Reasons for the Destruction of the Technological Bridge

The paper considers the conditions and causes that led to an accident during the construction of a bridge crossing over the Volga on support № 4. For the construction of the pile foundation of the main supports, a SENNEBOGEN 7700 erection crane was used, installed on an auxiliary technological bridge. The accident occurred on 06.12.2020. The SENNEBOGEN 7700 crane fell from the technological bridge into the water when moving a diesel hammer with a cage weighing 61 tons to the storage site. Analysis of the accident recording of the external surveillance camera, the results of the diving survey and the information decoded from the parameter recorder allow to conclude that the crane was lifting a load less than the maximum load capacity according to the project. The parameter recorder before the time of the accident showed that there was no overload. The accident was caused by the destruction of one of the ceiling beams on which the crane was located. This beam was found destroyed at the bottom of the river. To determine the reasons for the destruction of the beam, the expert organization EDO Research Center LLC conducted an expert examination of the support beams BO1. To do this, the destroyed elements of the bridge were raised from the bottom of the river, and the studies of the metal of the beam, welds, and the entire structure were carried out. A full analysis of the design and working documentation, according to which the beams were made, was carried out. The article analyzes the reasons that led to the destruction of the beam, and provides recommendations for the designers, manufacturers and enterprises operating technical devices at the hazardous production facilities. The organization-customer of such structures should entrust their manufacture only to the specialized organizations. The manufacturing organization is obliged to prepare a passport with a serial number, instructions for installation and operation, documents confirming the performance of the designated type and scope of non-destructive testing of welds, provide the design with a marking plate, and apply personal marks of welders to the welds. The operating organization, in case of doubt as to the quality of the manufacture of the product, should not use such structures in the construction of especially hazardous facilities.