Structure Repairs & Rehabilitation

Report
Structure Repairs &
Rehabilitation
Presentation From TSG
Structure Repairs & Rehabilitation
This presentation is not for low strength
masonry building.
Low Strength Masonry Building is Laid in
• a) Fired brick work in clay & mud mortar
• b) Random rubble ; Un coursed,
Undressed stone masonry in weak
mortars made of cement-sand , limesand & clay-mud
Structure Repairs & Rehabilitation
Type Of Building Construction based On Design &
Supervision
• Engineered Building
(Designed & supervised By Engineer)
• Non-Engineered Building
(Built by Mason, Carpenters without Input From
Engineer)
• Semi Engineered Building
(Ex. In masonry Building, where Load bearing wall had
not been properly designed. Generally It is built by
Architect & Contractors without involving Engineer
effectively)
• Pre- Engineered Buildings
(Those Non Engineered building which comply IS 4326,IS
13827, IS 13828 ,IS 13935)
Structure Repairs & Rehabilitation
Life Of Structure Depend Upon:
A. Geography Of Location
B. Building Material
C. Technology
D. Workmanship
Structure Repairs & Rehabilitation
Categories Of Seismic Damage
Damage Categories
Extent Of Damage In General
Suggested Post Earth Quake
Action
G1
Slight Non Structural Thin Crack in Plaster, Falling of
Damage
Plaster bits in limited parts
Building Need Not to
Vacated., only architectural
repairs required.
G2
Slight Structural
Damage
Small crack in walls, Falling of
Plaster in large bits over large
areas; Damage of non structural
Parts like projecting of cornice,
kitchen chimney etc.(The load
carrying capacity is not reduced
appreciably.)
Building Need Not to
Vacated., Cracks in walls
need grouting. Architectural
repairs carried out to
achieve durability. Seismic
strengthening is desirable.
G3
Moderate Structural
Damage
Large & deep Crack in walls;
Cracking of walls, columns, piers,
& tilting or falling of chimney.
(The load carrying capacity of
structure is partially reduced.)
Building Need to be
Vacated for structural
restoration & seismic
strengthening. Finally
Architectural treatment
may be carried out.
Structure Repairs & Rehabilitation
Categories Of Seismic Damage
Damage Categories
Extent Of Damage In General
Suggested Post Earth Quake
Action
G4
Severe Structural
Damage
Gaps occur in walls; Inner or
outer wall collapse; Failure of
ties. Approximate 50% of the
main structural elements fail. The
building takes a dangerous
states.
Building has to be vacated.
For demolishing or
extensive restoration &
strengthening work has to
be carried out.
G5
Collapse
A large part of whole of the
building collapses.
Redesign & construction of
Building .
This Table is useful for cost deciding estimation for
rehabilitation of building.
Structure Repairs & Rehabilitation
Earthquake Effects on Soils & Foundations & Solutions
For Foundations
Type “I” Rock Or Hard Soil-Well graded gravel Mixtures
with or without clay binder, and clayey sands poorly
graded or sand clay mixtures(GB,CW,SB,SW & SC)
N>30
Type “II” Medium Soils- All soils N= 10 to 30 & Poorly
Graded Sands Or Gravely Sands with Little or No
fines (SP) with N>15
Type “III” Soft Soils Other than SP with N < 10.
Structure Repairs & Rehabilitation
S.
Type Of Soil Damaging Effect Of
No.
Earth quake
Earth quack Resisting
Feature for foundation
1.
2.
Use any foundation type
•Use any foundation type
•Use tie beams in case of
Individual column
Foundations
3.
a.
Type I Hard
Type II
Medium
None
•Not much in Zones
II & III
•Relative Lateral
Movement Possible
in Zone IV,V
Type III Soft Not Much In Zone II
Low Water
Table
Relative Movement
Is Possible In Zone
III to V
Use Any Type of Foundation.
