US Patent 8979452 Anchor bolt, anchor, connecting nut and clamping nut

An anchor bolt comprising: a shaft part with a male screw thread; and a head part connected to the shaft part and having an attachment hole with a closed-end bottom to receive a bolt therein defined at a tip surface of the head part and a breaking groove provided at an outer side surface of the head part. The breaking groove is formed at an outer surface of a portion in which the attachment hole is defined. A torque equal to or greater than a fixed value exerted on a tip portion between the tip surface and the breaking groove of the head part causes the breaking groove to be broken, thereby causing the tip portion between the tip surface and the breaking groove of the head part to be removed.