APPLICATION OF DEVS FRAMEWORK IN CONSTRUCTION SIMULATION

The Discrete Event Systems Specification (DEVS) framework is based on systems engineering principles and is used for modeling and simulation in many application domains. This framework supports a number of important features such as component based hierarchical simulation model development, scalability, reusability and distributed simulation. This paper demonstrates the application of the DEVS framework for construction simulation through a simple, but representative real world application. The application focuses on analyzing the work flow between various trade contractors in production home building. The software tool ‘DEVSJAVA’ is used for modeling and simulation of the construction application. DEVSJAVA is object oriented; it implements the DEVS framework using Java programming language. This paper consists of three main components: (i) current overview of the state-of-theart in construction simulation methods and tools; (ii) introduction to the DEVS framework; and (iii) detailed construction example to highlight the application of DEVS framework. 1 CONSTRUCTION SIMULATION Construction operations involve a number of repetitive tasks similar to manufacturing operations, for example, earth hauling, tunneling, road construction, and glass installation on tall buildings [Abourizk et al 1992]. This demonstrates the potential to apply discrete event simulation techniques (especially process and resource based simulation) for modeling and analysis of construction operations. The history of construction simulation dates back to 1960’s with the development of simple networking concepts [Abourizk et al 1992]. These networking concepts were used as a modeling framework to study construction operations. As a first attempt, “link-node” model was developed and used to assist selection of construction equipment [Teicholz 1963]. After this, the CYCLONE (Cyclic Operations Network) modeling framework was developed by Halpin [1977]. CYCLONE consists of five basic modeling elements such as ‘normal’, ‘combi’, ‘queue’, ‘function’ and ‘counter’. The functionality of each modeling element is documented in the literature [Halpin 1977, Abourizk et al 1992]. This was followed by the development of a software tool using micro computer called MicroCYCLONE [Lluch and Halpin 1982]. The application of CYCLONE to model and analyze a number of construction scenarios is described in detail by Halpin and Riggs (1992). CYCLONE modeling framework provided the foundation for many construction researchers to develop a number of construction simulation tools in the past 20 years. This includes the development of (i) INSIGHT system based on CYCLONE with interactive user interface [Paulson 1987]; (ii) CYCLONE with advanced resource handling capabilities called RESQUE [Chang and Carr 1986]; and (iii) UM-CYCLONE with menu driven user interface [Ioannou 1990]. A discrete event simulation system with object oriented design concepts called ‘COOPS’ (Construction Object-oriented Process Simulation System) was developed [Liu and Ioannou 1992]. Further, CIPROS, an objectoriented system for simulating construction plans was developed [Odeh et al 1992]. A simulation programming language, called STROBOSCOPE, (State and Resource based Simulation of Construction Operations), was designed and developed to specifically model and simulate construction operations [Martinez and Ioannou 1994]. STROBOSCOPE is based on three phase activity scanning approach. A detailed discussion of the three simulation strategies namely process interaction, activity scanning and event scheduling is provided by Martinez and Ioannou [1999]. The application of hierarchical simulation modeling (HSM) method in construction simulation was demonstrated through a bridge project [Sawhney and Abourizk 1995]. Though a number of construction simulation tools were developed following the CYCLONE methodology, their use was mostly limited to academic and research community [Abourizk and Hajjar 1998]. This is primarily APPLICATION OF DEVS FRAMEWORK IN CONSTRUCTION SIMULATION Sivakumar Palaniappan Anil Sawhney Del E. Webb School of Construction Ira A. Fulton School of Engineering Arizona State University Tempe, AZ 85287-0204, U.S.A. Hessam S. Sarjoughian Arizona Center for Integrative Modeling & Simulation Dept. of Computer Science and Engineering Ira A. Fulton School of Engineering Arizona State University Tempe, AZ 85281-8809, U.S.A. Palaniappan, Sawhney, and Sarjoughian attributed to the significant differences between the simulation model representation and the real world construction system. This made the process of developing and understanding the simulation model more tedious for construction experts who have limited amount of time to apply simulation in construction. To overcome this difficulty, the concept of special purpose simulation (SPS) was introduced as an application framework for developing construction simulation tools [Hajjar and Abourizk 2000]. SPS is based on object-oriented application framework and the constructs of SPS tools are similar to the objects of real world system. Three independent customized simulation tools were developed based on the SPS concept [Hajjar and Abourizk 2002]. They are (i) ‘AP2-Earth’ for the analysis of large earth moving projects (ii) ‘CRUISER’ for modeling aggregate production plants and (iii) ‘CSD’ for construction site dewatering. The use of the above tools by large construction companies demonstrated the success of SPS based simulation tools. Based on the experience gained through the development of SPS based simulation tools, a unified modeling methodology for construction simulation was proposed [Hajjar and Abourizk 2002]. This approach resulted in the development of a simulation tool development and utilization environment called ‘Simphony’. Simphony is an integrated environment for construction simulation. The development time for new SPS tools was reduced significantly due to the construction simulation object library provided within the Simphony framework. To understand the important features of Simphony, the reader can refer to Abourizk and Mohamed (2000). In an effort to extend the field of construction simulation, the authors undertook this experimentation with DEVSJAVA. The objective of this work is to demonstrate the application of DEVSJAVA in construction simulation through an example problem in production home building. The remaining content in the paper is organized as follows: The next section presents an introduction to the DEVS framework. The third section presents background information about production home building and the details of the example problem. The simulation model development using DEVSJAVA is described in the fourth section. A discussion on the simulation results is presented in the fifth section. Finally the sixth section presents conclusions based on the simulation results and the contribution of this work.