Terms of the problem: heritage, cities, risk, vulnerability, robustness, resilience

Terms of the problem:
heritage, cities,
risk, vulnerability, robustness, resilience.
Franco Bontempi
School of Civil and Industrial Engineering University of Rome La Sapienza
franco.bontempi@uniroma1.it
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Index
1.The heritage
2.The city
3.General concepts
4.More concepts
5.Reflections

The heritage
What is, its contribution, cultural dimensions.
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Motivation after Maslow
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Design after Schleich

What is heritage (1)
• Cultural heritage is often associated with grandiose monuments and iconic
archaeological sites that can hold us in awe of their beauty, history and sheer
scale.
• However, the understanding of cultural heritage has undergone a marked
shift during the last few decades in terms of what it is, why it is important,
why it is at risk and what can be done to protect it.

What is heritage (2)
• Cultural heritage today encompasses a broader array of places such as
historic cities, living cultural landscapes, gardens or sacred forests and
mountains, technological or industrial achievements in the recent past and
even sites associated with painful memories and war.
• Collections of movable and immoveable items within sites, museums,
historic properties and archives have also increased significantly in scope,
testifying not only to the lifestyles of royalty and the achievements of great
artists, but also to the everyday lives of ordinary people.
• At the same time intangibles such as knowledge, beliefs and value systems
are fundamental aspects of heritage that have a powerful influence on
people’s daily choices and behaviors.

Heritage contributions (1)
• Heritage contributes to social cohesion, sustainable development and
psychological wellbeing.
• A considerable wealth of experience exists in protecting heritage from
disasters and in harnessing the potential of a well maintained historic
environment to strengthen the resilience of communities.
• Nevertheless, with a few notable exceptions, efforts to protect heritage from
disaster risk remain fragmented and efforts to draw on heritage as an
instrument for building resilience remain inconsistent.
• Protecting heritage promotes resilience.

Heritage contributions (2)
• The safeguarding of cultural heritage is important and must be ensured for
future generations, not only because it is a source of the cultural identity of
a local community, but also because cultural heritage is a driving force of the
economy.
• Natural events may become disasters if one is unprepared, and the
preparation includes a proper maintenance of historical centres of cities,
where the most important art works and cultural assets of a community are
hosted.
• In addition, a well maintained and living historic environment is very resilient
to natural phenomena.

Heritage drives sustainable development/economies
• Today, as in the past, cultural heritage continues to perform its irreplaceable
role as a source of meaning and identity for communities and individuals.
Heritage is not a relic of the past, but is increasingly instrumental in steering
sustainable development and the wellbeing of communities.
• Many people, especially the poor, depend directly on ecosystems for their
livelihoods, their economic, social and physical well-being, and their cultural
heritage, and this calls for the conservation, as appropriate, of the natural
and cultural heritage of human settlements, the revitalization of historic
districts and the rehabilitation of city centres.

Heritage drives sustainable development/economies
• The safeguarding of cultural heritage sites and of the ensemble of intangible
cultural expressions, knowledge and skills that, collectively, define a
community, can be considered in itself a contribution to human wellbeing.
• Cultural heritage is also a powerful asset for inclusive economic
development, by attracting investments and promoting green, locally based,
stable and decent jobs related to a wide range of sustainable activities in
areas such as tourism, conservation, construction, food production,
traditional healing and, the production of crafts of all kinds and the arts in
general.

Heritage for inclusive social development
• Finally, cultural heritage appears also to be closely connected to the
fundamental components of an inclusive social development.
• As a vehicle to express values and identity, and organize communities and
their relationships through its powerful symbolic and aesthetic dimensions,
cultural heritage is essential to the spiritual wellbeing of people.
• The acknowledgment and conservation of the diversity of cultural heritage,
fair access to it and equitable sharing of the benefits deriving from its use
enhance the feeling of place and belonging, mutual respect and sense of
collective purpose, and ability to maintain a common good, which has the
potential to contribute to the social cohesion of a community and reduce
inequalities.

Disasters are driving losses to heritage
• There has emerged a growing awareness that the loss of cultural properties
and their values as society-related capital is essentially the loss of a common
catalyst that creates a ‘sense of place’ for all generations of people.
• Disasters caused by natural and human-induced hazards result in the
destruction of countless historical properties, museums and archives that
hold the history of humanity within their walls. Cultural landscapes and
natural heritage are being destroyed, and with them valued ecosystem
services.

Heritage contributes to resilience
• In the same way that biological diversity increases the resilience of natural
systems, cultural diversity has the capacity to increase the resilience of social
systems.
• The maintenance of cultural diversity into the future, and the knowledge,
innovations and outlooks it contains, increase the capacity of human systems
to adapt to and cope with change.
• Cultural heritage, as a key component of cultural diversity, is a critical
consideration for any strategy to build the resilience of communities.

Resilience
• It is “the ability of a system and its component parts to anticipate, absorb,
accommodate, or recover from the effects of a hazardous event in a timely
and efficient manner, including through ensuring the preservation,
restoration, or improvement of its essential basic structures and functions”.
• Resilience applies to both people and the built and natural environment and
is shaped by both physical and social factors.
• Experience has shown that degradation of natural resources, neglected rural
areas, urban sprawl and poorly engineered new construction increase the
vulnerability of communities to disaster risks. On the other hand, a well-
conserved natural and historic environment, based on traditional knowledge
and skills, considerably reduces underlying vulnerability factors, strengthens
the resilience of communities and saves lives.

