Process of design
To introduce the challenge of creative design and to explain approaches by which it may be achieved.
The lecture begins by considering a definition of design and some objectives. It discusses how a designer can approach a new problem in general and how a structural designer can develop a structural system. It concludes by considering differences of emphasis in design approach for different classes of structures.
1. DESIGN OBJECTIVES
The results of successful design in structural engineering can be seen and used by everyone (see Figure 1).
The question is: how can professional designers develope and eventually produce better designs than those previously encountered to benefit and enhance the performance of human activities? In particular, how can steel be used used effectively in structures for:
- travelling quicker and more easily over awkward terrain requiring bridges
- enabling basic industrial processes to function requiring, for example, machinery supports, docks, and oil rig installations
- aiding communications requiring masts
- enclosing space within buildings as in Figure 2
Design is 'the process of defining the means of manufacturing a product to satisfy a required need' from the first conceptual ideas through study of human intentions to the detailed technical and manufacturing stages with the ideas and studies communicated with drawings, words, and models.
Designers? All people are capable of creative conceptual ideas - they are continuously processing information and making conscious imaginative choices, e.g. of the clothes they wear, of the activities they engage in, and the development of ideas they pursue, causing changes.
In structural design, prime objectives are to ensure the best possible:
- unhindered functioning of the designed artefact over a desired life-span
- safe construction system completed on time and to the original budget cost
- imaginative and appealing solutions for both users and casual observers
These points could possibly be satisfied by either:
- simply making an exact copy of a previous artefact, or
- 're-inventing the wheel' by designing every system and component afresh
Both of these extreme approaches are unlikely to be entirely satisfactory. In the case of the former, the problem may well be slightly different, e.g. the previous bridge may have stimulated more traffic flow than predicted or vehicle weights may have increased. Economic and material conditions may have changed, e.g. the cost of labour to fabricate small built-up steel elements and joints has increased compared to the production cost of large rolled or continuously welded elements; additionally, corrosion resistant steels (e.g. weathering steels) have reduced maintenance costs relative to mild steel. Energy consumption conditions may have changed, e.g. relating to the global discharge of certain chemicals, the cost of production of certain materials, or the need for greater thermal control of an enclosed space. Finally, too much repetition of a visual solution may have induced boredom and an adverse cultural response, e.g. every adjacent building is produced in the Post Modern style.
With the latter approach, 'life is often just too short' to achieve the optimal solution whilst the client frets.... Civil and structural engineering projects are usually large and occur infrequently, so a disenchanted client will not make a second invitation. Realisation of new theoretical ideas and innovations invariably takes a great deal of time as history shows repeatedly. Thus, methodical analysis of potential risks and errors must temper the pioneering enthusiast's flair.
Positive creative solutions must be achieved for all aspects of every new problem. The solutions will incorporate components from the extremes above, both of fundamental principles and recent developments. However, throughout the design process it is prudent to maintain a clear grasp of final objectives and utilise relatively simple technical means and solutions.Read more