Scaling API-first – The story of a global engineering organization
ICOSSAR PO et al
1. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Sapienza – University of Rome
Pierluigi Olmati, Ph.D. student, P.E.
Francesco Petrini, Ph.D., P.E.
Konstantinos Gkoumas, Ph.D., P.E.
Sapienza - University of Rome
Dipartimento di Ingegneria Strutturale e
Geotecnica
Blast resistance assessment of a reinforced precast
concrete wall under uncertainty
2. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Presentation outline
2
• Introduction
• Component damage levels and response
parameters
• Blast scenario and targets
• Blast scenario
• Precast cladding wall panel
• Input data
• Fragility curves
• Calculation procedure
• Results
• Conclusions
3. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Presentation outline
3
• Introduction
• Component damage levels and response
parameters
• Blast scenario and targets
• Blast scenario
• Precast cladding wall panel
• Input data
• Fragility curves
• Calculation procedure
• Results
• Conclusions
4. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Introduction
The case of the Ronan Point apartments building
4
Reference:
NISTIR 7396: Best practices for reducing the potential
for progressive collapse in buildings. Washington DC:
National Institute of Standards and Technology (NIST),
2007.
Details:
-apartment building,
-built between 1966 and 1968,
-64 m tall with 22 story,
-walls, floors, and staircases were made of
precast concrete,
-each floor was supported directly by the walls in
the lower stories (bearing walls system).
5. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
5
Cause Damage Pr. Collapse
Details:
-apartment building,
-built between 1966 and 1968,
-64 m tall with 22 story,
-walls, floors, and staircases were made of
precast concrete,
-each floor was supported directly by the walls in
the lower stories (bearing walls system).
The event:
-May 16, 1968 a gas explosion blew out an
outer panel of the 18th floor,
-the loss of the bearing wall causes the
progressive collapse of the upper floors,
-the impact of the upper floors’ debris caused the
progressive collapse of the lower floors.
Introduction
The case of the Ronan Point apartments building
6. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Collapse probability
6
LOAD STRUCTURE RESPONSE
Truck bomb
1.8 ton TNT
A. P. M. Building
Before 19/05/95
A. P. M. Building
After 19/05/95
HAZARD COLLAPSE
RESISTENCE
P[●]: probability
P[●|■]: conditional probability
H: Hazard
LD: Local Damage
C: Collapse
NISTIR 7396
UFC 4-023-03
References:
EXPOSURE
VULNERABILITY
ROBUSTESS
∑i = P[C]P[LD|Hi]P[Hi] P[C|LD]
LOCAL EFFECTCAUSE GLOBAL EFFECT
7. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Presentation outline
7
• Introduction
• Component damage levels and response
parameters
• Blast scenario and targets
• Blast scenario
• Precast cladding wall panel
• Input data
• Fragility curves
• Calculation procedure
• Results
• Conclusions
9. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
9
Component damage levels θ [degree] μ [-]
Blowout >10° none
Hazardous Failure ≤10° none
Heavy Damage ≤5° none
Moderate Damage ≤2° none
Superficial Damage none 1
Blowout: component is overwhelmed by the blast load causing
debris with significant velocities.
Hazardous Failure: component has failed, and debris velocities range from
insignificant to very significant.
Heavy Damage: component has not failed, but it has significant
permanent deflections causing it to be un-repairable.
Moderate Damage: component has some permanent deflection. It is
generally repairable, if necessary, although
replacement may be more economical and aesthetic.
Superficial Damage: component has no visible permanent damage.
Component damage levels (CDL’s)
Source: US Army Corps of Engineers
10. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Presentation outline
10
• Introduction
• Component damage levels and response
parameters
• Blast scenario and targets
• Blast scenario
• Precast cladding wall panel
• Input data
• Fragility curves
• Calculation procedure
• Results
• Conclusions
14. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
14
Panel dimensions:
3500x1500x150 mm
(137x59x6 in.)
Panel reinforcement:
12 φ10 mm (0.4 in.)
