Proceedings of the First International Congress on Construction History, Madrid, 20th-24th January 2003, ed. S. Huerta, Madrid: I. Juan de Herrera, SEdHC, ETSAM, A. E. Benvenuto, COAM, F. Dragados, 2003. Inventing a history for structural engineering design Bill Addis It is often convenient to as sume that history is a series commercial, contractual, management, social, of facts waiting to be discovered. But there are so political, etc.).' many facts. The facts that we do discover are, to a large extent, auto-selected according to who we are Despite much searching, however, it became clear and why we are looking for them. This influences that very few people had attempted to answer the where we look for facts and what we do with them author's most burning question -how were the when we have found them. The history that is so structures designed? To a large extent, the challenge generated can be very personal, even subjective, and became to create or invent the idea of a history for the great challenge is to persuade others of the value engineering designo Rather than using someone else' s or reward to be gained from adopting a certain map to navigate the territory, the challenge was to approach to history. draw a new map. And an important aspect of this As a practising design engineer, the author's own challenge was to distil the very essence of journey into the past began with questions about how engineering design, and, especially, to distinguish it people in former times might have designed things. fram general ideas of «technology» and «engineering The search uncovered a wonderful range of material science».2 in various different strands of structural engineering Engineers themselves have seldom been effective history: is promoting the nature of their art -they have generally been too busy getting on with projects- - the development of different types of structure and this is nearly as true today as five hundred or a (e. g. suspension bridges, timber roof trusses, thousand years ago. Professor Fritz Leonhardt, from dams, masonry domes); Stuttgart, was one of the most eminent design engineers of the 20th century. In a book about what - developments and inventions in engineering technology (especially materials, plant and engineers do he wrote: machinery, and methods of manufacture or construction); Der Beruf des Bauingenieurs ist in der Offentlichkeit fast nicht bekannt. Wenn vam bauen die Rede is, dan n denkt - biographies of engineers; man die meisten an den Architekten. Wenn ein the stories of individual projects; - Bauingenieur Bauten entwirft, dann wird er in den - developments in engineering science and Zeitungcn als Architekt besprochen. So ging es dem mathematics «<theory» and techniques of Vervasser fast sein ganzes Leben hindurch. Ich bin der analysis), and Meining. daJ3 die Bauingenieure im wesentlichen selbst - various non-technica] issues (economic, daran schuld sindJ (Leonhardt, 1981). 114 B. Addis In essence, to design an arte1'act is to plan what you were able to convince themselves that the resulting are intending to do be1'ore you start, and to devise a structure could, indeed, be built, and then that they practical and economic way 01' constructing it. With were able to persuade the clients and even the public characteristic simplicity, Oye Arup once wrote that: that they would be possible. And furthermore, they were so success1'ul in putting their case that they Design is nothing el se than indicating a sensible way of were able to raise the considerable sums of money building. lt includes al! drawings, specifications, necessary to undertake the projects. descriptions and detailed instructions about what should be bui!t and how it should be built (Arup 1985). 11'the engineer's job is to be summed up in one phrase, then, it can be to create the confidence lo start Even de1'initions such as this, however, overlook a huilding. This provides a focus for historical study. most important aspect 01' engineering design -the How, at different times and places, have engineers process 01' achieving the necessary confidence to found the necessary confidence to build? begin building. It is one thing to sketch a magni1'icent 11',at any time in history, the project engineer did bridge or roo1' for a building, quite another to be not feel confident that a certain structure would work, con1'ident that it can be constructed and will sa1'ely he would have to decide what he needed to do in carry the loads to which it may be subjected. This order to gain that confidence. This is the art of the aspect distinguishes 1'undamentally the work 01'those engineer. Seeing and understanding how something engaged in civil and structural engineering from those similar has already been done is probably the most engaged in the design of small machines or consumer important help an engineer can gel. For artefacts, who never need to address questions as to unprecedented or especially challenging problems, whether their creation will work 1'irst time, or be safe, scientists and mathematicians (01'ten called or be possible to make. «philosophers» in ancient times) have al so been an Engineering design is a process with two key imponant source of expertise that can raise the outputs: engineer' s con1'idence. This confidence must overcome any doubts about - a description of what has to be manu1'actured success the engineer may harbour, as well, of course, and built: materials, speci1'ications, dimensions, as any doubts by the client whose money and construction method. This may be a verbal reputation are also at risk. A history of engineering instruction, but, especially when the building is design, then, must address these di1'ferent aspects 01' large or complex, would usually be written the design process: down or in the form oí' a drawing or a model: and - what was the final design for the anefact or - a just(fication or explanation of the design structure? proposals that have been made. This may be - how was the final design arrived at or devised? achieved on the strength of precedent, 1'ull- - what means did the design engineer use to scale tests, experiments on small physical increase his confidence, hefore commenÓng models, various calculations, or the use of construction, that the proposed structure would mathematical models, nowadays based on work and could be constructed, sufficiently 1'or engineering science. him to begin building. A study 01' what engineers do can make the A history of confidence among engineering process seem all very mechanicaJ, with resulting designers would be a challenging subject to undertake artefact an almost inevitable resulto But this is not since con1'idence depends very much on the how it seems to the design engineer, him or herself. experience and the cultural and intellectual It is important to consider the challenge and the background oí' the engineer as well as the context in unknown aspects of a project that the design team which the engineer is working. There are also faces. From an engineer' s point of view, the principal important questions about how di1'ferent engineers in achievement in constructing the Pantheon, or a large the past might have perceived the gap between what cathedral or the Ei1'fel Tower, was that some people they knew had already been done and what they ]nventing a history for structural engineering desing 1]5 might have believed to be possible, though not yet and stmcture, as well as what we now eall the internal know by what means. And the confidence is needed environment (Jighting, heating, ventiJation and at even the most fundamental leve]s such as the acoustics) in a single, holistic design process. The reliability and sophistication of mathematieal visual appearance, sense of space and function (the calculations and the accuracy of dimensions «architecture» in the modern, narrow sense) became a generated by geometric techniques of producing distinct concern during the fifteenth and sixteenth drawings of complex shapes or eonnections in a centuries. About a century later, designers first began buiJding. A history of engineering design needs to to think about the load-bearing aspects ofbuildings in address these aspects of the skilJ. This was a terms of loads (weight), materials and structure. challenge that faced the author when working in the Thinking separately about materials and stmctures team devising an exhibition about the work of grew during the late-seventeenth and eighteenth engineers some years ag04 -had do you put on centuries, folIowing Galileo's work, and aspects of display? On that occasion the answer to this question the internal environment carne to be considered included a collection of the engineer' s aids to independently of the fabric of the building during the calculation -tables of Jogarithms, slide mIes and Jate-nineteenth and early twentieth centuries. mechanical and electrical calculators. There were also It is al so worth noting that structural understanding some design engineers' notebooks with their ]ittJe is neither a new phenomenon, nor one that requires a sketches and the calculations they made when know]edge of statics and elasticity. It is a commonly- exploring a new idea. These things really do capture he]d misconception that new types of structure and something of what engineers do, but their apparent stmcturaJ forms were devised first by mathematicians insignificance may stilI give only a hint at how a final or scientists and later taken up by builders, engineers grand scheme may have come about. or other designers of stmctures. In fact, the opposite There are, of course, prablems in using modern is the case, with perhaps just one exception -the words like «engineer», «desigll» and «designef» to hyperbolic paraboloid, whose stmctural properties refer to the construction of a Gothic cathedral or, were discovered in the 1930s.