Symbolism
• The symbolism inherent in heritage is also a powerful means to help victims
recover from the psychological impact of disasters. In such situations, people
search desperately for identity and self-esteem. Traditional social networks
that provide mutual support and access to collective assets are extremely
effective coping mechanisms for community members.
• The virtues of heritage should be recognized and built upon, while at the
same time, those aspects of heritage that contribute to physical, social and
attitudinal vulnerability should be appropriately addressed through efforts to
promote a robust culture of prevention.

Kind of knowledge
• Both modern science and indigenous knowledge play vitals roles in reducing
communities’ risks. Taking advantage of scientific and technological
advances does not imply disregarding the capacities and resources already
available locally. Indigenous knowledge for disaster reduction lies in the
accumulated experience that comes with the close relationship of
communities to their environment.
• Communities have learned to read the signs in the sea, the skies and wildlife
to predict hazards. Direct experience with disasters has taught many
communities the duration, location, time, frequency, intensity, predictability,
onset and possible behavior of the hazards linked to these events.
• Likewise, local technologies and construction practices often reflect
adaptations to the environmental conditions.

Cultural dimensions
• Cultural values and beliefs underlie the decisions people make when facing
risk and coping with disasters.
• Moreover, cultural values provide a source of pride and identity that can
inspire communities to undertake bold actions. An understanding of these
values can greatly enhance the effectiveness of risk communication and can
speed economic as well as psycho-social recovery after disaster strikes.
• Understanding how people interpret risks and choose actions based on their
interpretations are vital to any strategy for disaster reduction.
• These issues have significant implications for efforts to cultivate a ‘culture of
prevention’, particularly as they relate to risk communication and motivation
to act on that information.

Recovery
• Cultural heritage can play an important role in the recovery of the victims of
disasters.
• Often, cultural insensitivity or ignorance in post-disaster recovery
programmes can have adverse effects on people.
• It was found that those villages which were reconstructed on the basis of
traditional architecture, with courtyards and surrounding verandahs using
locally available materials and skills and cluster planning of neighbourhoods,
were adapted by the villagers much more successfully than those that had
‘city-like’ layouts, with wide streets forming grid patterns and row housing
built using imported building materials and construction technology.

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Es.

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/03/18/NZ_53_01.html?refresh_ce

Understanding of culture
• An understanding of culture is an important instrument for the many
organizations working to build resilient communities and nations.
• The tools for cultivating culturally informed approaches to risk reduction can
be quite basic, including an openness and sensitivity to cultural differences.
• Spending time with communities and asking about their views and
experience is essential.
• Investments in understanding culture yields dividends in fostering a genuine
culture of prevention and promoting resilience in disaster-affected
communities.

The city
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2

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Complexity after Perrow

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City after Lynch
Kevin Andrew Lynch (January 7, 1918 – April 25, 1984)
was an American urban planner and author. He is known
for his work on the perceptual form of urban
environments and was an early proponent of mental
mapping. His most influential books include The Image of
the City (1960), a seminal work on the perceptual form
of urban environments, and What Time is This Place?
(1972), which theorizes how the physical environment
captures and refigures temporal processes.
A student of architect Frank Lloyd Wright before training
in city planning, Lynch spent his academic career at the
Massachusetts Institute of Technology, teaching there
from 1948 to 1978. He practiced site planning and urban
design professionally with Carr/Lynch Associates, later
known as Carr, Lynch, and Sandell.

Performance of the city
The degree of good city performance is determined by its ability
of providing biological, psychological, social and cultural requirements to its
inhabitants.

Vitality
• The degree to which the city sustains the essential, biological performance
of human beings: this is the supports of our bodies needs such as water, air,
energy and food, there should be sufficient supply of them to sustain life,
moreover good settlement should be free of danger, poisons and disasters,
then it supports safety for its inhabitants.

Sense
• It is the degree of fit between the physical city (form) and the way people
recognize and organize it in their minds.
• In other words, it is the degree of homogeneity between environment and
observer. Sense then, reflects the clarity with which people perceive the
space.
• Sense depends upon spatial structure, quality, the culture and the current
purpose of the observer.

Fit
• It is the match between the action (function) and the physical city (form).
• It is “ how well the spatial and temporal pattern of a settlement matches the
customary behavior of its inhabitants”.
• When there is congruence between form and patterns of behaviors, people
feel comfortable; conversely, absence or lack of fit could make it
uncomfortable and difficult to behave through an area.

Accessibility
• That is not means the ability to reach transportation only, but to access to all
things such as services, information, other places and to other peoples also,
then an interaction is established between these variables.
• Access offers the degree of choice and diversity presented to us.
• A place should provide people with information about physical ways of
reaching it.

Control
• It the degree to which the environment is under the control of the people
who actually use it or reside in it.
• According to Hall, control gives people feelings of power and stability.
• People feel in control when there is enough social and physical space to do
as they need.

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Lynch’s Theory of Good City Form

Components

Sense (1)
• It is clearly believed that building the image of an environment is a two way
process, it is the result of an interaction between the observer and the
environment in which he lives.
• The process is not just how we see things and others, but also how others
see us as a part of environment.
• Consequently, it reflects the influence of observer and environment on each
other: “ nothing is experienced by itself, but in relation to its surroundings,
the sequences of events leading up to it”.

