Structural Design Optimization Techniques

Structural Design and Optimization
Part I – V edition, 2023
Prof. Ing. Franco Bontempi
Docente di TEORIA E PROGETTO DI PONTI – GESTIONE DI PONTI E GRANDI STRUTTURE
Facoltà di Ingegneria Civile e Industriale
Università degli Studi di Roma La Sapienza
franco.bontempi@uniroma1.it
29-Jan-23 STRUCTURAL DESIGN AND OPTIMIZATION 2023 2
Abstract
• Structural engineering can nowadays make use of very remarkable computational
tools. This availability can lead to affirm that the entire process of designing and
verifying the quality of a structure can be automated.
• Paradoxically, the opposite is true: powerful tools require deep reflections on what
are the bases of structural design in order to consciously address the procedures
of representation and optimization available today.
• In this only in this way, that optimization can represent an effective fundamental
component of structural design, in order to try to maximize the performance of
the structures and their sustainability.
• In order to obtain a correct optimization, it is therefore necessary to examine the
roots of the design, to understand its meanings and evaluate the limits of the
different numerical implementations.
• The lessons of the course will develop the concepts underlying structural
optimization while presenting specific significant applications
• Monday 30 January
15.00-18.00 (3 hours)
• Prof. Franco Bontempi
• Basis of structural design
• The art of structural engineering. The
principles of design. The creative process.
Structural concept. Design context and
structural requirements. Structural values.
Design by evolution and innovation.
Integration and specialization. Path of
loads. Structural schemes and their limits.
Structural analysis.
DAY 1
• D. Billington, The Tower and the Bridge: The New Art of
Structural Engineering
• E. S. Ferguson, Engineering and the Mind’s Eye.
• H. Simon, The Science of Artificial.
• G. Madhavan, Come pensano gli ingegneri. Intelligenze
applicate.
• B. Munari, Da cosa nasce cosa. Appunti per una
metodologia progettuale.
• P. L. Nervi, Scienza o arte del costruire?
• E. Torroja, La concezione Strutturale.
• L.E. Robertson, The Structure of Design.
• W. Lidwell, K. Holden, J. Butler, Universal Principle of Design.
• U. Kirsch, Structural Optimization. Fundamentals and
Applications.
• S. Adriaenssens, P. Block, D. Veenendaal, C.Williams. Shell
Structures for Architecture: Form Finding and Optimization.
• M. Sarkisian, Designing Tall Buildings: Structure as
Architecture.
• Tuesday 31 January
10.00-13.00 (3 hours)
• Qualitative and quantitative aspects of
structural optimization
• Setting up the structural problem.
Uncertainties and undefinitions. Limited
rationality and partial knowledge.
Structural modeling. Solution of the
structural problem and its critical
judgment. Naïve setting of optimization
problems. Optimization algorithms.
Stochastic aspects. Heuristic approaches.
Discrete structural schemes.
DAY 2
15.00-18.00 (3 hours)
• Dr. Valentina Tomei
• Optimization strategies for the design of
gridshell type structures
• Notes on the types of structural optimization
and on the single-objective and multi-
objective optimization algorithms of an
evolutionary type. Notes on strategies for
finding the optimal shape: form-finding.
Gridshell type structures. The role of form in
gridshells. The role of structural optimization
in gridshell design: examples of design
strategies.
• Wednesday 1st February
15.00-18.00 (3 hours)
• Prof. Elena Mele
• Optimization of structures for tall
buildings
• Behavior of tall buildings, "premium for
height" and structural types. Notes on the
evolution of the structural design of tall
buildings and recent trends: the search for
efficiency and the role of robustness.
Diagrid structures and structural patterns:
sectional and topological optimization.
Patterns inspired by isostatic lines.
Generative design and shape grammar.
DAY 3
10.00-13.00 (3 hours)
• Prof. Francesco Petrini
• Optimization in the performance design of
buildings under wind action and seismic
action
• Application of optimization methods to real
problems. Performance-based design: general
aspects and specific characteristics.
Optimization of devices for the control of
vibrations of tall buildings under the action of
the wind. Risk-based design of reinforced
concrete frames in seismic zone with
development of an optimization procedure
based on the gradient method.
DAY 4
• Thursday 2nd February
10.00-13.00 (3 hours)
• Dr. Innocenzo Becci
• Seismic recovery of prefabricated buildings
with the use of dissipation systems and
decoupling systems
• With a technical practice setting, the
presentation concerns the seismic
improvement design approach on
prefabricated structures with the use of
mechanical connection and dissipation
devices. For the typological conception of the
mechanisms and for the materials used in the
systems, the selection criteria and the
experiences of experimental feedback which
have made it possible to validate the expected
operating principles will be exposed.
15.00-18.00 (3 hours)
• Prof. Arch. Patrizia Trovalusci
• The construction of form in architectural
works: critical issues and advantages of
the mathematical/numerical approach
• The lesson presents, explores and
discusses mainly qualitative aspects
concerning works of architecture and is
accompanied by some examples of study
addressed in some degree theses (which
are available at this link:
https://sites.google.com/a/uniroma1.it/pa
triziatrovalusci/tesi-di-laurea/tesi-di-
laurea-sdc)
1983
FB

1988
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1992
1997
FORMULABILE
NON
FORMULABILE
Esprimibile in equazioni
HARD
RESTRICTED
Non esprimibile in equazioni
SOFT
WIDE
Prima
lezione
Seconda
lezione
Engineering vs Science
18
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Optimization of Prestressed Concrete
Surface Structures
19 29-Jan-23
Optimization of Prestressed Concrete
Surface Structures
20

