AUTOMATED CONSTRUCTION PLANNING FOR MULTI-STORY BUILDINGS

AUTOMATED CONSTRUCTION PLANNING FOR MULTI-STORY BUILDINGS Tang-Hung Nguyen 1 ABSTRACT This paper outlines a computer-based framework that can assist construction planners and schedulers in automatically generating sequences of construction activities to be required for the planning of a multi-story building. This framework employs the concept of threedimensional solid modeling for representing building components enabling extraction of geometric data necessary for deduction of spatial relationships between the building components. These relationships include information about the intersection, adjacency, containment, and separation among building spaces and/or components. The deduced spatial information then can be used to generate building zones in a multi-story building as well as construction activities to be performed in each zone. Automated methods to generate the building zones and construction sequences will be discussed. KEY WORDS Construction Planning, Construction Scheduling, Computer-Aided Building Design, Spatial Information, 3D Solid Modeling INTRODUCTION Construction planning and scheduling for a constructed facility involve generating sequences of various types of construction activities and different construction zones in which the activities take place. Since a construction schedule consists of hundreds of activities performed in multiple types of construction zones or spaces, it is not practical for project managers to develop manually the sequences of construction activities and their associated construction zones/spaces. In effect, when working with a building comprising of a large number of building components, especially the multi-story ones with complex geometric configurations, the construction planners usually encounter difficulties in manually generating sequences of construction activities to be performed in different spaces/zones of the building. Most of floors in a multi-story building are of a repetitive modular nature and often the building has several different groups of modular floors, each group with its own functions or configuration. Therefore, construction planners are likely to group floor spaces of these 1 Assistant Professor, Department of Civil Engineering and Construction, 120H CME Building, North Dakota State University, Fargo, ND 58105, Phone: +1 701/231-8646, Fax: 701/231-7431, hung.nguyen@ndsu.nodak.edu 1

buildings, which are adjacent-to each other (one below or above the other) and have the same functional requirements or configuration into different zones such as Lobby, Offices, Mechanical, Roof, Parking, etc. (Shaked and Warszawski, 1995). This grouping is helpful in simplifying the generation of construction activities to be performed in various floor spaces since all adjacent floors with the same function comprising a building zone may require similar construction tasks. Additionally, the sequence of construction activities to be performed in a zone can be determined on the basis of the information about spatial relationships between building components (i.e. intersection, adjacency, containment, and separation). For example, information about the connection between the two components, said beam-01 and column-02, indicates beam-01 is supported- by column-02, thus construction activities for column-02 (the supporting component) should be completed prior to those for beam-01 (the supported component). Another example of construction sequences based on spatial relationships is construction activities for a building floor below should be completed before starting those for the above. As a result, the spatial relations between building components as well as the grouping of common construction zones should be defined when developing construction planning and scheduling. However, it is too tedious for project planners to manually interpret these spatial relationships and construction zones from CAD (Computer-Aided Design) drawings since the volume of building information is usually large and complex. There is a need for automated mechanisms to deduce the spatial relationships among building components that then can be used to generate building zones as well as construction sequences for multi-story buildings. This paper outlines a computer-based framework that can assist construction planners and schedulers in automatically generating sequences of construction activities to be required for the planning of a multi-story building. This framework employs the concept of threedimensional (3D) solid modeling for representing building components enabling extraction of geometric data necessary for deduction of spatial relationships between the building components. The deduced spatial information then can be used to generate construction zones in a multistory building as well as sequences of construction activities to be performed in each zone. Various automated mechanisms to generate building zones and construction sequences will be discussed. BACKGROUND CHARACTERISTICS OF MULTI-STORY BUILDINGS Multi-story buildings are a special group of structures that have the following characteristics (Shaked and Warszawski, 1995): They are composed of a large number of horizontal floors Most of these floors are of a repetitive modular nature. Often, the building has several different groups of modular floors, each group with its own functions or configuration The building contains a large number of mechanical systems for transportation, communication, plumbing, heating, air conditioning, and so on 2

