Generating Temporary Structures with 4D Feature-Based Models

The proposed research focuses on providing automation support for generating temporary structures with feature-based 4D models to enable planners to develop possible alternatives of temporary structure plans rapidly and correctly. This should help make planning and managing construction schedules more efficient and effective.

To generate temporary structure plans, construction engineers today must manually understand and analyze the 4D context of the specific project situations from information (e.g., 2D drawings or 3D CAD models, construction schedules, etc.) that is not tailored for planning temporary structures. This is time consuming and error-prone. In addition, planning decisions are often made without evaluating possible alternatives. This is due to the absence of a formalized way to describe specific project situations with respect to temporary structure planning and the absence of a formalized way to represent planners' rationale to select appropriate temporary structures.

Previous research efforts have focused on developing models based on geometry 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 describing specific project situations with respect to temporary structure planning since the data available in geometric models does not sufficiently represent the semantics of components and actions related to temporary structure planning. Therefore, many types of information to support engineering decisions for planning temporary structures cannot be conveniently included in a geometry-based CAD model.

Feature modeling is an approach whereby modeling entities termed features are utilized to provide improvements for ordinary geometric modeling techniques. To apply feature-modeling techniques to temporary structure planning, we propose to identify the relevant features required for describing specific project situations and formalize the representation of the features. In this research, we propose to formalize a feature ontology that allows describing the specific project situations using features. In addition, we propose to investigate a formal way to represent planners' rationale to select appropriate temporary structures, which leverages the formal representation of the features described above.

One of the research issues of the proposed research is to represent the semantics of components and actions that are important to temporary structure planning using the features of components and actions. The component and action features collectively represent the contexts of specific project situations with respect to temporary structure planning. In this research, we propose to formalize an ontology using features to represent different specific project situations that affect temporary structure planning.

More importantly, all these features (i.e., component and action features) need to be considered with relation to the progress of other work on site since the same temporary structure is often utilized to support more than one activity. Hence, it is necessary to consider the features of components and actions "collectively" to determine what temporary structure would be appropriate to share. In this research, we propose to formalize a language to describe component and action feature relationships so that they can provide information needed to determine what temporary structure would appropriate to share.

The proposed feature ontology and component feature relationships enable construction planners to explicitly represent relevant information for planning temporary structures. Even with explicit representation of this information, planners still have to take steps to select appropriate temporary structures for the given situations. This is due to the absence of a formalized representation of the planners' knowledge about temporary structures and the lack of the reasoning mechanisms that automate the steps required for selecting temporary structures. In this research, we propose to formalize the representation of the planners' knowledge about temporary structures by classifying temporary structures according to the criteria that explain how the temporary structures work for specific project situations. We also propose to develop reasoning mechanisms that reason about the 4D context of the specific project situations to select appropriate temporary structures.

Thus far, we have reviewed previous research about product modeling, feature modeling, representation of component relationships, knowledge representation, and geometric modeling. From the literature review, I identified theoretical points of departure and useful frameworks that are applicable to the proposed research. We have also identified the areas that require elaboration, which sets up the contributions of the proposed research.

Useful theoretical backgrounds: techniques for geometric analysis, frameworks using KS as inference engine, reasoning mechanism that reasons in the 4D context of a project.

Requirements for expansion: identification and formalization of the features of components and actions with respect to temporary structure planning, richer definition of component relationships to represent mating conditions of component features, definition of action relationships to represent constraining relationships of action features, richer classification of temporary structures.

Jonghoon Kim is planning to defend his Ph.D. proposal on May. For now, he continues to revise his proposal draft based on the feedbacks from his committee members (Prof. Martin Fischer, Prof. Ray Levitt, Prof. Kos Ishii, Dr. John Kunz). In addition, he is developing a simple prototype system that he would use to prove the concepts of the proposed research.

Our simple prototype system (i.e., Scaffold Generator) consists of three modules (Figure 1). The first module (i.e., Feature Modeler) enables generation of feature-based 4D model. The second module (i.e., Need Identifier) enables identification of the activities that need scaffolds. The third module (i.e. Scaffold Selector) enables selection of appropriate temporary structures. The reasoning mechanisms of the second and third module analyze the properties of features of components and actions that are instantiated in the first module to generate appropriate temporary structure plans. Currently, the development of the second module is in progress. For now, the prototype is very limited in its application, but our future work will extend it for general application.

Figure 1 Scaffold Generator consists of three modules (i.e., Feature Modeler, Need Identifier, Scaffold Selector). The first module (i.e., Feature Modeler) enables generation of feature-based 4D model. The second module (i.e., Need Identifier) enables identification of the activities that need scaffolds. The third module (i.e. Scaffold Selector) enables selection of approproate tempoary structures.

Figure 2 This figure shows the user interface of the first module (Feature Modeler), which enables generation of feature-based 4D model. In this module, the user can select the activity (the upper window) and instantiate the features of component and action of the selected activity (the bottom window)

We are going to reformat Jonghoon Kim's PhD proposal according to NSF (National Science Foundation) guidelines and submit a grant application for the Division of Civil and Mechanical Systems.

The proposed research issues are threefold. We intend to submit a paper for each of the issues to academic journal (e.g., Journal of Construction Engineering and Management, Journal of Computing in Civil Engineering, etc.) We also intend to publish CIFE Technical Reports detailing the findings of this research.

Relationships between features

Representation of the planners' rationale to select appropriate temporary structures