Development of super high-strength bolts with tensile strengths of 1600 to 2000 N/mm2

High-strength bolts with much higher strengths are effective in bolted joints of high-strength steels to reduce the number of bolts for both labor saving and more rapid construction. This project is directed at developing super high-strength bolts with a 1600 to 2000 N/mm2 ultimate strength class as the joining parts intended for steel plates with an 800 N/mm2 ultimate strength class. This paper reports the results of the investigation of the resistance to the delayed fracture of high-strength bolts, prototype and shear tests of individual bolts, and the FEM analysis of a joint including multiple bolts aligned in a line.