9月17日上午11时，随着建筑工人在“鸟巢”的顶端取下了最后一块钢垫块，历时4天的国家体育场钢结构卸载顺利完成。“鸟巢”由被外力支撑的状态变成完全靠自身结构支撑。这也标志着国家体育场终于由图纸上的构想变为一个伟大的建筑物。国家体育场主体结构分成两个部分，即混凝土框架结构和钢结构，混凝土结构被钢结构罩在里面。钢结构由24桁架柱围绕着体育场碗状看台区旋转而成，整体外观酷似“鸟巢”造型。

The photo taken on September 17 shows an overlook of the Bird's Nest. [Xinhua] The steel structure of the National Stadium the main venue for the 2008 Beijing Olympic Games stood on its own yesterday after the last jack pad was removed. "Today is the birthday for the 'Bird's Nest,'" said Hou Zhaoxin, a top expert on the construction of 2008 Olympic projects. "With all the supporting structures removed, the huge skeleton of the National Stadium is able to stand on its own. The 'Bird's Nest' is born!" Designed by Swiss architecture firm Herzog & de Meuron, global engineering consultant ARUP and China Architecture Design and Research Group, the National Stadium is located on the North Fourth Ring Road in Beijing. The main body of the stadium is composed of 24 columns of trusses, which surround the bowl-shaped stands in the stadium. The structural elements support each other and converge into a grid formation, just like a bird's nest with interlocking branches and twigs. Construction started in December 2003 and the concrete work of the main stand was completed on November 15 last year. On August 31, the steel skeleton was welded together. The removal of the bracketing structures started on Thursday and was divided into seven steps. "During the process, 156 jacks were placed in 78 spots, and removal was done simultaneously on three levels the outside circle, the middle circle and the inside circle," said Li Aiqing, chairman of National Stadium Company, owner of the project. According to Li, the steel skeleton weighs 42,000 tons and can now bear a load of 11,200 tons of the roof and hanging parts. He said the entire steel structure would be completed by the end of November and the project completed by the end of next year. With a seating capacity of 91,000, the National Stadium will host the opening and closing ceremonies, track and field competitions and football finals during the Games. (China Daily)

Vocabulary:

truss: 构架, 桁架, 钢梁 bracketing structures: 支架,支撑结构 （英语点津陈蓓编辑）