Multi hazard approach to design of civil
structures
April 29th 2010
Multi hazard approach to
design of civil structures
Domenico Asprone
Dipartimento di Ingegneria Strutturale
Università degli Studi di Napoli Federico II
Multi hazard approach to design of civil
structures
April 29th 2010
Introduction
A strategic structure could be subject to more than
one critical action during its service life.
A sustainable design needs to consider all the
possible critical actions which the structure could
be subjected to.
Given the uncertainty involved, the sustainable
design needs to be addressed based on a
probabilistic framework.
Multi hazard approach to design of civil
structures
April 29th 2010
Multi-hazard structural
design/assessment
R  E V  H
risk
exposure vulnerability
hazard
Risk, hazard, vulnerability and exposure are
probabilistic quantities.
(a)
Multi hazard approach to design of civil
structures
April 29th 2010
Hazard
(a)
(b)
Multi hazard approach to design of civil
structures
April 29th 2010
Hazard
Multi hazard approach to design of civil
structures
April 29th 2010
Hazard
Multi hazard approach to design of civil
structures
April 29th 2010
Vulnerability
Seismic vulnerability
Multi hazard approach to design of civil
structures
April 29th 2010
Vulnerability
Non-structural elements
vulnerability
Multi hazard approach to design of civil
structures
April 29th 2010
Vulnerability
Tsunami
vulnerability
Multi hazard approach to design of civil
structures
April 29th 2010
Vulnerability
Termite vulnerability
Multi hazard approach to design of civil
structures
April 29th 2010
Exposure
Time dependence
Multi hazard approach to design of civil
structures
April 29th 2010
Exposure
Seismic zones
Multi hazard approach to design of civil
structures
April 29th 2010
Multi-hazard structural
design/assessment
Structural engineering issue:
In case of multiple hazard, the
design/assessment criterion can be written as
 C  P(C | EQ) EQ  P(C | Wind ) wind  P(C | Blast ) Blast  ...   dm
Total probability of
collapse
Acceptable
threshold
Multi hazard approach to design of civil
structures
April 29th 2010
Italian hazard
for civil structures
•
•
•
•
•
•
•
•
•
•
Earthquake;
Extreme service conditions;
Wind;
Snow;
Explosions;
Fire;
Flood;
Landslide;
Vulcan eruptions;
…
Multi hazard approach to design of civil
structures
April 29th 2010
Seismic hazard
Peak Ground Acceleration
Multi hazard approach to design of civil
structures
April 29th 2010
Seismic hazard
36 Seismogenic
zones
Multi hazard approach to design of civil
structures
April 29th 2010
Seismic hazard
Attenuation law
Multi hazard approach to design of civil
structures
April 29th 2010
Seismic hazard
PGA
distribution
Multi hazard approach to design of civil
structures
April 29th 2010
Seismic hazard
Grid spacing 0.05° long-lat
Multi hazard approach to design of civil
structures
April 29th 2010
Seismic hazard
Pratica di Mare hazard
Limit states
Return Period
PGA
Multi hazard approach to design of civil
structures
April 29th 2010
Man-made blast hazard
Scenario definition
Blast scenario
30%
70%
Explosion takes place inside the structure
20%
20%
20%
20%
Explosion takes place outside a 10 m stand-off distance
from the structure
20%
10%
1st floor:
Car bomb
W=200 kg – 500
kg
2nd floor:
Backpack
bomb W=15
kg – 35 kg
3rd floor:
Backpack
bomb W=15
kg – 35 kg
4th floor:
Backpack
bomb W=15
kg – 35 kg
5th floor:
Backpack
bomb W=15
kg – 35 kg
Truck bomb
W=15,000kg 25,000kg
90%
Car bomb
W=200 kg 500kg
The induced overpressure normally consists
of a positive decaying phase followed by a
weaker negative phase.
The most critical aspect with respect to the
safety of the structure regards progressive
collapse mechanisms on the damaged
structure.
500
400
300
P [Mpa]
Multi hazard approach to design of civil
structures
April 29th 2010
Blast loading
200
100
0
0
0.005
0.01
-100
-200
t [s]
0.015
0.02
Multi hazard approach to design of civil
structures
April 29th 2010
Blast Scenarios Leading to Collapse
Multi hazard approach to design of civil
structures
April 29th 2010
Wind hazard
Critical issues:
• Wind direction;
• Low velocity
characterization;
• Spatial mesh refining;
• Season variation;
• Reliable hazard
characterization.
Multi hazard approach to design of civil
structures
April 29th 2010
Multi-hazard structural
design/assessment
Structural engineering issue:
In case of multiple hazard, the
design/assessment criterion can be written as
 C  P(C | EQ) EQ  P(C | Wind ) wind  P(C | Blast ) Blast  ...   dm
Total probability of
collapse
Acceptable
threshold
Multi hazard approach to design of civil
structures
April 29th 2010
Thank you