The purpose of the work is to analyze the results of tests of prefabricated crane beams for endurance during cyclic tests on a specially designed stand. The method of carrying out such tests is given. It indicates the inadmissibility of the operation of steel crane structures with cracks and the importance of research aimed at increasing the endurance and durability of crane beams. It proves the need to develop new crane beams (various profiles) to increase the period of accident-free operation of industrial buildings (using bridge lifting mechanisms with heavy duty) up to 25 years. It is proved that the developed prefabricated crane beam has improved (in comparison with the standard) characteristics.