The structural collapses are rare events that are characterized by complex dynamics: the identification of their causes and the explanation of their developments are not straightforward processes and depend on numerous different factors. A fundamental aspect is that, even if sometimes it is possible to identify the trigger that have materially caused the collapse, usually there is a complex background of situations that have made the event possible and that need to be accurately analyzed. The investigation of the interrelated aspects and concurrent causes is a fundamental task to assign conveniently the civil and criminal responsibilities. Starting from these considerations, the aim of this paper is to present some concepts that, in the Authors’ opinion, constitute a basis for the framework of the investigation activities. In the first part of thework two concepts are discussed.The first one is the concept of structural complexity, which is an attribute of the civil constructions that are characterized by significant interactions, strong nonlinearities, and large uncertainties. The second concept regards the extension to the Civil Engineering field of a model for the development of failures proposed by Reason (Swiss Cheese Model, 1990). In the second part of the paper some operational approaches are briefly introduced: the breakdown of the problem and the analysis of the timeline; they are essential tools for the assignment of the various responsibility profiles. At the end of the contribution, the concept of structural dependability is recalled as an antidote to avoid failures providing high-quality structural design.

1. CAPE TOWN, SOUTH AFRICA, 2-4 SEPTEMBER 2013
CAUSAL MODEL
FOR THE FORENSIC INVESTIGATION
OF STRUCTURAL FAILURES
Stefania Arangio, Chiara Crosti, Franco Bontempi
““SapienzaSapienza”” University of RomeUniversity of Rome
School of Civil and Industrial EngineeringSchool of Civil and Industrial Engineering
stefania.arangio@uniroma1.itstefania.arangio@uniroma1.it –– chiara.crosti@uniroma1.itchiara.crosti@uniroma1.it –– franco.bontempi@uniroma1.itfranco.bontempi@uniroma1.it

2. OUTLINES
•STRUCTURAL COMPLEXITY
•DEVELOPMENT OF FAILURES
(Reason’s Swiss Cheese Model)
•BREAKDOWN OF THE PROBLEM
•ANALYSIS OF THE TIMELINE
BASIC
CONCEPTS
OPERATIONAL
TOOLS
FRAMEWORK OF THE INVESTIGATION ACTIVITIES
•ASSIGNMENT OF THE RESPONSIBILITY PROFILES
chiara.crosti@uniroma1.it
2/20

3. chiara.crosti@uniroma1.it
3/20
BEHAVIOR
Linear Nonlinear
COUPLING
INTERACTIONS/CONNECTIONS
UNCERTAINTIE
S
Low
High
Loose
Tight
Perrow, 1984
COMPLEXITY
EXISTING ADJACENT MASONRY BUILDINGS.

4. chiara.crosti@uniroma1.it
4/20 COMPLEXITY
EN 1998-3: 2005 (E)

5. chiara.crosti@uniroma1.it
5/20
NTC 2008 (Italian Building Code)
AGGREGATE OF BUILDINGS
•Delimited by an open space;
•Composed by various adjacent
non uniform constructions;
•Built in different epochs;
•Built with different materials;
•They had different owners;
•Experienced different uses and
modifications during time
COMPLEXITY
Neglecting these aspects can have significant consequences on the structures even
up the occurrence of catastrophic collapses

6. OUTLINES
•STRUCTURAL COMPLEXITY
•DEVELOPMENT OF FAILURES
(Reason’s Swiss Cheese Model)
•BREAKDOWN OF THE PROBLEM
•ANALYSIS OF THE TIMELINE
BASIC
CONCEPTS
OPERATIONAL
TOOLS
FRAMEWORK OF THE INVESTIGATION ACTIVITIES
•ASSIGNMENT OF THE RESPONSIBILITY PROFILES
chiara.crosti@uniroma1.it
6/20

7. PRECURSORI
PSCOLOGICI
AZIONI CHE
AGISCONO
ERRORI LATENTI A LIVELLO
LOCAL BEHAVIORS
LATENT ERRORS
ACCIDENTAL CONDITIONS
LATENT ERRORS IN
THE ADMINISTRATION
AND DESIGN
ACTIONS THAT
IINFLUENCE
THE SAFETY
PSICOLOGICAL
PRECURSORS
INTRINSIC SAFETY
FAILURE
chiara.crosti@uniroma1.it
7/20
Reason, 1991
DEVELOPMENT OF FAILURES
SWISS CHEESE MODEL

8. OUTLINES
•STRUCTURAL COMPLEXITY
•DEVELOPMENT OF FAILURES
(Reason’s Swiss Cheese Model)
•BREAKDOWN OF THE PROBLEM
•ANALYSIS OF THE TIMELINE
BASIC
CONCEPTS
OPERATIONAL
TOOLS
FRAMEWORK OF THE INVESTIGATION ACTIVITIES
•ASSIGNMENT OF THE RESPONSIBILITY PROFILES
chiara.crosti@uniroma1.it
8/20