Panel materials:
Concrete fcm=35 MPa (5000 psi)
Steel B450C (≈GR60)
Blast scenario and targets
Precast cladding wall panel
15. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
15
Symbol Description Mean COV Distribution
fc Concrete strength 28MPa 0.18 Lognormal
fy Steel strength 495 MPa 0.12 Lognormal
L Panel length 3500 mm 0.001 Lognormal
H Panel height 150 mm 0.001 Lognormal
b Panel width 1500 mm 0.001 Lognormal
c Panel cover 75 mm 0.01 Lognormal
W Explosive weight 227 kgf 0.3 Lognormal
R Stand-off distance 15 m 20 m 25 m 0.05 Lognormal
Blast scenario and targets
Input data
16. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Presentation outline
16
• Introduction
• Component damage levels and response
parameters
• Blast scenario and targets
• Blast scenario
• Precast cladding wall panel
• Input data
• Fragility curves
• Calculation procedure
• Results
• Conclusions
18. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
18
Fragility curves
Flowchart
CDL (j)
Z=i
MC analysis
FC-CDL (i, j, k)
FC-CDL (j,k)
FC-CDL (k)
i=N ?
j=M ?i=i+1
j=j+1
YES
NO
NO
YES
• CDL: Component Damage Level
• R: Stand-off distance
• Z: Scaled distance
• FC-CDL: numerical Fragility Curves
of the Component Damage Level
• i: the i-th point, of the j-th FC-CDL
corresponding to the k-th R
• j: the j-th CDL
• k: the k-th stand-off distance
• MC analysis: Monte Carlo analysis
• N: number of FC-CDL points, or
number of the Z
• M: number of the CDL
• L: number of the stand-off
distance
• Interpolated FC-CDL: lognormal
interpolated Fragility Curves of the
Component Damage Level
R=k
k=L ?
YES
NO
k=k+1
FC-CDL
Lognormal
Interpolation
Interpolated
FC-CDL
j=1 i=1 k=1
INTENSITY MEASURE
• CDL: Component Damage Level
• R: Stand-off distance
• Z: Scaled distance
• FC-CDL: numerical Fragility Curve
of the Component Damage Level
• i: the i-th point, of the j-th FC-CDL
corresponding to the k-th R
• j: the j-th CDL
• k: the k-th stand-off distance
• MC analysis: Monte Carlo
analysis
• N: number of FC-CDL points, or
number of the Zs
• M: number of the CDLs
• L: number of the stand-off
distances
• Interpolated FC-CDL: lognormal
interpolated Fragility Curve of the
Component Damage Level
23. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
23
Fragility curves
Flowchart
CDL (j)
Z=i
MC analysis
FC-CDL (i, j, k)
FC-CDL (j,k)
FC-CDL (k)
i=N ?
j=M ?
i=i+1
j=j+1
YES
NO
NO
YES
• CDL: Component Damage Level
• R: Stand-off distance
• Z: Scaled distance
• FC-CDL: numerical Fragility Curves
of the Component Damage Level
• i: the i-th point, of the j-th FC-CDL
corresponding to the k-th R
• j: the j-th CDL
• k: the k-th stand-off distance
• MC analysis: Monte Carlo analysis
• N: number of FC-CDL points, or
number of the Z
• M: number of the CDL
• L: number of the stand-off
distance
• Interpolated FC-CDL: lognormal
interpolated Fragility Curves of the
Component Damage Level
R=k
k=L ?
