| Nowadays,the informatization level of China's construction industry needs to be improved,BIM Technology meets this need,however,BIM forward design has a long way to go,most of the applications are still in the stage of transfor 2D design results into BIM models,that's not a good way to use computer,and there are few cases where BIM can really add value to the project,in someway BIM increases the burden of design,On the other side,with the innovation of design and the requirement of aesthetics,the structures became more and more complex and irregular,clear the logic behind the structures are important,that's way we need Parametric design,and bridge engineering has its particularity in this application,so,how to start from the source of design,introducing forward design into design workflow has become the key to bridge BIM life cycle application.This paper has done the following works:(1)This paper summarizes the characteristics of BIM in Bridge Engineering,and the main application of BIM in different design stages is summarized combined with typical cases.The mode and main obstacle of BIM application in design industry are analyzed.And introduced the example of automatic pile placement and parameter driven variable section box girder with Revit and dynamo.It reflects the fact that BIM core modeling software,which emphasizes model refinement too much,is not competent for preliminary conceptual design.(2)The definition,advantages and application levels of parametric design are introduced,through a typical case,this paper explains the idea of generative design using rhino+grasshopper platform,combined with the characteristics of Bridge Engineering,realizing terrain analysis,road selection and road centerline fitting,intelligent model and data extraction in parametric way.For arch bridge,truss bridge,cable-stayed bridge and suspension bridge,GH programs are given,and the result meet the requirements when the parameters are debugged.(3)The forward design framework of “PD+FEA+BIM”is given,this paper also explains the relationship between BIM and PD and the necessity of their combination,The idea of model reconstruction based on parameterized skeleton line is introduced.GH calculator is developed for different types of components,which can automatically find the position of variable cross-section to generate cross-section,and automatically segment the special-shaped components.At the same time,GH algorithm and ghpython are used to extract the computing information(nodes,cells and sections)of parameterized model.And integrated into Midas beam element model for structural overall mechanical analysis.The complex shaped components is cleaned up and exported to INP file for ABAQUS solid element analysis.(4)Take an asymmetric camber arch bridge as an example,from the beginning of design,the constraints of design are quantified as the parameters that affect the design,and the GH algorithm is used to generate shapes in the process of body creation,a flexible and adjustable preliminary design model is obtained,the rapid interaction with Midas and the docking with BIM information platform have been successfully realized.It shows the feasibility and efficiency of forward design workflow based on parameterization and BIM. |
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