Sense (2)
• Sense of the city as mentioned above represents the relationship between
physical environment and cognition, since its components are the observer
and his environment, this sense can be broken into six elements:
• Identity,
• Structure,
• Meaning,
• Congruence,
• Transparency (Immediacy),
• Legibility

Identity
• “Identity is the characteristic that allow us to differentiate one space from
another”.
• It is the character and spatial attributes of an object or a place that enhance
the ability of recognizing and identifying an environment, those attributes of
the object make it distinct, ultimately unique and easily separable, then it
stands for individuality or oneness.
• Place identity is closely linked to personal identity, “I am here supports I am”.
• There is not only an identity of place, but also an identity of events which
differs naturally from the first as it gives peoples a means to remember
events that happened, thus helps them to structure their life.

Structure
• It is how the object is placed in the space considering its relation to the
observer and to other objects, as the object is not seen isolated from
surroundings but as a part of all environmental components.
• “The architect has to realize that the forms of his buildings react on adjacent
forms”.
• Norberg-Schulz and Lynch refer to organization when they talk about
structure.

Meaning
• Meaning is that which the place stands for or represent.
• It is a hidden character of the object and the deepen sense that reflects the
importance of the object, this sense may be practical or emotional.
• The meaning is a complicated notion, its sides are difficult to be specified,
but can be separated from the form in the early stages of analysis. A
particular city may stands for enjoyment, power, vitality, mystery or
something else presented in mental image of its inhabitants.
• Lynch says that “the visual environment should be meaningful; that is, its
visible character should relate to other aspects of life”.
• Steinitz (1968) made an inference that the city becomes more meaningful
and known to its inhabitants when there is a congruence between its
physical form and activity.

Congruence
• It is the relationship of the form to its function.
• In other words, how is the environmental structure congruent with
nonspatial structure.
• For instance, what degree of congruence between a residential building and
family size.
• Congruence can be tested by comparing abstraction of place with
abstraction of function.

Transparency (Immediacy)
• It stands for the degree of visibility of process occurring in the place to users.
• In other words, it is the degree to which one can actually see what's going.
• There are many events occur in the city such as selling, buying and
movement, how many of them we can see actually. Definitely, we see less of
what actually happening.

Legibility
• It is the term that has been used for along time in urban planning defined as
“the ease with which its parts can be recognized and organized into a
coherent pattern”.
• This definition estates that degree of legibility depends upon the formation
of cognitive maps within wayfarers mind.
• Legibility is “the degree of distinctiveness that enables the viewer to
understand or categorize the contents of a scene the greater the legibility
the greater the preference”.
• It is the quality which makes an area understandable.

Notes on legibility (1)
• Lynch considers Legibility as a physical and spatial characteristic of the
environment, so visual sensations of color, motion, smell, touch and
sound…etc. are all cues of orientation that reinforce legibility. This view
postulates that environmental surroundings influence immediately spatial
cognition, and spatial representation is isomorphic to the physical structure.
• According to Lynch definition, legibility can enhance the identity, structure
and the meaning of environmental surroundings. The city may has strong
identity and character but still confusing and unclear because of confusion of
its path system.

Notes on legibility (2)
• Identity and structure are the formal components which help us to perceive
and organize both of space and time in themselves, while congruence,
transparency and legibility are the informal ones which create interaction
between environment and other sides of our lives.
• It worth mentioning that Lynch's initial interest was of legibility, but soon the
focus adjusted to the issue of the city's mental representation. This led Lynch
to the concept of imageability and the identification of the city elements
(paths, edges, nodes, landmarks, and districts). The sketch map drawn by
city's dweller is more accurate and legible than that drawn by a visitor
because image clarity is improved by familiarity and its conformity with
stereotype.

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Lynch’s Theory of Good City Form

General concepts
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3

Structural System

FAR FIELD ZONE
EXCHAGE ZONE
STRUCTURE
FAR FIELD ZONE
EXCHAGE ZONE
STRUCTURE
INFRASTRUCTURE
OBJECT
NET
Local / Punctual
Scale
Global / Regional
Scale
Structural
System
Infrastructural
System
Also if artificial,
these systems
need to have
necessarily
evolutive soundness,
ecological coherence
and sustainability
characteristics
Structure / Infrastructure

Ecology
1. The branch of biology dealing with the relations and interactions
between organisms and their environment, including other
organisms.
2. The set of relationships existing between organisms and their
environment: desert ecologies.
3. The set of relationships existing between any complex system and
its surroundings or environment.
4. Ecological engineering uses ecology and engineering to predict,
design, construct or restore, and manage ecosystems that integrate
"human society with its natural environment for the benefit of
both“.

Survivability
• Survivability is the ability to remain alive or continue to exist.
• Ecological: Following disruptive forces such as flood, fire, disease, war,
or climate change some species of flora, fauna, and local life forms are
likely to survive more successfully than others because of consequent
changes to their surrounding biophysical conditions.
• In engineering, survivability is the quantified ability of a system,
subsystem, equipment, process, or procedure to continue to function
during and after a natural or man-made disturbance.
• For a given application, survivability must be qualified by specifying the
range of conditions over which the entity will survive, the minimum
acceptable level functionality, and the maximum acceptable downtime.

