预应力技术从1928年法国弗来西奈用高强度钢丝作预加力时开始,五十多年来在混凝土结构方面得到了广泛的发展和应用。但在钢结构,特别是在起重机结构中的应用,研究得很少。由于预应力技术是节约钢材的主要途径,南昌起重设备厂根据一些用户的特殊要求,设计试制了三台预应力双梁桥吊,通过比较,比通用桥吊主梁可节约钢材30%左右。本文主要 Prestressing technology began with the use of high-strength steel wires as pre-energizing force in 1914 in Nice, France, and has been widely developed and applied in concrete structures for more than 50 years. However, there has been little research on the application of steel structure, especially in the structure of cranes. As the prestressed technology is the main way to save the steel, Nanchang lifting plant according to the special requirements of some users, trial design and manufacture of three prestressed double girder bridge crane, by comparison, universal bridge crane girder can save about 30% of steel . This article mainly