一、前言目前,国外生产的通用桥式起重机的大梁以偏轨箱形梁居多(图1b)。近来日本又发展了半偏轨箱形梁(图1c),并在葫芦小车双梁桥式起重机上形成系列,起重量从3～20吨。美国克利夫兰起重机及工程公司生产的 I. Foreword At present, the girders of the universal bridge cranes manufactured overseas are mostly box girders with offset beams (Figure 1b). Recently, Japan has also developed a semi-partial rail box girder (Figure 1c), and in the hoist trolley double girder overhead crane to form a series of lifting capacity from 3 to 20 tons. Cleveland, United States cranes and engineering company