. Iran e/q, 20.6.1990
Deaths-50,000
Mag. 7.4
10
https://www.emaze.com/@ATQLQCO/suhey-hernandez-.-Iran-Earthquake

11. Gujarat e/q, 26.1.2001
Deaths-20,085, Mag. 7.6
11
(en.wikipedia.org)

12. Latur, india e/q 29.3.1993
Deaths – 9748
Mag. 6.2
12
(www.indiatoday.intoday.in)

13. NEPAL EARTHQUAKE
13
2015, Magnitude: 7.9, deaths over 5000
http://www.ibtimes.co.uk/nepal-earthquake-you-cant-
rule-out-more-earthquakes-come-1500883

14. AFGHANISTAN EARTHQUAKE
14
26th October, 2015
www.slate.com/blogs/the_slatest/2015/10/26/afghanistan_and_pakistan
_earthquake_is_deadly.html

15. 15
CAUSES OF FAILURE OF MASONRY
BUILDINGS
 POOR QUALITY OF MORTAR
 IRREGULARITY IN PLANE AND VERTICAL
DIRECTION
 NO PROVISION OF BANDS
 NO THOROUGH STONES
 HEAVY MASS CONCENTRATION AT ROOF
LEVEL
 UNSYMMETRICAL BUILDINGS AND FULL
OPENINGS
 UNCONFINED WALL CORNERS
 INADEQUATELY DESIGNED CANTILEVER
ELEMENTS
15

16. CAUSES OF FAILURE OF RCC BUILDINGS
 SOFT STOREY (ONE IN WHICH LATERAL
STIFFNESS IS LESS THAN 70% OF THAT IN THE
STOREY IMMEDIATELY ABOVE OR LESS THAN 80%
OF THE COMBINED STIFFNESS OF THREE
STOREYS ABOVE)
 POOR DETAILING OF BEAM COLUMN JUNCTIONS
 PROVISION OF FLOATING COLUMNS
 PLAN AND MASS IRREGULARITY
 INADEQUATE FOUNDATION
 POUNDING OF BUILDINGS
 INADEQUATE DESIGN AND DETAILING
 INADEQUATE CONNECTVITY LIKE ISOLATED
STAIRCASES AND WATER TANKS NOT PROPERLY
ANCHORED
16

17. 17

18. 18
NORMALLY STRUCTURES REQUIRING REPAIR
ANDREHABILITATION ARE MORE SUSCEPTIBLE
TO DAMAGE, HENCE REPAIRAND
REHABILITATION IS VERY IMPORTANT
18

19. CAUSES OF DETERIORATION OF
RCC
 PENETRATION OF
WATER/CHEMICALS LEADING TO
CARBONATION, CHLORIDE
INGRESS, LEACHING, SULPHATE
ATTACK, ALKALI SILICA REACTION
ETC LEADING TO
CORROSION IN THE
REINFORCEMENT
19

20. MAIN REASON OF PENETRATION OF WATER
 POROSITY OF CONCRETE
20

21. PRECAUTIONS TAKEN TO PREVENT
POROSITY
 ADEQUATE STRENGTH OF
CONCRETE
 PROPER COMPACTION
 WATER PROOFING ON ROOF
 PLASTER ON CONCRETE
 WATER PROOFING PAINTS ON
EXPOSED PLASTERED SURFACE
21

22. CAUSE OF DETERIORATION OF CONCRETE
 AGING OF STRUCTURE
 POOR QUALITY
◦ POOR QUALITY OF
TESTING/INVESTIGATION
◦ POOR QUALITY OF DESIGN
◦ POOR QUALITY OF EXECUTION IN
TERMS OF
MATERIALS/COMPACTION/PAINTS/CO
VER/RCC
◦ POOR QUALITY OF MAINTENANCE
22

23. SELECTIONOF MATERIALS FOR
REHABILITATION/ RETROFITTING
 TECHNICAL REQUIREMENTS
 COST
 AVAILABILITY
 EXPERT’S ADVICE
 IMPORTANCE OF THE STRUCTURE
 BALANCE LIFE OF THE STRUCTURE
 TOXICITY OF THE MATERIAL
 AESTHETIC CONSIDERATION
23