Evolution
1. Any process of formation or growth; development: the evolution
of a language; the evolution of the airplane.
2. A product of such development; something evolved: the
exploration of space is the evolution of decades of research.
3. Biology: the change in the gene pool of a population from
generation to generation by such processes as mutation, natural
selection, and genetic drift.

Sustainability
• Sustainability is the process of change, in which the exploitation of
resources, the direction of investments, the orientation of technological
development and institutional change are all in harmony and enhance both
current and future potential to meet human needs and aspirations.
• The organizing principle for sustainability is sustainable development, which
includes the following interconnected domains: environment, economic and
social. Sub-domains of sustainable development have been considered also:
cultural, technological and political.
• Sustainable development, is the development that meets the needs of the
present without compromising the ability of future generations to meet their
own needs.

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Scheme of sustainable development

Vulnerability
• The state of being exposed to the possibility of being attacked or harmed,
either physically or emotionally.
• Vulnerability refers to the inability (of a system or a unit) to withstand the
effects of a hostile environment.
• A window of vulnerability (WOV) is a time frame within which defensive
measures are diminished, compromised or lacking.
• The understanding of a system vulnerability, as a methodological approach,
involves the analysis of the risks and assets of the system itself.

Risk

Risk
• A probability or threat of damage, injury, liability, loss, or any other negative
occurrence that is caused by external or internal vulnerabilities, and that
may be avoided through preemptive action.
• At its simplest, risk is the possibility of an adverse outcome. Risk is often
expressed in terms of a combination of the consequences of a series of
events and the associated likelihood of occurrence. The probability,
frequency of occurrence and impact of an event are factors which should be
considered in any analysis of risk.
• Possibility of loss or injury

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Risk concern
cause
causa
effect
effetto
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Option 1 – Risk avoidance, which usually
means not proceeding to
continue with the system;
this is not always a feasible
option, but may be the only
course of action if the
hazard or their probability of
occurrence or both are
particularly serious;
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Rigopiano

Option 2 – Risk reduction, either through
(a) reducing the probability
of occurrence of some
events, or (b) through
reduction in the severity of
the consequences, such as
downsizing the system, or
(c) putting in place control
measures;
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Risk=Probability·Magnitudo
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Prevention
Protection

Option 3 – Risk transfer, where insurance
or other financial
mechanisms can be put in
place to share or completely
transfer the financial risk to
other parties; this is not a
feasible option where the
primary consequences are
not financial;
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Using insurance and risk transfer effectively
• In some respects the use of insurance for cultural heritage may seem
problematic, for example in terms of estimating the appropriate insurance
value of something that is unique, priceless and often intangible.
• However, the insurance industry plays an important role in promoting
investments in risk reduction, specifically as a means to reduce the cost of
losses.
• One of the primary functions of insurance is to spread losses and to reduce
financial exposure; this is often the only means that owners and managers of
heritage assets have to invest in recovery or restoration after damage.
• Business interruption and denial of access, for instance, are important
considerations for many heritage managers.

Insurance for the damage or for the event
• Important lessons were learned about testing the insurance policy to see if
coverage was ‘for the damage’ or ‘for the event’.
• A similar situation property was damaged by hurricanes Rita and Katrina.
This was subsequently the subject of litigation and it was decided in the US
case that even if the building had not been damaged, it would have suffered
the same business interruption loss because of the devastation to the
surrounding area and therefore the claim was allowed.

More about insurance
• Another important issue is the appropriateness of the insurance policy to
the heritage site: a cultural heritage site contains an inherent and unique
series of values which deserve a higher degree of care and consideration
than modern property counterparts.
• This heightened sensitivity needs to be applied when assessing requirements
for property insurance for cultural heritage sites to ensure that the
appropriate levels of cover is achieved. For these reasons, the choice and
level of coverage is extremely important, with significant differences
between ‘Total reinstatement’ and ‘No rebuilding insurance’, for instance.
• Insurers will often conduct surveys as part of their consideration as to
whether to accept a risk, and even if they do not ultimately accept that risk
the prospective insured will still have the benefit of the recommendations.

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Option 4 – Risk acceptance, even when it
exceeds the criteria, but
perhaps only for a limited
time until other measures
can be taken.

Option 1 – Risk avoidance, which usually means not proceeding to continue
with the system; this is not always a feasible option, but may be
the only course of action if the hazard or their probability of
occurrence or both are particularly serious;
Option 2 – Risk reduction, either through (a) reducing the probability of
occurrence of some events, or (b) through reduction in the
severity of the consequences, such as downsizing the system, or
(c) putting in place control measures;
Option 3 – Risk transfer, where insurance or other financial mechanisms can
be put in place to share or completely transfer the financial risk to
other parties; this is not a feasible option where the primary
consequences are not financial;
Option 4 – Risk acceptance, even when it exceeds the criteria, but perhaps
only for a limited time until other measures can be taken.

