冶金工业厂房,一般都有三大特点:跨度大、厂房高、吊车重。对厂房结构的强度、刚度和耐久性都有较高的要求。因此,厂房的主要承重结构都比较大而重,特别是钢筋混凝土柱,一般都在30吨上下,甚至有的超过50吨。大型预制钢筋混凝土柱的搬运和吊装,对一般施工单位来就是存在一定困难的。我们于1961年在改建某炼钢厂工程中,由于钢 Metallurgical industrial plants generally have three major characteristics: large spans, high plant heights, and heavy cranes. There is a high requirement for the strength, stiffness and durability of the plant structure. Therefore, the main load-bearing structures of the factory buildings are relatively large and heavy, especially the reinforced concrete columns, which are generally about 30 tons, and some even exceed 50 tons. The handling and hoisting of large-scale prefabricated reinforced concrete columns is difficult for the general construction unit. We rebuilt a steel plant project in 1961 due to steel