Retrofitting and retrofitting techniques

1. Retrofitting of
Masonry Buildings
Submitted by-
MANISH SHARMA
Submitted to-
Dr. AKILAHMAD

2. Retrofitting-
It is a technique for upgrade the strength
and structural capacity of an
existing/damaged structure to enable it to
safely withstand the effect of strong
earthquake in future.

3. Retrofitting techniques:-
 Structural or global
retrofitting
1. Adding shear wall
2. Adding infill wall
3. Adding bracing
4. Adding wing wall/
buttresses
5. Wall thickening
6. Mass reduction
7. Supplemental damping
and Base isolation
 Member or local
retrofitting
1. Jacketing of beams
2. Jacketing of columns
3. Jacketing of beam column
joints
4. Strengthening individual
footings

4. Failure mechanism of a masonry
building:-
 Out-of- plane failure
 In-plane failure
 Connection failure
 Diaphragm failure
 Pounding
 Failure due to opening in the walls
 Non-structural component failure

5. Out-of- plane failure:-
Inadequate anchorage of wall into the roof
diaphragm.
Limited tensile strength of masonry.
More pronounced response at higher levels.

7. In-plane failure:-
In plane failures of walls in un-reinforced masonry
structure are due to excessive bending or shear.
Commonly it leads to form double diagonal shear
cracking.

8. Connection failure:-
This type of failure is characterized by diagonal cracks disposed on both
the wall’s edge causing separation and collapse of the corner zone.

9. Diaphragm failure:-
Diaphragm failure is a rare phenomenon in the event of seismic
motion. In plane rotation of the diaphragm ends and absence of
good shear transfer between diaphragm and reaction walls account
for damages at corner of the walls.

10. Pounding:-
When adjacent roof levels of the two buildings and vertical brick
walls faces flush with one another ,the pounding action causes
structural distress due to out-of-plane vibrations.

11. Non-structural component failure:-
Parapet walls, partition walls, mumty, water tanks, projections and
staircase are non structural elements behave like cantilevers if they
remain unrestrained and are subjected to greater amplification as
compared to ground motion becoming prone to failure.

12. MASONRY CRACKING:-
GRADE
CRACKS
DAMAGE LEVEL DEFINATION FOR LOAD BEARING MASONRY
G0 Undamaged No visible damage
G1 Slight damage Hairline cracks
G2 Moderate damage Cracks 5-20 mm
G3 Heavy damage Cracks 20 mm or wall material dislodge
G4 Partial destruction Complete collapse of individual wall material
or roof support
G5 Collapse More than one wall collapsed or more than
half of roof

13. REPAIRING TECHNIQUES OF MASONARY:-

19. Jacketing:--
Most popular method for strengthening of buildings columns.
Types:-- 1.Steel jacket 2.Reinforced concrete jacket 3.Reinforced
polymer composite (RPC) jacket
Purpose of Jacketing:-
 To increase shear strength.
 To increase flexural strength
 To increase concrete coinforment

21. Indian Codes for Earthquake Design:-
 IS: 1893-2002 (part-1) Criteria for Earthquake Resistant Design of Structures
(Part 1 :General Provision and Buildings) - Code of Practice.
 Practice IS: 4326-1993 Earthquake Resistant Design and Construction of
Buildings – Code of practice.
 IS: 13920-1993 Ductile Detailing of Reinforced Concrete Structures
subjected to Seismic Forces – Code of Practice
 IS: 13935-1993 Repair and Seismic Strengthening of Buildings – Guidelines
 IS: 13828-1993 Improving Earthquake Resistance of LowStrength
Masonary Buildings - Guidelines
 IS: 13827-1993 Improving Earthquake Resistance of Earthen Buildings –
Guidelines

22. Shaking table test:-

23. Conclusions:-
 Seismic Retrofitting is a suitable technology for protection of a variety of structure.
 it has matured in the recent years to a highly reliable technology.
 But, the expertise needed is not available in basic level.
 The main challenge is to achieve a desired performance level at a min cost. Which can
be acheived through a detailed nonlinear analysis.
 Optimization techniques are needed to known the most efficient retrofit for a particular
structure.
 Proper design codes are needed to be published as code of practice for professionals
related to this field.

24. REFERENCES:-
 Agarwal, P. and Shrikhande, M., 2006, Earthquake Resistant Design of
Structures, 2nd Edition, Prentice-Hall of India Private Limited, New Delhi.
 Fastening for seismic retrofitting- state of art report, comite euro. International
Du Beton,Thomas Telford,UK,1995.
 EERI, 1999, Lessons Learnt Over Time – Learning from Earthquakes Series:
Volume II Innovative Recovery in India, Earthquake Engineering Research
Institute, Oakland (CA), USA.
 Murthy,C.V.R.,2004 IITK-BMTPC Earthquake Tip, New Delhi.

25. Thank You...