DEFINE CONTEXT
(social, individual,
political, organizational,
technological)
RSK ANALYSIS
(for the system are defined organization,
scenarios, and consequences of
occurences)
RISK ASSESSMENT
(compare risks
against criteria)
RISK TREATMENT
option 1 - avoidance
option 2 - reduction
option 3 - transfer
option 4 - acceptance
MONITOR
AND
REVIEW
RISK
MANAGEMENT
RISK
ANALYSIS
RISK
ASSESSMENT
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Risk concern

Risk=Probability·Magnitudo
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Prevention
Protection

Risk=Probability·Magnitudodo
discretizationinlog-logplane
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probability
severity

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probability
severity

Reference: Bontempi, F. (2005) Frameworks for structural analysis, In: Innovation in Civil and Structural
Engineering Topping, BHV ed., pp. 1-24
HPLC
High Probability –
Low Consequences
LPHC
Low Probability –
High Consequences
Complexity
Non linear issues and
interaction mechanisms
Designapproach:
StochasticDeterministic
QUALITATIVE RISK
ANALYSIS
PROBABILISTIC
RISK ANALYSIS
PRAGMATIC
ANALYSIS OF
RISK SCENARIOS
Low Probability – High Consequences Events

Taleb, Nassim Nicholas (April 2007). The Black Swan: The Impact of the Highly Improbable (1st ed.). London:
Penguin. p. 400. ISBN 1-84614045-5.
A Black Swan is an event with the following three attributes.
1. First, it is an outlier, as it lies outside the realm of regular expectations,
because nothing in the past can convincingly point to its possibility.
Rarity -The event is a surprise (to the observer).
2. Second, it carries an extreme 'impact'.
Extreme “impact” - the event has a major effect.
3. Third, in spite of its outlier status, human nature makes us concoct
explanations for its occurrence after the fact, making it explainable and
predictable.
Retrospective (though not prospective) predictability - After the first
recorded instance of the event, it is rationalized by hindsight, as if it could
have been expected; that is, the relevant data were available but
unaccounted for in risk mitigation programs. The same is true for the
personal perception by individuals.
Black Swan Event
84

Black Swan Theory (1)
• The theory was developed by Nassim Nicholas Taleb to explain:
1. The disproportionate role of high-profile, hard-to-predict, and rare events
that are beyond the realm of normal expectations in history, science,
finance, and technology.
2. The non-computability of the probability of the consequential rare events
using scientific methods (owing to the very nature of small probabilities).
3. The psychological biases that blind people, both individually and
collectively, to uncertainty and to a rare event's massive role in historical
affairs.

Black Swan Theory (2)
• The black swan theory or theory of black swan events is a metaphor that
describes an event that comes as a surprise, has a major effect, and is often
inappropriately rationalized after the fact with the benefit of hindsight. The
term is based on an ancient saying that presumed black swans did not exist –
a saying that became reinterpreted to teach a different lesson after black
swans were discovered in the wild.
• Taleb's "black swan theory" refers only to unexpected events of large
magnitude and consequence and their dominant role in history. Such events,
considered extreme outliers, collectively play vastly larger roles than regular
occurrences

More concepts
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4

Activities

RESILIENCE 89
Time horizon
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RESILIENCERESILIENCE
CONSTRUCTIONS
NEW
EXISTING
COLLAPSED
“As Designed”
“As Built”
“As Actual”
“As Failed”
«As …»

92
Structural response & safety format

Levels of Structural Crisis
UsualULS&SLS
VerificationFormat
Structural Robustness
Assessment
1st level:
Material
Point
2nd level:
Element
Section
3rd level:
Structural
Element
4th level:
Structural
System

Relevance
A
B C

Ideal structural response

Role of imperfections

97
Load or displacement imposed (1)

98

99

Design

• Ma, oltre a queste osservazioni, mi sembra opportuno concludere
osservando in via generale che, relativamente ai metodi di calcolo e alle
normative, si debba evitare di dar loro importanza eccessiva, per non
mettere in ombra la progettazione vera e propria.
• La quale ha nel calcolo soltanto una delle sue fasi, seppure fondamentale,
mentre trova in altre questioni aspetti altrettanto qualificanti: intendo
soprattutto la concezione generale delle strutture; l’armonica distribuzione
delle masse; i particolari costruttivi; l’analisi dei problemi esecutivi e dei
costi; l’esame critico del comportamento generale della costruzione
comprendente anche, e non secondariamente, la presenza di elementi non
strutturali e della parte del terreno coinvolta dalla struttura.
• Fatti, questi, che debbono entrare nel vivo del processo progettuale,
divenendo una forza unica e ogni volta diversa. Fatti che non possono essere
unitariamente colti da elaborazioni numeriche e computers come invece può
riuscire a fare la mente umana con gli insostituibili ausili, peculiari soltanto
ad essa, dell’intuizione, dell’inventiva, della fantasia, della creatività.
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- IL CONVENZIONALISMO NEL CALCOLO STRUTTURALE SISMICO – P. Pozzati 5 marzo 2004

105
105
Semplicità
• Il criterio più generale di progetto riguarda la semplicità: per l’Ingegneria
questo è un valore fondamentale, perché pone i fondamenti per la certezza
di comportamento.
• Questo vale diventa, quindi, una strategia globale per non introdurre
ulteriori complessità in un ambiente già di per se altamente incerto.

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Regolarità geometrica e simmetria
• La regolarità geometrica riguarda la disposizione in pianta ed in elevazione
della struttura; riguarda l’adozione di una configurazione geometrica chiara,
lineare, con limitate eccentricità e variazioni brusche di masse o rigidezze,
con possibili simmetrie e ripetizioni.
• Questo è un criterio che coinvolge tutte le scale strutturali, dai componenti
all’intera struttura: si pensi alle connessioni delle aste nelle strutture
reticolari al fine di evitare sollecitazioni parassite o alla disposizione di un
intero edificio.

