在工程建设中,常会遇到一些抛物线图形,特别是在公共建筑中,如图1所示为某体育馆的平面和剖面示意图,整座建筑物呈橄榄形,由对称的四条抛物线和八条不同半径的圆弧曲线组成。屋盖结构为索网-索拱结构,屋面钢拱和主悬索都呈抛物线形。图2所示为鱼腹式吊车梁,它的外形也采用抛物线形,图3所示为采用抛物线形结构的拱桥。抛物线图形的施工放线比较复杂,实地放线前,需进行一定的内业计算。根据图纸平面尺寸, In the construction of the project, often encounter some parabolic graphics, especially in public buildings, as shown in Figure 1 for a gym and a cross-sectional schematic plan, the entire building was olive-shaped, symmetrical four parabolas and eight different radii The arc curve. Roof structure for the cable network - cable arch structure, roof steel arch and main suspension are parabolic. Figure 2 shows a fish-shaped crane beam, which also uses a parabolic shape, Figure 3 shows a parabolic arch bridge structure. Parabolic graphics construction more complicated pay-off, the actual line before the release, the need for some computing industry. According to the drawing plane size,