Temporary Structure Planning Generation Using Feature-based Modeling

Temporary structures are a critical element of the overall construction plan. Failure in planning appropriate temporary structures affects safety, quality, and productivity adversely (Chini and Genauer 1997). According to an OSHA report (OHSA 2003), an estimated 2.3 million construction workers, or 65% of the construction industry, work on scaffolds frequently. Every year $90 million are lost due to not properly planning temporary structures. Business losses due to related schedule delays may well exceed these direct losses. Planning temporary structures requires planners to consider constraints introduced not only by the building component itself (e.g., concrete wall, roof) but also by the features expressing temporary structure planning rationale (e.g., work face, base surface, and scaffolding) and their relationships. For example, the need for scaffolding for painting a concrete wall is determined by the relative position of the work face to the base surface from which scaffolding is supposed to be raised. Current industry practice lacks a formalized approach and tools to help planners consider those features and their relationships in terms of temporary structure planning. Therefore, we propose to investigate a formal way to represent features pertaining to temporary structure planning and subsequently to leverage the represented features to facilitate the temporary structure planning process. The goal of this research is to provide a computer model that is useful for planners who wish to generate appropriate temporary structures. To do this, planners’ rationale for deriving temporary work from permanent work and knowledge about temporary structures must be formalized into computer interpretable form. Previous research efforts have focused on developing semantically rich product models based on geometric models by extracting information from components to support engineering tasks such as design review, scheduling, and cost estimation. However, geometric models are limited in their usefulness for linking planning rationale with the models since the data available in geometric models is at a low, microscopic level (Shah and Mantyla 1995). For instance, boundary representation models are expressed in terms of edges, faces, curves, etc., and constructive solid geometry (CSG) in terms of solid primitives and set operators. Therefore, many types of information to support engineering decisions for planning temporary structures cannot be conveniently included in a simple geometry-based CAD model consisting of low level data. Feature modeling is considered a next step in the development of product modeling techniques beyond geometric modeling methods. Feature modeling is an approach whereby high-level modeling entities termed “features” are utilized to provide engineering meaning to ordinary geometric modeling techniques (Shah and Mantyla 1995). In this proposed research, we will use the concept of features to represent planners’ rationale for planning temporary structures. We will also provide mechanisms that enable a computer system to reason about a 4D production model to automatically generate temporary structures for a given building design and selected construction methods. We anticipate that the success of this research will make 4D models more complete by adding temporary structures and their activities to set them and dismantle them.