3. CONTENTS
The discussion is divided into the following sections :
• Introduction
• Retrofitting Techniques
• Economic features of various Retrofitting Techniques
• Need of Retrofitting in Pakistan
• New trends of Retrofitting in Pakistan
4. Retrofitting
• Upgrading of certain building systems (existing structures) to
make them more resistant to seismic activity (earthquake
resistance)
• Structures can be
– Earthquake damaged
– Earthquake vulnerable
Retrofitting proves to be a better economic consideration and
immediate shelter to problems rather than replacement of
building.
18. Retrofitting Of Masonary Structures
PRINCIPLE OF SEISMIC SAFETY OF MASONRY
BUILDINGS
• Integral box action
• Integrity of various components
– Roof to wall
– Wall to wall at corners
– Wall to foundation
• Limit on openings
19. Retrofitting Of Masonary Structures
METHODS FOR RETROFITTING OF MASONRY BUILDINGS
REPAIRING (IMPROVING EXISTING MASONRY STRENGTH)
• Stitching of cracks
• Grouting with cement or epoxy
• Use of CFRP (carbon fiber reinforced polymer) strips
22. Retrofitting Of Masonary Structures
RETROFITTING OF EQ. VULNERABLE BUILDINGS:
• External binding or jacketing
• Shotcreting
• Strengthening of wall intersections
• Strengthening by cross wall
• Strengthening by buttresses
• Strengthening of arches
30. Need of Retrofitting in Pakistan
There are considerable number of reinforced concrete
structures in Pakistan that do not meet the requirements
of current design standards because of inadequate design
and/or construction errors and need structural upgrading
specially to meet the seismic design requirements.
After 2005 earthquake, the awareness and need of
seismic detailing has increased.
Retrofitting is the best solution to strengthen such
buildings without replacing them
31. New Trends in Retrofitting in
Pakistan
Strengthening Techniques
• Reinforcement Strengthening
• R.C Jacketing
• Externally Bonded Plates For Flexural Strengthening
• Shear/Compression Strengthening by Confinement
Carbon Fiber Reinforced Polymer (CFRP)
Composite System
32. New Trends in Retrofitting
SIKA Construction Chemicals Division, Imporient
Chemicals (PVT) Ltd. is widely involved in the
use of these materials for retrofitting in Pakistan.
The retrofitting done by SIKA, involves the
following materials
• CFRP Strips (Sika CarboDur)
• Structural Epoxy Adhesive (SikaDur-30)
• Glass and carbon Fabric (Sika Wrap)
35. CFRP Composite System
Characteristics
• Precise Material Properties
• Fully Corrosion resistant
• High Strength
• Extremely Lightweight
• Range of Sizes Available for Optimum Design
• Very easy application
• Applicable on both uniform and non-uniform
sections
38. Steel vs Composites
Steel Composites
Low material cost High material cost
High installation cost Low installation cost
corrosive Non- Corrosive
Heavy Light weight
Fabrication required No fabrication required
High maintenance cost Low maintenance
44. Park Towers F10 Islamabad:
– The structure needed an important strengthening and retrofit after
recent earthquake
– All structural cracks were epoxy injected, and many beams were
strengthened in flexure at the basement level.
67. Refrences
• Aslam, M., Mirza, W.H., Report (2010),“Rehabilitation &
Retrofitting of R.C. Structures with Carbon Fibre Composite
Systems”, SIKA Construction Chemicals Division, Imporient
Chemicals (PVT) Ltd.Lahore, Pakistan
• Khurram,N., (2009), “Performance of retrofitted reinforced
concrete columns against pseudo cyclic load”, M.Sc. Research
Thesis, University of Engineering and Technology, Lahore,
Pakistan
• Javed M. (2009), Seismic risk assessment of unreinforced brick
masonary building system of northern Pakistan‟, Department of
Civil engineering, U.E.T. Peshawar.
• Khan Shahzada et al, „Experimental seismic performance and
evaluation of unreinforced masonary buildings‟, Department of
Civil Engineering, U.E.T. Peshawar.
68. Refrences
• M. Eigawady et al, (july 2004),‟ A review of conventional
seismic retrofitting techniques for URM‟, Amsterdam.
• C. Amarnath, (april 2007),‟handbook on seismic retrofit of
building‟, central public works department, Madras, India.
• Charlotte. A. C. bouvier, (2003),‟Techniques for seismic
retrofitting of concrete structures‟, MIT.
• Andrew Smith and Thomas Redman (Jan. 2009), „A
critical review of retroftting methods for unreinforced
masonry structures‟, University of Bristol.
