Causes of Failure of High-Tensile Stud Bolts Used for Joining Metal Parts of Tower Crane

[摘要] The causes of the failure of a high-tensile stud 2M48-6gx500 10.9 made from steel grade 30HGSA which led to a temporary inoperability of a tower crane were investigated. The bolts were used to assemble the tower sections and collapsed after 45 days from the moment the crane was commissioned. The cracks in the fracture are identified as fatigue with the characteristic sites of nucleation, sustainable development and static dolomite. To determine the possible causes of stud bolts destruction, metallographic, durometric and mechanical tests were carried out from which it follows that the stud bolt material in its original state corresponded to the delivery conditions. The destruction of the stud bolt appears to have resulted from a combination of several unfavorable factors: uncertainty about the actual tension of the stud bolt due to the lack of information about the magnitude of the twist factor; partial displacement of the centers of the brackets holes and rotation of the stud bolt axis during the sections' assembly; no tight contact on the support surfaces of the section brackets. All this led to a discrepancy between the actual design of the stud bolt, the appearance of additional forces and the destruction of the stud bolt.

[发布机构] Polytechnic Institute, South Ural State University, Lenin Avenue, 76, Chelyabinsk; 454080, Russia^1;Architecture and Construction Institute, South Ural State University, Lenin Avenue, 76, Chelyabinsk; 454080, Russia^2

[学科分类] 土木及结构工程学

[关键词] Additional forces;Metal parts;Original state;Partial displacement;Steel grades;Stud bolts;Support surfaces;Twist factors