107
107
Iperstaticità e ridondanza
• La ridondanza strutturale consiste nel prevedere la duplicazione dei percorsi
e dei meccanismi resistenti, ponendoli in parallelo, in modo da assicurare la
sicurezza globale dell’opera anche in caso di crisi da parte di un sistema
resistente, per mezzo della ridistribuzione dei percorsi di carico.
• A questa si accosta il concetto di iperstaticità, che consiste nel progettare
strutture con vincoli ed interconnessioni sovrabbondanti rispetto alla
quantità strettamente necessaria.
• Entrambi i criteri assumono un importante ruolo nel governo del
comportamento strutturale, indirizzando nelle dovute forme le modalità di
collasso.

108
108
Prevedibilità nel tempo
• Riguarda la necessità di utilizzare materiali, componenti o soluzioni il cui
comportamento sia il più possibile prevedibile.
• Anche in questo caso, alterazioni brusche ed imprevedibili dei
comportamenti meccanici di materiali e componenti, che si ripercuotano
sulla risposta strutturale complessiva, non possono essere accettabili.

109
109
Principio di precauzione
• Il criterio si rivolge alla scelta dei materiali e prodotti strutturali da usare
nelle opere affinché si possa garantire il rispetto dei requisiti
precedentemente indicati. Nel caso si scelgano materiali e prodotti non
esplicitamente citati nelle norme si richiede che tali materiali possano essere
impiegati solo se il produttore ne garantisce prestazioni in linea con quanto
richiesto dalla norma stessa.
• Per poter essere utilizzato ai fini strutturali, un materiale o un componente
devono avere caratteristiche geometriche, chimiche, fisiche e meccaniche,
certe.

112
Design method
Problem solving

113
Constructive attitude
Knowledge of the design
method, how it is done or to
know things, is a liberating value:
it is a "do-it-yourself" yourself.

114
Design method
Problem solving

115
Constructive attitude
Knowledge of the design
method, how it is done or to
know things, is a liberating value:
it is a "do-it-yourself" yourself.

116
No archistar

117
Luxury is the manifestation of the
uncivilized wealth that wants to
impress who is poor.
It is the manifestation of the
importance that is given to the
exteriority and reveals the lack of
interest in the whole cultural
elevation.
It's the triumph of appearance on
the substance.
Disvalori
Anti-values

118
Simplifying means trying to solve the
problem by eliminating everything that is
not needed to perform the functions
Simplifying is to reduce costs, reduce
machining, assembly, and finishing times.
One wants to solve two issues together in
one solution. Simplifying is a hard work and
requires a lot of creativity.
Complicating is much easier, just add
anything what comes to your mind without
worrying if costs go beyond sales limits,
you take more time to realize the object,
and so on.
Valori
Values

119
It is necessary, however, to say that the general
public is more inclined to evaluate the manual
"so much work" that it takes to do a
complicated thing than to recognize the "so
much work" mental that it wants to simplify,
since then you can not see it.
Indeed, people in the face of simple solutions,
which may have required lengthy research and
trials, say: but how, is everything here? but this
I knew I did too!

120
It is important to consider things
not only for what they are, but
also for what they might be.
Generally, the same thing can be
looked at in many respects, and
sometimes the less obvious
points of view are most useful.
It's always worth it, when
something is happening for what
it is, to go deep into the exam to
see what else it might be.
Sostenibilità
Sustainability

Robustness

RESILIENCE 123
Time horizon
13/06/2018

124
Structural Robustness (1)
ATTRIBUTES
RELIABILITY
AVAILABILITY
SAFETY
MAINTAINABILITY
INTEGRITY
SECURITY
FAILURE
ERROR
FAULT
permanent interruption of a system ability
to perform a required function
under specified operating conditions
the system is in an incorrect state:
it may or may not cause failure
it is a defect and represents a
potential cause of error, active or dormant
THREATS
NEGATIVE CAUSE
STRUCTURALQUALITY
less robust
more robust

125
• Capacity of a construction to show regular decrease of its
structural quality due to negative causes.
• It implies:
a) some smoothness of the decrease of structural performance
due to negative events (intensive feature);
b) some limited spatial spread of the rupture (extensive
feature).
• Fragility is the opposite of robustness.

QUALITY
DAMAGE or ERROR
REQUIRED
PERFORMANCE
NOMINAL
PERFORMANCE
NOMINAL
SITUATION
126

127
Es.

128
Es.

effect
time 129
Runaway (1)
13/06/2018

EFFECT
Runaway(2)
13013/06/2018

STRUCTURE
& LOADS
Collapse
Mechanism
NO SWAY
“IMPLOSION”
OF THE
STRUCTURE
“EXPLOSION”
OF THE
STRUCTURE
is a process in which
objects are destroyed by
collapsing on themselves
is a process
NOT CONFINED
SWAY
131
Bad vs Good Collapse

13/06/2018 132
https://www.ilfattoquotidiano.it/2017/05/16/terremoto-crollo-del-campanile-di-accumoli-chiusa-inchiesta-per-7-
indagati/3590620/

Es.

