An Expression-Based Template Method For Steel Structure Node Design

Computer-Aided Design softwares have been widely used in construction projects in recent years.In steel structure field,polular CAD softwares can only output traditional two-dimensional drawings,and they can not supply enough information for numerical control machining period and assembling period.The thesis realizes three-dimensional visualization with the Visualization Toolkit,so it's possible to supply integrated information for the whole construction process including structure design, manufacture and assemblage.Based on the three-dimensional visualization,the thesis raises the following question. Usually CAD softwares can only supply a small proportion of all node types for auto-modelling and it takes long time to wait for the update version to supply more node types.The thesis innovates the Double Level Development Model.The first level is for the programmers to develop a template tool,and the second level is for the steel structure engineers to develop template node types with the template tool.This Double Level Development Model may bring a lot more experienced engineers in developing template node types and make node design much easier.The thesis develops a method of solid modelling based on defining variables and expressions and implements a template tool.Template node type developer is supposed to do research on the specific node type ,find out the reliant relations in dimensions or positions among the member elements of the node,and express them in the form of expressions with variables.This will enable the template tool to model the node and define the style of final effect drawings.If auto checking computations are needed for this kind of node,the developer should also compose a C language file,in which he could use the variables defined in template node.Several representative template nodes have been developed with this tool.