William G. Godden Structural Engineering Slide Library

Professor Godden

The Structural Engineering Slide Library was collected over the period 1950 through 1980. It was developed as a visual resource for illustrating structural systems in undergraduate courses in structural analysis and design. Each structure is identified, and a brief description is given. The collection was made available in 1980. For publication on the Internet, the original collection and writing have been retained, largely without editing, but supplemented with additional slides and more recent structures. The original slides are numbered in the form Nx, the additional slides in the form Nx.y.

The Structural Engineering Slide Library is the product of 30 years of teaching structural analysis, structural design, and architectural engineering to undergraduate and graduate students in Europe and the United States. During this period the author has traveled extensively and has used color photography to bring to the classroom illustrations of structural engineering so that theory can be related directly to practice. The resulting slides are not always the standard type of book illustrations, but rather views taken from specific angles for the express purpose of illustrating particular facets of structural theory, response, or design. Over the years, this has developed into a large and comprehensive collection taken in many countries, covering all kinds of structural engineering, historic as well as modern. The Slide Library is a selection of 560 slides from this larger collection.

In teaching courses on structural analysis, the author has found such a resource invaluable in supplementing the rigor of engineering analysis with applications to real life. Without such immediate illustration, engineering mathematics can be uninteresting, difficult to understand, and easily misapplied. In addition, it is often useful to start analysis with an actual structure rather than with a line diagram, to develop an expertise in structural idealization alongside the necessary competence in equation solving. As the advent of microcomputers makes the analysis of complex structures readily available to students early in their training, without necessarily developing an equivalent knowledge of structural geometry and response, careful illustration becomes increasingly important. Finally, it is found that in certain courses the use of case studies is an ideal means of both teaching and learning the whole process of structural engineering from the choice of geometry, to structural idealization, equation solving, and finally to design, construction, and structural behavior. Hence the Library has been developed with these three uses in mind, and having this resource available makes possible certain kinds of teaching that might otherwise be difficult.

Most structural systems are illustrated, and throughout the Library certain structures are singled out in each section for more extensive coverage using overall views, views from different angles, and close-ups of details such as boundary supports that have a significant influence on the method of analysis and on the resulting structural behavior.

The Library consists of these slide sets:

Most chapters deal with the subject matter in two ways, historically and by subdivision into structural types. Sets A through F are similar in layout, except that Set F: Columns, Rigid Frames, Grids and Slabs covers more than one topic. Set G: Structures Under Construction is different in that it deals with a series of structures under construction. This is an important topic, as it is during construction that deflections can sometimes be seen, for example, the gross deflections in a partially completed suspension bridge. The structural system and the degree of indeterminacy in the construction phase are often completely different from the load-carrying system after completion, as in a continuous bridge constructed from a series of simply supported precast beams that only gains its continuity with the casting of the integral deck slab. This set can be used in a general discussion of constructional procedures and the way analysis is done at different stages.

There are other ways that topics can be derived from the Library. It is interesting to start an introductory course on structural analysis with a discussion of boundary conditions, degrees of freedom, and internal force releases, by selecting examples from all of the sets to show the generality of these concepts. It is also a simple matter to take a 'horizontal cut' through the library and group together slides dealing with masonry structures, concrete, prestressed concrete, steel, or timber structures.

The earliest slides were taken on the original Kodachrome film using a Leica camera with 35mm Summaron, 50mm Elmar, and 135mm Hektor lenses. The dyes in this material have remained remarkably stable over a long period, and there is no discernable fading. Its one drawback was the very slow speed which made it difficult to take interior shots without time exposures. The most recent slides have been taken on Kodachrome 64 and Ektachrome 400 using a Nikon camera with 35mm, 50mm, and 105mm Nikkor lenses. High speed Ektachrome is ideal for indoor shots of poorly lighted stadia.

The author would like to make the following acknowledgements: to Dr. Leonhardt and his staff in Stuttgart for arranging visits to two of his bridges under construction; to Mr. Charles Seim of the State of California Baytoll Crossing Authority for arranging visits to the Dumbarton Bridge during the early and latter stages of construction; and to Mr. F. T. Godden of London who provided slides of the cable-spinning operation during the construction of the Forth Suspension Bridge and also supplied some pictures of the bridges by Stephenson and Telford. Photo credits. Acknowledgements (online version).

... William G. Godden, December 1980