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IABSE Working Group Forensic Structural Engineering
Pre-‐Conference Short Course
Forensic Structural Engineering Causes of Failures & Investigations
Geneva, September 22, 2015
Course Chairmen: Fabrizio Palmisano & Karel Terwel
Synopsis
“Engineering investigation of the causes of structural failures of buildings, bridges, and other constructed facilities, as well as rendering opinions as to the cause(s) of the failures and giving testimony in judicial proceedings, is a field of professional practice of its own, often referred to as forensic structural engineering” (R.T. Ratay, 2010). This short course is one of the activities of the IABSE Working Group ‘Forensic Structural Engineering’. The ultimate objective of the WG is to mitigate structural failures and improve forensic engineering practices. To these ends the activities of the WG include seminars, workshops, short courses, presentation and publication of papers for the purpose of increasing the awareness and working knowledge of students and practicing engineers of the causes, prevention and consequences of failures, for the ultimate goal of ensuring the safety and reliability of structures. The WG organized sessions on forensic structural engineering at the IABSE Madrid 2014 symposium which were well attended, demonstrating that there is much interest in the practice of forensic structural engineering. The short course is aimed at structural engineers who want to acquire a working knowledge of forensic structural engineering, practicing forensic engineers who want to learn from and share with other practitioners, and university students who wish to gain an advanced understanding of forensic structural engineering to underpin future research/career interests.
Objectives Provide structural engineers with an insight to the state-‐of-‐the-‐art practice of forensic investigation of structural failures, and into lessons learned from failures to understand and mitigate design errors and construction defects.
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Schedule
• 9:00 – 9:30 Registration and coffee
• 9:30 – 10:00 Robert T. Ratay 1) An Overview of Forensic Structural Engineering
• 10:00 – 11:00 Karel Terwel 2) Causes of structural failures and underlying factors Ø Goal: give an overview of characteristics of failures and causes. Ø Based on study of 741 Dutch cases with comparison of international studies. Ø Characteristics of failures: types of structures, types of structural elements, types of damage, fatalities,
loads during failures, elements involved, used materials, main causes (design/construction errors, etc.), phase of discovery.
Ø Comparison of international cases: studies of e.g. Schneider Matousek, Fruehwald, Hadipriono. Ø Selected information from the WG’s recent survey of forensic engineering practices in IABSE member
countries: some countries suffer more from extreme weather and earthquakes -‐> relative influence of human errors is smaller.
Ø Underlying factors: human errors? It appears that organizational factors such as safety culture, allocation of responsibilities, risk management, control, communication and collaboration, and knowledge infrastructure are determining.
• 11:00 – 11:15
Coffee break
• 11:15 – 12:15 Huibert Borsje & Karel Terwel 3) Cases of failures/collapses Highlighting some important types of failures: Ø Detailing concrete (balconies Maastricht). Ø Facades (Façade residential building Amsterdam). Ø Temporary structures during construction (temporary support for floor of B-‐tower). Ø Unexpected behaviour of materials (incorrect stainless steel in swimming pools, alkali-‐silica reaction,
Nickel Sulphide inclusions in glass)
• 12:15 – 13:30 Lunch
• 13:30 – 14:30 John F. Duntemann 4) The forensic investigation process Ø First steps after a failure.
o Field observation. o Search for survivors/victims. o Assurance of public safety. o Temporary stabilization, repair.
Ø Assessment. o Questioning. o Existing documents. o Inspections. o Testing. o Re-‐calculations. o Structural performance. o Reporting.
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• 14:30 – 15:30
Fabrizio Palmisano 5) Investigation of failures in concrete and masonry structures + specific cases Participants will be interactively involved in the lecture. Two different cases will be discussed: the collapse of Giotto Avenue building in Foggia (concrete structure) and the partial collapse of ‘Palazzo Edilizia’ in Salerno (masonry structure). The application of the methodology described in the previous lecture will be step-‐by-‐step analysed with reference to the case studies. The case studies will focus mainly on the following issues: Ø Giotto Avenue building collapse: material defects, conceptual and detailing design deficiencies, linear
and probabilistic analyses. Ø Partial collapse of ‘Palazzo Edilizia’: surveys, testing, linear and nonlinear analyses, hidden structural
defects.
