Construction Method Models: the Glue Between Design and Construction

Research Performed by Florian Aalami

Main Advisor: Martin Fischer

Sponsored by National Science Foundation

"The most time-consuming and difficult aspect of the job-management system, planning, is also the most important. It requires an intimate knowledge of construction methods combined with the ability to visualize discrete work elements and to establish their mutual interdependencies." (Clough and Sears 1991)

Today's construction planning process is largely a manual and time-consuming process. The translation of a design to a construction schedule requires manual interpretation of data and knowledge in the planner's mind. Today's construction-method knowledge is either retained in the minds of experienced construction personnel or as paper-based method statements. In either case, the information is not easily accessible and does not support the automation of the construction planning process. Further, construction schedules generated with this "informal" construction-method knowledge are difficult to maintain and replan because the reason behind the existence of activities and their sequencing is not explicit.

We have developed customizable construction method model templates (CMMT) by generalizing activity elaboration (generation) and sequencing knowledge. In a method-driven, hierarchical planning process, activity elaboration and sequencing knowledge is captured in user-selected construction method models. In such a planning system, construction methods are the glue between design and construction. In their most simple form, construction methods have been modeled as skeletal nets, where the number, type, and sequencing of activities are predefined. Representing construction methods as skeletal plans has two main limitations: the inter-linking of different skeletal plans is a manual process and it is impractical to provide-a priori-an exhaustive set of construction method models. Hence, the main challenge of our research was to define and test a computer-interpretable representation for construction method-based planning knowledge that is general yet supports the customized representation of project- and company-specific knowledge. Planners can use these method templates to define and store general construction method knowledge. The CMMT has been implemented in the Construction Method Modeler (CMM) planning system using Intellicorp's PowerModel object environment on SUN computers. Jacobus Technology's Schedule Simulator software, VRML, and Java3D are used to visualize and manipulate the resulting 4D models. CMM has been used to model approximately 50 construction methods for reinforced concrete building and process plant construction. The construction methods modeled have between one and eleven constituting activities.

Planners can use these methods to rapidly generate construction schedules and 4D models. They choose a construction method to refine (elaborate) a particular activity. Using the planning knowledge from the CMMT and the information in an IFC-compliant product model, CMM automatically generates the appropriate number of activities, links the activities with their related components in the 3D product model, and embeds the activities in the critical path project network. Planners can now rapidly generate realistic construction plans for one or multiple designs using a range of different construction methods.

Links:

Using Method Models to Generate 4D Production Models with the CMM Planning System

View examples of 4D Visualizations generated by the CMM Planning System

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