The Design of Modern Steel Bridges - TEDI

Preface
Bridges are great symbols of mankind’s conquest of space. The sight of the
crimson tracery of the Golden Gate Bridge against a setting sun in the Pacific
Ocean, or the arch of the Garabit Viaduct soaring triumphantly above the deep
gorge, fills one’s heart with wonder and admiration for the art of their builders.
They are the enduring expressions of mankind’s determination to remove all
barriers in its pursuit of a better and freer world. Their design and building
schemes are conceived in dream-like visions. But vision and determination are
not enough. All the physical forces of nature and gravity must be understood
with mathematical precision and such forces have to be resisted by manipulating
the right materials in the right pattern. This requires both the inspiration
of an artist and the skill of an artisan.
Scientific knowledge about materials and structural behaviour has expanded
tremendously, and computing techniques are now widely available to manipulate
complex theories in innumerable ways very quickly. But it is still not
possible to accurately cater for all the known and unknown intricacies. Even
the most advanced theories and techniques have their approximations and
exceptions. The wiser the scientist, the more he knows of his limitations.
Hence scientific knowledge has to be tempered with a judgement as to how far
to rely on mathematical answers and then what provision to make for the
unknown realities. Great bridge-builders like Stephenson and Roebling provided
practical solutions to some very complex structural problems, for which
correct mathematical solutions were derived many years later; in fact the clue
to the latter was provided by the former.
Great intuition and judgement spring from genius, but they can be helped
along the way by an understanding of the mathematical theories. The object of
this book is to explain firstly the nature of the problems associated with the
building of bridges with steel as the basic material, and then the theories that
are available to tackle them. The reader is assumed to have the basic degreelevel
knowledge of civil engineering, i.e. he or she may be a final-year
undergraduate doing a project with bridges, or a qualified engineer entering
into the field of designing and building steel bridges.
The book sets out with a technological history of the gradual development of
different types of iron and steel bridges. A knowledge of this evolution from
the earliest cast-iron ribbed arch, through the daring suspension and arch
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