木结构桥梁一般跨度都比较小,超过10公尺以后,构造就很复杂。现在我国公路部门大跨度的木桥,大多采用钉板梁桥或毫乌式桁架等,这些形式大都构造复杂,所费的木材亦多。笔者在朝鲜民主主义人民共和国时,发现有两种跨度较大的钢木混合结构桥梁,构造很简单,制做时不需要很高的技术。第一种桁架形式如下图(1): Wood bridges are generally smaller span, more than 10 meters later, the structure is very complicated. At present, the long-span wooden bridges in the highway sector in our country mostly adopt the nail-plate girder bridge or the ceilings such as the ceilings. Most of these forms are complicated in structure and cost much timber. When I was in the Democratic People’s Republic of Korea, I found that there are two kinds of steel-wood hybrid bridge with large span, which is simple in structure and does not require very high technology. The first form of truss is shown in the following figure (1):