http://www.wise-uranium.org/img/stavaa.gif

Resilience

RESILIENCE 137
Time horizon
13/06/2018

Definition (not univocal):
A resilient community is defined as the one having the ability to absorb disaster
impacts and rapidly return to normal socioeconomic activity.
MCEER (Multidisciplinary Center for Earthquake Engineering Research), (2006). “MCEER’s Resilience Framework”. Available at
http://mceer.buffalo.edu/research/resilience/Resilience_10-24-06.pdf
NEHRP (National Earthquake Hazards Reduction Program), 2010. “Comments on the Meaning of Resilience”. NEHRP Technical
report. Available at http://www.nehrp.gov/pdf/ACEHRCommentsJan2010.pdf
MCEER framework for resilience evaluation:
Initial losses Recovery time, depending on:
• Resourcefulness
• Rapidity
Disaster strikes
Systemic
Robustness
(disaster) resilience

(disaster) resilience
Definition (not univocal):
A resilient community is defined as the one having the ability to absorb disaster
impacts and rapidly return to normal socioeconomic activity.
MCEER (Multidisciplinary Center for Earthquake Engineering Research), (2006). “MCEER’s Resilience Framework”. Available at
http://mceer.buffalo.edu/research/resilience/Resilience_10-24-06.pdf
NEHRP (National Earthquake Hazards Reduction Program), 2010. “Comments on the Meaning of Resilience”. NEHRP Technical
report. Available at http://www.nehrp.gov/pdf/ACEHRCommentsJan2010.pdf
MCEER framework for resilience evaluation:
Resilience is inversely proportional to the area A.
(dQ/dt)
L0
TR
(dQ/dt)0
A

Combined effect of discrete events and continuous deterioration
big earth uake,
human error, …
nrecoverable uality level survivability threshold
System
demission
ecovery
elasticity
egradation of the uality due to
continuous occurrences e.g. aging
LP e e t
P e e t
LC
C
eight of the
discrete event

Hazards
Losses
(disaster)
Event

Pre-event
uring the event
Aftermath of
the event
Long-runistorical
i. Historical political decisions (e.g. political regime) influence the initial system quality Q0.
This parameter is related the initial system state.

Pre-event
uring the event
Aftermath of
the event
Long-runistorical
ii. Urban and social service planning is relevant for the pre-event system integrity and it is
one of the factors determining the trend of system quality before the event (dQ/dt) and the
amount of immediate losses (ΔQ). The first parameter is by a statistical correlation
between the political decision and the quality trend, while the second parameter can be
modeled by the system fragility.

Pre-event
uring the event
Aftermath of
the event
Long-runistorical
iii. Fast decisions are taken during the event or a disaster (on the basis of knowledge and
experience from similar past events - if any - and the system properness knowledge). The
political decisions in this phase influence the initial slope of the recovery phase (dQR/dt).
This parameter can be modeled by a statistical correlation between the political decision
and the quality trend.

Pre-event
uring the event
Aftermath of
the event
Long-runistorical
iv. Emergency plans and prioritization of recovery actions are relevant in the aftermath of the
event (recovery phase). In addition, the declaration of a state of emergency can have a
substantial short and long-term effect on the local economy. The actions in this phase
influence the shape of the recovery function fR(t).

Pre-event
uring the event
Aftermath of
the event
Long-runistorical
v. Urban and social service re-planning on the basis of the consequences of the occurred
event are relevant in the long run (influencing the losses and the recovery for the next
discrete event).

Robustness / Resilience
1 bar
determinate structure
fragile
n bar
indeterminate structure
robust
1/n bar
stand-by structure
resilient
Passive behavior before Active behavior after

References: Taleb, Nassim Nicholas (November 2012). Antifragile: Things That Gain from Disorder(1st ed.). London:
Penguin. p. 519. ISBN 1-400-06782-0.
People/systems/organizations/things/ideas can be described in one
of three ways:
- fragile
- resilient, or
- antifragile
"Some things benefit from shocks; they thrive and grow when
exposed to volatility, randomness, disorder, and stressors and love
adventure, risk, and uncertainty. Yet, in spite of the ubiquity of the
phenomenon, there is no word for the exact opposite of fragile.
Let us call it anti-fragile. Anti-fragility is beyond resilience or
robustness. The resilient resists shocks and stays the same; the
anti-fragile gets better".
“an i- ragili y”

Antifragile
• Taleb introduces the book as follows:
• "Some things benefit from shocks; they thrive and grow when exposed to
volatility, randomness, disorder, and stressors and love adventure, risk, and
uncertainty. Yet, in spite of the ubiquity of the phenomenon, there is no
word for the exact opposite of fragile. Let us call it antifragile. Antifragility is
beyond resilience or robustness. The resilient resists shocks and stays the
same; the antifragile gets better.“

References: Taleb, Nassim Nicholas (November 2012). Antifragile: Things That Gain from Disorder(1st ed.). London:
Penguin. p. 519. ISBN 1-400-06782-0 .
-----
----
“an i- ragili y”
Things that are fragile
break or suffer from
chaos and randomness.
The resilient, or
robust, don’t care if
circumstances become
volatile or disruptive
(up to a point).
Things that are anti-
fragile grow and
strengthen from
volatility and stress (to
a point).