YES
NO
k=k+1
FC-CDL
Lognormal
Interpolation
Interpolated
FC-CDL
j=1 i=1 k=1
Fragility curves for
n° M CDLs and the
k-th stand-off
distance (R)
Fragility curves for
n°M CDLs and n°L
stand-off distances
(R)
Fragility curve for
the j-th CDL and the
k-th stand-off
distance (R)
• CDL: Component Damage Level
• R: Stand-off distance
• Z: Scaled distance
• FC-CDL: numerical Fragility Curve
of the Component Damage Level
• i: the i-th point, of the j-th FC-CDL
corresponding to the k-th R
• j: the j-th CDL
• k: the k-th stand-off distance
• MC analysis: Monte Carlo
analysis
• N: number of FC-CDL points, or
number of the Zs
• M: number of the CDLs
• L: number of the stand-off
distances
• Interpolated FC-CDL: lognormal
interpolated Fragility Curve of the
Component Damage Level
24. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
24
Fragility curves
Computing the fragility curve
Fence barrier
Vehicle bomb
w [kgp]
p [W]
Stand-off distance
r [m]
p [R]
Cladding wall
θi
p [Θi]
(1) R=R0 W=W1 Z=Z1
(2) R=R0 W=W2 Z=Z2
(3) R=R0 W=W3 Z=Z3
……..
(N) R=R0 W=WN Z=ZN
Z
1
2
3
N
P(X>x|Z)
Fragility curve for the j-th CDL and the k-th
stand-off distance (R)
Monte Carlo
Simulation
31. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
31
Fragility curves
Failure Probability
CDL
Mean W=227 kgf COV=0.3 lognormal distribution
R, COV=0.05 lognormal distribution
FC analysis MC analysis Difference Δ%
R = 20 m
SD 100.0 % 100.0 % 0.0 %
MD 96.6 % 97.5 % 0.9 %
HD 55.7 % 55.5 % 0.3 %
HF 13.6 % 12.1 % 11.0 %
R = 25 m
SD 100.0 % 100.0 % 0.0 %
MD 74.6 % 77.3 % 3.5 %
HD 14.2 % 12.6 % 11.2 %
HF 1.02 % 1.02 % 0.0 %
R = 15 m
SD 100.0 % 100.0 % 0.0 %
MD 97.9 % 99.9 % 2.0 %
HD 93.6 % 96.9 % 3.4 %
HF 67.8 % 72.6 % 6.6 %
32. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Presentation outline
32
• Introduction
• Component damage levels and response
parameters
• Blast scenario and targets
• Blast scenario
• Precast cladding wall panel
• Input data
• Fragility curves
• Calculation procedure
• Results
• Conclusions
33. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
33
Conclusions
0
20
40
60
80
100
3.0 3.5 4.0 4.5 5.0
Pf(X>x0|Z)
Z
Moderate Damage
Safe
Unsafe
Example
• Fragility curves can be helpful in the design of precast
concrete wall panels, or cladding panels in general.
34. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
34
Conclusions (2)
• It is important to define a appropriate thresholds for the
probability of failure.
• The probability of failure computed by means of
fragility curve analysis and Monte Carlo analysis
shows a maximum difference of 11 % for the case
study wall panel. The question is, is this acceptable?
• In a future study, it could be useful to implement
fragility surfaces instead of fragility curves.
• Furthermore, it could be useful to account for the
structural deterioration of the wall panel on computing
the fragility curves.
35. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
Thank you for your attention
35
Pierluigi Olmati, Francesco Petrini, Konstantinos Gkoumas
Sapienza - University of Rome, Dipartimento di Ingegneria Strutturale e Geotecnica
This study is partially supported by StroNGER s.r.l. from the fund “FILAS - POR FESR LAZIO
2007/2013 - Support for the research spin-off”.
36. Blastresistanceassessmentofareinforcedprecastconcretewallunderuncertainty
ICOSSAR 2013
11th
International Conference on Structural Safety & Reliability
June 16-20, Columbia University, New York, NY
Pierluigi Olmati
Francesco Petrini
Konstantinos Gkoumas
36
Pierluigi Olmati, Francesco Petrini, Konstantinos Gkoumas
Sapienza - University of Rome, Dipartimento di Ingegneria Strutturale e Geotecnica
Fence barrier
Vehicle bomb
w [kgp]
p [W]
Stand-off distance
r [m]
p [R]
Cladding wall
θi
p [Θi]
0
20
40
60
80
100
3.0 3.5 4.0 4.5 5.0
Pf(X>x0|Z)
Z
Moderate Damage