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What Works and Does not Work in the Science and Social Science of Earthquake Vulnerability , January 28-29, 2011. Pre - disaster Mitigation Strategies - Special Reference to Pakistan. Prof. Sarosh H Lodi NED University of Engineering and Technology . INRTODUCTION.

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pre disaster mitigation strategies special reference to pakistan

What Works and Does not Work in the Science and Social Science of

Earthquake Vulnerability,

January 28-29, 2011

Pre - disaster Mitigation Strategies - Special Reference to Pakistan

Prof. Sarosh H Lodi

NED University of Engineering and Technology

slide2

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.
slide6

Model 1

Model of infill to increase seismic resistance a cost effective solution

slide8

MATERIAL PROPERTIES

f’c= 21 MPa

fy= 415 MPa

Fcm= 2.1 MPa

GEOMETRIC PROPERTIES

slide9

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

slide10

MODELING PARAMETERS OF INFILL (STRUTS)

For retrofitted strut:

For ordinary strut in above equation use:

Ec = 0 and tc = 0

a = Depth of strut t = Width of strut

tc = Thickness of shortcrete Ec = Modulus of Elasticity of shortcrete

Em = Modulus of Elasticity of infill Efe = Modulus of Elasticity of frame

hcol = Depth of column Ic = Moment of inertia of column

hinf = Height of infill Ldiag = Diagonal length of infill

q = Inclination angle of infill

slide11

STRENGTH OF INFILL (STRUTS)

For Compression strut:

For Tension tie:

slide12

TIME PERIOD AND BASE SHEAR

FOR BARE FRAME

FOR INFILL FRAME

slide14

FAILURE MECHANISM

BARE FRAME

FOR INFILL FRAME

slide16

Model 2

Addition of strength to the infill to increase seismic resistance

slide17

RETROFITTED MODELS

  • BY MAKING STRONGER COLUMN AND BEAM WHICH ARE TO BE FAILED IN PREVIOUS ANALYSIS
    • RCC OR STEEL JACKETING OF COLUMNS
    • RCC OR STEEL JACKETING OF BEAMS
  • BY INTRODUCING A SPINE
slide18

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” thshortcrete with 6”c/c steel

Retrofitted Elements

Retrofitted Elements

slide20

FAILURE MECHANISM OF RETROFITTED MODELS

Retrofitted columns and beams with infill

Retrofitted infill wall

structural retrofitting of ggps nayasher 3

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

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.

structural retrofitting of ggps nayasher 31

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

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.

structural retrofitting of ggps nayasher 33

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

VIEW OF SCHOOL

A view of school is shown in figure below.

structural retrofitting of ggps nayasher 34

Y

X

Z

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

TYPICAL SECTION OF WALL

Typical wall section of the construction in the area is shown in figure below.

structural retrofitting of ggps nayasher 35

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

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

structural retrofitting of ggps nayasher 36

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

ANALYTICAL MODELLING

Axial behaviour is modelled as follows

structural retrofitting of ggps nayasher 37

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

ANALYTICAL MODELLING

Shear behaviour is modelled as follows

structural retrofitting of ggps nayasher 38

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

ANALYSIS OF RETROFITTED SCHOOL

A view of the mathematical retrofitted model is shown in figure below

structural retrofitting of ggps nayasher 39

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

ANALYSIS OF RETROFITTED SCHOOL

A view of retrofitted long wall is presented in figure below which shows the jacketing scheme around the openings.

structural retrofitting of ggps nayasher 310

STRUCTURAL RETROFITTING OF GGPS NAYASHER # 3

ANALYSIS OF RETROFITTED SCHOOL

A view of retrofitted short wall is shown in figure below which displays a typical wall without openings.