... and erection of the Prefabricated(pre-engineered) Steel Building Hengda Steel Structure(HDSS) has totally six subsidiaries ... -up welded H-section , hot-rolled H-section, channel, steel column, steel beam),standard frames, secondary framing, roof & wall materials ... -up welded H-section , hot-rolled H-section, channel, steel column, steel beam),standard frames, secondary framing, roof & wall materials ...