The systems have vertical components that span various floors, horizontal components that repeat themselves on each floor, and central service units (e.g. machines for elevators, water tanks, etc.) on one of the floors or outside of the building The vertical parts of the systems are housed in vertical shafts that penetrate horizontal surfaces and isolate the space within. Due to the repetitive modular nature, floors in a multi-story building that are adjacent-to each other and have the same function (e.g. office) and the same spatial configuration should be grouped into a zone, says office. One of the benefits from the grouping is that only construction sequences for one floor should be developed and applied to other floors in the same zone since construction activities to be performed in floors located in the same zone are usually similar to each other. PREVIOUS WORK Previous research efforts have been made towards automation in generating construction scheduling using integrated building information models or four-dimensional (4D) planning models by integrating 3D visualization with the time attribute. (Williams, 1996) developed a 4D model for the generation of graphical construction plan on the basis of simulation, visualization, and communication. (Collier and Fischer, 1995) conducted a case study of a hospital building to demonstrate the feasibility of using visual-based 4D modeling in construction scheduling. (McKinney and Fischer, 1998) studied the effectiveness of a hybrid 4D application using the contemporary software Primavera, AutoCAD, Jacobus Simulation Toolkit, and Walkthru. (Tommelein and Zouein, 1993; Thabet and Beliveau 1994; and Choo et al. 1999) focused on modeling the different types of work spaces required by construction activities. The proposed models are aimed at generating a schedule to eliminate spatial conflicts, given the geometric attributes of the project-specific activity space requirements that are defined by the user. As the large number of activities that may be up to hundreds require multiple types of spaces in a given schedule, it would be impractical to expect the user to describe these activity space requirements manually. (Choi and Flemming 1996; and Hegazy and Elbeltagi 1999) addressed the algorithms to automate the allocation of coarse spaces at site for site layout planning. To support the site layout automation, the user is required to define qualitative and quantitative adjacency constraints (e.g. close, far, and so on) between spaces. In short, the construction planning/scheduling literature describes useful background but does not describe detailed methods to automate the generation of spatial relationships between building components/spaces as well as sequences of construction activities. Our research complements the research done within the area of automated construction planning by developing the mechanisms necessary to generate construction zones and sequences using the deduced spatial relations among building components. 3

3D CAD SYSTEMS TO SUPPORT AUTOMATED DEDUCTION OF SPATIAL RELATIONS Recently, the emergence of solid modelers has offered solutions for the representation of 3D geometric information of design products (i.e. building components). Different computerbased systems (Eastman et al. 2002; Fischer et al, 2001; Haymaker et al., 2001; and Griffis& Sturts 2000) have been developed using 3D solid modeling techniques with emphasis on the integration of various design and construction applications. Solid modeling provides various representation schemes using primitives such as vertices, edges, faces, cells, and loops. In building design, such primitives are suitable for a complete and unambiguous description of building components and particularly their geometrical data available in the CAD system can be extracted to deduce information about spatial relationships between the building components (Nguyen and Oloufa, 2002). In effect, Nguyen and Oloufa have developed algorithms to deduce different spatial relationships between building components such as adjacency, connection, containment, separation, and intersection, which may be required for different building design activities such as construction planning, constructability reasoning, and code compliance checking (Nguyen and Oloufa, 2001 and Nguyen et. al, 2004). In the current work, these algorithms will be revised with extensions as necessary to meet particular needs. THE AUTOMATED SYSTEM FOR CONSTRUCTION PLANNING The automated generation of construction zones and sequences for multi-story buildings by the proposed system requires integration of a 3D geometrical model with the associated schedule of construction activities. The automated system provides a comprehensive building design tool that enables visualized construction planning, linkage between the 3D geometric product model and the bar chart schedule. ZONES Zones are spaces or groups of spaces, which serve as autonomic units in the construction planning process (Shaked and Warszawski, 1995). In multi-story buildings, they can be defined by (a) their nature, as horizontal and vertical; (b) their designation, as basement, lobby, mechanical, office, elevator shaft, etc; and (c) their location. For this particular work, zones in a multi-story building will be defined by designation due to the simplicity. Several floors that are adjacent to each other and have very similar configuration or layout will be assigned to a common zone that defined by the designation of the floors. For example, all office floors in a multi-story building with the same configuration can be grouped to zone office. Further, the spatial relations (e.g. below, above, adjacent-to, connected-to, etc) between the various zones have an effect on the planning of construction activities performed in the various spaces. For example, the construction activities to be performed in a zone below should be completed prior to those for the zone above. The proposed system is able to automatically deduce the spatial relations and use the spatial information to generate various building zones. 4

