Retrofitting of building

1. Retrofitting Of Buildings.
Shehr Yaar Abdullah (17CE23)
CED, Balochistan UET, Khuzdar, PAK.
 Point in Question:
 Represented By

2.  Content Of Topic:
1. Introduction to retrofitting.
2. Goals of retrofitting.
3. Need of retrofitting.
4. Why retrofitting is required?
5. To retrofit or not?
6. Stages of retrofitting.
7. Condition assessment of buildings & its Steps.
8. Material used in retrofitting
9. Classification of retrofit techniques.
10. Existing retrofitted structures in Balochistan.
11. Critical remarks.
2

3.  INTRODUCTION TO RETROFITTING:
3
 Retrofitting is the process of addition of new features to
older buildings, heritage structures, bridges etc.
 Retrofitting is the process of modification of existing
structural members to increase its resistance to load.
 It reduces the vulnerability of damage of an existing
structure during a near future seismic activity.
 It helps to increase the strength, resistivity and overall
lifespan of the structure.

4.  GOALS OF RETROFITTING:
4
 To increase the lateral strength and stiffness of the building.
 To increase the ductility and aims to avoid the brittle modes of failure.
 To increase the integral action and continuity of the members in a
building.
 To eliminate or reduce the effects of irregularities.
 This aims to eliminate the possibility of progressive collapse.
 To ensure adequate stability against overturning and sliding.

5.  NEED OF RETROFITTING:
5
The need for retrofitting can arise due to any of the following
reasons:
 Building not designed to standard code.
 Subsequent updating of code and design practice.
 Subsequent upgrading of seismic zone.
 Deterioration of strength and aging and Modification of existing
structure.
 In Pakistan, almost 75% of total buildings are non-engineered
buildings made up of earthen walls, stone walls, brick masonry
walls, etc. These buildings are more vulnerable to seismic
activities.

6.  Why retrofitting is required?
6
The need for retrofitting due to problem face in concrete structure:
 Damage to the structural members.
 Excessive loading.
 Errors in design or construction.
 Seismic damage.
 Structural failure.
 In Corrosion due to penetration.

7.  TO RETROFIT OR NOT?
A decision depends on many factors.
 Lifeline buildings, such as hospitals must necessarily be retrofitted, in
view of their extreme importance. But should the aim of retrofit be to raise
this capacity to 100%.
 Lifeline buildings such as fire stations, hospitals, power stations,
telephone exchanges, television stations, radio stations, railway
stations, air ports.
 Important service and community buildings such as schools, cinema
halls, multiplexes, marriage and other assembly halls, the capacity
should be raised to 100%.
7

8. STAGES OF RETROFITTING:
1. Selection of
objective
of retrofit
B
2. Reviewing
the initial
considerations
C
3. Obtaining
the
information
of Building
4. Seismic
Evaluation
E
5. Decision to
retrofit or
demolish
F
6. Selection
and Design
of retrofit
strategies
G H IA D
7.Verification of
retrofit scheme
8. Construction
9. Maintenance &
Monitoring

9. 9
 CONDITION ASSESSMENT OF BUILDINGS:
o Condition assessment describes the process of assessing the actual condition of a
structure in relation to the requirement. It indicates whether the structure is
satisfactory, or, whether repair and rehabilitation are necessary. Condition
assessment includes the following steps.
1. Initial inspection and appraisal.
2. Review of documents.
3. Detailed investigation.
4. Reporting and recommendations.

10. 10
Condition assessment of building has two major steps:
I. Visual Inspection
II. Detailed Investigation
 Visual Inspection:
Thoroughly visual inspection of following factors,
IX. Misalignment.
X. Deformation.
XI. Cracks in welds.
XII. Missing bolts / rivets.
I. Concrete cracks
II. Spalling & Staining
III. Disintegration of the surface,
IV. Honey-combing.
V. Exposed reinforcement Steel
corrosion.
VI. Stress concentration.
VII. Crippling or buckling.
VIII.Bowing.

11. 11
 Detailed Investigation:
It proposes of following steps,
1) Obtaining the properties of the structural materials used in the building.
2) Determining the type and disposition of reinforcement in building.
3) Locating deteriorated material and other defects.
 Tests for detailed investigation
A number of tests are available to study the condition of the material in a
structure:
 Rebound Hammer test
 Thermal methods
 Radiography
 Electromagnetic techniques
 Stress wave propagation method Intrusive Tests
 Core test
 In-Situ Shear test
 Flat-Jack test
 In-Situ Permeability

12. MATERIALS USED IN RETROFITTING:
Materials
Ferro-
Concrete
Fiber-
Reinforced
Polymer
Fiber-
Reinforced
Concrete.
Micro-
Concrete
Quick Setting
Cement
Mortor
Epoxy Resin
Epoxy
Mortor

13.  CLASSIFICATION OF RETROFIT TECHNIQUES:
Retrofitting techniques are basically classified as,
I. Global Retrofit Strategies II. Local Retrofit Strategies
 Global Retrofit Strategies
 To provide increased lateral
stiffness and strength to the
building as a whole. And, to ensure
that a total collapse of the building
does not occur.
 Local Retrofit Strategies
 To avoid failure of the components,
and also thereby enhance the
overall performance of the
structure
 More than one combination of
local and global retrofit strategies is
possible
13

14. 14
 GLOBAL TECHNIQUES:  LOCAL TECHNIQUES:
 Addition of Infill Walls
 Addition of Shear walls or
wing walls or Buttress Walls
 Addition of Steel Braces
 Reduction of Irregularities
and Mass Reduction.
• Concrete Jacketing,
• Steel Jacketing

15. 15
Infill Walls:

16. 16
Concrete Jacketing:
It involves addition of a layer of concrete, longitudinal bars and closely spaced ties.
The jacket increases both the flexural strength and shear strength of the column.
To increase the flexural strength, the additional longitudinal bars need to be anchored to the
foundation.
If the jacket is only partially around the existing column, the new bars can be welded to the existing
bars.
It involves drilling holes in the existing beam. But drilling holes for the stirrups at closing spacing
damages the beam.

17. 17
Steel Jacketing:
It refers to encasing the column with steel plates and filling the gap with non-shrink
grout.
If the shear capacity needs to be enhanced, the jacket is provided throughout the
height of the column.
Circular jackets are more effective than rectangular jackets.
The plates are attached to the tension face of a beam to increase the flexural
strength, whereas they are attached to the side face of a beam to increase the shear
strength.

18. 18
Steel Jacketing:

19. 19
EXISTING RETROFITTED STRUCTURES IN BALOCHISTAN:
• World’s famous boot house in Quetta, Balochistan.
Retrofitting
• Quaid E Azam Residency, Ziarat, Balochistan.
Retrofitting

20. 20
CRITICAL REMARKS:
Increase in the capacities( strength, stiffness, ductility, stability and integrity) of
concrete structure.
The reduction in loss of lives, damage of the essential facilities and functional
continuity of life-span of structures.
Decrease the working space of concrete structure due to extension in structural
elements and affect the appearance.
Increase in lateral stiffness with high shear concentration near wall. ■ Increase in
overturning moment at foundation.

21. THANK
YOU! 
Shehr Yaar
Abdullah
Shahwani
Phone
+92-333-8259405
Email
shehryarabdullah008@gmail.com