& Use plinth bend.
Use Plinth beam to connect
all type of foundation such as
isolated, combined column
footings Or provide rafts Or
piles as needed for the loads.
Structure Repairs & Rehabilitation
S.No.
Type Of Soil
3.
b.
Type III Soft
Some relative movement
Liquefiable with in Zone II
high water table Relative Lateral & Vertical
movements in Zone III
3c.
Black Cotton
Soil
Damaging Effect Of Earth
quake
Earth quack Resisting Feature
Use Plinth beam to connect isolated
Foundations
Use piles going to stable soil layer or
minimum 10 m length. Driven piles
preferable.
Liquefaction resulting in
tilting/ overturning of
buildings & structures
likely in zones IV & V
Improve the soil to a depth of 7 to 8m
or up to stable layer if met earlier,use
dynamic compaction or by compaction
piles. Use piles going to stable soil layer
or minimum 10 m length. Driven piles
preferable.
Soil not seen to be
affected in intensity VII
shaking in Latur, Jabalpur
earthquakes but effect of
ground motion amplified
on the buildings
Use Plinth beams to connect individual
column footings. Use Plinth Band in
case of strip foundations. Use of under
ream piles preferable
Structure Repairs & Rehabilitation
Retrofitting is needed for following defects Rectification
•
•
•
•
•
Crack & Spalling In Structural Members
Crack & Settlement In Flooring
Crack & Spalling in Non Structural Members
Leakage In Water Supply & Drainage System
Redesigning existing structure for nature forces
Cracks May Be Horizontal, Vertical & Diagonal
Structure Repairs & Rehabilitation
Crack & Spalling In Structural Members
• Cracks Occur Due To Settlement In Foundation
• Cracks Due To Earth Quack ,Wind,cyclone
• Crack Due To Overloading Of Structure
• Crack Due To Reduction in Load Carrying
Capacity of Structure Due To Weathering
• Crack Due To Improper Design Of Structure
• Crack due to Poor connection Of Structural
Members Resulted From Poor Workmanship
Structure Repairs & Rehabilitation
Crack & Settlement In Flooring
• Due To Improper Plinth Filling
• In case of black cotton soil in foundation, if it has
been not replaced up to sufficient depth by Good
Soil under plinth (For generating enough Counter
weight upon black cotton soil)
• Variation in Water Table within the Plinth Sub base
(this occur in frequent flooding area & near sea
soar)
• Improper curing, Improper laying, Poor Quality of
Mortar.
• Improper Design for loading i.e. thickness & type of
flooring.
Structure Repairs & Rehabilitation
Crack & Spalling due to Non Structural Reasons
• Crack In R.C.C.
• Crack In Water Proofing Work
• Crack In Brick work
• Crack In Plaster
• Crack In finishing
This cracks occur due to shrinkage, thermal
expansion, carbonation, moisture changes in
soil, creep, weed.
Structure Repairs & Rehabilitation
Leakage In Water Supply & Drainage
• It may result from structural cracks & settlement
• Improper selection of pipe thickness
• Improper selection of Supports & its spacing to
Pipe
• Improper making Of joints
• Non Provision for contraction & expansion
(Particularly when pipe is passing over different
type of structure)
• Non Testing of Pipe before & after laying
• Insufficient soil cover over pipe
Structure Repairs & Rehabilitation
These Crack occur
around opening due
to drying shrinkage &
thermal movement in
a building, resulting
weakening in the wall.
Structure Repairs & Rehabilitation
Expansion & thickening of
roots creating
concentration of stress at
joints & weak locations such
as openings.
Structure Repairs & Rehabilitation
The long horizontal crack resulted due to
deflection of slab and lifting of edge of the slab, It
combined with horizontal movement in the slab
due to shrinkage.
