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SIMPLE/RAPID SEISMIC
EVALUATION METHODS
Advanced Earthquake Engineering
CIVIL-706
Instructor:
Lorenzo DIANA, PhD
Why evaluation of existing buildings?
Rapid Visual Screening Advanced Earthquake Engineering CIVIL-706 -1-
Why evaluation of existing buildings?
Rapid Visual Screening Advanced Earthquake Engineering CIVIL-706 -2-
• Regeneration of existing cities implies the assessment of existing cities
• The assessment of existing cities implies the assessment of different aspects
• Assessment of seismic behaviour becomes and important central aspect
Strategy: Selection by steps
Rapid Visual Screening Advanced Earthquake Engineering CIVIL-706
Rapid evaluation
Vulnerability score
Sophisticated modeling
Retrofitting
e.g., FEMA or OFEG
STOP If OK?
STOP If OK?
-1-
By the end of today’s course…
Advanced Earthquake Engineering CIVIL-706
You will be able to answer:
• Why we do a rapid visual screening?
• What are the examples for conducting such a seismic assessment? (in US and CH)
• What are the particular means for that?
Ph
oto
: EE
RI
Rapid Visual Screening -2-
Why to do rapid screening?
Example of a building group
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening -3-
Prioritizing the building group
Red: imminent collapse
Yellow: on the edge
Green: Safe
Why to do rapid screening?
Example of a building group
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening -4-
Main Steps…
1. Identify the building class
2. Detect structural irregularities
3. Estimate the height
4. Determine the soil
5. Estimate the construction year
6. Take photo for later references
Photo source: www.eagle-wi.gov
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening -5-
1. Building classification:
• Constructional material
• Structural properties
2. Basic score:
Probability of collapse
3. Score modifiers
Masonry, concrete with in-fills, steel structures, and etc.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
Main Steps…
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155 • FEMA 154 = Rapid Visual Screening
(RVS) of buildings for potential seismic hazard
• One of the US seismic evaluation methods
• RVS – Rapid Visual Screening
• Identifying seismically hazardous buildings that need further analysis
• Level 1 and Level 2
Acknowledgment for the contribution to create the slides
Final Score = BS + ∑ SM
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Probability of collapse for the maximum
considered earthquake
Final Score >= Cut-off score
BS = - log10(P[collapse|MCER])
Basic Score
Score modifiers
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
L, M, M-H, H, V-H 5 different seismicity Regions
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Building identification portion of Data Collection Form
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data Land Register Cadastre
Sanborn maps Design drawings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
General Information - Number of stories. - Floor Area. - Year of construction - Determination of the Key Code Adoption Dates: • Seismic Code Adopted (Code year) • Improvements adopted (Benchmark year) In Basic Score determination a post Code year is assumed. Score modifiers are applied if the building is constructed before Code Year or after Benchmark year.
- Addition - Occupancy
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
SOIL TYPE A predefined soil class C-D is assumed. Score modifiers are applied for soil class A, B or E. Soil class F implies a soil-evaluation needed.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
GEOLOGIC HAZARD • Liquefaction • Landslide • Surface fault rupture
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
GEOLOGIC HAZARD • Liquefaction SOFT SOILS, SANDS and LOAMS Increase of pore pressure soil from solid to fluid state. Seismic event can augment pore pressure till the equivalence with the pressure above.
Nigata (Japon), Kawagishi-cho Apartment Complex 1964
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
GEOLOGIC HAZARD • Liquefaction SOFT SOILS, SANDS and LOAMS Shear resistance of soil is negligible. The building undergoes rocking or sinking due to the incapacity of soil to resist vertical or lateral load.
