High strength bolted structure and method of securing nut and torque-shear type high strength bolt and joining method using same

In combination, a Torque Shear type high strength bolt assembly comprising:

• a Torque-Shear type high strength bolt and a tightening tool for tightening said Torque-Shear type high strength bolt, wherein said Torque-Shear type high strength bolt comprises:
• a male thread portion for engaging a female thread;
• a head portion and a shaft portion located at an end of the male thread portion, said head portion comprising a head having a seat face facing the male thread portion and having a front end on a side of the head opposite to the seat face and said shaft portion is located between said head portion and said male thread portion;
• a pintail for torque control formed with a breakneck disposed on the front end of said head, with said breakneck comprised of a groove located between the front end of said head and said pintail;
• a washer having a polygonal shape and having an outer diameter larger than the diameter of the outer circumference of said head located and abutted between the seat face of said head and a steel member to be joined;
• said washer having an inner surface defined by an inner diameter larger than an outer diameter of said shaft portion of said high strength bolt;
• and further comprising:
• said tightening tool for tightening said bolt by the pintail, said tightening tool having an inner sleeve and an outer sleeve;
• the inner sleeve of said tightening tool gripping the pintail and the outer sleeve of said tightening tool engaging said washer;
• whereby friction force is generated between the washer and the steel member to be joined as a counter force of rotational torque for torque control of the bolt.

A bolting method for a steel member using a Torque-Shear type high strength bolt;

• wherein said Torque-Shear type high strength bolt is comprised of:
• a male thread portion for engaging a female thread;
• a head portion and a shaft portion located at an end of the male thread portion, said head portion comprising a head having a seat face facing the male thread portion and having a front end on a side of the head opposite to the seat face and said shaft portion is located between said head portion and said male thread portion;
• a pintail for torque control formed with a breakneck disposed on the front end of said head, with said breakneck comprised of a groove located between the front end of said head and said pintail;
• said bolting method comprising:
• when screwing a male thread into a female thread of a screwing side to tighten the bolt, inserting and abutting a washer of a polygonal shape and an outer diameter larger than the diameter of the outer circumference of the head between the seat face of said head and the steel member to be joined, said washer having an inner surface defined by an inner diameter larger than an outer diameter of said shaft portion of said high strength bolt;
• using a tightening tool comprised of an inner sleeve and an outer sleeve operating in association, and engaging the washer with the outer sleeve and gripping and rotating the pintail by the inner sleeve so as to control the tension introduced to the bolt by the breakneck made to break at a selected breaking torque by a rotational torque obtained as a reaction force of the washer through the outer sleeve.