21
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FORMULABILE
NON
FORMULABILE
Esprimibile in equazioni
HARD
RESTRICTED
Non esprimibile in equazioni
SOFT
WIDE
Prima
lezione
Seconda
lezione
1. Structural Art
A. Billington:
• Efficiency, economy, and elegance
• Engineering and Science
• The three dimensions of structures
• Structural Art and Society
B. Nervi
2. Attitude
3. Values
• Simplicity
• Simmetry
• Predictability
• Durability
• Robustness
• Resilience
4. Structuring an unstructured problem
• Elementary view
• Wide view
• Complexity
• Uncertainty
5. Mind’s Eye
6. Patterns of Design
• Evolutive vs Innovative Design
• Bias
• Limits
• Failures
7. Design Strategies
• Copy
• Assemble
• Dismantle
• Integration vs Specialization
Index Part I
1. Structural Art
A. Billington:
B. Nervi
2. Attitude
3. Values
• Simplicity
• Simmetry
• Predictability
• Durability
• Robustness
• Resilience
Index Part I
1.
2.
3.
• Elementary view
• Wide view
• Complexity
• Uncertainty
5. Mind’s Eye
• Bias
• Limits
• Failures
• Copy
• Assemble
• Dismantle
• Elementary view
• Wide view
• Complexity
• Uncertainty
5. Mind’s Eye
• Bias
• Limits
• Failures
• Copy
• Assemble
• Dismantle
STRUCTURAL ART
STRUCTURAL ART
STRUCTURAL DESIGN AND OPTIMIZATION 2023
1 ingredienti
Efficiency

Economy
Elegance
STRUCTURAL DESIGN AND OPTIMIZATION 2023 34
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2 previously not existing / already existed
Engineering and Science
Coventional view of Vannevar Bush

Basic Belief (almost wrong)
~ links between scientific research and technology
General Theories and Complete Insights
3 scientific – social - symbolic

Disciplines dealing with forms in space
sculpture fill the space
architecture organize the empty space
structure support loads in space
Artificial Forms controlling Natural Forces
The Creative Role of Constraints
The Creative Role of Imperfection
NB

NB
4 analytical apparatus

NB
Critica nei confronti della scienza
Disturbata visione sintetica del problema
Distacco fra mentalità
Sensibilità statica
Allontanamento dalla comprensione
La invenzione strutturale non è favorita …
Corrispondenza fra impostazione teorica e realtà fisica
ATTITUDE

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NB
Design method
Problem solving
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Design
Desi method
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.
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No archistar
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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
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impress who is poor.
importance that is given to the
Luxury
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.
Valore
Value
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not needed to perform the functions
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!
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Indeed, people in the face of simple solutions,

Semplice correttezza
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
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it is, to go deep into the exam to
Non ammettere soluzioni arbitrarie o formali
NB
NB
• L’ergonomia è la disciplina che si occupa dell’interazione tra un sistema e lo
scopo per il quale è progettato, e si propone di migliorarne la funzionalità
rispetto al suo utente.
• Human factors and ergonomics (commonly referred to as HF&E), also known
as comfort design, functional design, and systems, is the practice of
designing products, systems, or processes to take proper account of the
interaction between them and the people who use them.
Ergonomia
Ergonomics
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Esempio
Example
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Quality
Tactile Design (1)

Tactile Design (2)
Tactile Design (3)
Alienation
NB
Buona comprensione del mondo statico
Il ruolo dell’educazione
La forma mentis nella comprensione dei concetti fisici
Diffuso e irragionevole pregiudizio
Metodo di inquadramento dei problemi

Carattere di indirizzo generale
Onesta correttezza
Piena consapevolezza
Pressioni di ogni genere
Progettazione
Trascurare la semplice direttiva
Sirena tentatrice
Differenze minime e accomodamenti
Mente sgombra
Problem solving

Indipendenza di spirito
Sensibilità statica
Circoli viziosi
L’ideazione di un sistema resistente è un atto creativo
Decisioni rapide e paralizzanti incertezze
Effetti delle incertezze statiche
I due estremi
NB https://it.wikipedia.org/wiki/Nicolas_Bourbaki
Nicolas Bourbaki
• Nicolas Bourbaki è l'eteronimo con cui, a partire dal 1935 e sostanzialmente
fino al 1983, un gruppo di matematici di alto profilo, in maggioranza francesi,
scrisse una serie di libri per l'esposizione sistematica di nozioni della
matematica moderna avanzata. Con questa operazione scientifica il gruppo
aveva l'obiettivo di fondare l'intera matematica sulla teoria degli insiemi
attraverso testi che fossero il più possibile rigorosi e generali. Nel corso di
questa attività furono introdotti nuovi termini e nuovi concetti che hanno
avuto un'influenza importante nella matematica del XX secolo.
• Si pensa che la scelta del nome dato al gruppo, avvenuta per scherzo, sia
riconducibile al cognome del generale francese dell'Ottocento di origine
greca Charles Denis Bourbaki.