9. DEFINITION OF
PRINCIPAL FUNCTIONS /
GLOBAL PARTS
DEFINITION OF
INTERFACE VARIABLES /
COMPONENTS
DEFINITION OF
DETAILED FUNCTIONS /
LOCAL ELEMENTS
DEFINITION OF
PRINCIPAL FUNCTIONS /
GLOBAL PARTS
DEFINITION OF
INTERFACE VARIABLES /
COMPONENTS
DEFINITION OF
DETAILED FUNCTIONS /
LOCAL ELEMENTS
chiara.crosti@uniroma1.it
9/20 BREAKDOWN
TOP-DOWN
APPROACH
BOTTOM-UP
APPROACH
Reverse Engineering Approach – Back Analysis Techniques

10. chiara.crosti@uniroma1.it
AUTORIZZATI I PERITI
- AD ESEGUIRE IL SOPRALLUOGO SUI
LUOGHI DI CAUSA;
- AD ACQUISIRE E PRENDERE VISIONE
DELLA DOUMENTAZIONE GIA' IN ATTI;
- AD ACQUISIRE EVENTUALE ULTERIORE
DOCUMENTAZIONE RITENUTA
NECESSARIA PRESSO UFFICI PUBBLICI E
PRIVATI (previo avviso e eventuamente alla
presenza dei consulenti di parte)
1) Accertino i periti la
casua del disastro
colposo di cui
all'imputazione
provvisoria sub A),
con particolare riferimento
anche alla:
1-a) correttezza o meno (sotto il profilo tecnico)
della progettazione e della direzione dei lavori
da parte dell'arch. Giovanni PAPARELLA;
1-b) correttezza o meno
- del "piano di demolizione" elaborato nel
febbraio 2008 dal geom. Vincenzo ZAGARIA,
- del "piano di sicurezza e coordinamento"
elaborato dal medesimo ZAGARIA,
e
- del "piano operativo di sicurezza' redatto da
Salvatore CHIARULLI nell'agosto 2008;
1-c) correttezza o meno delle modalita' di
demolizione concretamente poste in essere a
far data dall'ottobre 2008;
1-d) violazione o meno delle norme per la
prevenzione degli infortuni sul lavoro
eziologicamente influenti sulla produzione del
disastro;
1-e) correttezza o meno delle determinazioni
assunte dall'Ing. Rosario PALMITESSA all'esito
del sopralluogo del 30.9.2011, tenuto conto del
reale stato dei luoghi;
1-f) correttezza o meno della condotta tenuta
dall'Ufficio Edilizia Pubblica e Privata del
Comune di Barletta a fronte della
comunicazione prot. n. 56024 del 21.9.2011
inviata dall'arch. Giovanni PAPARELLA al
Dirigente del Settore Edilizia arch. Francesco
GIANFERRINI, in considerazione delle
problematiche concernenti la pubblica e privata
incolumita' da quell'Ufficio gia' affrontate in
relazione all'immobile con accesso da via De
Leon n.6;;
1-g) violazione o meno della normativa in tema
di costruzioni in zona sismica.
2) 3)
4) Riferiscano
quant'altro necessario e
utile ai fini di giustizia.
Iperitisarannotenutiatenerecontodelleosservazionichesarannoformulatenelcorsodelleoperazioniperitalidaiconsulentitecnici,nominatidalleparti,ea
renderneloroadeguatamotivazionenellarelazioneperitale.
2-a) Accertino i periti la legittimita'
degli atti del procedimento
amministrativo sfociato nella
deliberazione del consiglio
comunale della Citta' di Barletta
n.4 del 10.1.2008 e degli atti
anche di provenienza privata, a
quella deliberazione conseguiti,
comprese la d.i.a. prot. n. 7001
dell'1.2.2008 e allegati e la
successiva d.i.a. prot.50018 del
18.82010;
2-b) Accertino i periti se, a fronte
della perizia giurata dell'arch.
Giovanni Paparella del 29.5.2006
con gli allegati relativi (gia' in atti),
vi fosse l'obbligo, fissato
espressamente da una norma di
legge, per l'Ufficio Tecnico del
Comune di Barletta di verificare la
corrispondenza della situazione
dei luoghi, rappresentati nella
perizia giurata, alla situazione
reale degli stessi, tenendo anche
conto del Regolamento Edilizio
Comunale vigente al momento
dei fatti.
3-a) Effettuino i periti un esame comparato
degli elaborati grafici posti a corredo delle due
denunce di inizio attivita', la n.7001
dell'1.2.2008 e la n. 50018 del 18.8.2010, al
fine di constatare se il restringimento operato
sulle planimetrie allegate alle due d.i.a.
riguardasse il solo lato confinante con l'edificio
prospiciente di Via de Leon o anche gli altri lati
del quadrlatero interessato dall'intervento
edilizio Giannini;
3-b) precisino e specifichino i periti, la natura e
le modalita' esecutive delle indagini finalizzate
all'esecuzione delle palificate ed iniezioni sui
confini, alle quali l'arch. Paparella fa riferimento
nell'Ordine di Servizio del 21.9.2011 e alle cui
operazioni quell'ordine di servizio e' anche
finalizzato, sia all'interno del cantiere sia nelle
proprieta' confinanti e specifichino la
compatibilita' e la possibilita' di esecuzione di
tali indagini con lo stato dei residui corpi di
fabbrica, al netto di quanto gia' demolito alla
data del 21 settembre 2011, come
rappresentato negli elaboati grafici e fotografici,
gia dpositati a corredo della consulenza del
pubblico ministero;
3-c) verifichino e accertino i periti la storia
amministrativa e strutturale dell'intero edificio
crollato, con specifico riferimento agli aspetti
tecnico-costruttivi e agli eventuali interventi di
ristrutturazione, ampliamento, sopraelevazione,
sostituzione o modifica di parti strutturali,
nonche' alla regolarita' amministrativa e
progettuale di tali opere, ove e nella misura in
cui siano state effettuate.
1 2 3
BREAKDOWN10/20