Nigata (Japon), Kawagishi-cho Apartment Complex 1964
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
GEOLOGIC HAZARD • Landslide Movement of the soil due to loss of slope stability. Landslide may occur if height of the slope is bigger than the distance to the slope. Pre-field information should be verified during the on-site survey.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
GEOLOGIC HAZARD • Surface fault rupture Due to shallow earthquake (<20km distance) Significant displacement of the earth’s surface
Canterbury earthquake in New Zealand, 2010
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Pre-field building data
GEOLOGIC HAZARD • Liquefaction • Landslide • Surface fault rupture
If one of the 3 geologic hazard is identified, a detailed structural evaluation is needed.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
ADJANCENCY Adjacent buildings may lead to several types of damage during earthquakes: • Pounding • Falling hazards from adjacent buildings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
ADJANCENCY Adjacent buildings may lead to several types of damage during earthquakes: • Pounding • Falling hazards from adjacent buildings
GAPS VH seismicity region = 2 inches (5.08 cm) per storey H seismicity region = 1.5 inches (3.81 cm) per storey MH seismicity region = 1 inches (2.54 cm) per storey M seismicity region = 0.5 inches (1.27 cm) per storey L seismicity region = 0.5 inches (1.27 cm) per storey
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
ADJANCENCY • Pounding
IF a) Minimum gap not respected
+ b) Floors are separated vertically by more than 2 ft (60.69 cm) OR b) One building is two or more stories taller than the adjacent OR b) The building is at the end of a row of 3 or more buildings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
ADJANCENCY • Pounding
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
ADJANCENCY • Pounding
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
• Severe vertical irregularities • Moderate vertical irregularities
• Plan Irregularities
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
1. Sloping site 2. Weak and/or soft story 3. Out-of-plane setback 4. In plane setback 5. Short column/pier 6. Split levels
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
1. Sloping site
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
1. Sloping site - Foundations at different levels - Irregularities and non-symmetry in both horizontal and
vertical directions - Irregularity in stiffness and mass - Centre of mass and centre of stiffness of a storey do not
coincide with each other and are not in a vertical line for different floors
- Lateral load leads to torsional response - Different column heights at the same storey level
Drastic variation in stiffness of columns of the same storey
Short stiff columns uphill attract higher lateral forces and are prone to damage
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
1. Sloping site
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155 IRREGULARITIES • Vertical Irregularities
1. Sloping site
2 cases: 1) Along slope NO TORSIONAL EFFECTS but shear damages to shorter
columns uphill 2) Across slope TORSIONAL EFFECTS
CM
CS
ACROSS SLOPE ACTION
ALONG SLOPE ACTION
Side-walk survey
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
1. Sloping site If at least 1 storey slope from one side to the other
= MODERATE VERTICAL IRREGULARITY
(for W1 typology = SEVERE) W1 typology = LIGHT WOOD FRAME SINGLE or MULTIPLE FAMILY DWELLINGS of ONE or MORE STORIES
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
2. Weak and/or soft storey - Weak Storey = when a story has less strength (fewer
walls and columns) than the storey above or below - Soft Storey = when the stiffness of one storey is
dramatically less than that of most others
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
IRREGULARITIES • Vertical Irregularities
2. Weak and/or soft storey
CRIPPLE WALLS (for W1) =
MODERATE VERTICAL IRREGULARITY (SEVERE if crawl space is occupied)
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
2. Weak and/or soft storey
OCCUPIED SPECE OVER a garage (for W1) =
SEVERE VERTICAL IRREGULARITY
IRREGULARITIES • Vertical Irregularities
2. Weak and/or soft storey
SOFT STORY =
SEVERE VERTICAL IRREGULARITY
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
2. Weak and/or soft storey
ONE STORY PARTICULARLY TALL =
SEVERE VERTICAL IRREGULARITY
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155 IRREGULARITIES • Vertical Irregularities
3. Out-of-plane setback - When the seismic-resisting system at one story is not
aligned vertically with the seismic-resisting system of the storey above or below
- An outside survey may not indicate set-backs in the interior walls and the seismic-resisting system of the building
Side-walk survey
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
3. Out-of-plane setback
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
3. Out-of-plane setback
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
3. Out-of-plane setback
If the setback is greater than 2 ft (60.96 cm) =
SEVERE VERTICAL IRREGULARITY
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
4. In plane setback - When elements of the seismic force-resisting system at
upper levels are offset from elements at the lower level - Damage can be concentrated in horizontal elements that
connect the offset lateral elements and in vertical elements at the upper level
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
4. In plane setback
MODERATE VERTICAL IRREGULARITY
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
5. Short column/Pier - When columns (or piers) are shorter than typical
columns, these shorter and stiffer columns attract greater lateral load significant damage
- 3 main cases: a) Some columns/piers are much shorter than the
typical columns/piers in the same line
If at least 20% of the columns in line are short = SEVERE VERTICAL IRREGUALRITY
Le misure preventive (di cui il daspo fa parte) sono provvedimenti gravissimi, eredità del fascismo, che minano le libertà degli individui senza alcun processo e senza il diritto a una difesa Note this deficiency is typically seen in older concrete and steel building types.
