WORDS: structural health monitoring; suspension bridge; experimental; real-time condition
STRUCTURAL CONTROL AND HEALTH MONITORING
Struct. Control Health Monit. 2008; 15:183–206
Published online 23 May 2007 in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/stc.213
Monitoring the collision of a cargo ship with
the Vincent Thomas Bridge
H. Yun1, R. Nayeri1, F. Tasbihgoo1, M. Wahbeh1, J. Caffrey1, R. Wolfe1,
R. Nigbor1, S. F. Masri1,*,y, A. Abdel-Ghaffar1 and L.-H. Sheng2
1Viterbi School of Engineering, University of Southern California, Los Angeles, CA 90089-2531, U.S.A.
2California Department of Transportation (Caltrans), Sacramento, CA 95819, U.S.A.
SUMMARY
On 27 August 2006, the Vincent Thomas Bridge, a 1850-m suspension bridge located in the larger
metropolitan Los Angeles region, was struck by a large cargo ship passing under the bridge. Moderate
damage to the maintenance scaffolding at the main span of the bridge was observed. This incident left
transportation authorities wondering about the structural integrity of the bridge. A real-time continuous
monitoring system that had been recently installed on the bridge successfully recorded dynamic response
before and after the incident, as well as during the collision. Analysis of these valuable data allows
transportation authorities to quantify the effects of the collision on the bridge structural condition, which
would otherwise be infeasible with traditional visual bridge inspection approaches. A forensic study
was performed to assess the structural condition of the bridge before and after the incident. Both global
(multi-sensor) and local (single-sensor) identification methods were applied to detect whether significant
changes occurred in the bridge vibration signature. Copyright # 2007 John Wiley amp; Sons, Ltd.
KEY
assessment; system identification; Eigensystem Realization Algorithm; Natural Excitation
Technique
1. INTRODUCTION
1.1. Motivation
The demand on advanced transportation infrastructure increases in every region of the world.
In the United States and across the world, more highways and bridges are being built than in the
*Correspondence to: S. F. Masri, Viterbi School of Engineering, University of Southern California, Los Angeles,
CA 90089-2531, U.S.A.
yE-mail: masri@usc.edu
Contract/grant sponsor: U.S. National Science Foundation (NSF)
Contract/grant sponsor: Air Force Office of Scientific Research (AFOSR)
Contract/grant sponsor: National Aeronautics and Space Administration (NASA)
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附件2：外文原文
The development of steel structures in Portugal — the influence of Patrick Dowling
Antoacute;nio Ressano Garcia Lamas
Abstract
The paper describes the influence of Professor Patrick Dowling in the authors career and in the development of steel structures in Portugal based on university research and teaching and the creation of the Portuguese Association for Steel and Composite Construction.
Keywords: Portugal; Steel; Structures; Research
1.Introduction
Up to the advent of reinforced concrete and the First World War, Portugal followed the majority of European countries in the use of iron and steel. After that, foundries existed but the structural products were imported with high taxation to protect a developing cement industry in Portugal and the Colonies.
The first steel mill was built in 1961 in Seixal, across the river from Lisbon, fed by iron ores and coal from Angola. However, this big investment did not halt the decline in the use of structural steel which became almost limited to industrial buildings since the main production of this plant was reinforcing bars and only small profiles were rolled.
The state of the norms for steel structures reflected this decline and Portugal lived with an outdated code until the 1980s. More precisely, a vicious circle of reasons contributed towards a reduction in the use of structural steel, amongst which was the lack of research and teaching on the subject at universities.
The situation was very different in the field of concrete, where the National Laboratory for Civil Engineering (LNEC) was one of the worldrsquo;s leading institutions and Portugal was an active participant in the CEB and in the writing of the concrete Model Codes. Portugal being located in an earthquake risk zone, the research developed at LNEC on the seismic behaviour of concrete structures and the availability of advanced regulations gave confidence and dominance to concrete. As a consequence all Civil Engineering courses involved extensive teaching of concrete subjects and none in steel or composite structures.
A few years before the 1974 democratic revolution a profound reform of the higher education system took place, namely in Civil Engineering. A large programme of training new researchers in fields not sufficiently covered by universities or public laboratories was set up, offering grants to study abroad. Instituto Superior Teacute;cnico (IST)–the Faculty of Engineering of the Technical University of Lisbon–was one of the first institutions to profit from this programme, and steel structures were wisely chosen at the Department of Civil Engineering1 as a topic requiring the training of new lecturers.
Having just finished a long compulsory military service, due to the ongoing colonial war, I was awarded a grant to follow the M.Sc. course in Steel Structures at Imperial College. My university structural training had been thorough but insufficient in geometric and material non-linearities, precisely because they were less relevant for concrete structures. I remember how these complexities of steel appealed to me and I became interested in pursuing a further degree in London, but the changes at the university required my return. I went back wrongly believing that I would be able to start a Ph.D. in Lisbon. However, 1975 was a time as exciting for the young Portuguese generation as unsuitable for starting a research project and, at the beginning of 1976, I applied to return to Imperial College and to take advantage of the interrupted grant.
By then I was sure that I wanted to study under the supervision of Patrick Dowling, the lecturer who had most impressed me during the M.Sc. course. He was dynamic, concerned with tackling the more recent structural problems in steel and a natural leader who had attracted a team of young researchers from different countries which I wanted to join.
Following the development of new design rules, stimulated by the ECCS and based on a network of structural steel research centres, these were golden times for steel research in Europe and Patrickrsquo;s team was prominent. Non-linear behaviours of stiffened plates and box-girders were the topics of the day and several large-scale models were being experimentally analysed under his supervision. He not only accepted me as a research student but, until the renewal of my Portuguese grant, supported my stay at Imperial College by offering me work in some of these projects. The subject of my thesis was thus naturally determined, and I studied the effects of shear lag on the buckling of wide flange box-girders4 for the next three years.
Our student–supervisor relation evolved into a lasting friendship and I discussed with him not only aspects of my thesis but also projects for my return to Portugal. In several of those projects I have requested his help
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