一九七○年五月至八月,我院在为河南某钢铁厂氧气顶吹转炉炼钢车间的设计中,首次采用了单跨及双跨公用两种12米预应力下承式托架。这种托架与一般下承式钢托架相同,主要特点是:不占用屋架下方柱间的净空,可解决安全走道不足的问题,因为此种托架下 From May to August of 1970, in our design for the oxygen top-blowing converter steelmaking workshop of a steel plant in Henan Province, the first two-meter and two-span publicly-used 12m prestressed bottom brackets were used for the first time. . This kind of bracket is the same as the general through-steel bracket. The main feature is that it does not take up the headroom between the columns below the roof truss, which can solve the problem of insufficient safety walkways, because under this bracket