سیستم گسترش کارکرد کیفیت فازی برای تصمیم گیری طراح های ساختنی

During the conceptual stage of a building design, major design decisions that have the greatest influence on buildability of a project are taken. Quality function deployment (QFD) is an integrated decision-making methodology that can assure and improve the alignment of elements of design and construction processes with the requirements of customers. On the basis of the enlarged customer concept, QFD has the potential to be developed as a quantitative approach for buildability evaluation. This paper presents the findings of a research effort to adapt House of Quality (HOQ) to meet the needs of buildable designs in the construction industry and to develop a fuzzy QFD system for buildability evaluation. In this system, the fuzzy set theory is integrated into HOQ to capture the inherent impreciseness and vagueness of design-relevant inputs and facilitate the analysis of design-relevant QFD information. An example is presented to illustrate the system, which provides a viable decision-making method for quantitative buildability evaluation at the early design phase.

Design-construction integration during the early stage of a project provides the potentials for designers to give their clients better value-for-money designs. Buildability (or constructability), which emphasizes the integration of design and construction to improve the chances of achieving a better-quality project, completed in a safe manner, on schedule, and for the least cost [1], has been regarded as an important concept to realize this integration in the construction industry. Previous research efforts into buildability have documented concepts; developed principles and ways to improve buildability; identified barriers; quantified costs/benefits; and provided project-level models, approaches and guide to implementation. All of these efforts focused on management systems and organizational commitment to the buildability concept and proposed to use them to overcome the technical and contractual barriers that limit the integration of design and construction. When there is no direct organizational and managerial support for buildability implementation, the integration of design and construction heavily depends on the designers' prior construction experience [2]. However, the designers often are only partially knowledgeable about, and sometimes not aware of, the design-relevant construction inputs [3]. In addition, the decision-making process at early design stages tends to be ill structured and occurs in an unsystematic way. Quality function deployment (QFD) is an integrated decision-making methodology that can assure and improve the alignment of elements of design and construction processes with the overall requirements of a construction project. QFD has the potential to aid the development of a structured and systematic method to support the process of buildable-design decision making with suitable adoption and extension to facilitate its implementation. The objective of this paper is to address the challenge of developing a fuzzy QFD system to support buildable design decision making. The research objectives are, first, to adapt House of Quality (HOQ) to provide a systematic and structured method to support the integrated decision-making process of buildable designs; second, to integrate fuzzy set theory into HOQ to facilitate the processing of design-relevant QFD information.

In this paper, a fuzzy QFD system for buildable designs based on the mechanisms of conventional QFD methodology and fuzzy set theory has been presented. This system provides a quantitative method and advances the conventional QFD methodology for early buildability evaluation in three aspects: • The HOQBD (Fig. 4) is constructed to support the integrated evaluations of buildable designs through adapting matrices of conventional HOQ. • Triangular fuzzy numbers are used to intuitively represent the linguistic and imprecise nature of decisions and judgments of buildable designs. • Fuzzy inference mechanism is established to process the design-relevant HOQBD information. The differences between the proposed fuzzy QFD system and the traditional QFD methodology is that the QFD-relevant data are expressed and represented as linguistic terms rather than as crisp numbers, and the linguistic data is processed by algorithms embedded in the system's internal environment. Future study can be pursued on developing a computerized intelligent decision support system for quantitative buildability evaluation in the linguistic and group decision-making environment. The early and efficient acquisition and utilization of buildability knowledge and information is the major bottleneck in automated buildability analysis. To remove this bottleneck, future researches can also consider the combination of automated knowledge acquisition techniques (e.g., [34] and [35]) with the proposed fuzzy QFD system to support automated buildability analysis in the early design phases.