Structure Repairs & Rehabilitation
Drying shrinkage and thermal contraction of slab exert a pull on the wall
because of this pull results in bending of the wall which causes cracking
at a weak section, that is, at the lintel or sill level of the window
openings. Such cracks generally occurs when windows and room spans
are very large. This cracks can be avoided by providing slip joints at slab
supports on the walls.
Structure Repairs & Rehabilitation
Flexural Tension Cracks At Lintel Level Due to Shrinkage &
contraction of R.C.C. Slab
CRACK ON LINTEL LEVEL
Structure Repairs & Rehabilitation
Thickness of plaster is
too much & silt content
is also Very High
Structure Repairs & Rehabilitation
Vertical crack under
window occur when
wall have large
window opening &
little wall space on
both side of opening.
Difference in stress
between wall portion
adjoining to window
& wall under sill
results in crack.
CRACK
Structure Repairs & Rehabilitation
Cantilever Chajja
not having main
bars on upper face
Structure Repairs & Rehabilitation
When two adjacent walls shake in different
directions, their joint at corners comes under a lot
of stress. This causes crack at the junction of two
walls
CRACK
In Normal conditions,
cracks in this location
comes when one of
wall expand more
than short wall.
Structure Repairs & Rehabilitation
Similarly the walls bends outward or inwards
horizontally in the middle of its height, this stretching
causes tension and causes horizontal cracks in the
walls. This happens at the eve level of gable wall.
CRACK
Structure Repairs & Rehabilitation
When the long wall bends outward or inwards
vertically in the middle of its length, this stretching
causes tension and causes vertical cracks in the
walls.
CRACK
Structure Repairs & Rehabilitation
Many times the wall gets pulled from its corners. This
results in to tearing of wall in diagonal direction. In the
wall if there is a window or a door, then the diagonal
crack occur at their corners.
Diagonal
Crack
Structure Repairs & Rehabilitation
Make sure there are no hidden conduits within
masonry
Structure Repairs & Rehabilitation
Redesigning existing structure for nature forces
It is a comprehensive task & require planning which
include following Information gathering.
• Field investigations including details of sub strata,
foundation details, extent of damage
• Type of Existing structure & Design Data Collection
• Checking of Members stability
• Identification of components required to be
strengthened
• Cost Estimates (it is feasible up to 60% of new
construction)
• Then rehabilitation Method or Procedure is decided.
Structure Repairs & Rehabilitation
Crack Investigation
• Location
• Profile (vertical, Horizontal, Diagonal)
• Crack Size throughout length (Width,Depth & length)
Thin crack< 1mm
Medium Crack >1 to 2 mm
Wide Crack > 2 mm
Crack may be non-uniform width. i.e. Tapper in
width(narrow at one end & wider at other end. )
• Static or Live cracks
Structure Repairs & Rehabilitation
Diagonal cracks accompanied by outward tilting of
external walls
Moderate
cracking
could be
controlled to
some extent
by providing
water- proof
apron as
shown in a
slide.
Floor is
replaced by
brick ballast up
to 600 mm
depth &
relaying base
concrete &
flooring .
When foundation rest on B.C. Soil, drying out is likely to be more at the
periphery of the building and less in the inner regions. However in rainy
seasons reverse movement is there but cracks remains unclosed fully .
Structure Repairs & Rehabilitation
Diagonal cracks across the corner of a building
affecting two adjacent walls
These cracks are due to drying shrinkage of the foundation
soil when building is built on shrinkable clay soil and has a
shallow foundation
Structure Repairs & Rehabilitation
Flexible waterproof Apron Around a building to
reduce moisture variation in soil under the building
Inside
This 2.0 m wide
apron is generally
is made around 0.5
m below G.L. 1 to 2
month after
monsoon
Outside
Tar felt or
Alkathene
Sheet
Lime concrete 100 mm
thick laid to slope
1 in 30, Chased 30 to
40 mm into masonry
Structure Repairs & Rehabilitation
• Cracks are static or live, is monitored & recorded
by “Tell-Tale” method
Widening Of Crack
Crack
in wall
Quick setting
mortar or
Adhesive
Marking
Crack in
in Glass
Glass strips
Glass strips of 2 to 3
C.M. in width & 10 to
12 C.M.in length
Structure Repairs & Rehabilitation
Structural Repairs
Load Bearing Walls: PROCEDURE IN NEXT SLIDE
CRACK IN BRICK
PLACING OF RCC
BLOCK AFTER
CUTTING HOLE IN
B.W.
