rapid visual screening of critical facilities in the kingston metropolit
TRANSCRIPT
RAPID VISUAL SCREENING OF CRITICAL
FACILITIES IN THE KINGSTON
METROPOLITAN AREA IMPLICATIONS FOR POST EARTHQUAKE
RESPONSE
Outline of Presentation
Background
Rapid Visual Screening (RVS-FEMA 154 Methodology)
Purpose
Overview of methodology
Overview of RVS process
Results of Survey
Implications for Earthquake Response
Conclusion and Recommendations
2
Background
The KMA is the focal point for most of the island’s
administrative commercial financial and institutional
sectors.
Combined population of these parishes at the end of 2011
equates to 670,012 (STATIN 2012)
Vulnerability of KMA to Earthquakes, as evidenced by
devastating impacts of historical events (1692,1907) and
the anticipation of reoccurrence of major events.
Majority of development in the KMA took place post 1907,
during a period of relatively low seismic activity (seismic
performance relatively unknown)
3
Background- Continued
On average over 200 earthquakes are recorded
annually by the Jamaica Seismograph Network.
Approximately 10 are felt event.
The felt events have magnitudes (Mw) ranging from as
low as 3 and greater.
Current earthquake frequency data from the EQU shows
the highest levels of seismicity is associated with the
eastern part of Jamaica (Kingston St. Andrew, Portland
& St. Thomas) accounting for over 75% of the
earthquake events on the island.
4
REGIONAL PLATE TECTONICS
5
Background (Cont’d)
Critical Facilities- The primary physical structures, technical
facilities and systems which are socially, economically or
operationally essential to the functioning of a society or
community, both in routine circumstances and in the extreme
circumstances of an emergency (UNISDR 2009)
Critical facilities assessed include Fire Stations, Health
Centers and Police Stations.
Populations at their most vulnerable immediately after
earthquake due to collapsed structures fires resulting in
injury.
Ability of critical facilities and first responders to service this
need is paramount to saving lives and property.
6
No known Seismic Assessment of critical facilities in a comprehensive way.
Detailed Structural Assessments are time consuming and often times expensive.
Critical Infrastructure Aged with perceived insufficient structural maintenance
First Step
RVS-FEMA 154 (Rapid Visual Screening) technique first proposed 1988 and further modified in 2002 considered ideal for executing initial assessment of critical facilities
Widely adapted and used worldwide after suitable modifications
Background (Cont’d) 7
RVS (FEMA 154)METHODOLOGY 8
Rapid Visual Screening (RVS-FEMA 154
Methodology
Purpose - the Rapid Visual Screening (RVS) procedure
was developed by the Federal Emergency Management
Agency (FEMA) to provide preliminary estimation of the seismic
vulnerability of buildings and categorising them as:
those that are expected to have acceptable seismic
performance
those that may be seismically hazardous and should
therefore undergo detail structural engineering assessment.
Audience - developed for a broad audience, including
building officials and inspectors, government agencies and
public and private-sector building owners.
9
Overview of Methodology
RVS uses a method based on a “sidewalk survey” to
effect the visual inspection of the building from the
exterior and, if possible from the interior without
conducting any structural calculations.
It utilizes a damageability grading system that requires
the evaluator to:
Identify the primary lateral load resisting system
(Building type)
Structural and non-structural characteristics that may
negatively impact seismic performance.
10
Overview of Methodology
Data Collection Form - Field data is captured on Seismic
Data Collection Form selected based on the region’s seismicity
(Low, Medium and High).
Determining Seismicity of area
11
Overview of Methodology
Example of Data
Collection Form
12
Overview of Methodology Cont’d
Categorization dependent on a final performance score “S”
that is analyzed against a predetermined cut-off score; with
those below the cut-off score being deemed potentially
seismically hazardous and vice versa.
Cut-off Score - determined based on the priority placed on
two main factors; Safety and the Cost of executing detailed
assessment.
A cut-off score of 2.0 is suggested by FEMA as a sufficient
value for regular use, however in cases where higher level
of safety is required higher scores such as 2.5 or 3.0 are
utilized.
13
Overview of Methodology Cont’d
Determining final performance score “S”
A Basic Hazard Score is assigned to each building type which
signifies the probability of collapse of the building, given the
ground motion corresponding to the maximum considered
earthquake (MCE) having a 2% probability of exceeding in 50
years.
This score is then modified by adding or subtracting the
assigned values of structural and nonstructural characteristics
that applies to the particular building to produce a final
expected performance score.