VALUES
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Value: simplicity
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1
Value: regularity
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2
Value: predictability
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3

Design as Foresight
http://abyss.uoregon.edu/~js/21st_century_science/lectures/lec08.html
Chaotic vs. Non Chaotic Evolution
Precauzione
• precauzióne s. f. [dal lat. tardo praecautio -onis, der. di praecavere
«guardarsi, essere cauto» (comp. di prae- «pre-» e cavere «stare in
guardia»), prob. attraverso il fr. précaution]. –
1. Prudenza, cautela, circospezione nell’agire per evitare pericoli, danni,
rischi imminenti e possibili: operare, muoversi, avanzare con p.; comportarsi
con p.; guidare con estrema p.; anche, attenzione, delicatezza nel maneggiare,
nel toccare qualcosa: trasportare con mille precauzioni un vaso di cristallo.
2. Atto, provvedimento attuato a scopo di cautela, di prudenza, di
prevenzione: adottare le dovute p.; prendere precauzioni (spesso con
riferimento alla profilassi anticontraccettiva); abbiamo agito con ogni possibile
p.; p. igieniche, sanitarie; non prese nessuna p. contro la peste (Manzoni).
Principio di precauzione
1. Criterio adottato da istituzioni governative e scientifiche in base
al quale vengono sospese quelle attività e produzioni dell'uomo
per le quali non sia possibile escludere una loro potenziale
influenza dannosa sull'ambiente.
2. Criterio di gestione del rischio in condizioni di incertezza
scientifica circa possibili effetti dannosi ipoteticamente collegati a
determinate attività, installazioni, impianti, prodotti, sostanze.
Introduzione e utilizzo dell’amianto negli Anni Sessanta
147
All’inizio degli
Anni Sessanta,
l’amianto era
considerato
come un ottimo
materiale
innovativo, e ne
erano vantate
applicazioni in
testi tecnici di
riferimento: una
chiara,
devastante,
violazione del
principio di
precauzione.
L’industria Italiana del
Cemento 1983;12:759–72.
Es.
Cemento 1983;12:759–72.
Cemento 1983;12:759–72.

Time horizon
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4
29-Jan-23 154
Value: durability
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Runaway per degrado
Minaccia dormiente
Evoluzione
Iperbolica!
• È evidente che una
protratta assenza - colposa o
dolosa - della dovuta
manutenzione ordinaria
comporta la necessità di una
manutenzione straordinaria, i
cui costi non possono essere
additati a cause impreviste e
imprevedibili.
• It is evident that a
protracted absence - culpable
or malicious - of the due
ordinary maintenance entails
the need for extraordinary
maintenance, the costs of
which cannot be pointed to
unexpected and
unpredictable causes.

Value: robustness
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Structural Integrity
• Structural integrity is the ability of an item—either a structural
component or a structure consisting of many components—to
hold together under a load, including its own weight, without
breaking or deforming excessively.
• It assures that the construction will perform its designed function
during reasonable use, for as long as its intended life span.
• Items are constructed with structural integrity to prevent
catastrophic failure, which can result in injuries, severe damage,
death, and/or monetary losses.
Structural Robustness
• Capacity of a structure (structural system) to show regular
decrease of its structural quality (integrity) due to negative causes.
• It implies:
a) some smoothness of the decrease of structural performance due
to negative events
(intensive feature);
a) some limited spatial spread of the ruptures
(extensive feature).
Structural Robustness: Intensity Feature
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
STRUCTURAL
QUALITY
less robust
more robust
Nominal
configuration
Damaged
configuration
Usual
ULS
&
SLS
Verification
Format
Structural Robustness
Assessment
1st level:
Material
Point
2nd level:
Element
Section
3rd level:
Structural
Element
4th level:
Structural
System
Level of Structural Failures
“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
STRUCTURE
& LOADS
Collapse
Mechanism
NO SWAY
SWAY
Bad vs Good Collapse: Extensive Feature
Fail-Safe
• A fail-safe in engineering is a design feature or practice that in the
event of a specific type of failure, inherently responds in a way
that will cause no or minimal harm to other equipment, the
environment or to people.
• Unlike inherent safety to a particular hazard, a system being "fail-
safe" does not mean that failure is impossible or improbable, but
rather that the system's design prevents or mitigates unsafe
consequences of the system's failure. That is, if and when a "fail-
safe" system "fails", it is "safe" or at least no less safe than when it
was operating correctly.
Synonym: Damage Tolerance
• Property of a structure relating to its ability to sustain defects
safely until repair can be effected.
• The approach to engineering design to account for damage
tolerance is based on the assumption that flaws can exist in any
structure and such flaws propagate with usage.
• In engineering, structure is considered to be damage tolerant if a
maintenance program has been implemented that will result in the
detection and repair of accidental damage, corrosion and fatigue
cracking before such damage reduces the residual strength of the
structure below an acceptable limit.