Typologies: C1, C2, C3, PC1, PC2, RM1, RM2
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
5. Short column/Pier - When columns (or piers) are shorter than typical
columns, these shorter and stiffer columns attract more of the lateral load significant damage
- 3 main cases: b) The columns/piers are narrow compared to the
depth of the spandrels
If the height is less then 50% of the depth of spandrels = SEVERE VERTICAL IRREGUALRITY
Apply if: Figure (a): Some columns/piers are much shorter than the typical columns/piers in the same line. Figure (b): The columns/piers are narrow compared to the depth of the beams. Figure (c): There are infill walls that shorten the clear height of the column. Note this deficiency is typically seen in older concrete and steel building types.
Typologies: C1, C2, C3, PC1, PC2, RM1, RM2
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Vertical Irregularities
5. Short column/Pier - When columns (or piers) are shorter than typical
columns, these shorter and stiffer columns attract more of the lateral load significant damage
- 3 main cases: c) There are infill walls that shorten the clear height
of the column
SEVERE VERTICAL IRREGUALRITY
Apply if: Figure (a): Some columns/piers are much shorter than the typical columns/piers in the same line. Figure (b): The columns/piers are narrow compared to the depth of the beams. Figure (c): There are infill walls that shorten the clear height of the column. Note this deficiency is typically seen in older concrete and steel building types.
Typologies: C1, C2, C3, PC1, PC2, RM1, RM2
Note this deficiency is typically seen in older concrete and steel building types.
IRREGULARITIES • Vertical Irregularities
6. Split levels - When floors or roof floors in one part are not aligned
with the floors or roof floors levels in other part - Damage is concentrated in the elements that connect
the offset floor level to the vertical framing
MODERATE VERTICAL IRREGULARITY
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
1. Torsion 2. Non-parallel systems 3. Re-entrant corners 4. Diaphragm openings 5. Beams do not align with columns
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
1. Torsion - When a building has a good lateral-load resistance in
only ONE DIRECTION
OR - When there are stiffness eccentricities in the seismic-
force-resisting systems which may cause twisting around vertical axis
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
1. Torsion - Mainly in CORNER or FRONT buildings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
1. Torsion - Mainly in CORNER or FRONT buildings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
1. Torsion - Mainly in CORNER or FRONT buildings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
2. Non-parallel systems - Wedge-shaped buildings triangular in plan are
susceptible to torsion and collapse
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
3. Re-entrant corners - Buildings with long wings. E,T,L,U,+ shaped with
projection of more than 20 ft (6.09 m) - STRESS CONCENTRATION at re-entrant corners could
lead to damage and collapse - In addition buildings are likely to experience torsion
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
IRREGULARITIES • Plan irregularities
4. Diaphragm openings - Large openings in floors or roofs weaken the diaphragm
and reduce its ability to transfer seismic forces. - Floors and roofs have the role of distributing seismic
forces to vertical structures.
- IF large openings have a width > 50% of the width of diaphragm
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
IRREGULARITIES • Plan irregularities
5. Beams do not align with columns - When exterior beams do not align with columns in plan - Mainly in concrete buildings
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
Exterior falling hazards • Unbraced chimneys • Unbraced parapets • Cornices • Heavy veneers • Heavy claddings • Overhangs • Appendages • Canopies
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
Damage and deterioration • Abandoned buildings • Beams, floors, roofs sagging • Beams or columns broken • Settlement occurred • Visible distressed from prior earthquake not repaired • Fire damage not repaired • For wood buildings: wood rotted • For unreinforced masonry buildings: mortar eroded
away • For concrete buildings: concrete damaged or eroded
such as the rebar is exposed • For steel buildings: elements are corroded • Foundations with cracks
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
FEMA Typologies Every BUILDINGS TYPE has its own BASIC SCORE providing a measure of the expected seismic performance. 17 building types (steel plate shear walls buildings, earth buildings, native Americans buildings are excluded).
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk survey
Determination of the BASIC SCORE
1) Calculation of the peak response of the building for a given set of ground motions (MCER)
2) Calculation of the probability of complete damage given the peak response
3) Calculation of the probability of collapse given the probability of complete damage
4) Calculation of the BASIC SCORE
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Determination of the BASIC SCORE
1) Calculation of the peak response of the building for a given set of ground motion (MCER)
Peak response of the building is calculated as the intersection of the building CAPACITY CURVE and the DEMAND SPECTRUM of EARTHQUAKE GROUND MOTION .
