Experiences using building information modeling for a construction ...

icccbe 2010

© Nottingham University Press Proceedings of the International Conference on  Computing in Civil and Building Engineering  W Tizani (Editor)

Experiences using building information modeling for a construction project M. H. Tsai, C. H. Wu, A. Matin Md, S. L. Fan, S. C. Kang & S. H. Hsieh National Taiwan University, Taipei, Taiwan

Abstract Many researchers have found that Building Information Modeling (BIM) can facilitate various aspects of construction management, especially in the communication between and coordination of resources. Such management tools can also increase the likelihood of identifying problems prior to actual construction and thus avoid costly re-work. Although the advantages of BIM are generally recognized, the effort required and possible problems engineers may encounter when using BIM tools still need further investigation. In this research, we observed an actual project, a nine-floor office building with one basement level, and recorded the steps taken during the process of creating a BIM model. We recorded the time taken to create a BIM model from existing 2D drawings using Autodesk Revit Architecture, a BIM software application. We also recorded the time taken to link the schedule (built on MS-Project) with the BI model. The results provide decision-makers and construction professionals with an estimation of the time cost and human resource requirements involved in using BIM tools to build 3D/4D BIM models. The study also provides potential users with a better understanding of how BIM tools are applied in construction projects. Keywords: building information modeling, 4D simulation, construction management

1 Introduction Miscommunication of project information is a prevailing factor in two-thirds of problems arising in the construction industry (Dawood et al. 2002). It has become widely accepted in the construction industry that current processes and delivery methods incur approximately 30 percent wastage. Davis (2007) noted that the construction industry suffered a 20 percent decline in productivity in comparison to other industries. Furthermore, an NIST study attributed a yearly loss of $15.8 billion dollars to a lack of information sharing and process continuity (Gallaher et al. 2004). The majority of current planning processes in the construction industry continue to be based on 2D drawings (Azhar et al., 2008). Under current practices, managers search 2D drawings for a component’s dimensional details and then construction documents to obtain other data regarding the building component. The process is often time consuming, inaccurate, and not very useful (Goedert and Meadati, 2008). For this reason, it is important to find a BIM tool that can be fully utilized throughout the life cycle of the construction project. This will achieve significant improvements in terms of quality and efficiency within the physical tasks of the project. BIM has recently received widespread attention in the architectural, engineering and construction (AEC) industries (Azhar et al. 2008; Roorda and Liu 2008). Due to societal needs, business drivers,

and converging technologies, BIM is becoming an inevitable method of delivery and management in the built environment. Over the last few years, an increasingly significant amount of marketing and media attention has surrounded Building Information Modeling. Research efforts have demonstrated that BIM and 4D approaches provide a faster and more effective way of communicating information between concerned project parties. Among the many benefits that result from this, they facilitate superior designs which enable improved and innovative solutions (Staub-French et al. 2008; Manning and Messner, 2008). Numerous case studies have showed that the use of BIM resulted in time and cost savings by anticipating possible construction conflicts, improving cost estimation, and elimination of rework (Ku et al. 2008; Koo and Fischer 2000; Hartmann et al. 2008). Four-dimensional visualization technology offers another means to facilitate coordination in building projects. The technology has been most prominently used to assist in the 4D planning and scheduling process within the construction and project management framework. Essentially, it is a process that binds 3D models with their corresponding construction work schedule. The usage of this type of 4D visualization technology has emerged rapidly (Hsieh et al., 2006) in the past decade, mainly due to increased awareness of the benefits of 4D CAD applications (Mckinney and Fischer, 1998; Kam et al., 2003; Ma et al., 2005; Dawood et al., 2005). The benefits of using 4D-modeling techniques over traditional tools are well described in several of the abovementioned papers; key benefits include increased productivity, improved project coordination, and optimized on-site resource utilization. Some of the research presents solutions for creating time schedules and 4D simulations based on data stored in the BIM model (Staub-French et al. 2008; Tulke and Hanff 2007). However, the literature suggests, the key to success is to change business workflow, rather than simply applying the technology (Smith 2007; Hartmann and Fischer 2009). For a construction manager accustomed to 2D drawings, completely redesigning a project using 3D modeling software is likely to be an overwhelming task. A more practical method would be to construct the 3D/4D BIM models by extracting data from existing 2D drawings (Fan et al. 2009). However, the extensive time required to construct 3D/4D BIM models from 2D drawings is still a major drawback and is a key reason to why constructors struggle to apply 3D/4D model technology. This study focuses on providing contractors with useful empirical data for applying BIM technology in building projects. The broader purpose of this research is to advance the use of building information modeling in construction projects and to create a single repository of data for the users. Herein, we first use a case study to quantify the labor and time needed for constructing 3D/4D BIM models from 2D drawings and paper-based documents. We then suggest how to streamline the use of BIM tools based on our experiences.

2 Case study: application of the workflow 2.1 The Project The case study focuses on a typical research building in National Taiwan University (Figure 1). The project is a precast reinforced concrete construction building possessing a seismic isolation system at the mid-storey. The building consists of an underground parking basement and nine floors with a total height of approximately 41.4 m and a total floor space of 9686.44 m². The construction period was six months. The BIM model of the building has a total of 4163 elements.