24. REHABILITATION METHODS
 SAND BLASTING FOR REMOVAL OF
CORROSION
 BINDING/ADDING OF ADDITIONAL
REINFORCEMENT
 WELDING
 ANCHORING TO THE EXISTING MEMBERS
THROUGH SHEAR KEYS OR ANCHORS
 SHOTCRETING
 PLATE BONDING
 JACKETING
 FIBRE WRAPPING
 UNDERPINNING
24

25. PROCEDURE
 REMOVAL OF LOOSE
MATERIALS/RUST
 PROVIDING PROTECTIVE
LAYER/COATING
 PROVIDING BONDING COAT
BETWEEN OLD AND NEW
MATERIAL/SURFACES
 PROVIDING STEEL
MEMBERS/WELDING/ANCHORS/
SHEAR KEYS TO ENSURE
MONOLITHIC ACTION
25

26. RETROFITTING
 PLATE BONDING
 FIBRE WRAP TECHNIQUES
THROUGH GLASS
FIBRES/CARBON FIBRES
 RCC JACKETING
26

27. MASONRY STRUCTURES
28

28. VULNERABILITY
 BRICK/STONE MASONRY
STRUCTURES ARE MORE
VULNERABLE?
 DISASTER= VULNERABILITY X
HAZARD
 BRICK STRUCTURES ARE MORE IN
THE COUNTRY
 SO WE NEED SAFE BRICK MASONRY
STRUCTURES
 IF NOT, WE NEED TO MAKE THEM
SAFE BY RETROFITTING.
29

29. SEISMICSTRENGTHENING/ RETROFITTING
 THE TECHNIQUE TO UPGRADE THE
STRUCTURE FOR EARTHQUAKE
RESISTANCE TO THE LEVEL OF
PRESENT DAY CODAL REQUIREMENTS
HAVING ORIGINAL STRUCTURAL
INADEQUACY OR INADEQUACY DUE
TO MATERIAL DEGRADATION OVER
TIME OR DUE TO ALTERATIONS
CARRIED OUT DURING ITS USE OVER
THE YEARS
30

30. SEISMIC STRENGTHENING
 MAIN PURPOSE OF SEISMIC
STRENGTHEING IS TO
UPGRADE/PROVIDE THE SEISMIC
RESISTANCE ON A BUILDING SO THAT
IT BECOMES SAFER UNDER
EARTHQUAKE OCCURANCES
 AVOIDING THE POSSIBILITY OF
BRITTLE MODES OF FAILURE BY
PROPER REINFORCEMENT AND
CONNECTION OF RESISTING MEMBERS
31

31. IS CODES
 CODES
◦ IS 13935 (JUNE 2009) – GUIDELINES FOR
REPAIR, RESTORATION, CONDITION
ASSESSMENT AND SEISMIC
STRENGTHEING OF MASONRY BUILDINGS
◦ DRAFT CODE WITH COMMENTARY ON
SEISMIC EVALUATION AND STREGTHENING
OF EXISTING BUILDINGS FOR RCC
STRUTURES
32

32. GENERAL PROVISIONS REQUIREDIN MASONRY
BUILDINGS
 PLINTH BAND
 LINTEL BAND
 ROOF SLAB/ROOF BAND
 CORNER REINFORCEMENT
 BRICK WORK IN CEMENT MORTAR
OF 1:6
 RESTRICTED OPENINGS
 ADEQUATE FOUNDATION
33

33. SELECTIONOF MATERIALS ANDTECHNIQUES
FOR RETROFITTING
 CEMENT
 STEEL
◦ BOLTS, RODS, ANGLES, BEAMS,
CHANNELS, EXPANDED METAL, WELDED
WIRE FABRIC
 ADMIXTURES TO IMPROVE NON-
SHRINKAGE (GROUTS CONSISING
POLYMER, NON-SHRINK CEMENT AND
SPECIAL SANDS), BOND (EPOXY
RESINS) ETC.
34

