Research On A Common Method For The Extraction And Management Of IFC-based Bim Data

Due to the comprehensiveness of building projects,dozens of disciplines are involved in the construction and management of the urban infrastructure,public and civil buildings.The situation that a number of different software tools are used in each discipline has become common.When the building data needs to be used for business tasks,data interoperability between diverse software tools become an inevitable need.However,the difference in data formats between these tools will inevitably increase the difficulty of searching,extracting,and managing the big data from numerous buildings in the city.It is impossible to realize the information management of the smart city if the problem related to the data extraction and management of urban building projects can't be addressed.Based on the Industry Foundation Classes(IFC),a public data standard of Building Information Modeling(BIM),it is the first time that a common method to realize data interoperability throughout the building lifecycle is developed.Through the proposed method,a BIM-based partial model can be automatically extracted according to user-defined requirements,and several core problems related to the model data management have been addressed,including multi-model combination,object decomposition,and data processing of multiple interrelationships.The main work of this study is summarized as follows:(1)The IFC representation methods of building data from different disciplines.An IFC-based BIM data interoperability experiment,including architectural,structural and MEP models from a practical project,was first conducted to thoroughly analyze interoperability issues between heterogeneous software tools.The fundamental causes were analyzed deeply,and thus an improved method for BIM interoperability management based on IFC was innovatively proposed.Furthermore,the IFC representation methods and logical structures for different building information were concluded according to the results of this experiment.This work provides a reliable data basis for BIM-based extraction and management.(2)XML-based extraction of partial models from building information models.By using the mathematical logic and set theory,the selection set was firstly developed for integrating user-defined extraction requirements.Several rules for extracting the partial model were also proposed to standardize the syntactic and semantic representation of the IFC-based partial model.Furthermore,the XML schema was adopted to design the selection set-based generic language for extracting BIM-based partial models.The mapping from extraction requirements to IFC data and the corresponding partial model extraction algorithm were implemented by C++ programming language.Through this method,the partial model extraction at the object,attribute,and relation levels can be fully addressed.The proposed extraction method can lay the foundation for the search and extraction of big data from smart city building projects.(3)Management of object information based on IFC instances.This study focused on some core problems related to building information management,including multi-model combination,object decomposition,and object attribute processing.It is beneficial to improve the standardized management of smart city building projects based on BIM technology.According to the inconsistent problems related to spatial structure and corresponding measurement units,the combination algorithm of multiple IFC models was developed under the consistent spatial structure;Through an analysis of geometric features of building objects,different objects can be automatically decomposed according to user-defined rules;The object attributes were represented with different interrelationships,so the method to process these attributes was proposed to deal with multiple interrelationships.(4)Case study.The proposed method has been applied to several practical projects for the extraction and management of BIM data.The results demonstrated the feasibility and validity of the proposed method.