Synonym: Graceful Degradation
• Ability of a computer, machine, electronic system or network to
maintain limited functionality even when a large portion of it has
been destroyed or rendered inoperative. The purpose of graceful
degradation is to prevent catastrophic failure.
• Ideally, even the simultaneous loss of multiple components does
not cause downtime in a system with this feature.
• In graceful degradation, the operating efficiency or speed declines
gradually as an increasing number of components fail.
Es.
Run-away
175
29-Jan-23 STRUCTURAL DESIGN AND OPTIMIZATION 2023 29-Jan-23 176
https://www.stradeeautostrade.it/ponti-e-viadotti/i-
concetti-elementari-alla-base-della-robustezza-strutturale-
di-ponti-e-viadotti-prima-parte/
https://www.stradeeautostrade.it/ponti-e-viadotti/i-
concetti-elementari-alla-base-della-robustezza-strutturale-
di-ponti-e-viadotti-seconda-parte/
Robustezza strutturale
Value: resilience
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Definition
• The ability to be happy, successful, etc. again after something difficult or bad
has happened
Black Swan Event
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Taleb, Nassim Nicholas (April 2007). The Black Swan: The Impact of the Highly Improbable (1st ed.).
London: Penguin. p. 400. ISBN 1-84614045-5.
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.
Taleb, Nassim Nicholas (April 2007). The Black Swan: The Impact of the Highly Improbable (1st ed.).
London: Penguin. p. 400. ISBN 1-84614045-5.
1. Structural Art
A. Billington:
B. Nervi
2. Attitude
3. Values
• Simplicity
• Simmetry
• Predictability
• Durability
• Robustness
• Resilience
• Elementary view
• Wide view
• Complexity
• Uncertainty
5. Mind’s Eye
• Bias
• Limits
• Failures
• Copy
• Assemble
• Arrangements in series vs parallel
Index Part I
1. Structural Art
A. Billington:
B. Nervi
2. Attitude
3. Values
• Simplicity
• Simmetry
• Predictability
• Durability
• Robustness
• Resilience
STRUCTURING
AN
UNSTRUCTURED PROBLEM
UNSTRUCTURED PROBLEM
Hadamard
185
Chaotic vs. Non Chaotic Evolution
Problemi di Meccanica Strutturale
• I problemi di Meccanica Strutturale sono definibili nell'insieme come
problemi strutturati (nel senso di essere compiutamente organizzati) e ben
posti (nel senso di presentare caratteri di regolarità e risolubilità);
• in particolare, si fa riferimento, infatti, ad un inquadramento hard, in cui:
188
1) le strutture presentano schema globale e
caratteristiche locali univocamente definite in termini
geometrici;
2) le caratteristiche meccaniche dei materiali sono
fissate ed i limiti di resistenza assegnati;
3) le condizioni al contorno, in termini di condizione di
vincolo e di carico, specificati;
4) la soluzione è nella gran parte dei casi unica: nei casi
in cui si possano avere più soluzioni, esistono quasi
sempre tecniche risolutive capaci di individuarle; nei
casi in cui la soluzione non esista, esistono tecniche
per individuare tale mancanza;
5) considerazioni legate alla praticabilità ed
all’economia della soluzione sono inserite solo
indirettamente e tendenzialmente a posteriori,
mentre sono esclusi aspetti della soluzione non
analiticamente inquadrabili come l’estetica.
189
Nota (1)
• Tutte queste posizioni, permettono di avere un inquadramento formale del
problema di meccanica strutturale, che permette un processo risolutivo
completamente analitico, anche se alle volte estremamente lungo e
complicato. In tempi moderni, tale processo risolutivo ha trovato grande
sollievo nell’utilizzo di codici di calcolo automatico estremamente generali ed
efficienti.
190

Nota (2)
• Lo sviluppo operativo di queste tecniche risolutive, se da una parte non trova
l’interesse del settore più teorico della Meccanica Strutturale (ovvero della
Scienza delle Costruzioni), riveste importanza per la Tecnica delle
Costruzioni, in quanto permette di affrontare compiutamente problemi reali,
caratterizzati da complessità geometrica e comportamento non lineare.
191
Problemi di Ingegneria Strutturale
• In termini generali, i problemi dell’Ingegneria Strutturale presentano aspetti
più estesi ed indefiniti, che li riconducono alla categoria più ampia dei
problemi non strutturati e potenzialmente mal posti, che sono formulabili
coerentemente solo in termini soft;
• infatti:
192
1) le costruzioni hanno schemi globali da individuare,
non solo in termini geometrici, ma anche e
soprattutto in funzione dei meccanismi resistenti che
si sviluppano;
2) i materiali reali necessitano di un inquadramento
entro modelli che ne rappresentano solo
parzialmente ed imperfettamente le caratteristiche e
di cui vanno decisi i limiti di resistenza; in termini
generali, il criterio di crisi di una costruzione non è
univocamente definito;
3) le condizioni al contorno, vanno interpretate,
assumendo decisioni in termini di vincoli e di carico;
4) la soluzione è nella gran parte dei casi non unica e
non esistono tecniche per individuarle, ma solo
schemi generali e regole euristiche;
5) la realizzabilità pratica ed i costi costituiscono
valutazioni primarie, essenziali ed imprescindibili,
insieme ad altri valori come la semplicità e l’estetica.
193
Ingegneria Strutturale
• Infine, e questo è un aspetto che distingue la professione, l’Ingegneria
Strutturale deve confrontarsi con l’assunzione di responsabilità e con il
quadro normativo attraverso il quale la Società si tutela regolando le attività.
• L’Ingegneria Strutturale è, infatti, la disciplina che si occupa
responsabilmente di ideare, calcolare, realizzare e gestire valide opere
artificiali, ossia costruzioni, che supportino la Società ed i suoi membri nel
soddisfacimento delle proprie necessità e dei propri desideri, basandosi su
metodi scientifici, utilizzando tecniche opportune, adottando corrette
valutazioni euristiche.
194
ELEMENTARY VIEW
Design as Problem Solving: Top-down development
copertura omogenea
approfondimento
196
IDEATORE
deduttivo
Design as Problem Solving: Bottom-up development
copertura omogenea
sviluppo di
un filone
197
ASSEMBLATORE
induttivo
Design as Problem Solving: Mixed development
198
REALE
abduttivo
Design by Bruno Munari Analysis process and synthesis process (1)
DATI
CALCOLO
RISULTATI
START
END
Pre-processing
Post-processing
200