34. 35
35

35. SEQUENCE OF RETROFITTING
 REPAIR/REHABILITATION
 ALL CRACKS SHOULD BE FULLY
REPAIRED
◦ PRESSURE INJECTION OF NON-SHRINK
CEMENT POLYMER GROUT FOR 0.5 TO 5 MM
CRACKS
◦ REPAIR BY EXPANSIVE CEMENT MORTAR,
QUICK SETTING CEMENT, ADDL. SHEAR OR
FLEXURAL REINFORCEMENT, STEEL MESH,
STEEL RODS
36

36. REPAIR/STRENGTHENING OF WALLS
 BY GROUTING (CEMENT WATER MIXTURE
OR POLYMERIC MORTAR)
 BY ADDITION OF VERTICAL REINFORCEMENT
CONCRETE COVERINGS ON THE TWO SIDES
OF THE WALL
 BY PRESTRESSING WALL
37

37. HORIZONTAL SEISMIC BELTS
 TO BE PROVIDED
◦ ON ALL WALLS
◦ ON BOTH THE FACES
◦ JUST ABOVE THE LINTEL
◦ BELOW ROOF
◦ BELOW FLOOR
◦ IN CASE OF RCC SLAB ROOF BELT NOT
REQUIRED
◦ NOT REQUIRED AT PLINTH LEVEL UNLESS
PLINTH HEIGHT IS MORE THAN 900 MM
38

38. ON ALL WALLS
ON BOTH THE FACES
ABOVELINTEL
39

39. 40

40. 41

41. 42

42. SEISMICBELTS AROUNDDOOR/WINDOW
OPENINGS
 IN CATEGORY “D” AND “E” BUILDINGS
 MESH OF GAUGE 10 WITH 8 WIRES IN
VERTICAL DIRECTION SPACED AT 25 MM IN A
BELT WIDTH OF 200MM OR
 GAUGE 13 WITH 10 WIRES IN VERTICAL
DIRECTION SPACED AT 25 MM IN A BELT
WIDTH OF 250MM (IN CAT. C BUILDINGS
ALSO)
43

43. AROUNDOPENINGS
44

44. 45

45. 46

46. 47

47. VERTICAL SEISMICBELTS AT CORNERS
 AT THE CORNERS OF ROOMS
 JUNCTIONS OF THE WALLS
 WIDTH ON EACH SIDE OF THE
CORNER TO BE KEPT 25 MM
EXTRA TO THE WIDTH OF THE
MESH
 REIFORCEMENT TO BE STARTED
BELOW 300 MM BELOW PLINTH
LEVEL
48

48. 49
AT EXTERNAL CORNERS

49. 50

50. 51

51. 52

52. VERTICAL REINFORCEMENTAT
INSIDECORNER
53

53. 54

54. ROOFS CONSISTING OF STEEL JOISTS FLAT OR SEGMENTAL
ARCHES MUST HAVE HORIZONTAL TIES HOLDING THE JOISTS
HORIZONTALLY IN EACH ARCH SPAN SO AS TO PREVENT
SPREADING OF JOISTS
55

55. ANCHORS
 MECHANICAL ANCHORS
 CHEMICAL ANCHORS
56

56. 57
PROCEDURE OF ANCHORING

57. 58

58. SPECIFICA
TIONS FOR
HORIZONT
AL SEISMIC
BELT
SPEC. FOR
VERITICAL
REINFORC
EMENT
59

59. 60

60. 61

61. 62

62. 63

63. 64

64. 65

65. 66

66. Additional steps
 Repair and rehabilitation to be carried
out prior to retrofitting.
 At the external corners, on each face
of the wall, the width of the mesh for
corner reinforcement may be kept as
minimum 250 mm on each wall so that
it covers minimum one brick.
 The mesh reinforcement at the
corners may be kept minimum 300
mm below ground level
67

67. •On the internal cross walls
since stiffening is available,
horizontal seismic belt can
be restricted just to have
anchoring effect on cross
wall. In the present case
this was limited to 600 mm.
68