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Seismic demand (MCER)
Capacity Curve (buildings classification)
Performance Point
Determination of the BASIC SCORE
1) Calculation of the peak response of the building for a given set of ground motions (MCER)
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Determination of the BASIC SCORE
1) Calculation of the peak response of the building for a given set of ground motions (MCER)
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Determination of the BASIC SCORE
2) Calculation of the probability of complete damage given the peak response
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Fragility curves are lognormal cumulative distribution functions describing the structural behavior of building type
Determination of the BASIC SCORE
2) Calculation of the probability of complete damage given the peak response
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Sd,c median value of spectral displacement for the complete structural damage state
Sd,c = ΔC HR(α2/ α3) ΔC story drift ratio
HR building height
α2 modal height factor
α3 modal shape factor
βS,C standard deviation
Sd,c
Determination of the BASIC SCORE
3) Calculation of the probability of collapse given the probability of complete damage
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
P[collapse] = collapse factor x P[complete damage] Collapse factor are provided for each Model Building Type. The collapse factor is small for light wood frame single or multiple-family dwellings (W1) (3%) and larger for Model Building Types more prone to collapse, such as unreinforced masonry bearing-wall buildings (URM) (15%).
Determination of the BASIC SCORE
4) Calculation of the BASIC SCORE
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
BS = -log10(P[collapse])
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Determining the final score:
SL1 = BS + ∑ SM SL1 >= SMIN
Cut-off score is mainly considered to be 2.0
!S cu t o ff b u ild in g is O K
S cu t o ff fu r th e r in ve s tig a tio n
BS
SM
Level 2 Level 2 analysis provides specific SCORE modifiers for every VERTICAL or PLAN irregularity.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
VL2
PL2
Level 2 There are specific SCORE modifiers also for: REDUNDANCY and POUNDING. Redundancy In rapid visual screening, redundancy observed due to multiple bays of lateral elements on each side of the building is beneficial to seismic performance.
Pounding There are a variety of pounding configurations, as discussed in for level 1.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
M
Level 2 Specific BUILDING TYPE score modifiers: 1. S2 buildings: K BRACING GEOMETRY
When braces intersect the column at the mid-height without horizontal connection to the diaphragm
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
M
Level 2 Specific BUILDING TYPE score modifiers: 1. S2 buildings: K BRACING GEOMETRY 2. C1 buildings: FLAT PLATE MOMENT FRAME
When a concrete moment frame lacks a dropped beam running through the column, the risk of punching shear failure at the column increases.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
M
Level 2 Specific BUILDING TYPE score modifiers: 1. S2 buildings: K BRACING GEOMETRY 2. C1 buildings: FLAT PLATE MOMENT FRAME 3. PC1/RM1 building: with roof-to-wall ties
Do not combine with post-benchmark or retrofit modifier
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
M
Level 2 In addition BUILDING TYPE SPECIFIC STATEMENTS: 1. S2 buildings: K BRACING GEOMETRY 2. C1 buildings: FLAT PLATE MOMENT FRAME 3. PC1/RM1 building: with roof-to-wall ties 4. PC1/RM1 building with closely spaced walls
When buildings are used as offices or for some other use, they may have relatively close spaced partitions that can provide some redundancy for carrying gravity loads and additional damping.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
M
Level 2 In addition BUILDING TYPE SPECIFIC STATEMENTS: 1. S2 buildings: K BRACING GEOMETRY 2. C1 buildings: FLAT PLATE MOMENT FRAME 3. PC1/RM1 building: with roof-to-wall ties 4. PC1/RM1 building with closely spaced walls 5. URM buildings: GRABLE WALLS are present
Out-of-plane wall failure might occur, compromising gravity support for the roof above.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
Side-walk + internal survey
If multiple modifiers occur in the same section, the score modifier is the sum of the applicable modifiers, but is subject to a cap. The cap corresponds to the maximum value for the given seismicity range.
M
Level 2 Level 1 gives: SL1 = Final Level 1 score VL1 = Vertical Irregularity score PL1 = Plan irregularity score S’ (Adjusted baseline score) = (SL1 – VL1 – PL1) Level 2 gives: SL2 = Final Level 2 score VL2 = Vertical Irregularity sum score PL2 = Plan irregularity sum score M = Modifiers sum score SL2 = (S’+ VL2 + PL1 + M)
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
If multiple modifiers occur in the same section, the score modifier is the sum of the applicable modifiers, but it is subject to a cap. The cap corresponds to the maximum value for the given seismicity range.
Advanced Earthquake Engineering CIVIL-706 Rapid Visual Screening
FEMA 154/155
SL1 or SL2>= SMIN
!S cu t o ff b u ild in g is O K
S cu t o ff fu r th e r in ve s tig a tio n
Cut-off score is mainly considered to be 2.0