SYSTEM ARCHITECTURE The prototype system is developed on a personal computer under the contemporary Windows platform. Visual C++ is the programming development environment for the user interface. AutoCAD has been selected as the graphic tool used to produce 3D geometric models. Microsoft Project is the project planning/scheduling environment. The architecture of the automated system comprises of three major components: 3D CAD system, the application development tool, and the scheduling software. The 3D CAD system (i.e. AutoCAD by Autodesk, Inc.), as a key component of the prototype system, undertakes various function including 3D geometric representations and representations of functional attributes of building components. The application development tool selected for this prototype system is ObjectARX. This development tool is an AutoCAD Runtime Extension programming environment that includes a number of C++ dynamic link libraries (DLLs) that enable developments of AutoCAD applications (ObjectARX, 2002). The main reason for selection of ObjectARX as a programming environment for the implementation of this work is that the set of DLLs in ObjectARX can operate directly with core AutoCAD data structures and code, thus providing suitable mechanisms for accessing AutoCAD database to extract geometric data of building components that are necessary for deducing spatial relations and generating construction sequences. Microsoft Project as a scheduling tool is used in this system to display a bar chart scheduling environment. It contains essential scheduling data (e.g. duration, start/finish time, and sequencing of a specific construction activity) and links the temporal relationships among various construction activities from start to completion of the project. Scheduling Tool MS Project User Interface 3D CAD System AutoCAD (3D geometric model) Application Development Tool Visual C++ ObjectARX Figure 1. Architecture of the Automated System 5

AUTOMATED MECHANISMS TO GENERATE CONSTRUCTION PLANNING The proposed system is developed with the emphasis on the engine that is capable of automatically generating building zones and construction sequences to be performed in a multi-story building. The generation engine basically consists of a set of mechanisms containing several functions or methods, which are designed for extracting basic building information stored in the AutoCAD database and deducing complex information needed for construction planning. In the context of this research, the complex information to be deduced includes spatial relationships among building components/zones, which then can be used to generate construction sequences. The process of the deduction can be summarized as follows. First, the mechanisms retrieve basic geometric data about vertices, edges, and faces from the 3D CAD database representing building spaces (e.g. floors) and rely on reasoning of suitable algorithms to deduce the spatial relations between the building spaces. Next, the deduced information about the spatial relations is used to assigns the repetitive floors/spaces into common building zones. Finally, the sequences of construction activities to be performed in the zones are generated on the basis of the deduced information about the spatial relationships between building components comprising the building zone that can also be automatically defined by the proposed system. For example, construction activities for a supporting component should be completed prior to those for its supported component. The functions or methods responsible for the deduction in the automated mechanisms have been developed on the basis of the logics in deduction algorithms. DEDUCTION ALGORITHMS Algorithms to deduce spatial relationships between building components that have been developed in (Nguyen and Oloufa, 2001 and Nguyen et. al. 2004) have been revised with extensions to address the generation of zones and construction sequences in multi-story buildings. In the proposed 3D CAD system, building components are represented by geometric and functional data, which can be retrieved to deduce other complex building data. In this particular work, a deduction mechanism initially extracts the basic data of a building component (e.g. column, floor) about its geometry (e.g. dimensions and location) from the 3D CAD system and then checks for conditions of spatial relationships, i.e. adjacent-to, above, below, supported-by, intersected-with, and so on among the building components. In addition, the functional data (e.g. office, lobby, parking, etc.) of a building floor can be extracted by the automated mechanisms to generate building zones each of which contain floors having the same function and configuration. Each building component is defined in the proposed system with construction activities necessary for its completion, which can be specified by the user. Therefore, once the spatial relations between building components contained in a zone have been defined, the sequence of construction activities associated with the components can be generated. 6

USER INTERFACE An interface allows the user to specify geometrical and functional data of all building components comprising a given multi-story building and to acquire the output results from the system. The interface between the user and the proposed system can be summarized as follows. First, from the AutoCAD drawing editor, the user is prompted to input geometric data and dimension (X-side, Y-side, Z-side, and location) describing the desired building components (e.g. footings, columns, beams, slabs, and so on). The AutoCAD interface provides high-level and precise mechanisms for manipulating various types of geometric data structures and high-level geometric modeling objects such as prism, cylinder, polygon, line, etc. for creating basic design objects such as columns, beams, slabs, walls and so on. These basic objects can be "assembled" to create more complex building components such as rooms, floors, or building zones. At the lowest-level data structures, the basic objects are represented as 3D solids by means of primitive representation elements such as vertices, edges, and faces whose basic information are stored in AutoCAD database. Then, new AutoCAD commands, named CheckTopo and ConstructionGenerator, that were added into the proposed system are called to deduce spatial relations and generate construction sequences. These two new AutoCAD commands are developed in the ObjectARX programming environment and are loaded into the proposed system to carry out extraction of basic data and deduction of complex building data. The CheckTopo command is responsible for deduction of topological or spatial information, whereas the ConstructionGenerator is able to generate building zones and construction sequences. Figure 2 shows the example output from the prototype system indicating the spatial relationships between components of a given multi-story building. The deduced spatial relations then can be retrieved to generate common zones of building floors with similar geometry and function as well as sequences of construction activities to be performed in these zones. Figure 2. Example Outputs from the Proposed System 7