• 15:30 – 16:00 Tea break
• 16:00 – 16:45 Huibert Borsje 7) Investigation of failures in steel structures + specific case In July 2011, during construction work, the roof of the football stadium Grolsch Veste in the Netherlands partially collapsed. As a result of this accident, two workers were killed and nine injured, some of them critically. After this accident an investigation was started to determine the technical cause(s) of the collapse. This investigation was set-‐up as described in the previous lecture about the forensic investigation process. The participants will be guided along the steps of the process the investigators have taken to solve the problem.
• 16:45 – 17:00 Huibert Borsje 6) WYSIATI – What you see is all there is Most of us go through life assuming (and sometimes insisting) that we see ‘everything’ and that we are right about our observations. This short lecture will show the participants that we often don’t see everything we have to see and sometimes even see non-‐existing things. It will be explained why it is so difficult to separate observation and interpretation.
• 17:00 Fabrizio Palmisano & Karel Terwel 7) Closing
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Lecturers’ biographical notes Huibert Borsje, MSc., is a structural engineer, graduated at the Delft Technical University and now working as a senior scientist at TNO the Netherlands. From the beginning of his career, over 25 years ago, he is investigating damage. The first years he was mainly focusing on damage analysis of concrete structures, both material related damage and structural damage. Later on his work developed into forensic engineering of structural damage in general. Last years he has investigated several severe collapses of buildings and other structures, in order of the Public Prosecution, the Labour Inspectorate of the Ministry of Social Affairs and Employment and The Dutch Safety Board. John Duntemann, P.E., S.E., is a Senior Principal at Wiss, Janney, Elstner Associates, Inc. in Northbrook, Illinois, USA. He is a licensed structural engineer primarily engaged in the assessment and rehabilitation of existing structures, and specializes in the assessment of structural distress and serviceability problems. He is a graduate of the University of Illinois at Urbana-‐Champaign, where he received a Bachelor of Science degree in Civil Engineering and a Master of Science in Structural Engineering. He is a member of IABSE and serves on Working Group 8 Forensic Engineering and the Outstanding Structure Award (OStrA) Committee. He is also a member of the American Society of Engineers (ASCE) Standard Committee for Minimum Design Loads for Buildings and Other Structures (ASCE 7) and a contributing author to the Forensic Structural Engineering Handbook published by McGraw-‐Hill. Fabrizio Palmisano, MEng., Ph.D., P.E., is an Adjunct Professor of Structural Mechanics at the Politecnico di Bari and Director of the Engineering and Architecture Consulting Company ‘PPV Consulting’. He was responsible for many structural projects in Italy and in 2005 he received the fib ‘Diploma to Younger Engineers’ award in the design and construction category. He was involved in the vulnerability assessment of many buildings and, on behalf of the Public Prosecutor Office, he investigated some of the most important collapses occurred in Italy in the last 15 years. In 1998 he received, from the Italian Minister of the Interior, the 'Diploma of merit' with medal for the service done in the seismic vulnerability assessment of buildings struck by the 1997 Umbria-‐Marche earthquake. He is author of more than 90 articles on structural engineering, referee of scientific international journals and member of scientific and technical Italian and International Committees. Robert T. Ratay, Ph.D., P.E., is a structural engineer in private practice and a Visiting Professor at Columbia University in New York, where he developed and teaches the graduate course of Forensic Structural Engineering. His five decades of practice encompass design, failure analysis, and teaching. Dr. Ratay has been an expert consultant/witness on some 200 cases of structural problems. He is the editor of three books: Handbook of Temporary Structures in Construction, 3rd edition, Forensic Structural Engineering, 2nd edition, and Structural Condition Assessment; published numerous articles and lectured widely in the US and abroad on the subject of forensic structural engineering. Dr. Ratay is a Fellow of IABSE, and the founding Chair of its Working Group on Forensic Structural Engineering. Karel Terwel (1975) studied Civil Engineering at Delft University of Technology (DUT) and graduated in 2001. From 2001 until 2007 he was working as a structural designer/ project leader at Zonneveld Engineers on complex structural designs like two office towers (height: 146m) for the government in The Hague (awarded Dutch concrete prize 2013) and the Palace for music in Utrecht. Since 2007 he has been a lecturer (from 2015: assistant professor) on structural design at DUT. In 2013 Terwel founded Coenraedt B.V. He is committed to providing consultancy in investigations of structural failures, second opinions and structural risk management. He finished his PhD on influencing factors for structural safety in 2014. He is member of the Platform Structural Safety in the Netherlands, of IABSE’s WG8 Forensic Engineering and of the editorial advisory board of the ICE’s journal Forensic Engineering.