Analysis process and synthesis process (2)
DATI
CALCOLO
RISULTATI
START
END
START
END
MODIFICA
K=K+1
K=0
DATI
K
CALCOLO
RISULTATI
K
TEST
SI’ NO
Pre-processing
Post-processing
201
Analysis process and synthesis process (3)
START
END
MODIFICA
K=K+1
K=0
DATI
K
CALCOLO
RISULTATI
K
TEST
SI’ NO
ANALISI
SINTESI
202
203
29-Jan-23
Es.
Example: long span suspension bridge
STRUCTURAL
QUALITY
- design life
- railway
runability
- highway
runability
- free channel
- robustness
- durability
- management
GLOBAL
GEOMETRY
AND
TOPOLOGY
TOPOLOGY
- suspension system
- towers
- towers foundation
- anchor system
- main deck
- deck landing
- ...
GLOBAL GEOMETRY
- main span
- sx span
- dx span
SECTIONAL GEOMETRY
- continuous girder sections
- transverse section
- main cables
- hangers
- towers
- secondary elements
MATERIALS
CHARACTERISTICS
- girders
- cables
SYNTHESIS OF
STRUCTURAL
SOLUTION
AND
DOCUMENTATION
BOUNDARY
CONDITIONS
CONSTRAINTS:
rigid and elastic
constraints,
imposed
displacements
NATURAL
ACTIONS
- temperature
- wind
- earthquake
ANTROPIC
ACTIONS
a) permanent
loading
system
b) variable
- railway
- highway
c) accidental
CONVENTIONAL
MODELING:
QUASI
STATIC
REPRESENTATION
BASIC STRUCTURAL
CONFIGURATION
PARAMETERS
- individuation
- definition
- uncertainty
- description
- bounding
GLOBAL
MODELING
- 2D
- 3D
MODELING WITH
DYNAMIC INTERACTION
ALTERNATIVE STRUCTURAL
CONFIGURATIONS
GLOBAL
OPTIMIZATION
- topology
- morphology
- parametric
LOCAL
OPTIMIZATION
- girders section
- transverse
section
- restraint zone
EXPERT AND
FIXED CHOICES
MEASURES
a) qualitative
b) materials volumes
c) serviceability
- modal characteristics
- deflections
- deformations
- reversibility
d) collapse scenarios
- collapse characteristics
- robustness
e) accidental scenarios
- configurations
- risks
DETAILED
MODELING
EXTENDED
MODELING
1
2 3
4
5
6
7
Numerical Modeling for the
Structural Analysis and Design of
MESSINA STRAIT BRIDGE:
subdivision and development of activities.
FB - june 6, 2005 / franco.bontempi@uniroma1.it
205
Prescriptive vs Performance Approach (1)
207
Prescriptive vs Performance Approach (2)
208
SS0a
PRESCRIBED
DESIGN
PARAMETERS
SS0b
ESTIMATED
DESIGN
PARAMETERS
SS1
initiation and
development
of fire and
fire efluent
SS2
movement of
fire effluent
SS3
structural response
and fire spread
beyond enclosure
of origin
SS4
detection,
activitation and
suppression
SS5
life safety:
occupant behavior,
location and
condition
SS6
property
loss
SS7
business
interruption
SS8
contamination
of
environment
SS9
destruction
of
heritage
(0)
DESIGN
CONSTRAINTS
AND
POSSIBILITIES
(1+2)
ACTION
DEFINITION
AND
DEVELOPMENT
(3+4)
SYSTEM
PASSIVE
AND ACTIVE
RESPONSE
BUS
OF
INFORMATION
RESULTS
DESIGN
ACTION
RESPONSE
SAFETY
&
PERFORMANCE
Fire
209
Fire
210

WIDE VIEW
29-Jan-23 STRUCTURAL DESIGN AND OPTIMIZATION 2023 211 STRUCTURAL DESIGN AND OPTIMIZATION 2023 212
29-Jan-23
29-Jan-23
Enorme complessità di fattori
LOOSE
couplings
TIGHT
LINEAR interactions NONLINEAR
216
System Complexity (Perrow)
HPLC
Eventi Frequenti con
Conseguenze Limitate
LPHC
Eventi Rari con
Conseguenze Elevate
Complessità:
Aspetti non lineari e
Meccanismi di interazioni
Impostazione
del problema:
DETERMINISTICA
STOCASTICA
ANALISI
QUALITATIVA
DETERMINISTICA
ANALISI
QUANTITATIVA
PROBABILISTICA
ANALISI
PRAGMATICA
CON SCENARI
217
Analysis Approaches
Calcoli matematici elevati …
I calcoli molto complicati non servono
Solo un mezzo di indagine …

UNCERTAINTY

Isostatic and hyperstatic systems
Sistemi iperstatici
MIND’S EYE
L'occhio vede solo ciò
che la mente è preparata
a comprendere
(Henri Bergson)
Henri-Louis Bergson (Parigi, 18 ottobre 1859 – Parigi, 4 gennaio 1941) è stato un filosofo francese. La sua opera superò le tradizioni ottocentesche dello Spiritualismo e
del Positivismo ed ebbe una forte influenza nei campi della psicologia, della biologia, dell'arte, della letteratura e della teologia. Fu insignito del Premio Nobel per la
letteratura nel 1927 sia «per le sue ricche e feconde idee» sia «per la brillante abilità con cui ha saputo presentarle».
Occhio clinico

