Traditionally, the one-to-one interaction between heterogeneous software has become the most commonly used method for multi-disciplinary collaboration in building projects, resulting in numerous data interfaces, different data formats, and inefficient collaboration. As the prevalence of Building Information Modeling (BIM) increases in building projects, it is expected that the exchange of Industry Foundation Classes (IFC)-based data can smoothly take place between heterogeneous BIM software. However, interoperability issues frequently occur during bidirectional data exchanges using IFC. Hence, a data interoperability experiment, including architectural, structural and MEP models from a practical project, was conducted to analyze these issues in the process of data import and re-export between heterogeneous software. According to the results, the fundamental causes of interoperability issues can be concluded as follows: (a) software tools cannot well interpret several objects belonging to other disciplines due to the difference in domain knowledge; (b) software tools have diverse methods to represent the same geometry, properties and relations, leading to inconsistent model data. Furthermore, this paper presents a suggested method for improving the existing bidirectional data sharing and exchange: BIM software tools export models using IFC format, and these IFC models are imported into a common IFC-based BIM platform for data interoperability.

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SUMMARYUsing the concept of lumped masses and rigid #oor slabs, several mathematical models were built using a popular PC-based "nite element program to model a tall building with a frame-core wall structural system. These models were analysed to obtain the "rst nine mode shapes and their natural frequencies which were compared with those from "eld measurements, using numerical correlation indicators. The comparison shows several factors that can have a signi"cant e!ect on the analysis results. Firstly, outriggers connecting the outer framed tube system to the inner core walled tube system have a signi"cant e!ect on fundamental translational mode behaviour. Secondly, detailed modelling of the core considering major and minor openings as well as internal thin walls has the strongest in#uence on torsional behaviour, whose measurements were shown to be an important aspect of the dynamic behaviour for the structure studied. Fine tuning of an analytical model requires not just considering variation in values of structural parameters but also attention to "ne detail.

The numerous construction projects in China provide the best environment for the development of information technology applied in building design. Various commercial CAD/CAE software applications are purchased by design firms for multi-disciplinary design tasks. However, researches on integration and interoperability are seldom considered. This study pursues a breakthrough point of integration in the architectural and structural domains and expects further development in other aspects. A central building information modeling (BIM) framework based on the industry foundation classes (IFC) is proposed to handle the data exchange between IFC-compatible architectural models and structural models. A central XML(extensible markup language)-based unified finite element model (FEM) is proposed for model conversion among various commercial structural CAE software applications. In addition to bidirectional data interfaces among IFC-based BIM, XML-based FEM and various commercial FEMs, some other components such as visualization, calculation and model editing/check are also equipped into the prototype system. Key words: integration, industry foundation classes (IFC), building information modeling (BIM) CLC number: TU 201.4 Document code: A IntroductionAs the increasing building projects in China bring development of information technology utilized in the construction industry, the competition among various commercial CAD/CAE software applications becomes rigorous. Although based on a common architectural model, model data from multi-disciplinary programs lack direct information exchange with each other under a unified data exchange standard. This becomes a bottleneck of improving design efficiency among multidisciplines in the architecture, engineering, construction and facility management (AEC/FM) domains [1] . Integration and interoperability are gaining in importance in recent decades. However, due to integration scope (e.g., CIFE [2] ), data exchange standard, breakthrough strategies, etc., little success for the research on the integrated building design system (IBDS) has been achieved both domestically and internationally.A lot of efforts are directed towards the building information modeling (BIM) solution concept, where an object-oriented central model is used for exchanging information by electronic means among software applications. Then, n-dimensional model is an extension of BIM by incorporating all the design information required at each stage of the lifecycle of a building project. Recent research on the applications of BIM or n-dimensional model includes Refs. [3][4][5].As a data exchange standard of product models, standard for the exchange of product (STEP) model data [6] is developed and maintained by the ISO technical committee (TC184/SC4) and is now mostly focused on industries other than building construction. Industry foundation classes (IFC) [7] is the successor of STEP and is oriented toward the construction industry. In the IFC platform, objects are assembled in BIM to define the building representat...

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