Integrity of beam braces and threaded spindle for conjoint operation of two 5 MN bridge cranes

Abstract

The beam connects two bridge cranes with the overall lifting capacity of 500 t (2x250 t) and enables their simultaneous conjoint operation during the refurbishment or capital repair of hydroelectric equi-pment at the hydro power plant "Djerdap 2". Two braces are being installed instead of two hooks when that situation occurs. Braces are loaded with 250 t (2.5 MN) each, while threaded spindle is loaded with 500 t (5 MN). Integrity of structures is a relatively new scientific and engineering discipline which in a broader sense comprises state analysis, behaviour and loosening diagnostics, service life evaluation and refurbi-shment of structures, which means that, beside the usual situation in which it is necessary to evaluate the integrity of a structure when a flaw gets detected by means of non-destructive tests, this discipline also comprises structural stress state analysis. Detection of internal defects by means of ultrasonic testing was performed in order to analyze the state of braces and of the threaded spindle. On the basis of performed analytical calculations it was determined that their integrity would not be jeopardized during the refurbishment or capital repair of hydroelectric equipment at the hydro power plant "Djerdap 2".