Research On Expert System For Rapid Modeling Of Beam Bridge Based On BIM

It has become the future trend of bridge maintenance industry that changing the way of bridge disease detection recording method from traditional way to digital way.However,the realization of 3D visualization of bridges is the basis of completing the digital recording of bridge disease detection;Moreover,girder bridges account for about 70%of the total number of expressway bridges,and girder bridges' structures are more standardized.Therefore,in this thesis,it can use expert knowledge and expert system to realize the rapid modeling of girder bridge;In addition,the application of BIM technology in bridge industry has become the development trend of bridge industry.Based on the above industry background and technical prerequisites,this paper proposes an expert system method for rapid modeling of beam bridge based on BIM.This method designs knowledge library and reasoning mechanism and realizes the rapid modeling of bridge and component family library by combining bridge expert knowledge and experience.The specific research contents are as follows:Firstly,BIM concept,expert system theory,bridge structure knowledge and general modeling process of bridge and components are studied.On this basis,an expert system for rapid bridge modeling is proposed;Secondly,combining the accuracy,hierarchy and coupling characteristics of bridge structure knowledge,choosing production rules combined with formula expression as a way of knowledge expression.According to the characteristics of knowledge,the types of knowledge library(BIM component family knowledge library,component structure parameter library,model splicing library and model drawing library)are divided,and the data storage structure of knowledge base is classified and designed;Then,the top-down reasoning method is used to complete the modeling of bridge component family library and the reasoning process design of bridge modeling,the core contents of these two reasoning processes include component structure parameter library reasoning and model rendering library reasoning,in this process,a formula analyzer is designed for the analysis and calculation of formula expressions;Subsequently,the parametric modeling of the bridge basic components is completed by using the boundary representation method,and the component family library and the bridge model are drawn by using the matching algorithm.Then,the model and scene visualization are completed by using OSG three-dimensional graphics engine.Finally,a three-tier structure is adopted to design and develop the expert system for bridge rapid modeling,which realizes the functions of component modeling,full bridge rapid modeling and knowledge base editing.Based on the developed expert system in this paper,the feasibility and accuracy of the method are verified by comparing the results of the modeling with those given by the experts through the Intuitive display of the 3D model and the side reflection of the structural parameters.Moreover,this method improves the flexibility and extensibility of parametric modeling,and can meet the needs of rapid modeling of 3D model of beam bridge.