11. chiara.crosti@uniroma1.it
EXAMPLE OF BACK ANALYSIS PROCESS: COLLAPSE OF AN AGGREGATE OF BUILDINGS
BREAKDOWN
A
B
11/20

12. chiara.crosti@uniroma1.it
BREAKDOWN
[1] Master Thesis : “Analisi non lineare di aggregati edilizi in muratura”,
Student: Molinaro S., Advisor: Bontempi F., Co-Advisor: Arangio S.
Geometry Finite Element Model [1]
12/20

13. chiara.crosti@uniroma1.it
BREAKDOWN
Mechanical properties of the masonry
Volume weight w 18 kN/m3
Longitudinal elastic modulus E (cracked conditions) 500 N/mm2
Tangential elastic modulus G (cracked conditions) 200 N/mm2
Compression strength fm 200 N/cm2
Design compression strength fd 166.7 N/cm2
Shear strength (o fvm0) in absence of normal stress 3.5 N/cm2
Design shear strength t0d (o fvd0) in absence of normal stress 2.9 N/cm2
[1] Master Thesis : “Analisi non lineare di aggregati edilizi in muratura”,
Student: Molinaro S., Advisor: Bontempi F., Co-Advisor: Arangio S.
[1]
13/20

14. chiara.crosti@uniroma1.it
Modeling of the various steps of the demolition
BREAKDOWN
common wall Horizontal actions due to
vaulted ceilings
step 1 step 2 step 3
Step 1:
represents the situation before
demolition
Step 2:
shows an advanced condition of
demolition where most of vaults of
building A have been eliminated
and the lateral thrust of the vaults
of building B are sustained mainly
by the buttresses
Step 3:
the remaining part
of building A was
demolished and
the wall alone
could not sustain
all the actions.
[1]
14/20

15. chiara.crosti@uniroma1.it
BREAKDOWN
In color only the deformation between 0.0028 and 0.015 (limit in the Italian Building Code) [1]
Step 1 Step 2 Step 3
15/20

16. OUTLINES
•STRUCTURAL COMPLEXITY
•DEVELOPMENT OF FAILURES
(Reason’s Swiss Cheese Model)
•BREAKDOWN OF THE PROBLEM
•ANALYSIS OF THE TIMELINE
BASIC
CONCEPTS
OPERATIONAL
TOOLS
FRAMEWORK OF THE INVESTIGATION ACTIVITIES
•ASSIGNMENT OF THE RESPONSIBILITY PROFILES
chiara.crosti@uniroma1.it
16/20

17. DESIGN/STRUCTURAL
ASPECTS
CONSTRUCTION ASPECTS/
SAFETY AT WORK
NOT ADEQUATE DEMOLITION
ACTIVITIES
SCARCE
ADMINISTRATIVE
SUPERVISORY
ACTIVITIES
SCARCE
CONTROL ACTIVITIES/
DIRECTION/
SAFETY RELATED ACTIVITIES
DEFICENT
DEMOLITION PLAN
NOT ADEQUATE
UNDERSTANDING OF THE
EXISTING
STRUCTURAL SYSTEM
(AGGREGATE OF BUILDINGS)
DEFICIENT
DESIGN
NON
COMPLIANCE
WITH THE
TECHNICAL CODE
ADMINISTRATIVE PRACTICES
CONSTRUCTION
AUTHORIZATION
URBAN
AUTHORIZATION
STARTCOLLAPSE
chiara.crosti@uniroma1.it
TIMELINE
ADMINISTRATIVE
PRACTICES
DESIGN
PHASE
REALIZATION
PHASE
EXAMPLE OF BACK ANALYSIS PROCESS: COLLAPSE OF AN AGGREGATE OF BUILDINGS
17/20

