一九六八年二月国际预应力混凝土学会在米兰召开会议,决定对一些国家(如美国、加拿大和其他太平洋及远东国家)的预应力混凝土结构的耐久性和实际使用情况,作一次调查。其主要情况介绍如下:美国:美国使用预应力混凝土是比较新的。预应力混凝土桥梁共报导了6280座,其中百分之九十是用先张法,在 In February 1968, the International Prestressed Concrete Society held a meeting in Milan to decide on the durability and actual use of prestressed concrete structures in countries such as the United States, Canada, and other Pacific and Far East countries. The main situation is described as follows: United States: The use of prestressed concrete in the United States is relatively new. A total of 6,280 prestressed concrete bridges were reported, of which 90 percent were pre-tensioned.