Industry Foundation Classes Based Integration of Architectural Design and Structural Analysis

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.

基于ADE的IFC到CityGML层次转换模型

新型城市化建设和管理过程中,借助建筑信息模型(building information modeling,BIM)与地理信息系统(geographic information system,GIS)的数据集成,不但能实现建筑物的精细化表达,而且室外信息得以兼顾,实现空间分析及室内外一体化表达。但BIM与GIS两种不同的数据格式无法直接实现数据的互通。为此,首先分析了模型IFC和CityGML在文档形式等方面的差异,并实现了多个简单建筑物IFC模型到CityGML3.0 LOD2、LOD3的转换。其次,针对上述数据集成实验中语义丢失问题,扩展GIS的CityGML3.0数据格式,提出CityGML B-Con扩展模型,完善IFC到CityGML3.0的一对一映射关系。最后,实现多个不同复杂程度建筑物IFC模型到CityGML B-Con扩展模型的转换。实验结果表明,利用CityGML B-Con模型能实现BIM与GIS的数据集成。宏观层面来说,能够增强转换后建筑物外观的细节程度,微观层面而言,BuildingConstructiveElement和BuildingInstallation的子类得以区分,IfcStair、IfcRamp和IfcBeam等建筑构件都能通过一对一映射的方式转换至CityGML中,克服了CityGML原有标准在建筑物构件表达方面的缺陷,有效减少了BIM源数据语义信息的丢失。

Dynamically loading IFC models on a web browser based on spatial semantic partitioning

Industry foundation classes(IFC)is an open and neutral data format specification for building information modeling(BIM)that plays a crucial role in facilitating interoperability.With increases in web-based BIM applications,there is an urgent need for fast loading large IFC models on a web browser.However,the task of fully loading large IFC models typically consumes a large amount of memory of a web browser or even crashes the browser,and this significantly limits further BIM applications.In order to address the issue,a method is proposed for dynamically loading IFC models based on spatial semantic partitioning(SSP).First,the spatial semantic structure of an input IFC model is partitioned via the extraction of story information and establishing a component space index table on the server.Subsequently,based on user interaction,only the model data that a user is interested in is transmitted,loaded,and displayed on the client.The presented method is implemented via Web Graphics Library,and this enables large IFC models to be fast loaded on the web browser without requiring any plug-ins.When compared with conventional methods that load all IFC model data for display purposes,the proposed method significantly reduces memory consumption in a web browser,thereby allowing the loading of large IFC models.When compared with the existing method of spatial partitioning for 3D data,the proposed SSP entirely uses semantic information in the IFC file itself,and thereby provides a better interactive experience for users.

NIBU: a new approach to representing and analysing interior utility networks within 3D geo-information systems

Facility management departments’responsibilities include monitoring and maintenance of building infrastructure,such as water,gas or electricity.Very often these tasks are completed using paper maps,which make integrated analysis of networks challenging.Ability to consider interior network structure and provide semantic and connectivity information supporting the required analysis operations are thus crucial.This paper presents an approach relying on Building Information Model(BIM)as a data source for obtaining information about interior utilities.The semantic and connectivity information of BIM is mapped onto a new model called Network for Interior Building Utilities(NIBU).NIBU is based on the semantic categorisation of utilities,and the spatial functions that have to be performed.Three scenarios(‘maintenance operation’,‘emergency response’and‘inspection operation’)are developed to test the proposed approach.The model and its functions are implemented in spatial DBMS.The model is populated directly from a BIM server applying an Industrial Foundation Class(IFC)parser developed in-house.Five analysis functions are implemented to support spatial operations:trace upstream,trace downstream,find ancestors,find source and find disconnected.The investigation proves that BIM provides both the required semantics and attributes,and connectivity information that can facilitate analysis of interior utility networks.NIBU provides a simple yet flexible way to manage interior network information,which can be integrated into Digital Earth.