中文摘要：

五百米口径球面射电望远镜（Five hundred meter Aperture Spherical radio Telescope，FAST）将会成为世界上最大的单口径射电望远镜。FAST有三个创新性的工程概念，其中之一就是提出了主动反射面的概念。背架结构是反射面单元中连接主索网和面板的支撑结构。三种方案的背架结构样机已经设计和制造出来：单层弦支结构、单层网架结构和空间三角锥网架结构。三种样机的刚度实验，分别进行了不同背架结构在相同外力荷载下的实验位移变形比较，背架结构在外力荷载下位移变形的实验值和仿真值比较，以及在不同温度荷载下位移变形的比较。实验得到了背架样机的刚度特性，验证了仿真的设计和优化，也对FAST背架原型设计提供了参考。

英文摘要：

Five hundred meter Aperture Spherical radio Telescope（FAST） will be the largest radio telescope in the world which has three innovative engineering concepts. One of them is the active main reflector. Back-structure is the connection between panel and cable mesh of the reflector, which is significant of the entire FAST project. Three prototype back-structures have been designed and manufactured. They are cable supporting single-layer structure, single-layer grids structure and triangular pyramid structure. Stiffness experiments of the three prototypes took place. Compared displacements of different back-structures, between experiments and analyses data, and compared through different temperatures. The stiffness features are obtained. This serial stiffness experiments confirm prior designs and optimization. And have great reference in the future design.