国际预应力混凝土协会(FIP and fib)名誉主席
法国技术科学院院士 Michel Virlogeux 的序言和评语
Foreword by Michel VIRLOGEUX
But society lost interest in bridges about 80 or 100 years ago, when bridge construction became more industrial, when bridge design became more and more mastered and controlled. Bridge construction was no more an adventure, and, except perhaps for Fritz Leonhardt, engineers became anonymous partners in the large industry which had to rebuild road and railway networks after the Second World War, and later to develop them into the modern transport system of our time.
This has suddenly changed 15 or 20 years ago when some architects – beginning with Santiago Calatrava – introduced in the domain of bridges the ideas of the modern "free" architecture, which we can see, for an example, in the famous museum of Bilbao designed by Frank Gehry. Shapes come from fantasy, and no more from functional or structural needs.
This is certainly not my own philosophy of design, nor even of architecture, but we must recognize that they helped changing the minds in such a way that, in the same time as architecture more generally, bridges attract very much attention today.
I started designing bridges much before this evolution, almost 40 years ago now, following a more traditional line. For me the bridge design must directly come from a purely structural flow of forces, aiming at an efficient balance of loads and forces, from the point where they are applied to the foundations; the bridge elegance must come from the proportions, the shapes, which have to evidence and express this flow of forces; slenderness and transparency will come from a minimal – and thus efficient – use of construction materials, steel and concrete.
Because designers are also responsible for the cost of their constructions, almost always paid by public money; aesthetics and ethics cannot be separated; the designer must achieve architectural perfection in a full respect of functional, financial and structural needs. Not forgetting maintenance, which command to concentrate the materials in a limited number of strong elements.
We cannot escape from the three goals of architecture given by Vitruvius Pollio, the great Roman engineer, twenty centuries ago:
– utilitas, which means in the same time public utility, functional needs and economy;
– firmitas; of course the structure has to be safe and easily maintainable;
– and venustas, at the end, beauty, elegance.
To achieve these goals, I have always worked with an architect, since I consider that I am not able to develop alone shapes which could perfectly express the structural concept that
I created. And also because confronting ideas is always fruitful. Not forgetting the other engineers who have worked with me, "my" structures owe much to Auguste Arsac – who has been my Professor of Architecture when I was student – Philippe Fraleu, Bertj Mikaelian, Alain Spielmann, Jean-Vincent Berlottier, and Aymeric Zublena. With a special mention for Charles Lavigne: many of my best bridges have been designed with him, and many of his with me. The Normandy Bridge, designed with Charles, and even more the Millau Viaduct, designed with Lord Foster, have received a world wide reputation, an enormous mediatic attention which show that elegance can be achieved in full respect with functional, economical and structural needs, in the line of what David Billington calls the structural art.
And then, which connection with this book written by Mr. Yingliang Wang and Zongyu Gao? It is very clear in fact, since this book will show the works of many engineers, evidencing their creations among which many very good structures; it will convince engineers that it is not any more acceptable to design heavy, inelegant and boring structures which, by reaction, push some architects and some engineers to design crazy and expensive bridges; it will also demonstrate, specially for the younger engineers who will take our place in the years to come, that there are so many structural solutions that variety – which is a clear need in our modern world – can be achieved without deviating from a cartesian, logical and economical approach.
It will also show, I hope, that elegance does not need unnecessary complexity and can be produced, on the contrary, by simple and pure lines.
Honorary President of FIP and fib
Member of the French Academy of Technology
Member of the Indian Academy of Engineering Michel Virlegoux
Bonnelles, October 22, 2007 |
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