Failed Bridges

Case Studies, Causes and Consequences

Joachim Scheer, Linda Wilharm

• Publisher: Ernst & Sohn
• Year: 2011
• ISBN:
  9783433600979
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

When bridges fail, often with loss of human life, those involved may be unwilling to speak openly about the cause. Yet it is possible to learn from mistakes. The lessons gained lead to greater safety and are a source of innovation.
This book contains a systematic, unprecedented overview of more than 400 bridge failures assigned to the time of their occurrence in the bridges' life cycle and to the releasing events. Primary causes are identified. Many of the cases investigated are published here for the first time and previous interpretations are shown to be incomplete or incorrect. A catalogue of rules that can help to avoid future mistakes in design analysis, planning and erection is included.
A lifetime's work brilliantly compiled and courageously presented - a wealth of knowledge and experience for every structural engineer.

1

Introduction

1.1 Retrospect

My career in construction began in 1946. This was shortly after the end of World War II and I was unable to find a place to study in a faculty for civil engineering because the German universities were overcrowded and older applicants, many of them returning from the long war years, were rightly given preference over us school-leavers.

I therefore started an 18-month building apprenticeship with the aim of becoming a skilled construction worker. At that time I was living in Bremen on the right bank of the Weser and my work took me to a building site in Neustadt on the left bank. It was there, on 18 March 1947, that I witnessed the Bremen bridge catastrophe [1]; surging ice masses swept in by floodwater, together with unmanned boats and barges torn from their moorings, destroyed all the bridges in the town in the space of only a few hours. In the morning I had crossed over a road bridge from the right to the left bank and in the late afternoon I returned to the right bank of the city on one of the last trains over one of the last bridges still standing. This bridge too had been swept away by late evening. The lesson I learned from this disaster was that even with consideration of the fact that immediately after the war the conditions on the river Weser in the city of Bremen were provisional and unusual in many ways, in the end human beings can often only do little in the face of the forces of nature and sometimes nothing at all.

Fortunately, no one was killed in this, my first experience of a collapse disaster. The same is true for the second failure event, which I clearly remember from my practical work on the building site. During concreting of a coal bunker for an industrial power plant, a column-mounted, open-topped cubic box with a side length of approximately 12 m, the inner form-work gave way just above ground level shortly before all the walls had been filled. Most of the concrete spilled out onto the floor of the bunker, accompanied by a dreadful noise I clearly remember even to this day, over 60 years later, caused by the friction of the gravel against the wooden edges of the hole in the formwork. Once the experts had ascertained that the floor scaffolding would not collapse under the huge weight it had not been designed to bear, we worked for hours using buckets on ropes to take the concrete up and out of the bunker. What did I learn from this? The pressure on formwork can be enormous; 24 to 26 times height in meters in kN/m², and that was something I never forgot later when working on a new standard for scaffolding. And also that concrete, which is no longer needed, can never be allowed to set; the fire brigade can be very helpful here.

We heard little about building accidents or the failure of load-bearing structures during our studies at the University of Darmstadt. Certainly our Professor for Steel Construction referred to the collapse of the civic hall in Gorlitz in 1908 [2] to teach us what we should consider when using gusset plates to join chord members. And some years later, this lecturer Kurt Klöppel, told us as his assistants about the terrible accident during the building of the Frankenthal Rhine bridge in 1940 [3], where 42 were killed, and about his investigation into the cause of the failure. From this I learned some basic rules: firstly, that bad luck (see Section 3.7) can always be in play and that engineers must therefore be thorough and imaginative when thinking through the possible failure scenarios. Secondly, that short and simple rules such as long members being more liable to buckle than short members should only be used with the greatest of care because, like all rules, they only apply in certain circumstances. In Frankenthal, it was a short pin-ended wall in a truss system susceptible to buckling, which became so dangerous on account of the great deflection forces.