Figure 1. Case study research building in National Taiwan University

2.2 Implementation In this study, there were two stages involved: transposing 2D drawings to a 3D model, and establishing the 4D model. Section 2.3 describes how a 3D model was created from existing 2D drawings using BIM software. Section 2.4 illustrates how a construction schedule was created from a paper-based schedule. The duration of each activity and the relationships between activities are also provided. The implementation was conducted by two graduate students, an undergraduate student of the Computer-Aided Engineering Group at National Taiwan University, and an undergraduate studying construction management at Tamkang University in Taiwan.

2.3 Transposing the 2D Drawings into a 3D Model A 3D model was created from existing 2D drawings using the BIM software, Revit Architecture. The method of transposing the 2D drawings consisted of the following four steps (Figure 2): Step1. Setting up the grid and level. Step2. Inputting each layout plan to its corresponding level. Step3. Building the 3D model with Revit built-in elements and customized elements. Step4. Modifying the 3D model.

Figure 2. The steps for transposing the 2D drawings into a 3D model

2.4 Establishing the 4D model A construction schedule was created using MS-Project from a paper-based schedule. The schedule provided activity durations and the relationships between activities. The schedule data and the 3D model were exported separately to Autodesk NavisWorks, a 4D simulation package. This was followed by the linking of 3D objects in the model to the activities in the time schedule, both automatically and manually. The method of establishing the 4D model consisted of the following steps (Figure 3): Step1. Exporting the 3D model from Revit to NavisWorks. Step2. Exporting the schedule from MS-Project to NavisWorks. Step3. Linking 3D objects in the model to activities in the time schedule. Step4. Checking the relationship between 3D objects and the schedule.

Figure 3. The steps for establishing the 4D model

3 Case study: time taken in transposing 2D drawings to a 4D model 3.1 Times Taken In this study, 230 labor-hours were spent to build a 4163-element BIM model. The hours were broken down into the following stages: (1) training, (2) transposing 2D information into the 3D model, and (3) establishing the 4D model. Table 1, shows how the hours were distributed across the stages. Following, is a detailed description of each stage. (1) Training: this stage required 54 hours, consisting of 10 hours of Revit and 8 hours of NavisWorks training each week. The students underwent three weeks of training. (2) Transposing 2D information into the 3D model: this stage required 156 hours, distributed across four steps: setting up the grid and levels, inputting each layout plan to each level, building the 3D model with Revit built-in elements and customized elements, and modifying the 3D model. In building the 3D model, 3973 Revit built-in elements were used, each element required approximately 2 minutes, resulting in a total time of 126 hours spent to apply the Revit built-in elements. We then applied customized elements to the 3D model, customizing each element took 2 hours on average. A total of 30 hours was spent applying customized elements.

(3) Establishing the 4D model: this stage required 20 hours, consisting of four steps: exporting the 3D model from Revit to NavisWorks, exporting the schedule from MS-Project to NavisWorks, linking 3D objects in the model to activities in the time schedule, and checking the relationship between 3D objects and the schedule. The results given in Figure 4 indicate that the process of converting the 2D information into the 3D model takes significantly longer than the process of establishing the 4D model. As part of this study, we analyzed the time taken for each activity and provided suggestions for more effective utilization of BIM tools. In addition, we were able to outline the resources needed for setting up a BIM tool. A summary of these findings and recommendations is presented in the following section.

Table 1. Time taken in transposing 2D drawings to a 4D model

Stages

Time Taken (labor-hours) (1) Training 54 • Personnel training over three weeks 54 (2) Transposing 2D information into the 3D model 156 • Setting up the grid and levels 1 • Inputting each floor layout to each level 0.5 • Building the 3D model with Revit built-in elements and 147 customized elements • Modifying the 3D model 7.5 (3) Establishing the 4D model 20 • Exporting the 3D model from Revit to NavisWorks 5 • Exporting the schedule from MS-Project to NavisWorks 4 • Linking 3D objects to the activities in the time schedule 1 • Checking the relationship between 3D objects and the schedule 10 Total 230

Figure 4. Breakdown of times taken in different stages of transposing 2D drawings to a 4D Model

3.2 Recommendations 3.2.1 Maintain a Systematic Drawing Numbering System It is recommended that participants adopt a consistent and systematic numbering system for all drawings. A practical method would be to adopt a 5-digit system, where the first digit refers to the type of the drawing, and other four digits refer to the specific location ID. This is preferable over naming the drawings according to their locations, in order to minimize the time required to transpose 2D information into the 3D model. 3.2.2 Develop a BIM Element Library As explained earlier, applying customized element is very time-consuming, requiring on average two hours of labor time compared to two minutes for each built-in element. Therefore, it is recommended that developers store the custom elements built in each project, so they are readily available for future projects. Such a BIM-element library would effectively reduce the time spent building customized elements. 3.2.3 Information Sharing In establishing the 4D model, without information sharing, the names of the elements and the names of activities in the schedule would not be identical. Therefore, it is recommended that the personnel establishing the construction of the 3D model consult with the scheduler before building the model to set up consistent naming of activities/stages. By doing this the automatic linking function provided by the 4D software can be used effectively when synthesizing the model and schedule data.

4 Conclusions This research presented a case study on constructing a 3D/4D BIM model from 2D drawings and paper-based documents. The construction of a typical nine-floor building was observed. The time taken in constructing the 3D/4D BIM model and the steps involved in using the BIM tools were recorded. Two hundred and thirty hours of labor was required to construct a 4163-element 4D model for the nine-story building studied. The results of the study provide contractors with useful empirical data for estimating the time needed to construct a 3D/4D model from 2D drawings and paper-based documents; it also provides constructors with recommendations that became apparent in the study.

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