18. DESIGN/STRUCTURAL
ASPECTS
CONSTRUCTION ASPECTS/
SAFETY AT WORK
NOT ADEQUATE DEMOLITION
ACTIVITIES
SCARCE
ADMINISTRATIVE
SUPERVISORY
ACTIVITIES
SCARCE
CONTROL ACTIVITIES/
DIRECTION/
SAFETY RELATED ACTIVITIES
DEFICENT
DEMOLITION PLAN
NOT ADEQUATE
UNDERSTANDING OF THE
EXISTING
STRUCTURAL SYSTEM
(AGGREGATE OF BUILDINGS)
DEFICIENT
DESIGN
NON
COMPLIANCE
WITH THE
TECHNICAL CODE
ADMINISTRATIVE PRACTICES
CONSTRUCTION
AUTHORIZATION
URBAN
AUTHORIZATION
STARTCOLLAPSE
chiara.crosti@uniroma1.it
TIMELINE
DEMOLITION /RECONSTRUCTION OF A BUILDING THAT ENDED WITH A COLLAPSE
CAUSAL
JOINT
18/20

19. OUTLINES
•STRUCTURAL COMPLEXITY
•DEVELOPMENT OF FAILURES
(Reason’s Swiss Cheese Model)
•BREAKDOWN OF THE PROBLEM
•ANALYSIS OF THE TIMELINE
BASIC
CONCEPTS
OPERATIONAL
TOOLS
FRAMEWORK OF THE INVESTIGATION ACTIVITIES
•ASSIGNMENT OF THE RESPONSIBILITY PROFILES
chiara.crosti@uniroma1.it
19/20

20. DESIGN/STRUCTURAL
ASPECTS
CONSTRUCTION ASPECTS/
SAFETY AT WORK
NOT ADEQUATE DEMOLITION
ACTIVITIES
SCARCE
ADMINISTRATIVE
SUPERVISORY
ACTIVITIES
SCARCE
CONTROL ACTIVITIES/
DIRECTION/
SAFETY RELATED ACTIVITIES
DEFICENT
DEMOLITION PLAN
NOT ADEQUATE
UNDERSTANDING OF THE
EXISTING
STRUCTURAL SYSTEM
(AGGREGATE OF BUILDINGS)
DEFICIENT
DESIGN
NON
COMPLIANCE
WITH THE
TECHNICAL CODE
ADMINISTRATIVE PRACTICES
CONSTRUCTION
AUTHORIZATION
URBAN
AUTHORIZATION
STARTCOLLAPSE
chiara.crosti@uniroma1.it
Time
Responsability
RESPONSIBILITY PROFILE20/20

21. ATTRIBUTES
THREATS
MEANS
RELIABILITY
FAILURE
ERROR
FAULT
FAULT TOLERANT
DESIGN
FAULT DETECTION
FAULT DIAGNOSIS
FAULT MANAGING
DEPENDABILITY
of
STRUCTURAL
SYSTEMS
AVAILABILITY
SAFETY
MAINTAINABILITY
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
INTEGRITY
ways to increase
the dependability of a system
An understanding of the things
that can affect the dependability
of a system
A way to assess
the dependability of a system
the trustworthiness
of a system which allows
reliance to be justifiably placed
on the service it delivers
SECURITY
High level / active
performance
Low level / passive
performance
ATTRIBUTES
THREATS
MEANSMEANS
RELIABILITYRELIABILITY
FAILURE
ERROR
FAULT
FAULT TOLERANT
DESIGN
FAULT TOLERANT
DESIGN
FAULT DETECTIONFAULT DETECTION
FAULT DIAGNOSISFAULT DIAGNOSIS
FAULT MANAGINGFAULT MANAGING
DEPENDABILITY
of
STRUCTURAL
SYSTEMS
AVAILABILITY
SAFETY
MAINTAINABILITY
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
INTEGRITY
ways to increase
the dependability of a system
An understanding of the things
that can affect the dependability
of a system
A way to assess
the dependability of a system
the trustworthiness
of a system which allows
reliance to be justifiably placed
on the service it delivers
SECURITY
High level / active
performance
Low level / passive
performance
chiara.crosti@uniroma1.it

23. StroNGER S.r.l.
Research Spin-off for Structures of the Next Generation
Energy Harvesting and Resilience
Rome – Athens – Milan – Nice Cote Azur
Sede operativa: Via Giacomo Peroni 442-444, Tecnopolo Tiburtino,
00131 Roma (ITALY) – info@stronger2012.com
Str
o N
GER
www.stronger2012.com