扭曲箱形构件的空间坐标表示法

国家体育场屋盖结构的几何构型非常复杂,立面和肩部构件均为扭曲箱形构件,在设计中采用了三维建模软件CATIA解决复杂建筑结构的空间建模问题。由于扭曲箱形构件在建筑工程中极少应用,传统的制图方式已经无法表达其几何形状,本文提出一种适合于扭曲箱形构件的节点坐标表示法,通过构件棱线上的特征点、端点或与其他构件的交点,采用三次B样条曲线拟合构件的棱线,以获得扭曲箱形构件连续光滑的轮廓线。本文给出了空间坐标法误差控制原则、控制点间距计算方法、曲率突变点的处理方法等。最后,文中给出了施工图表示方法与数据检验的实例。

3D-coordinate representation method for twisted box-sections

As the geometry of the roof structure of the National Stadium is very complicated and its members on the facade and shoulder area are in twisted boxsections,3D software CATIA is applied in the design to offer a solution to 3D modeling for complicated building structures.Since twisted box-sections are rarely used in the construction project,the traditional drawing method can no longer represent geometry of the members.This paper presents a 3D-coordinate representation method for twisted box-sections,which helps achieve smooth outlines of twisted box-sections through the characteristic points and end points on the ridge of these members and intersections with other members by fitting the ridge of the members with cubic B-spline curve.This paper also proposes the rule for tolerance control of 3D-coordinate representation method,the method to calculate the interval of the control points and processing method to deal with the accident points of curvature radius.Finally,an example for the construction drawing representation method and data check is provided.