Structure Repairs & Rehabilitation
•
•
•
•
Repairing Of Crack Due To Settlements
Replace all crack bricks
Use R.C.C. Stitching Block In Vertical Spacing In Every
5th or 6th Course ( 0.5 meter apart ).
Stitching block has fallowing size.
Width is equal to wall width,
Length is equal to 1.5 to 2 bricks length &
Thickness equal to 1 or 2 bricks as per severity of
cracks
Mortar For Repairs 1:1:6 (1 Cement :1 Lime : 6 Sand)
Structure Repairs & Rehabilitation
Corrective Measures For Load Bearing Wall Building
• Therefore Shifting of Window, creation of more
window, Door ,Inbuilt construction of Almirah
should be carried out with due consideration to IS
code 13935:1993 & as explained in this
presentation.
• Proper Bearing to lintel over brick work to avoid
diagonal cracks & it can be done in retrofitting
work.
• It is advisable that keep window width as less as
feasible while height can be increased with fixed
small glass pans on top portion.
Structure Repairs & Rehabilitation
• Make structure floor, roof lighter as much as
possible.
• Avoid Un- symmetry of structure as much as
possible. For this purpose structure can be divided.
• Do Sand Pilling ,Stabilization of weak & sandy soil
having high water level.
• Proper Connections of building Elements.
• Use steel to strengthen load bearing wall as per code
requirement.
• Provide adequate plinth protection.
• Avoid to built Rigid masonry Building resting on rock
in Earth Quack porn area.
Structure Repairs & Rehabilitation
Lateral Supports To Long Wall
R.C.C./B.W. Columns
Maximum 6m Interval
Buttress Maximum
6m Interval
Structure Repairs & Rehabilitation
• Avoid keeping shallow foundation on Black
Cotton Soil.
• Use one type of foundation in a whole
building to avoid differential settlement.
• Physical quality check on material should me
periodic.
• A.R.C. which is structurally independent from
an existing building should be designed &
constructed in accordance with the seismic
requirements of new structures.
Structure Repairs & Rehabilitation
• Any existing seismic resistance building if
occupied for school building then the building
has to be rechecked for seismic resistance for
importance factor of 1.5.
• Projecting parts like cornices, facia stones,
parapets etc. should be avoided as for as
possible, otherwise they should be properly
reinforced and firmly tied to the main
structure Refer IS 1893 CLAUSE -7.12.2
• Ceiling plaster should be avoided as possible.
Structure Repairs & Rehabilitation
Avoid Cantilever Construction
Structure Repairs & Rehabilitation
• Whenever one un symmetrical building is divided
into two or more building by separation walls, the
structure of the divided building up to plinth
level is generally monolithic. Refer code IS 4326
5.1 to 5.2
• In load bearing construction even calculations
based on code- based seismic coefficients may
not indicate tension steel requirements, the
reinforcement suggested in the form of seismic
bands & vertical steel bars at corners & junction
of walls & jambs of openings must be provided
since these are safe guard for probable maximum
earthquake
Structure Repairs & Rehabilitation
PROVISION FOR FUTURE EXTENTION
Expansion
Joint With
Twin
Columns
For Future
Extension
Structure Repairs & Rehabilitation
• Either foundation is kept above maximum water
level or keep below natural water level.
• In load bearing walls , corrosion resistance
precautions should also be taken in ductility
detailing of cyclone prone & tsunami prone coastal
areas.
