Keywords: product model, bridge, prestressed concrete, hollow slab, IFC, IAI, ifcXML, XML, integration.

For a number of years, research and development on product models have been carried out in order to enable the interoperability of various application systems in a lifecycle of products and structures. Various standards and specifications for product models have been proposed. They include the Product Data Exchange Standard (PDES), International Organization for Standardization (ISO) 10303 known as STEP (Standards for The Exchange of Product model data), Industry Foundation Classes (IFC) of International Alliance for Interoperability (IAI), etc. We developed our product models for steel frames, penstocks, and prestressed concrete hollow slab bridges, and implemented them using eXtensible Markup Language (XML) to demonstrate the efficiency improvement by achieving the interoperability among application systems including 3D-CAD, code checking, quantity calculation, cost estimation, scheduling, and inspection for operation and maintenance [1]. However, the modelling approach employed then was a classical one that each class contains its all attributes inside of the class but not having its property classes outside.

Since a standard modelling methodology has not been established yet, different methods and approaches have been employed by various organizations for their objectives. Furthermore, there are various XML schemata and other languages for implementing product models. Therefore, we believe that it is important to develop a standard approach for both modelling and implementation for future development of product models for various products and structures.

Although research and development of product models for buildings have been done quite extensively, not so much outcome has been seen for developing standardised product models for civil engineering structures such as bridges, dams, harbours, etc. IAI has just started developing IfcBridge, which is based on IFC. However, more work and research will be needed to establish an international standard.

In this research, we selected IFC as a base for developing a product model for bridges. This paper presents the concept, application, and integration of the product model for reinforced and prestressed concrete hollow slab bridges.

Concrete members in bridges have more geometric freedom than typical building concrete members such as beams, columns, walls, and slabs. Moreover, concrete members contain rebars, voids, sheaths, etc. Thus, we represented a concrete member as a simple solid model comprised of a set of surfaces having a property of inside or outside of the member in our product model. In addition, contained members clearly indicate that they are "contained" in the concrete member.

In our product model, each rebar is represented as an object. The geometry of a rebar can be represented by extruding a circle to a direction expressed in a vector or revolving the circle in a curve, as IfcExtrudedAreaSolid or IfcRevolvedAreaSolid, respectively.

The ifcXML was selected to implement the developed product model after comparing with other XMLs. The authors implemented the schema of the product model and an instance of a prestressed concrete hollow slab bridge using ifcXML. Three application systems, i.e., a 3D-CAD system, PC bridge structural design system, and a rebar cover checking system, were integrated by the product model. The application test case showed the feasibility and practicality of the product model.

1

N. Yabuki and M. Furukawa, "An Integrated Design and Project Management System for Prestressed Concrete Hollow Slab Bridges", Proceedings of the Ninth International Conference on Computing in Civil and Building Engineering, Taipei, Taiwan, pp.1207-1212, 2002.

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