Reflections
13/06/2018 155
5

The standards

http://territorio.regione.emilia-romagna.it/codice-territorio/sismica/dossier-sentenze-della-causa-penale-conseguente-
al-crollo-delledificio-scolastico-jovine-di-san-giuliano-di-puglia/

Ergonomia delle norme

• «Ma un numero di regole eccessivo comporta vari degli
inconvenienti dianzi citati e in particolare:
- l'impoverimento dell'autonomia e della creatività, in
quanto l'opera del progettista è irretita dalle norme;
- la difficoltà di discernere ciò che veramente conta;
- la sensazione di avere, al riparo delle norme,
responsabilità assai alleviate;
- la difficoltà non infrequente di rendersi conto dei
ragionamenti che giustificano certe regole, rischiando di
considerare queste alla stregua di algoritmi, ossia di
schemi operativi che, una volta appresi, il pensiero non è
più chiamato a giustificare.»
13/06/2018 168
- Proliferazione delle normative e tecnicismo. Ultima lezione ufficiale del corso di Tecnica delle costruzioni
tenuta dal prof. Piero Pozzati nell'a.a. 1991-'92, presso la Facoltà di Ingegneria dell'Università di Bologna (3
giugno 1992).

Vn = 100
Cu = 2
q0 = 4
NB
Caratteristiche
Struttura
Vn = 100
Cu = 2
q0 = 2
Periodo
di ritorno
sisma
Vn = 50
Cu = 1
q0 = 2
Opere ordinarie, ponti, opere infrastrutturali
e dighe di dimensioni contenute o di importanza normale
Grandi opere, ponti, opere infrastrutturali
e dighe di grandi dimensioni o di importanza strategica
170

13/06/2018 171
Causes of System Failure
100%
Time
%offailure
Unknown phenomena
Known phenomena
Research level Design code level
past present future
A
BB B
C
Humanerrors

HAZARD
IN-DEPTH
DEFENCE
HOLES DUE TO
ACTIVE ERRORS
HOLES DUE TO
HIDDEN ERRORS
General Failure Model

13/06/2018 173
Due diligence
• Due diligence (also known as due care) is the effort made by an
ordinarily prudent or reasonable party to avoid harm to another
party. Failure to make this effort is considered negligence.
• It is necessary to discover all risks and implications regarding a
decision to be made
• Due diligence is also a dynamic concept in that it is a constantly
evolving standard of care that is determined by the requirements
of law, industry standards as well as professional and other codes
of practice.

Tecnica delle Costruzioni

Declaratoria
•Il settore della Tecnica delle Costruzioni si interessa
dell’attività scientifica e didattico-formativa inerente teorie
e tecniche rivolte sia alla concezione strutturale ed al
progetto di nuove costruzioni, sia alla verifica ed alla
riabilitazione strutturale di quelle esistenti.

• I contenuti scientifico-disciplinari riguardano:
- le azioni sulle costruzioni, compreso l’effetto dell’azio e sismica,
- il comportamento delle strutture in funzione della tipologia e della
morfologia, dei materiali, delle tec iche e delle tec ologie, dell’i terazio e
col terreno e con l'ambiente, dei modi e delle strategie d'uso e di controllo;
- metodi e strumenti per la progettazione strutturale, la realizzazione e la
gestione di strutture;
- valutazioni di vulnerabilità, affidabilità, comfort, sicurezza e durabilità;
- sperimentazione, collaudo e monitoraggio delle costruzioni;
- indagini storiche sul costruire, verifiche di sicurezza e soluzioni d'intervento
strutturale applicabili all’edilizia storica ed ai mo ume ti;
- architettura strutturale.

Statement della giornata (1)
•La Tecnica delle Costruzioni si occupa della concezione e
della progettazione strutturale.
•E’ una disciplina di sintesi - in cui confluiscono idee, teorie,
metodi, strumenti, sperimentazione, sviluppo storico e
principi empirici – che porta alla scelta oculata di schemi
portanti, elementi e componenti, materiali strutturali,
partendo da una solida e ampia base culturale.

•Il progetto strutturale riguarda con una visione olistica tutto
il ciclo di vita di una costruzione e l’ambiente in cui è
immersa, prevedendo necessariamente un percorso
decisionale caratterizzato da assunzione di responsabilità.

•L’analisi strutturale è il presupposto per capire ed esplorare
qualitativamente e quantitativamente il comportamento
strutturale in termini di prestazioni e sicurezza della
costruzione nel suo insieme, ivi compresi i componenti non
portanti.
•La corretta comprensione della relazione fra modello e
realtà è essenziale a tal fine.

•Lo studio di casi reali di costruzioni, in particolare nei casi di
fallimento, è fonte essenziale di aumento di conoscenza
della disciplina.

13/06/2018 181
• L’insegnamento della disciplina deve:
- partire dai principi meccanici generali,
- favorire una valida comprensione dei comportamenti strutturali
elementari e complessivi, anche alla luce della storia di
insuccessi costruttivi,
- predisporre a una fondata organizzazione della disposizione
delle varie parti strutturali supportata da una coerente scelta dei
materiali,
- aiutare ad individuare le possibili situazioni in cui una
costruzione può trovarsi in termini di azioni e configurazioni.

184
https://www.youtube.com/channel/UCW3IyXTBJVIiS6OZeSdIN7g

185
https://fr.linkedin.com/in/francobontempi

Terms of the problem: heritage, cities, risk, vulnerability, robustness, resilience

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