• IS 456 does not allow R.C.C. below M20 grade
Structure Repairs & Rehabilitation
• An A.R.C. that is not structurally independent should
be designed & constructed such that the entire
building conforms to the seismic resistance
requirements for new building.
The A.R.C. shouldn't increase the seismic force in
any structural elements of the existing building by
more than 5% unless the capacity of the structural
element subjected to the increased force is still in
compliance with the IS. Code.
The A.R.C. should not decrease the seismic
resistance of any structural element of the existing
building below that required by the design codes.
Structure Repairs & Rehabilitation
Importance Factor(I) For Building Depend Upon
• Functional Use Of Structure
• Hazardous Consequences Of Its Failure
• Post Earthquake Personal needs
• Historical Value
• Economic Importance
• School Building Have “I” value=1.5
“I” value
1.5
Zone
Building Retrofitting need
II
III
IV
V
C
D
E
E
Structure Repairs & Rehabilitation
Strengthening Arrangements Recommended For
Masonry Building
b = Lintel Bend
C = Roof Bend, Gable bend
d = Vertical steel at corners & junctions of
wall
f = Bracing in plan at tie level of Pitched
Roofs
g = Plinth band
Structure Repairs & Rehabilitation
Strengthening Arrangements Recommended For
Masonry Building
Retrofittin Number Of Storey
g Category
A
One, Two, Three
storey
B
One & Two Storey
Three Storey
C
One storey
Two & three storey
D
One & Two Storey
Strengthening
To Be Provided
`b, c ,f ,g
`b, c ,f ,g
`b, c, d, f, g
`b, c ,f , g
`b, c, d, f, g
`b, c, d, f, g
Structure Repairs & Rehabilitation
Elevation : Distance b1 to b8 changes as per Building
Retrofitting l1 Need
l2
b8
t
3
b2
b1
2
1
b5
h1
b4
h3 b
h2
b4
2
b7
b6
3
b4
2
1
b4
h2
b5
Structure Repairs & Rehabilitation
Table :Size, Position Of Opening In Above Figure
Description
`b5 (Minimum)
Building Retrofitting
Need/Category
C
D&E
230 mm
450 mm
0.55 m
0.50m
0.46m
0.42m
0.37m
0.33m
0.45 m
0.56 m
`h3 (minimum)
600 mm
600 mm
`b8 (Max.)
900 mm
900 mm
(b1+b2+b3)/l1
; (b6+b7)/l2 = shall not exceed
( For one Storey Building )
( For Two Storey Building )
( For Three & Four Storey Building )
`b4
Structure Repairs & Rehabilitation
For Masonry Structures following features is
consideded
• Plinth Belt in lieu of Plinth Band (if strata is
soft, non-uniform)
• Lintel level belt in lieu of lintel band
• Roof level/ Eve level/ Gable level band
• Reinforcement at corner of wall
• Shape, Size & location of Window In Wall
• Unsupported Wall length to Height Ratio
• Provide Cross wall, Brick Pillar &Buttress in
case of long wall more than 6.0 m
Structure Repairs & Rehabilitation
Elevation : Masonry Building With Limitations
t≥ 190 mm
≥40 t
t
Maximum
3.5 M
20 t
Buttress Wall
≤20 t
≤40 t
≤40 t
V
W
D
Buttress Can Be Avoided by increasing wall thickness
between the cross wall.
Structure Repairs & Rehabilitation
Masonry Building Retrofitting
• Buttress of full height having top width &
thickness = Wall thickness ‘t’ and Bottom width
= 1/6 of wall height.
• Brick Strength shall not be less than 5.0 N/Mm2
for two storey building.
• For type “D” retrofitting, Mortar shall be 1:5 (5
MPa) or 1:1 lime :6 sand (3 Mpa)
• For type E , Mortar shall be 1:1/4 lime:4 sand
(7.5 MPa) or 1:1/2 part lime:4
(6 Mpa)
Lime is added only to improve Workability.
