一、钢箱形梁的发展在第二次世界大战以前,铁路钢桥一直是选用标准轧制截面,用铆钉(或螺栓)连接起来,做成一定形状和尺寸的杆件。在大多数情况下,钣梁和桁梁几乎是结构型式的唯一选择。不论是上承式、穿式或半穿式,结构的所有构件都是在工厂制造好,而且通常是在厂内试拼装之后,再发送到工地。第二次世界大战之后,电焊技术和高精度的焰切工艺大大改变了钢结构的制造方法,做成更有效的整体式结构。其中,钢钣是主要元件,既经济,又实用。在大战期间,首先在造船中采用了钢钣焊接的大型预制单元,事实上就是薄壁箱形结构。现代的钢箱形梁桥,就是用钢钣焊接的闭合式箱形薄壁结构,是 First, the development of steel box girder Before the Second World War, the railway steel bridge has been the selection of standard rolling cross-section, with rivets (or bolts) connected to make a certain shape and size of the rod. In most cases, sheet girders and girders are almost the only choice of structure type. Whether it is bearing, wearing or semi-penetrating, all the components of the structure are made in the factory and are usually sent to the construction site after assembly in the factory. After World War II, welding technology and high-precision flame-cutting process have greatly changed the method of manufacturing steel structures to make a more effective monolithic structure. Among them, the steel sheet is the main component, both economical and practical. During the war, the first large-scale prefabricated unit of sheet metal welding was used in shipbuilding, in fact a thin-walled box structure. Modern steel box girder bridge, is the use of steel sheet welded closed box thin-walled structure is