K. Klöppel made frequent reference to the two German failure occurrences involving bridges built with the new structural steel St 52 in the mid nineteen-thirties – the railway bridge over Hardenberg Street in Berlin and the motorway bridge at Rüdersdorf [4] near Berlin (Section 4.8). This taught me that in civil engineering, as in medicine, an empirical procedure of observation, classification, and analysis can be helpful in averting danger in addition to the strictly scientific analysis of all the contexts. In connection with these two bridge failures, Klöppel was the guiding spirit of the “Preliminary Recommendations for the Selection of Steel Quality Groups for Welded Steel Construction” in 1960, which led in 1973 to Directive 009 of the German Committee for Steel Construction.

In 1954 the motorway bridge over the Lauterbach Valley near Kaiserslautern collapsed during reconstruction, fortunately without causing any deaths or injuries. Kurt Klöppel was commissioned with the inquiry into the cause of the accident and I was among the group of assistants working on the case. The accident and its causes are described in Section 3.3 of this book and it suffices again here to say what I learned from this failure: intermediate states during construction generally lead to extreme stressing of the component parts and must therefore be recognized and carefully investigated.

The collapse of falsework for the reconstruction of part of the motorway bridge over the Lahn Valley near Limburg [5] in 1961 killed 3 building workers and injured 11. I was on the scene of the accident shortly afterwards as a young consulting engineer working out of Wiesbaden. I remember feeling the great responsibility, which is part of our profession, and was acutely conscious of the risk that we can never fully avert.

10 years later I hurried to Koblenz, where a road bridge over the Rhine had collapsed during erection [6]. This incident, together with several other, apparently similar occurrences (Section 3.4), unavoidably resulted in an overreaction in international professional circles, in which I too participated, to prevent any recurrence of this type of failure during the construction of steel box girders. I also took part in the subsequent research, which led to a safe method for the assessment of the bearing capacity of stiffened steel plates as later implemented in building regulations.

I was back in Koblenz just one year later, this time appointed by the public prosecutor to investigate with my two assistants the cause for the collapse of the falsework for one of the last construction stages of a multi-span bridge (Section 11.4.1). 6 had been killed and 13 injured. In the course of this investigation, my belief was confirmed that the work of an expert witness must be determined only by the investigation into the cause of the incident and that even the most insistent demands for initial comments from representatives of the media must be refused.

During my 30 years of experience in the construction of guyed masts, reports of damage during construction and the large number of mast collapses all over the world including fatal accidents to mast erectors in the course of their work have impressed upon me the risk involved in the design, erection and operation of structures of this kind. It is therefore no surprise to me that many mast collapses occur during construction or reconstruction and I ask myself: were all the people involved adequately informed of the inherent danger of their actions, and has enough been done to prevent them from behaving like the “Sorcerer’s Apprentice” and bringing calamity upon themselves and others?

My own experience reflects what everyone “on site” knows: building work is often linked with failure; this has always been the case and always will be. Yet if we learn from the circumstances and mistakes leading up to disasters in the past, we may possibly help to reduce the number of failure occurrences, collapses and catastrophes in the future.

1.2 Aim

In the days before engineering science made it possible to predict the behavior of load-bearing structures, failures were the main source of education and progress for builders. In the same way today, load-bearing structures must prove themselves in practice. Machine and particularly car makers can run a pilot series to remedy defects before going into production, but the one-off nature and size of building structures make it impossible to test their load-bearing capacity and remove defects before construction.

When analyzing the causes of structural failures today, I find that there is hardly any case, which could have been prevented by more detailed calculation. Colleagues such as D. W. Smith [7] or O. M. Hahn [8] have looked into this question and have come to the same conclusion. The basic cause of most catastrophes was either that possibilities of failure were never even considered, conditions were not thoroughly investigated or that in some way rashness or even foolishness was predominant during design or construction. Also on some occasions, successful structures have been the cause of failure in later structures when seemingly unimportant changes, such as in size or slenderness, turned secondary factors into major influences [9].

It is also doubtful whether the safety theory based on a probability approach, which is now the basis for all new standards internationally, is likely to reduce the incidence of failure and collapse of structures. This is because the causes are not statistically distributed, but are rather gross errors that do not fit into any probability calculation. Such concepts are perhaps better suited for appraising the serviceability of our structures.