Structure Repairs & Rehabilitation
Height of the load bearing building in
B.W. shall be restricted to the
following.
1. For retrofitting category ‘B’ & ‘D’
building of 4 storey with flat roof or 3
storey plus Attic for pitched roof.
2. For category E, Building of 3 storey
with flat roof or 2 storey plus Attic for
pitched roof.
Structure Repairs & Rehabilitation
• Height of the building in Stone Masonry shall
be restricted to the following, where each
storey height shall not exceed 3.0 m and span
of walls between cross wall is limited to 5.0m
1. For retrofitting category A, B, building of 2
storey with flat roof or 1 storey plus Attic for
pitched roof .In case cement sand mortar 1:6,
the building up to 2 storey plus Attic for
pitched roof.
2. For category C,D– 2 storey with flat roof or 2
storey plus Attic for pitched roof with Cement
sand mortar or 1 storey plus Attic for pitched
roof with lime- sand or mud mortar.
Structure Repairs & Rehabilitation
• Minimum wall thickness in brick masonry
shall be one brick in one & two storey
construction, while in case of three storey,
the bottom storey wall thickness should be
one & half brick.
• Maximum wall thickness in stone masonry
shall be 450 mm & preferably 350 mm.
Structure Repairs & Rehabilitation
• Cross wall connection In steps
SECOND LIFT
600 mm
600 mm
FIRST LIFT
Structure Repairs & Rehabilitation
Wall to wall joints are to be made
by building wall ends in ladder form
A
B
C
•
Structure Repairs & Rehabilitation
In Each Layer Staggered Toothed Joint
A
B
Y
X
Plan 230 mm
A
B
Elevation Showing
115 mm
Vertical Joints
•
•
•
450 mm
View –X At A-A
230 mm
View –Y At B-B
Structure Repairs & Rehabilitation
• Strengthening Of Window When Its Position Is
Not As Per Table Above Slide No……..
60
30
75
6 Ø @ 150
150
X
Window
Two Nos
HYSD Bars
Section X-X
X
Structure Repairs & Rehabilitation
• 75 & 150 mm thick band of full width can be
Replaced by Composite Band having 2 mm
larger dia bar in section ‘A’& ‘B’ as below
100 mm
Top Brick
Laid While
Concrete is
Green
Section Type A
75 mm
38 mm
75 mm
Section Type B
Composite Band
With Side brick
acting also as
shuttering also
Structure Repairs & Rehabilitation
Recommended Longitudinal steel in
Reinforcement Concrete Bands
Span of Band
Between
Cross Wall
In M
Building
Category
“B”
Building
Category
“C”
Dia.
Φ
MM
Building
Category
“D”
No. Of
Bars
Dia.
Φ
MM
Building
Category
“E”
No. Of
Bars
Dia.
Φ
MM
No. Of
Bars
No. Of
Bars
Dia.
Φ
MM
5 or Less
2
8
2
8
2
8
2
10
6
2
8
2
8
2
10
2
12
7
2
8
2
10
2
12
4
10
8
2
10
2
12
4
10
4
12
Spacing Of Tor Ring/Links 6 mm @ 150 mm Or 8 mm @ 200 mm
Bends Thickness vary 75 mm for 2 bars & 150 mm for 4 bars
Structure Repairs & Rehabilitation
• Steel Profile In Band At Corner & Junction
Lap= 50 ф
Staggered
Structure Repairs & Rehabilitation
Pair of stone
with length= ¾
of wall
thickness
≤ 450
≤ 1200
≤ 1200
≤ 1200
CL
Plan showing Center bar in Casing
Casing in every 0.6 m is lifted & M15 or
Mortar 1:3 is Compacted around bar.
