Problems with rectification of hoist supports on the example of a semi-portal bridge-crane with a lattice structure

Abstract

The long period and conditions of operation are the cause of various types of severe damage to cranes used in the steelworks industry. Among the more dangerous and difficult to eliminate crane damage types, there is excess durable deflection of its supports from vertical axis. The object of the study is the semi-portal grab bridge-crane with steel lattice structure, for which deflection of a fixed support was detected that several times exceeded permissible values. For this crane, rectification was performed aimed at bringing fixed supports to the vertical line by stabilisation of the corrected location of the bearing structure of the crane using additional angle braces. The analysis of periodical geodetic measurements of the crane structure showed insufficient effect of the rectification, whereas loss of stability of some rods in the fixed support was detected. The study involved the FEM strength analysis of the crane, which revealed that the applied rectification method caused redistribution of forces in the rods of the fixed support, resulting in the loss of stability of some rods of the support, thus questioning the effectiveness of the rectification method applied.