As engineers continuously produce technical innovations with increasingly challenging load-bearing structures such as bridges with wider spans and of lighter design, cranes of higher lifting capacity and taller skyscrapers and towers, it can happen that due to the limitations of their standard of knowledge, they fail to identify hitherto unknown phenomena and dangers. They are often forced to extrapolate and to accept the risk this entails [10]. Here the progress made in the science of structural engineering has not brought about any radical changes.

H. P. Ekardt [11] spoke of the experimental practice of engineers and comments at one point: “Construction is in a state of continuous development, progressing through emergency situations and constantly breaking new ground in actual projects, creating something new, and in this respect is removed from state or legal control – the area to be controlled is in itself insufficiently objectified and defined for the requirements of law. What is needed is professional self-control based on knowledge, experience, balanced judgment and responsibility. Control and self-control are the two poles between which the practice of designing innovative load-bearing structures moves, particularly when the area of technology involved is in a state of rapid development. The effects of this professional self control are strengthened when setbacks are described, which manifest themselves in the failure of load-bearing structures, their causes discovered if possible and lessons drawn from them.” The foreword began with a quotation from George Frost [12] and in this sense these descriptions are intended to contribute to the science of engineering. This is the concept of my book.

The documentation of failures of load-bearing structures contained in this book does not aim to lecture the people involved in their design or construction after the event – as long as we exclude failures resulting from lack of responsibility. We should bear in mind that this is always easy after the failure has occurred. For this reason, the incidents are only described without naming the parties concerned, except in historic cases. I consider this to be appropriate in order to be fair to the colleagues affected while at the same time making use of the lessons their cases provide.

1.3 Structure

1.3.1 General information about the tables

The tables contain all the occurrences of failure, for which I was able to obtain adequate information. Of course, the question arises whether this form of documentation is useful. I have decided to use tables for the following reasons:

– Reports on failure events are scattered throughout scientific literature. I felt that a compilation of the cases known to date was called for.

– When statements are made about the frequency of failure types and causes, although they cannot fulfill statistical requirements because the total number of incidents is unknown, the sheer number of cases supports their validity. In particular, the availability of descriptions of cases in the tables means that the reader is not obliged to blindly follow my assessments. This is unfortunately not always true of summarizing works such as [7, 23].

The failure occurrences contained in the tables include details of the structure, the year of the failure and the number of people killed or injured. The reason for the failure is briefly noted and the main dimensions of the structure are given in rounded meters, when known, together with at least one source.

1.3.2 Structures included

Despite all the efforts made to ensure that information is comprehensive, a lot of chance is involved in the compilation of failure cases. The source references in the tables show how large the reservoir of information is. Nonetheless, the causes of and course of events leading up to certain cases of failure remain unknown to me although, due to their severe consequences or because of the important lessons to be learned from them, they should have been included. There are many different reasons for this; the degree of candidness in reports on failure cases varies greatly from country to country and the legal difficulties involved in objective reporting have increased over the years.

The data is not representative enough for statistical statements – and it is particularly important not to draw conclusions related to specific countries, as is unfortunately often done. Nevertheless, I have cautiously attempted to identify certain trends in the causes of accidents.

1.3.3 Causes considered

All causes of damage have been considered with the exception of acts of war, chemical action and natural catastrophes such as volcanic eruptions and landslides. Landslide hazard to bridges can often be avoided by a slight adjustment to the positioning of the bridge.

1.3.4 Sections of the book

I have arranged the book in the sections listed in Table 2, although different arrangements present themselves. The failures listed in Tables 3 to 11 are in chronological order.

1.3.5 Sources used

The primary sources for the failure cases included in this book are the publications on failures of load-bearing structures listed in Section 1.4. I have attempted to use the original reports named in these for my research and, as far as possible, have not depended on interpretations contained in later works. I have not always succeeded in this due to the vast number of cases: 440 + 96 = 536 are listed in the tables.

Further sources include expert reports made available to me by colleagues, my own expert reports, building authority records and also newspaper articles.