NB

29-Jan-23 STRUCTURAL DESIGN AND OPTIMIZATION 2023 253 254
Nonaka & Takeuchi: conoscenza esplicite e implicite
255
Intelligenza artificiale
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-8667.2009.00644.x
2010
Big Data
Aspetti sistemici difficili da valutare
1. il riverbero dello stato di degrado di una singola parte
strutturale (vincolo, singolo elemento, …) sul possibile
funzionamento e cambiamento dello schema statico
complessivo dell’opera;
2. l’influenza sul cambio delle modalità di collasso (ad esempio,
da meccanismo di rottura flessionale o per taglio, ovvero da
duttile a fragile, …)
3. l’individuazione dello scenario di contingenza che può
realisticamente avverarsi nel futuro prossimo per l’opera in
esame;
4. l’influenza sulla compatibilità dei materiali, nel rispetto del
principio di precauzione;
5. la robustezza strutturale.
EDUCATION

• La Tecnica delle Costruzioni si occupa della concezione e della progettazione
strutturale: è una disciplina di sintesi - in cui confluiscono idee, teorie, metodi,
strumenti, sperimentazione e principi empirici – che porta alla scelta oculata
di schemi portanti, elementi e componenti, materiali strutturali, partendo da
una solida e ampia base culturale.
• Tecnica delle Costruzioni deals with structural design and design: it is a
discipline of synthesis - in which ideas, theories, methods, tools,
experimentation and empirical principles come together - leading to the
choice of schemes, elements and components, structural materials, starting
from a solid and broad cultural base.
Statement #1
29-Jan-23 261
• 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.
• The structural design involves a holistic view of the entire lifecycle of a
construction and the environment in which it is immersed, necessarily
envisaging a decision-making path characterized by assuming responsibility.
Statement #2
29-Jan-23 262
• L’analisi strutturale è il presupposto per capire ed esplorare qualitativamente
e quantitativamente il comportamento strutturale in termini di prestazioni e
sicurezza: la corretta comprensione della relazione fra modello e realtà è
essenziale a tal fine.
• Structural analysis is the prerequisite for understanding and exploring
qualitative and quantitatively structural behavior in terms of performance
and safety: a proper understanding of the relationship between model and
reality is essential for this purpose.
Statement #3
29-Jan-23 263
• Lo studio di casi reali di costruzioni, in particolare nei casi di fallimento, è
fonte essenziale di aumento di conoscenza della disciplina.
• The study of real construction cases, particularly in cases of failures, is an
essential source of increased knowledge of the discipline.
Statement #4
29-Jan-23 264
• L’insegnamento della disciplina deve partire dai principi meccanici generali,
favorire una valida comprensione dei comportamenti strutturali elementari e
complessivi, 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.
• The teaching of the discipline must start from the general mechanical
principles, promote a good understanding of the elementary and overall
structural behaviors, prepare for a well-structured arrangement of the
various structural parts supported by a coherent choice of materials, help to
identify the possible situations where a construction can be in terms of
actions and configurations.
Statement #5
29-Jan-23 265
PATTERNS OF DESIGNS
PATTERNS OF DESIGNS
EVOLUTIVE vs INNOVATIVE DESIGN
a
CONOSCENZA
RICHIESTA
DA UN PROGETTO
EVOLUTIVO
CONOSCENZA
RICHESTA
DA UN PROGETTO
INNOVATIVO
CONOS
CONOS
CONOS
CONOS
CONOS
CONOS
CONOSCENZA
CENZA
CENZA
CENZA
CENZA
CENZA
RICHI
RICHI
RICHI
RICHI
RICHIESTA
ESTA
ESTA
ESTA
ESTA
DA UN
DA UN
DA UN
DA UN PROG
PROG
PROG
PROG
PROGETTO
ETTO
ETTO
EVOLU
EVOLUTIVO
TIVO
BASE DI
CONOSCENZA
ATTUALE
La crescita delle conoscenze
269
Evolutive vs Innovative Design
270

271
Es.
272
Northrop YB-49
273
275
277
Horten Ho 229
278
279
Northrop Grumman B-2 Spirit
280

283
BIAS
b
Misleading goals
286
Lorenz
287
Mental Heritage
288

Hybrid Solution
291
LIMITS
c
293
STRUTTURE
CON
COMPORTAMENTO
PER
FORMA
294
STRUTTURE
CON
COMPORTAMENTO
VETTORIALE
295
STRUTTURE
CON
COMPORTAMENTO
SEZIONALE
296
STRUTTURE
CON
COMPORTAMENTO
DI
SUPERFICIE
297
299
S Curve Reaching limits
300

301
The Vasa sinking
• The Swedish flagship Vasa‘s first and final sailing in August 1628 left fine fodder for future
management consultants – an all-purpose cautionary tale of an overbearing but technically clueless
boss pushing through his pet project.
• King Gustavus II Adolphus, striving to make Sweden a superpower (in his bid to make the Baltic fleet
join the Thirty-Year War), had wanted four new warships built fast. Workmen were already laying the
Vasa’s keel when the king ordered its length extended. His seasoned master shipwright, fearing to
challenge the famously hot-tempered king, went ahead.
• The shipwright then took ill, directed the project as best he could from his sickbed and died before it
was finished. His inexperienced assistant then took over, and the king ordered a second gun deck,
possibly spurred by false reports that rival Denmark was building a ship with double gun decks. The
result was the most lavishly appointed and heavily armed warship of its day, but one too long and too
tall for its beam and ballast – a matchless array of features on an unstable platform. When the
standard stability test of the day – 30 sailors running from side to side trying to rock the boat–tilted
the Vasa perilously, the test was canceled, and the ship readied for launch.
• Despite an obvious lack of stability in port, she was allowed to set sail and foundered a few minutes
later when she first encountered a wind stronger than a breeze. She drowned.
Evolutive Jump
304
307
29-Jan-23

