Keywords: virtual reality, 4D CAD, planning and scheduling, construction projects, coding system, structure steel, installation.

The current process for steel structure construction is divided into the following work packages: drawing design, detailing, estimating and cost analysis, prefabrication design, fabrication, delivery, and site erecting. It requires a lot of time, money and effort to design and build steel-structure projects. Simulation models are created to minimize the mistakes that usually happen on construction jobsites [1]. Those include three-dimensional (3D) or even four-dimensional (4D) visualization models. In this research, the authors propose to create a model that utilizes advanced virtual reality techniques with 4D graphic presentation to assist steel structure installation. The proposed model will ease the effort of installing steel structure on the jobsite and help solve some very complicated steel structure installation problems. The following are the research questions to be resolved:

1. The conversion of 2D drawings into a 3D model. Then add a 4th dimension (which is time).
2. The development of a 4D Virtual Reality (VR) model to fit job site conditions.
3. The real time incorporation of any adjustment or changes in a walk-through VR model.

One problem with 3D Virtual Reality is that it simulates a real world image as "walk-through", but in a time-stopped world. When a person stands in the virtual world generated by a 3D-VR model, what they can see is how the virtual world changes in relative to where they are standing. The virtual world itself does not change its shape or feature. But real world changes continuously. This real-world change should be reflected in the virtual world, but it is ignored in a 3D VR model. 4D Virtual Reality (4D VR) models can resolve this problem. A 4D VR model has more functions than 3D VR model in simulating job schedules and processes. In scheduling, the steel structure is a long-leading item and may cause a project delay if not scheduled properly. In this proposed 4D VR model, the steel structure is the major implementation.

Researchers have already started discussing implementations of using Virtual Reality systems in construction planning and management [2]. Most programs do not systematically go through every construction process [3,4]. 4D-visualization can help with planning and scheduling. But no software or program of 4D-visualization focuses on structure steel fabrication and erection [5,6,7,8]. In this research, a 4D-based Virtual Reality model will be developed for the steel erection process which has the potential to be extended to other construction processes.

The proposed system uses serial numbers to distinguish steel parts. A hand-held scanner may be introduced into the proposed model. It will communicate the content of radio frequency identification chips to different computer systems and to the scheduling software. By checking the data from the scanner, people can find out whether a task has already been done or is still ongoing. This serial-code system is different from bar-code system. It is not just a tracking code; it is part of the proposed real-time 4D-VR system. It has a broader site management perspective, aiming to deal with not only day-to-day but also item-to-item activities. This method can be used for all steel parts, including plates and bolts. The 4D VR system will show whether a piece of steel has been installed or not by using a colour code scheme.

The program is based on a multi-purpose model, which uses a steel series-code and a colour-code system to differentiate steel pieces, to help control the schedule of a project, and to describe the entire scope of construction. It relies on a 4D graphic scheduling and a VR environment to display real-time steel erection information. It helps with planning jobs, verifying erection information, controlling job schedules, site inspection, and other field related jobs.

1

K. Chau, M. Anson, J. Zhang, "Implementation of visualization as planning and scheduling tool in construction", Building and Environment, 38, 713-719. 2003. doi:10.1016/S0360-1323(02)00239-1

2

N. Dawood, E. Sriprasert, Z. Mallasi, B. Hobbs, "Development of an integrated information resource base for 4D/VR construction process simulation", Automation in Construction, 12, 123-131, 2002. doi:10.1016/S0926-5805(02)00045-6

3

CommonPoint, "Common Point Project 4D", http://www.commonpointinc.com/, 2006.

4

K. McKinney, M. Fischer, "Generating, evaluating and visualizing construction schedules with 4D-CAD tools", Automation in Construction, 7(6), 433-447, 1998. doi:10.1016/S0926-5805(98)00053-3

5

A. Crowley, A. Watson, "CIMsteel Integration Standards Release 2", the Steel Construction Institute. http://www.cis2.org/, 2000.

6

CAE Group, "CAE Group: The Eureka CIMsteel Project", http://www.cae.civil.leeds.ac.uk/past/cimsteel/cimsteel.htm, 2006.

7

AISC, "Electronic Data Interchange (EDI) of Structural Steel Data via CIMsteel Integration Standards, release 2", American Institute of Steel Construction, Inc. http://www.aisc.org/edi.html, 2002.

8

A. Ames, D. Nadeau, J. Moreland, "VRML 2.0 Sourcebook", 2nd edition, John Wiley & Sons, Inc., New York, NY, USA, 1997.

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