14
Overview of Methodology Cont’d
Building
Code
Building Description Building
Code
Building Description
W1 Light wood-frame residential and commercial
buildings
smaller than or equal to 5,000 square feet
C2 Concrete shear-wall buildings
W2 Light wood-frame buildings larger than
5,000 square feet C3 Concrete frame buildings with unreinforced masonry infill walls
S1 Steel moment-resisting frame buildings PC1 Tilt-up buildings
S2 Braced steel frame buildings PC2 Precast concrete frame buildings
S3 Light metal buildings RM1 Reinforced masonry buildings with flexible floor and roof
diaphragms
S4 Steel frame buildings with cast-in-place
concrete shear walls RM2 Reinforced masonry buildings with rigid floor and roof
diaphragms
S5 Steel frame buildings with unreinforced
masonry infill
walls
URM Unreinforced masonry bearing-wall buildings
(Also made to include Wattle and Daub structures – building
technique which utilizes a woven lattice of wood strips daubed
with wet soil such as clay and straw.)
C1 Concrete moment-resisting frame buildings
List of Building type Classifications
15
Overview of Methodology Cont’d
Score Modifiers
No. of Stories – medium rise (4-7 stories) and high rise (>7
stories)
Layout of building - Plan and Vertical Irregularities
Seismic code adoption dates - Pre and post benchmark
code
Soil type
16
Overview of Methodology Cont’d
Plan and Vertical Irregularity- design configuration that
negatively affect the response mechanism and transfer of load
throughout the structure.
Score Modifiers Cont’d
17
Overview of Methodology Cont’d
Seismic codes - refers to the time period within which
the building was constructed. i.e whether before initial
adaptation of seismic codes (Pre-code era) or after the
adaptation of significantly improved seismic coded (Post
benchmark era).
Where adaptation dates are not known FEMA 154
recommends 1941 for all building types except PC1 for
which 1973 is used.
Score Modifiers Cont’d
18
Overview of Methodology Cont’d
FEMA 154 manual has four Model Building Seismic Design
Provision for Post Benchmark Years. Model Building Seismic Design Provisions
Building Type BOCA SBCC UBC NEHRP
W1 1992 1993 1976 1985
W2 1992 1993 1976 1985
S1 * * 1994 *
S2 1992 1993 1998 1991
S3 * * * *
S4 1992 1993 1976 1985
S5 * * * *
C1 1992 1993 1976 1985
C2 1992 1993 1976 1985
C3 * * * *
PC1 * * 1997 *
PC2 * * * *
RM1 * * 1997 *
RM2 1992 1993 1976 1985
URM * * 1991 *
19
Overview of Methodology Cont’d
FEMA 154 has six (6) soil classification Soil Type Definitions Related Parameters Type A (hard rock) Measured shear wave velocity (vs) > 5000 ft/sec.
Type B (rock) vs between 2500 and 5000 ft/sec.
Type C (soft rock and
very dense soil)
vs between 1200 and 2500 ft/sec, or standard blow count( N)
> 50, or undrained shear strength (su) > 2000 psf.
Type D (stiff soil) vs between 600 and 1200 ft/sec, or standard blow count (N)
between 15 and 50, or undrained shear strength (su) between
1000 and 2000 psf.
Type E (soft soil) More than 100 feet of soft soil with plasticity index (PI) > 20,
water content (w) > 40%, and su < 500 psf; or a soil with vs ≤
600 ft/sec.
Type F (poor soil) Soils requiring site-specific evaluations:
Score Modifiers Cont’d
20
Overview of Methodology Cont’d 21
Overview of Methodology Cont’d
Interpretation of Final Score
Final score is derivative of the Basic Hazard score therefore,
it represent the estimated probability of that building
collapsing at the MCE.
It is the final score expressed as a negative of the logarithm
(Base 10) . Example a final score of 2.0 signifies a probability
of 10(^-2), which equates to a 0.01 or 1% chance of collapse.
The least final score which would produce a meaningful
interpretation is 0.0 as this equates to a probability of 1.0 or
100% chance of collapse.
22
RVS PROCESS 23
RVS Process
Step 1- Planning Stage
Selecting study area
Training screeners
Developing budget
Step 2- Pre-field Data Collection
Selecting Data collection form
Selecting Cut-off score
Reviewing geotechnical data for identifying soil type
24
RVS Process Cont’d
Step 3- Execution of screening (15-30 min for each
building).
Identify building type
Identify structural and non-structural components that
would affect seismic performance
Obtain approximate square footage of building
Complete a sketch of building layout (plan and one
elevation)
Take picture of building
Compute final score based on Basic hazard score and
applicable modifiers observed.