1.3.6 Abbreviations

The source column in the tables generally names at least one source per case, when possible the original source or a source relatively easily available to the reader which I have also used whenever possible. The source information in the tables is brief because the space provided does not allow full documentation of title and author. Table 1 lists the abbreviations selected for frequently used sources in alphabetical order.

Table 1 Abbreviations for sources used in Tables 3 to 11

Abbr.	Source, mainly journals	Details given
B + E	Journal “Beton + Eisen” (Concrete and Iron)	year, page
BI	Journal “Bauingenieur” (Civil Engineer)	year, page
BRF74	Manuscript for lecture at Conference of German Bridge Consultants Düsseldorf 1974
BRF76	as above, Passau 1976
BuSt	Journal “Beton- und Stahlbeton” (Concrete and Reinforced Concrete)	year, page
BT	Journal “Bautechnik” (Structural Engineering)	year, page
BMV82	Schäden an Brücken und anderen Ingenieurbauwerken-Dokumentation 1982 [5] (Damage to bridges and other civil engineering structures)	page
BMV94	as above, Documentation 1994 [13]	page
CivEng	Journal “Civil Engineering”	year, page
EB	Journal “Eisenbau” (Iron Construction)	year, page
El	Elskes, E.: Rupture des ponts métalliques [14] (Failure of metal bridges)	page
ENR	Journal “Engineering News Record”	year, date of issue, page
IABSE	IABSE Colloquium Copenhagen 1983, Introductory Volume [15]	IABSE, p.
IRB	Documentation of Fraunhofer Information	Document No.
	Centre IRB, Stuttgart
Pott	Pottgießer, H.: “Eisenbahnbrücken” [85] (Railway Bridges)	page
Sm	Smith, D.W.: Bridge failures [7]	page
SB	Journal “Stahlbau” (Steel Construction)	year, page
SBZ	Schweizer Bauzeitung (Swiss Journal of Building)	year, page
St	Stamm, E.: Brückeneinstürze und ihre Lehren [16] (Bridge collapses and their lessons)	page
W	Walzel, A.: Über Brückeneinstürze [17] (About bridge collapses)	page

1.3.7 Overview of failure cases

With reference to the tables, I have first made general observations as to the causes of failure for most of the structure types, including the attempt to allocate the failure occurrences to a specific cause category. This method frequently comes up against difficulties as described by Walzel as early as 1909 [17].

The question what was the cause is answered in various ways: where possible I have decided to give priority to reasons inherent in the actions of the participants over the technical causes resulting from these actions, since more can often be learned from the former. If, for example, a lack of information on the construction site led to a course of action that caused a failure, as a result of, say, overload, I have identified lack of information, i. e. a rash or irresponsible action as the primary cause of the failure and not the overload.

– Often several causes are responsible for the failure: nothing would have happened if only one or the other defect had been there.

– Allocation to a cause can also frequently be imprecise due to gaps in the data available. In these cases, the findings are of necessity subjective and have nothing to do with statistical science.

Following this, the cause or causes of the failure and the lessons to be learned from them are described in more detail for certain selected cases. The summarizing comments on certain groups of accidents allow or require more pertinent observations and conclusions. New insights in connection with the development of structure types and the experience gained can lead to measures being taken to prevent repetition of mistakes, such as the revision or supplementation of building regulations.

The lessons learned from the failure occurrences are described in Sections 12 and 13.

1.4 Earlier publications on the failure of load-bearing structures

As far as I know, the ...

Table of contents

• Cover
• Title Page
• Copyright Page
• Foreword
• Preface to the English edition 2010
• Preface to the German edition 2000
• 1: Introduction
• 2: Failure of bridges, general information
• 3: Failure during construction
• 4: Failure in service without external action
• 5: Failure due to impact of ship collision
• 6: Failure due to impact from traffic under the bridge
• 7: Failure due to impact from traffic on the bridge
• 8: Failure due to flooding, ice floes, floating timber and hurricane
• 9: Failure due to fire or explosion
• 10: Failure due to seismic activity
• 11: Failure of falsework
• 12: Lessons for the practice
• 13: Lessons for teaching
• 14: Literature
• 15: Geographical Index
• 16: Sources of drawings and photographs
• Index