SIZE EFFECT
d
312
SCALE
EFFECTS
313
Extrapolation
Effetto di scala – Size Effect
317
The Spruce Goose
318
Quebec Bridge
319
Quebec Bridge Failure
320

Chord Members
321
2nd Quebec Bridge
322
323
A 380
FAILURES
e
Causes of System Failure
100%
Time
%
of
failure
Unknown phenomena
Known phenomena
Research level Design code level
past present future
A
B
B B
C
Human
errors
327
Eccesso di Norme Tecniche
• «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.»
- 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).
329
General Failure Model

Swiss Cheese Model for Failure
HAZARD
I
N
-
D
E
P
T
H
D
E
F
E
N
C
E
HOLES DUE TO
ACTIVE ERRORS
HOLES DUE TO
HIDDEN ERRORS
DESIGN CLIMA
CONCEPTUAL DESIGN
DRAWINGS
CALCULATION
MATERIALS/COMPONENTS
CONSTRUCTION
USE
ACCIDENTS / EXCEPTIONS
MAINTENANCE
MONITORING
STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
threats
No
Yes
threats
STRUCTURAL
MATERIAL
& PARTS
No
Yes
passive
structural
characteristics
threats
FIRE DETECTION
& SUPPRESSION
No
Yes
active
structural
characteristics
threats
ORGANIZATION &
FIREFIGHTERS
No
Yes
threats
MAINTENANCE
& USE
No
Yes
threats
No
alive
structural
characteristics
Yes
STRUCTURAL
SYSTEM
CHARACTERISTICS
STRUCTURAL
SYSTEM
WEAKNESS
Structural
Fire
Design
332
STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
threats
No
Yes
threats
STRUCTURAL
MATERIAL
& PARTS
No
Yes
passive
structural
characteristics
threats
Yes
333
FIRE DETECTION
& SUPPRESSION
No
active
structural
characteristics
threats
ORGANIZATION &
FIREFIGHTERS
No
Yes
threats
MAINTENANCE
& USE
No
Yes
threats
No
alive
structural
characteristics
Yes
334
Formal Safety
Substantial SSubstantial securityafety
conoscenza
valutazione
scelta
decisione
esecuzione
29-Jan-23 336
conoscenza
valutazione
scelta
decisione
esecuzione
Judgement Errors
• Context dependence
• Contrast effect
• Recency effect
• Halo effect
• Plasticity
• Order effects
• Pseudo-opinions
• Vividness
• Wishful thinking
• Anchoring
• Social loafing
• Conformity
• The representativeness heuristic
• Law of small numbers
• Hot hand
• Neglecting base rates
• Nonregressive prediction
• Synchronicity
• Causalation
• Salience
• Minority influence
• Groupthink
Billington’s view of Tacoma Bridge failure.

DESIGN STRATEGIES
DESIGN STRATEGIES
COPY
a

Niente di più insensato
ASSEMBLE
b
Arrangement
in series or in parallel
In parallel In series
Morphological Optimization
Topological Optimization
Different functionalities
Closure of the Structural System in itself
INTEGRATION VS SPECIALIZATION
c
Lateral view
1
2
3
4
5
6
7
8
9
10
33 34 35 36 37
41 42 43 44
11
12
13
14
15
16
17
18
19
20
21 22 23 24 25
26 27 28 29
X
Z
2
2
2
3
3
3
4
4
4
4
4
5
5
5
5
6
6
6
6
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
8
8
8
8
8
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
10
10
10
10
10
10
10
33
33
33
33
33
33
33
33
33
33 34
34
34
34
34
34
34
34
34
34 35
35
35
35
35
35
35
35
35
35
35 36
36
36
36
36
36
36
36
36
36
36
36
36 37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
37
41
41
41
41
41 42
42
42
42
42 43
43
43
43
43 44
44
44
44
44
44
44
11
11
11
11
11
11
11
11
11
11
11
11
12
12
12
12
13
13
13
13
13
13
13
13
13
14
14
14
14
14
15
15
15
15
15
15
15
15
15
15
15
15
16
16
16
16
16
17
17
17
17
17
17
17
17
17
17
17
17
17
17
18
18
18
18
18
18
19
19
19
19
19
19
19
19
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19
19
19
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19
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19
19
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21
21
21
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21
21
21 22
22
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22
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22
22
22 23
23
23
23
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23 24
24
24
24
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24
24
24
24
24 25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
25
26
26
26
26
26 27
27
27
27
27 28
28
28
28
28 29
29
29
29
29
29
29
29
Z
Z
Z
Z
Z
Z
Z
Z
9
X
X
X
X
X
X
X
X
X
X
X
X
X
X
L
h
29-Jan-23

F
F
F
F/5 F/5 F/5 F/5 F/5
Load path / Reactions
29-Jan-23 29-Jan-23 STRUCTURAL DESIGN AND OPTIMIZATION 2023 362
Es.
Es.

