presentation on seismic vulnerability assessment

1. Presented By:
Er. Sitaula

2. Background
• What is Seismic Vulnerability?
 Susceptibility to damage during seismic events.
 Can be subjective or numerical quantity.
The systematic approach or framework to quantify the
seismic vulnerability is seismic vulnerability assessment

3. Why is seismic vulnerability assessment needed ???
Answer…..
Risk Management Risk Identification

4. Evaluation of the vulnerability of Structures (Buildings)
depends on many parameters
• Building Typology
• Structural Systems
• Seismic Capacities
• Ground Condition
• Other structural aspects
A major Exposure element to define the risk are buildings
Insights about buildings behavior during
seismic hazards

5. Vulnerability Assessment
Empirical
Constructed from
Historic
Earthquake
damage
assessment
Small no. of
parameters on
large number of
buildings
Analytical
Obtained form
mathematical or
computational
modeling of
exposure for an
assumed potential
level of hazard
Large number of
data on small
building numbers
Hybrid
Combination of
the data from
empirical methods
in conjunction
with analytical
method

6. Empirical Approach
Rapid Visual Screening
• First Step before detail damage assessment
• Qualitative estimation from exterior observation
Many countries have developed their own RVS technique
Few to name are
FEMA 154,
Basic Hazard Score, BSH = -log10[P(collapse)]
Final Score = BSH + SMs (score modifiers)
National Research Council (NRC) Canada’s
Structural Priority Index (SPI) = SI (Structural index) + NSI (Non
Structural Index)
Others are
Japans Seismic Index approach
NZ’s Initial Evaluation Procedure (IEP) followed by Detailed Seismic
Assessment(DSA) etc.,

7. Empirical Approach
Vulnerability Index Method
1. GNDT Approach
Matrix of qualification coefficient ‘Ki‘ of Four vulnerability classes
(A, B, C, D), each with 11 parameters having a fixed
weightage(considering importance) for each parameter
Vulnerability index Iv is evaluated using
Iv value normalized between 0-100 from 0 to 382.5 such that 0
indicating the least vulnerable to 100 worst.
Similarmatrix for RC building also , can be trasformed to Iv for
Masonry , Using

9. Empirical Approach
Vulnerability Index Method
2. European Macro-seismic EMS Approach Risk-UE project
• Building Typology Classes distributed to 6 vulnerability classes (A
to F) least most
• Such building are classified into four general typologies: Masonry,
RC, Steel and Wooden
• It categorizes the scale of damage to five grades D1(slight damage)
to D5(collapsed)

12. Empirical Approach
Vulnerability Index Method
2. Combined GNDT and EMS Approach
• Both method combined to certain correlation between them
• Mean Damage Grade Md is defined such that (0<Md<6)
where (I) represents the earthquake, hazard associated with macro-
seismic intensity, (V) is the vulnerability index, (Q) identifies the
ductility of a particular construction, ranging from 1 to 4.

13. Analytical Approach
• Also called theoretical approach
• Includes large number of parameters for small building numbers
• Focuses no hazard (SGM) simulation to assess the performance
behavior of the buildings
Moreover the methods considering non linearity of the structures are more
precise to assess the performance behavior and are mostly employed.
• Non-Linear static analysis (NLSA) - Pushover analysis (POA)
• Non-Linear time history analysis (NLTHA) - incremental dynamic
• analysis (IDA)
Linear approach Static approach
Non-Linear approach Dynamic approach

14. Analytical Approach
Non Linear Static Pushover (NLSPO-Analysis)
• Originally presented in in FEMA 273 and later updated in FEMA 356

15. Analytical Approach
Non-Linear time history analysis (NLTHA) - incremental dynamic
analysis (IDA)
• Most exact and precise method to assess the seismic performance of a
structure
• capacity to model wide diversity of non-linear material behavior,
irregularity in structures with geometric non-linearity, pounding
effects, and higher mode effects in tall buildings
• Concerned towards solving the dynamic equation of equilibrium
• Different accelerograms (time histories ) actual events, modified and
simulated are used

17. Hybrid Approach
Hybrid system considering both empirical and Analytical methods
• Data from actual field scenarios collected using empirical methods are
employed
• Statistical data obtained from empirical methods are required to be
sorted and categorized
• Experimental findings and parameters determined from evaluation
actual damage scenarios are used
• Analysis through analytical techniques like NLPOA and NLTHA is
done for a determined typology of buildings and failure categories