BAR CHART SCHEDULING In the proposed system, Microsoft Project is used to display a bar chart scheduling showing sequences of construction activities from start to completion of the construction project. Visual C++ environment is the key instrument for exchanging data between the 3D CAD system to the scheduling software. Basically, it is responsible for providing a link between the 3D geometrical model and the construction scheduling data for the automated system. Once the sequence of construction activities required to complete the construction of a particular building component (e.g. floor) has been defined from the 3D CAD system, the information about the construction sequence can be transferred to Microsoft Project to develop the construction scheduling for the project. Figure 3 shows the bar chart scheduling for the given multi-story building whose information about the sequence of construction activities were obtained from the 3D CAD system. CONCLUSIONS Figure 3. The Automated System Integrating 3D CAD and Scheduling In this paper, a prototype framework for construction planning for multi-story buildings has been developed and implemented with emphasis on the automated mechanisms to deduce spatial relationships between building components and to generate construction sequences. 8

The proposed framework makes use of 3D solid modeling techniques to represent building components, whose geometrical data can be extracted to deduce spatial relations among building components/spaces. The deduced spatial information then can be used to generate construction sequences. It is noted that the information about spatial relationships between building components is one of the major factors that determines the schedule of construction activities. The context of the current work is limited to the use of spatial information to establish construction sequences Other factors such as work spaces, resource availability, and so on, that may affect construction scheduling for a constructed facility should be taken into consideration before a practical construction schedule can be achieved. In the proposed system, the mechanisms responsible for automated generation of construction sequences have been developed on the basic of the logics of appropriate algorithms that are revised from those previously developed for deducing spatial relations between building components. The potential benefits of the automated system include facilitating construction planning and management, quickly identifying the occurrence of spatial conflicts among building spaces, and enabling construction planners to develop construction sequences correctly and rapidly, thus in turn helping reduce the time and cost to complete constructed facility. REFERENCES Choi, B., and Flemming, U. (1996). Adaptation of a layout design system to a new domain: Construction site layouts. Computing in civil engineering, ASCE, New York, p. 711 717. Choo, H. Y., Tommelein, I. D., Ballard, G., and Zabelle, T. R. (1999). WorkPlan: Constraint-based database for work package scheduling. Journal of Construction Engineering and Management, ASCE, 125 (3), p. 151 160. Collier, E., and Fischer, M. (1995). Four-dimensional modeling in design and construction. Tech. Rep. 101, Center for Integrated Facility Engineering, Stanford Univ., Stanford, Calif. Eastman C. et al. (2002). Strategies for Realizing the Benefits of 3D Integrated Modeling of Buildings for the AEC Industry. Proceedings of the 19 th International Symposium on Automation and Robotics in Construction, Washington DC, p. 23-25 Fischer M. et al. (2001). Geometric Representations for Construction Planning and Scheduling, Stanford University, Center for Integrated Facility Engineering, California. Griffis, F.H. & Sturts, C. (2000). Three-Dimensional Computer Models and the Fully Integrated and Automated Project Process for the Management of Construction, Construction Industry Institute Report RR152-11 Haymaker J. et al. (2001). Perspectors: Inferring Spatial Relations from Building Product Models. Stanford University, Center for Integrated Facility Engineering, California. Hegazy, T., and Elbeltagi, E. (1999). EvoSite: Evolution-based model for site layout planning. Journal of Computing in Civil Engineering, ASCE, 13 (3), p. 198 206. McKinney, K., Fischer, M., and Kunz, J. (1998). Visualization of construction planning information. Proc., Intelligent User Interfaces, Association for Computing Machinery, New York, p. 135 138. 9

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