25
RESULTS 26
Results
Total Critical Facilities in KSA- 77
Police Stations- 37
Health Centres- 33
Fire Stations- 7
Total Critical facilities surveyed- 66
11 Structures located on Soil Type F for which
the RVS was inapplicable, site specific
investigations required
27
Distribution of Fire Stations KMA
N
28
Location- Police Stations and Health
Centers 29
Composite Soil Map
B – Limestone/ Wagwater C-August Town Formation D-Liguanea Alluvium E- Mangrove/Salina F-Liquefaction 1907 F-Engineered Fill F-Landfill
30
Soil Type Definitions
Type A (hard rock)
Type B (rock)
Type C (soft rock and very dense soil)
Type D (stiff soil)
Type E (soft soil)
Type F (poor soil)
Distribution- Critical Facilities across
soil type
22%
9%
55%
14%
0%
10%
20%
30%
40%
50%
60%
B C D F
Distribution across Soil Types
Type B- 22%
Type C- 9%
Type D- 55%
Type F- 14%
31
Results- Police Stations 32
16% 14%
54%
16%
0%
10%
20%
30%
40%
50%
60%
% Concentration of Police Stations across soil types
Soil Type B Soil Type C Soil Type D Soil Type F
Results
19%
65%
16%
Overall Performance of Police Stations in KSA
Passed
Failed
Indeterminate
33
Results-Police Stations 34
Detailed Assessment
Soil Type Type of Facility Number Yes No Indeterminate
B Police Stations 6 2 4
C Police Stations 5 4 1
D Police Stations 20 18 2
F Police Stations 6 6 0 6
Subtotal 37 30 7
RVS Summary Table (Police Stations)
Results- Police Stations 35
10%
90%
Seismic Performance of buildings on Soil Type D
Passed
Failed
Reasons for Failure
54% of Police Stations
Located on Soil Type D
Final Scores ranged
between 0.5-2.4
9 Different Lateral Force
Resisting Systems
Results 36
14%
57%
29%
0%
10%
20%
30%
40%
50%
60%
% Concentration of Fire Stations across soil types
Soil Type B Soil Type D Soil Type F
Results
14%
57%
29%
Seismic Performance of Fire Stations within the KSA
Passed
Failed
Indeterminate
37
Results- Fire Stations 38
Detailed Assessment
Soil Type Type of Facility Number Yes No Indeterminate
B Fire Station 1 0 1
D Fire Station
4 4 0
F Fire Station
2 2 0 2
Total
7 6 1
RVS Summary Table (Fire Stations)
Results-(Health Centers) 39
33%
6%
52%
9%
0%
10%
20%
30%
40%
50%
60%
% Concentration of buildings across Soil types
Soil Type B Soil Type C Soil Type D Soil Type F
Results- (Health Centers)
30%
61%
9%
Performance of Health Centres in KSA
Passed
Failed
Indeterminate
40
41
Detailed Assessment
Soil Type Type of Facility Number Yes No Indeterminate
B Health Centers 11 3 8
C Health Centers 2 1 1
D Health Centers
17 16 1
F Health Centers 3 3 0 3
Total
33 23 10
Results- (Health Centers)
RVS Summary Table (Fire Stations)
42
6%
94%
Seismic performance of Health Centers on Soil D
Pass
Fail (16)
(1)
Reasons for Failure
52% of Health Centers
Located on Soil Type D
Final Scores ranged
between -0.5-2.9
Results- (Health Centers)
Pictures- Modifiers
Eg. of Vertical Irregularity - Harbour View Police
43
Pictures- Modifiers
Eg. of Plan Irregularity – Lawrence Tavern Police Station
44
PICTURES OF DEFECTS
York Park Fire Station 45
PICTURES OF DEFECTS
Franklin Town Police Station- Wall System
46
Implications for Emergency Response
Results suggest that initial response capacity of critical facilities would be limited by internal response to impact
Remaining functional facilities would likely become overwhelmed
Potential for increased casualties and property damage/loss depending on service area of each facility
Challenges to mounted a coordinated response- (potential for chaos/confusion)
47
Conclusion and Recommendation
Majority of critical failed facilities assessed located
on Soil type D which happens to be most
populous zone in the KMA
Urgent need to prioritize programme for detailed
Structural Assessments of Critical Facilities in the
KMA to determine seismic response
Seismic Retrofitting of critical facilities with lower
final scores
Extending use of RVS methodology to other
facilities such as Schools (Shelters)
48
49
THANK YOU
Questions
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