Research On 3D Visual-aided Design System Of Trapezoidal Steel Roof Truss

The steel roof truss, one of the most common load-bearing structure types at the top of the building, has the following advantages:easy construction, excellent mechanical properties, flexible structural arrangement, etc. Thus, it is widely used in various large-span buildings. At present, the 2D-based CAD software is mainly used to complete the roof trusses design, so that designers’ work efficiency has been significantly improved. But the 2D-based CAD software is difficult to meet the needs of practical engineering and design staff, because the joints structure and the bar members’spatial relationship are complicated. Therefore, designers often need to continuously modify the design results. However, through the 3D model people can preview and comparison design results by a more intuitive and comprehensive approach. Therefore, research and development of 3D steel roof visual-aided design system has become a hot research and development direction of structural engineering.In this paper, a steel roof 3D visualization-aided design system for trapezoidal steel roof has designed and developed. The development of this system was combine with Object-oriented programming technology and OpenGL graphics standard technology, use the Visual C++6.0 visual programming system as development platform and the current design codes and design manuals as basis. The main contents and achievements are as follows:(1) Studied on the interface program design of ANSYS and written truss finite element calculation program, then realized calculation of the truss member forces and the nodal displacements.(2) Tack the code, hot-rolled steel (GB/T 706-2008) as basis and fitted the arc segment of angle steels with third-order Bezier curves and surfaces, then achieve the establishment of bar members’ realistic 3D model.(3) Applied matrix stack technology to build the 3D model of the overall structure of the roof truss.(4) Design and implementation of the system. The system has three modules:parametric design module, structural analysis and member design module and visualization module of design results. Their main function is as follows:1) Parametric design module:includes design parameters determination, load calculations and material selection. 2) Structural analysis and member design module:achieve the structural finite element analysis, bar members design and joints design.3) Visualization module:the OpenGL graphics standard technology was be taken to achieve the establishment of bar members’3D model, joints’ 3D model and the whole model of steel roof structure, as well as realized the roaming browse function to the models.Example shows that the system is convenient and efficient computing, human-computer interaction and good interfaces. Furthermore, it made a useful exploration to visual-aided design of trapezoidal steel roof truss.