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Causal models for the forensic investigation of structural failures
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Causal models for the forensic investigation of structural failures

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The structural collapses are rare events that are characterized by complex dynamics: the identification …

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.

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  • 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
  • 22. 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

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