Towards an explicit design decision process: the case of the structural frame

Decisions made during the briefing and conceptual design stages of a building project are critical to its success. One of the earliest major decisions which can have a significant effect on downstream events and results is the selection of the structural frame. Given its importance to the efficacy of the finished building, the structural frame selection process should arguably be objective and transparent, the final decision being based on the frame's ability to perform against a range of criteria appropriate to the scheme in question. However, the heuristics underpinning such decisions tend not to be explicit and thus, are difficult for inexperienced clients to understand. This article reports on research which examined the criteria used by clients, structural engineers, architects and main contractors when selecting structural frames. These were established via a postal questionnaire survey of a stratified sample of design professionals, contractors and client organizations. The analysis reveals marked differences in the perceived importance of the criteria identified amongst the respondents, which may result in conflicts between design and construction advisers and their clients should they be made explicit in the design process. Nevertheless, it is important that such differences are revealed within the decision-making process if more appropriate design decisions are to be made in the future.