What Works and Does not Work in the
Science and Social Science of
Earthquake Vulnerability,
January 28-29, 2011
Prof. Sarosh H Lodi
NED University of Engineering and Technology
INRTODUCTION
•
Most of the buildings in the urban areas are semi –
engineered non-ductile reinforced concrete moment
resistant framed structures with very stiff masonry walls
but not designed and detailed to resist seismic forces.
•
Most of the buildings in the rural areas are non –
engineered load bearing stone/ brick masonry
structures with no resistance to seismic forces.
Typical Urban Buildings
Typical Urban Buildings
Typical Urban Buildings
Model 1
Model of infill to increase seismic
resistance a cost effective solution
COMPARISON OF BARE FRAME AND
INFILL FRAME
MATERIAL PROPERTIES
f’c = 21 MPa
fy = 415 MPa
Fcm = 2.1 MPa
GEOMETRIC PROPERTIES
PARAMETERS USED FOR ANALYSIS
BARE FRAME
FRAME WITH INFILL
Soil profile type =SD
Ct = 0.03 (For moment
resisting frame)
R = 5.5
Zone = 2B
Soil profile type = SD
Ct = 0.02 (For all other
building system)
R = 5.5
Zone = 2B
MODELING PARAMETERS OF INFILL
(STRUTS)
For retrofitted strut:
For ordinary strut in above equation use:
Ec = 0 and tc = 0
a = Depth of strut
tc = Thickness of shortcrete
Em = Modulus of Elasticity of infill
hcol = Depth of column
hinf = Height of infill
q = Inclination angle of infill
t = Width of strut
Ec = Modulus of Elasticity of shortcrete
Efe = Modulus of Elasticity of frame
Ic = Moment of inertia of column
Ldiag = Diagonal length of infill
STRENGTH OF INFILL (STRUTS)
For Compression strut:
For Tension tie:
TIME PERIOD AND BASE SHEAR
FOR BARE FRAME
FOR INFILL FRAME
COMPARATIVE ANALYSIS OF STRENGTH BASED
ON PERFORMANCE BASED ANALYSIS
FAILURE MECHANISM
BARE FRAME
FOR INFILL FRAME
COMPARATIVE ANALYSIS OF STOREY
DISPLACEMENTS
Model 2
Addition of strength to the infill to
increase seismic resistance
RETROFITTED MODELS
a) BY MAKING STRONGER COLUMN AND BEAM WHICH
ARE TO BE FAILED IN PREVIOUS ANALYSIS
i. RCC OR STEEL JACKETING OF COLUMNS
ii. RCC OR STEEL JACKETING OF BEAMS
b) BY INTRODUCING A SPINE
RETROFITTED MODELS
Retrofitted columns and
beams with infill
Retrofitted infill wall
2” thick shortcrete with
12”c/c steel
3” thick shortcrete with
8”c/c steel
6” thick shortcrete with 8”
c/c steel
8 “ th RCC wall & 4” th
shortcrete with 6”c/c steel
Retrofitted Elements
Retrofitted Elements
COMPARATIVE ANALYSIS OF STRENGTH OF
RETROFITTED MODEL
FAILURE MECHANISM OF RETROFITTED MODELS
Retrofitted columns and
beams with infill
Retrofitted infill wall
COMPARATIVE ANALYSIS OF STOREY
DISPLACEMENTS
Campaign
Typical Rural Buildings
Typical Rural Buildings
Typical Construction
INTRODUCTION
 School buildings are vital for a society
 They are places of learning
 They also play a significant role in the relief
operation in post-disaster situations.
 These buildings can be used as temporary shelters.
 Assessment of seismic vulnerability of school
buildings is essential to ensure safety of children
and teachers.
DESCRIPTION OF SCHOOL
 School consists of 4 classrooms.
 These have been divided into 3 blocks.
 Load resisting system consists of cavity walls of stone
rubble masonry.
 These provide resistance against gravity loads.
 Roofing system consists is of timber trusses and
corrugated metal sheeting.
 Construction inherently lacks resistance to lateral
loads.
PLAN OF SCHOOL
VIEW OF SCHOOL
 A view of school is shown in figure below.
TYPICAL SECTION OF WALL
Typical wall section of the construction in the area is shown
in figure below.
Y
X
Z
ANALYTICAL MODELLING

A mathematical model of the school was developed.

Finite Element Program SAP was employed.

Individual blocks were modelled as solid brick elements.

Mortar was modelled using non-linear springs.

Non-linear properties of mortar were defined using existing
constitutive models.

Geometric non - linearity were also taken into account.

Ground shakings were simulated using El-Centro ground
accelerations
Stress
ANALYTICAL MODELLING
 Axial behaviour is modelled as follows
Strain
Stress
ANALYTICAL MODELLING
 Shear behaviour is modelled as follows
Strain
ANALYSIS OF RETROFITTED SCHOOL
 A view of the mathematical retrofitted model is shown
in figure below
ANALYSIS OF RETROFITTED SCHOOL
 A view of retrofitted long wall is presented in figure
below which shows the jacketing scheme around the
openings.
ANALYSIS OF RETROFITTED SCHOOL

A view of retrofitted short wall is shown in figure below
which displays a typical wall without openings.
PROGRESS IN RETROFITING WORK
PROGRESS IN RETROFITING WORK
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
PROGRESS IN RETROFITING WORK
STRUCTURAL RETROFITTING OF
GGPS NAYASHER # 3
Thanks!