Rehabilitation & Retrofitting
of Engineered Buildings after
Earthquake Damages
Dr Khuram Iqbal
PhD & MPhil, Cambridge University UK
Managing Director
Agenda
• Understanding Ground Motions
• Understanding Oscillations of Structures
• Glimpses of Pakistan Building Code
• Dynamic Behaviour of Structures
• Variety of Earthquake Damages
• Variety of Rehabilitation Techniques
• Variety of Retrofitting Techniques
Seismic Waves
• During an earthquake, seismic waves arise from
sudden movements in a rupture zone (active fault) in
the earth's crust.
• Waves of different types and velocities travel different
paths before reaching a building's site and subjecting
the local ground to various motions.
• The ground moves rapidly back and forth in all
directions, usually mainly horizontally, but also
vertically
Faultline & Seismic Waves
Different Ground Motions due to
P-type & S-type Seismic Waves
Travel-time Curves of Seismic Waves
6
Inertial Force & Ground Acceleration
acting on a Building
Inertia force and relative motion within abuilding
CE-412: MODULE 1 ( Fall2015)
BUILDING CODE OF PAKISTAN
(seismic provisions 2007)
Abstract- The seismic provisions (2007) have been included in the Pakistan building Coad after
the unusual and unprecedented Kashmir earthquake of 2005. The provisions are based on
equivalent lateral force (ELF) Method where more emphasis has been laid over improving the
detailing of reinforced members to induce ductility in their behaviour. This assumption many times
leads to overdesign and increased cost of the construction. The performance Based design
(PBD) is instead based on advanced analysis on micro level for the specific site conditions. This
brings more precision and the performance of the building more closer to the real behaviour of
the building during earthquakes. In this research work an existing under construction building has
been analysed on both the seismic provision of Pakistan building code and performance based
design to check the suitability of both the methods. The results have shown that the ESF method
overestimates the base shear at one hand and the negative moments are underestimated as
compared to PBD. This can lead to major damage to the building in case of earthquake. The
PBD can also bring more economy and real picture.
International Design Codes
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Soils and Foundations
Structural Design Requirements
Structural Tests and Inspections
Masonry
Based on UBC (1997), Uniform Building
Code
• Structural Concrete
Based on ACI 318-05, Building
Requirements for Structural Concrete
Code
• Structural Steel
ANSI/AISC 341-05, Seismic Provisions for
American
Structural
Steel
Buildings,
Institute of Steel Construction
Seismic Zones in Pakistan
Seismic Zones in AJK & KPK
Seismic Zones and corresponding
Ground Acceleration Intensity
Real Time Earthquake Video 1
Real Time Earthquake Video 2
Simulations of Faultline &
Ground Movements
Dynamic Behaviour of a Bridge
Typical Bridge Span
Natural Frequency & Mode Shapes
f1 = 1.514 Hz (1st Bending Mode)
f2 = 2.295 Hz (1st Torsion Mode)
f3 = 4.346 Hz (2nd Bending Mode)
f4 = 6.299 Hz (Bend + Tors Mode)
Mode Shapes Simulations of Bridge
during Earthquake
Seismic Analysis Procedures
Response spectrum analysis
Time-history analysis
An elastic dynamic analysis of a structure
response of all
utilizing the peak dynamic
modes having a significant contribution to total
structural response. Peak modal responses are
calculated using the ordinates of the appropriate
response spectrum curve which correspond to
the
modal
periods.
Maximum
modal
contributions are combined in a statistical
manner to obtain an approximate total structural
response.
An analysis of the dynamic response of a
structure at each increment of time when the
base is subjected to a specific ground motion
time history
Popular Seismic Design Software
in Pakistan
Top 10 Earthquakes of the World
Pakistan Earthquake
18th October, 2005
Death: 75000 Mag-7.6
Ariel view
2005 Earthquake in Pakistan
Nepal Earthquake
25th October, 2015
Death: 5000 Mag-7.9
Afghanistan Earthquake
26th October, 2015
Death: 4000 Mag-7.6
Types of Earthquake Damages
Damages could include both Structural and Non-Structural
Damage to Structure can be:
A - due to ground movements and soil changes.
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Landslides
Ground liquefaction
Fault movements.
Seismic sea waves (Tsunami's)
B - due to building shape or dimensions
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Soft story failure.
Short column failure.
Torsional failure.
Pounding
Damages to Structural & Non-Structural
Elements of a Building
Non-Structural Elements
Structural Elements
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Plaster,
Parapets
Doors, windows, window glass panes etc
Dislocation of civil services like water supply, gas,
drainage pipes and electrical conduits/wiring
• Disturbed Roofing Tiles
• Flooring at ground level, etc
Foundation system
Load bearing walls
RCC beams/columns
Roofing
Lintels over door/windows, etc
Assessment Procedure for Evaluating a
Damaged Structure
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Physical Inspection of damaged structure
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Preparation and documenting the damages
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Collection of samples and carrying out tests both in situ and in laboratory
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Estimation of loads acting on the structure
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Estimation of environmental effects including soil structure interaction
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Taking preventive steps not to cause further damage
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Assessment of structural adequacy
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Remedial measures necessary to strength and repairing the structure
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Post repair evaluation
Slab & Beams Cracks
Road Cracks
Columns Cracks
Wall Cracks
3
Rehabilitation of Walls
• By Grouting (Polymer Morter or Cement Water Mixture
• By addition of vertical Reinforcement Concrete Covering on both sides of
Wall
• By Pre-Stressing Wall
Jacketing of RCC Columns
Carbon Fibre Wrapping on Column-Beam
Junctionsc
Disastermanagement
Carbon Fibre Wrapping on the whole Column
Disastermanagement
Glass Fibre Wrapping on Column & Beams
Disastermanagement
Mild Steel Plate Wrapping on Column-Slab
Junctions
Seismic Mesh Belts at Corners
19
On the both sides of all Walls below Lintel
Around all Openings
18
At External Corners
New Engineered Buildings constructed in Pakistan
– Post 2005 Earthquake  Concrete frame structure with G.I corrugated sheet roofing resting on
steel-trusses with thermo-pore false-ceiling underneath. Concrete hollowblock filling in between the pillars
 Load bearing brick walls with steel re-inforcement at corners, walljunctions and window openings. G.I corrugated sheet roofing resting on
steel-trusses with thermo-pore false ceiling underneath
 Pre-Engineered structures of light gauge steel structure with cement-Fiber
Board walls having glass wool insulation filling, G.I corrugated sheet
roofing resting on steel-trusses with thermo-pore false-ceiling underneath
Pre-Engineered
Light Gauge Steel (LGS) Construction
Do’s & Don’t
For
Earthquake
Resistant
Construction
Retrofitting of Important Structures which are
prone to Earthquake
Retrofitting Techniques
Global Level
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Add Shear Wall
Add Infill Wall
Add Steel Bracing
Add Wing Wall or Buttress
Mass Reduction
Base Isolation
Add Seismic Dampers at the base
Local Level
 Other localized Retrofitting can be achieved by jacketing with reinforced
concrete, wraping with FRP or GRP or MS Plate
Thank you!
Questions & Answers Session