68. Contd.
 Mesh reinforcement used should be
galvanized steel and anti rusting paint should
be applied on the cut points to prevent
corrosion.
 MS washers used on wire mesh should be
painted with anti corrosive paint. In the
present case, M.S. washers of size 50X50X5
mm were used to anchor the mesh
reinforcement.
 Since it was not possible to provide roof belt
of mesh of required width in central portion
due to segmental arch construction and
ventilators provided near the top portion, MS
flat belt was provided.
69

69. •The anchors are to be inserted into
the hole after the grout is inserted
within gel time, which is given 4
minutes for temperature of 30 degree
Celsius and 6 minutes for 20 degree
Celsius for the anchors and chemical
grout used from Hilti India Private
Limited.
70

70. •In the inside corner
reinforcement, a prefabricated
MS piece was used having two
holes, one used for inserting
into the bar which can be
adjusted at any position and
other end used for inserting
anchor. Chemical anchoring
was done thereafter.
Anchoring on wire mesh should
be in staggered (zig-zag)
manner. 71

71. 72
TRAINING, SKILL UPGRADATION AND
COMPETENCE DEVELOPMENT
• STAKEHOLDERS
– POLICY MAKERS
– TRAINERS
– PARTICIPANTS
– IMPLEMENTERS
POLICY MAKERS
TRAINERS
PARTICIPANTS
IMPLEMENTERS
72

72. Item 1
 Providing and fixing 250 mm wide or
required size seismic belt for
retrofitting with 12 gauge (2.64 mm
dia) galvanized iron welded mesh with
25 mm spacing of wire on walls at
required height (inside and out side
the building ) fixed in position with
headed nails at required distance
complete as per direction of Engineer-
in-charge. (Cut end of wire mesh to be
painted with NitoZinc Primer)
73

73. Item 2
 Providing and fixing stainless steel anchors of
8 mm dia (HAS-EM8 x 80 / 14) of HILTI or
equivalent on GI wire mesh at required
distance in staggered position i/c drilling of 10
mm dia hole with HILTI hammer drill machine
TE-6S or equivalent and cleaning of hole by
brush and blow out pump. Anchors shall be
fixed by resin and hardener pack of HILTI
make HY-150/330/2R or equivalent (35 holes
per tube of 330 ml) chemical. Mesh will be
fixed with MS washer of size 50x50x5 mm
painted with NitoZinc primer (FOSROC) on
top of the mesh with anchor screwed with nut
complete as per direction of Engineer- in-
charge.
74

74. Item 3
 Painting on galvanized iron / steel
work such as M.S. angle, flat, cold
twisted bars with Protective / Bond
coats i.e NitoZinc (FOSROC) primer of
approved brand and manufacture as
per direction of Engineer-in-
charge.(Surface area of steel work
shall be measured for payment)
75

75. Item 4
 Providing and Fixing steel
reinforcement bar 10 mm dia for
seismic strengthening of building at
inside corner i/c fixing with M.S. cleat
50x50x6 mm size having 2 holes. The
reinforcement bar shall pass through
one hole and other hole shall be used
for anchoring into brick / CC wall.
(The payment for steel reinforcement,
Anchor & grouting at floor and roof
shall be paid for separately)
76

76. Item 5
 Providing and fixing seismic band for
seismic strengthening of size 50x5
mm flat iron section at required level
including making necessary holes not
more than 75 cm apart and keeping in
position with nails and finally fixing
with Anchors ( Payments for Anchors
& its fixing shall be made separately).
77

77. Item 6
 28 mm thick Acrylic modified cement
mortar/micro concrete band at required level
with mix 1:1:2 (1 cement : 1 coarse sand : 2
graded stone aggregate 6 mm & down
nominal size) in two coats admixed with
polymer modified compound (Armourcrete /
Tapecrete) @ 10% of cement (by weight)
used area and including slurry coat of Acrylic
cement @ 2.2 kg / sqm mixed with polymer
modified compound (Armourcrete/ Tapecrete)
@ 10% of cement used and finished smooth
complete (top layer will be of 12 mm plaster).
78