1. Structural Art
A. Billington:
B. Nervi
2. Attitude
3. Values
• Simplicity
• Simmetry
• Predictability
• Durability
• Robustness
• Resilience
• Elementary view
• Wide view
• Complexity
• Uncertainty
5. Mind’s Eye
• Bias
• Limits
• Failures
• Copy
• Assemble
• Arrangements in series vs parallel
Index Part I
Abstract
• Structural engineering can nowadays make use of very remarkable computational
tools. This availability can lead to affirm that the entire process of designing and
verifying the quality of a structure can be automated.
• Paradoxically, the opposite is true: powerful tools require deep reflections on what
are the bases of structural design in order to consciously address the procedures
of representation and optimization available today.
• In this only in this way, that optimization can represent an effective fundamental
component of structural design, in order to try to maximize the performance of
the structures and their sustainability.
• In order to obtain a correct optimization, it is therefore necessary to examine the
roots of the design, to understand its meanings and evaluate the limits of the
different numerical implementations.
• The lessons of the course will develop the concepts underlying structural
optimization while presenting specific significant applications
• Monday 30 January
15.00-18.00 (3 hours)
• Basis of structural design
• The art of structural engineering. The
principles of design. The creative process.
Structural concept. Design context and
structural requirements. Structural values.
Design by evolution and innovation.
Integration and specialization. Path of
loads. Structural schemes and their limits.
Structural analysis.
DAY 1
• D. Billington, The Tower and the Bridge: The New Art of
Structural Engineering
• E. S. Ferguson, Engineering and the Mind’s Eye.
• H. Simon, The Science of Artificial.
• G. Madhavan, Come pensano gli ingegneri. Intelligenze
applicate.
• B. Munari, Da cosa nasce cosa. Appunti per una
metodologia progettuale.
• P. L. Nervi, Scienza o arte del costruire?
• E. Torroja, La concezione Strutturale.
• L.E. Robertson, The Structure of Design.
• W. Lidwell, K. Holden, J. Butler, Universal Principle of Design.
• U. Kirsch, Structural Optimization. Fundamentals and
Applications.
• S. Adriaenssens, P. Block, D. Veenendaal, C.Williams. Shell
Structures for Architecture: Form Finding and Optimization.
• M. Sarkisian, Designing Tall Buildings: Structure as
Architecture.
10.00-13.00 (3 hours)
• Qualitative and quantitative aspects of
structural optimization
• Setting up the structural problem.
Uncertainties and undefinitions. Limited
rationality and partial knowledge.
Structural modeling. Solution of the
structural problem and its critical
judgment. Naïve setting of optimization
problems. Optimization algorithms.
Stochastic aspects. Heuristic approaches.
Discrete structural schemes.
DAY 2
15.00-18.00 (3 hours)
• Dr. Valentina Tomei
• Optimization strategies for the design of
gridshell type structures
• Notes on the types of structural optimization
and on the single-objective and multi-
objective optimization algorithms of an
evolutionary type. Notes on strategies for
finding the optimal shape: form-finding.
Gridshell type structures. The role of form in
gridshells. The role of structural optimization
in gridshell design: examples of design
strategies.
15.00-18.00 (3 hours)
• Prof. Elena Mele
• Optimization of structures for tall
buildings
• Behavior of tall buildings, "premium for
height" and structural types. Notes on the
evolution of the structural design of tall
buildings and recent trends: the search for
efficiency and the role of robustness.
Diagrid structures and structural patterns:
sectional and topological optimization.
Patterns inspired by isostatic lines.
Generative design and shape grammar.
DAY 3
10.00-13.00 (3 hours)
• Prof. Francesco Petrini
• Optimization in the performance design of
buildings under wind action and seismic
action
• Application of optimization methods to real
problems. Performance-based design: general
aspects and specific characteristics.
Optimization of devices for the control of
vibrations of tall buildings under the action of
the wind. Risk-based design of reinforced
concrete frames in seismic zone with
development of an optimization procedure
based on the gradient method.
DAY 4
10.00-13.00 (3 hours)
• Dr. Innocenzo Becci
• Seismic recovery of prefabricated buildings
with the use of dissipation systems and
decoupling systems
• With a technical practice setting, the
presentation concerns the seismic
improvement design approach on
prefabricated structures with the use of
mechanical connection and dissipation
devices. For the typological conception of the
mechanisms and for the materials used in the
systems, the selection criteria and the
experiences of experimental feedback which
have made it possible to validate the expected
operating principles will be exposed.
15.00-18.00 (3 hours)
• Prof. Arch. Patrizia Trovalusci
• The construction of form in architectural
works: critical issues and advantages of
the mathematical/numerical approach
• The lesson presents, explores and
discusses mainly qualitative aspects
concerning works of architecture and is
accompanied by some examples of study
addressed in some degree theses (which
are available at this link:
https://sites.google.com/a/uniroma1.it/pa
triziatrovalusci/tesi-di-laurea/tesi-di-
laurea-sdc)
Structural Design and Optimization
Part I – V edition, 2023
Prof. Ing. Franco Bontempi
Docente di TEORIA E PROGETTO DI PONTI – GESTIONE DI PONTI E GRANDI STRUTTURE
Facoltà di Ingegneria Civile e Industriale
Università degli Studi di Roma La Sapienza
franco.bontempi@uniroma1.it

Structural Design Optimization Techniques

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