Structure Repairs & Rehabilitation
“S” shaped steel rod placed in a damroo shaped
through hole in random rubble wall and fully
encased in concrete
Structure Repairs & Rehabilitation
Vertical Steel Reinforcement in Masonry Walls
up to 350 mm thick as per Table
Vertical steel at corners and junction of walls up
to 350 mm thick should be embedded in plinth
masonry , foundations, bands &roof slab
Nos Of
Storey
Storey
Diameter Of HSD Single HYSD Bar in mm at each critical
Section (for above 350 mm, increase bar dia proportionally
Category C
Category D
Category E
NIL
10
12
Top
NIL
10
12
Bottom
NIl
12
16
Top
10
10
12
Middle
10
12
16
Bottom
12
12
16
One -------Two
Three
Structure Repairs & Rehabilitation
3/4B
One Brick Thick
One & Half Brick Thick
---Contain One Bar At Centre & M20 or 1:3 Mortar
Structure Repairs & Rehabilitation
Vertical deformed steel bar from foundation to roof,
anchored to masonry walls at wall junctions with
special connectors, also connected to the roof at the
top and encased in concrete.
PROP
Structure Repairs & Rehabilitation
X
Three Nails
•5Ø drilled in
splited
bamboo
Cross
bracings at
ends of room
• Half Split Bamboo Ties To Rafter
• Bras the 50 mm Dia Bamboo (B) To Rafter
• Seismic Bend & Rafter should be tied Properly
B
Structure Repairs & Rehabilitation
In the cyclone prone areas people keep the roof overhangs very
small so that during a cyclone its chances of getting blown off
are small. Along the coast of Kutchh, in Gujarat this practice is
common.
Structure Repairs & Rehabilitation
Along the Kutchh and Saurashtra coast in Gujarat, roof
is anchored to the walls through timber brackets so
that it does not get blown off during the cyclonic winds.
Structure Repairs & Rehabilitation
In long walls introduce pilasters
to strengthen it.
Structure Repairs & Rehabilitation
If the ground is sandy in which the foundation is sitting,
then high speed flood/surge water can scour the land
around and under the foundation of school, leading to
settlement and/or cracking of the wall.
Structure Repairs & Rehabilitation
Prolonged Flooding can weaken the mortar,
especially if it is mud mortar, and causing
cracking in walls or collapse.
Structure Repairs & Rehabilitation
Simple erosion of wall near its bottom, or
cracking, plaster peeling off and settlement
in floor.
Structure Repairs & Rehabilitation
Diagonal tying on the upper or underside of the
roof Prevents roof from getting distorted and
damaged
Structure Repairs & Rehabilitation
Anchoring roof to wall, reducing roof overhangs
and providing roof slope as per local tradition
Helps resist uplifting of roof from wall. Also help
prevent the roof from getting blown off
Structure Repairs & Rehabilitation
Seismic belt consisting of Weld mesh in lieu of Seismic Band.
It is approximately 220mm wide anchored to masonry wall
and encased in cement mortar.
Structure Repairs & Rehabilitation
Weld mesh belt approximately 220mm wide all
around the openings and anchored to masonry wall
and encased in cement mortar
Structure Repairs & Rehabilitation
Installing multiple strands of galvanized iron wires
pulled and twisted for pretension
Structure Repairs & Rehabilitation
Anchoring the roof rafters and trusses with steel
angles or other means
Structure Repairs & Rehabilitation
Encasing masonry column in cage of steel rods and
encased in micro concrete
Structure Repairs & Rehabilitation
Vertical seismic Belt & filling unwanted opening
Joints
Structure Repairs & Rehabilitation
Retrofitting in Urinal Basins
Structure Repairs & Rehabilitation
Girls Toilet After Retrofitting
Structure Repairs & Rehabilitation
Conclusion:
The Extent of School Building Repairing Depend
upon how well Retrofitting work has been
planned at all levels within financial constraint
while due consideration has to be given to
counter nature destructive forces.

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