Bridge Deck Analysis
Twenty-five years ago, fairly complex skew, prestressed concrete bridge decks could be
analysed with a fair degree of accuracy—but only by using manual methods. The famous
Rusch and Hergenroder influence surface charts, translated from the German by the Cement
and Concrete Association, gave surfaces for various stress and aspect ratios up to a 45° skew.
Full analysis of a bridge deck involved, amongst other techniques, the use of planimeters on
the way to calculating volumes under the influence surface, in turn leading to the calculation
of mx, my and mxy moments. The method was tedious, somewhat approximate and could often
take weeks. Indeed, if an error arose early on in the calculations, many days could be spent in
re-analysing. Now, it is possible to change a dozen variables and a computer program will
recalculate stresses and reactions in seconds.
There is still a need, however, perhaps more so now than in the past, for a bridge engineer
to understand how a bridge deck responds to various combinations of load and to be able to
decide if the ‘answer’ (output) is sensible. To be confident of this, an understanding of the
behaviour of non-symmetrical, eccentrically loaded, irregularly supported structures is
This book fulfils just that role. Written by two engineers who have, between them,
experience of almost all aspects of modern bridge design and analysis, it includes chapters on
every aspect of bridge deck analysis that a practising bridge engineer is ever likely to need.
Written in clear, unambiguous English, copiously and carefully illustrated, it represents years
of scholarship and research presented in a lucid and understandable style which should make
even the more complex theory understandable to all engineers.
In many aspects, the book contains either a novel approach to design or entirely new
methods. It covers construction in some detail, with sections on bearings, joints and aesthetics
not commonly found in bridge analysis books, loading (with prestress treated as a special case
of loading) and details of a unique graphical approach to moment distribution—a powerful
tool in engendering an understanding of fundamental structural behaviour. This is particularly