FAST背架结构优化选型及单元足尺模型试验研究

背架结构是500m口径球面射电望远镜（FAST）反射面支承结构的重要组成部分，其成型精度、自重大小及加工难易程度对FAST工作性能、项目造价及建设工期有较大影响。通过对多种背架结构形式进行细致的分析及优化，得到各自最优的结构参数及构造形式，并选取其中两种（单层结构、单层弦支结构）进行单元足尺模型试验，通过试验考察背架实际加工效果及性能。试验结果表明：普通钢结构加工工艺无法满足FAST较高的成型精度要求，需采取加设檩条调节层的构造措施；实际模型工作精度及构件应力水平与有限元模型分析结果吻合，满足功能要求；综合比较两模型的制作安装过程及工作性能，认为单层背架具有结构简单、易于制作、结构精度易于控制等优点，为两试验模型中的较优者。

Structural optimization and full-scale-model test for FAST back-structure unit

The back-structure plays a very important part in FAST (Five-hundred-meter Aperture Spherical Telescope) support structure. The shaping precision, weight and fabricating difficulty of back-structure have remarkable impact on the working performance, engineering cost and fabricating duration of FAST. The different structural types of back-structure were analysed and optimized separately and corresponding structural parameters were gained. Two of them (single-layer type and prestressed single-layer type) were chosen for a full-scale-model experiment, through which actual performances of back-structure were surveyed. The results reveale that normal manufacturing craft can not meet the need of high-level shaping precision, and a layer of adjustable purlin should be set. Also, the actual stiffness of model and strain level of elements reasonably agree with the FE simulating results. After a comprehensive comparison in terms of manufacturing process and final performace, the single-layer back-structure was judged to be better of the two test models.