When installing mechanical components on a concrete foundation, one end of this bolt, which is shaped like a J or L, is embedded in the concrete for use.  
The tensile strength of anchor bolts is determined by the tensile strength of the round steel itself, which is equal to the cross-sectional area multiplied by the allowable stress value (Q235B: 140 MPa, 16Mn or Q345: 170 MPa), representing the allowable tensile load capacity during design.
Anchor bolts are typically made of Q235 steel, which is smooth-surfaced. Threaded steel (Q345) has higher strength, but creating threaded connections for nuts is more challenging than with smooth-surfaced steel.
For smooth-surfaced anchor bolts, the embedment depth is generally 25 times the bolt diameter, followed by a 90-degree hook approximately 120 mm long.
 If the bolt diameter is very large (e.g., 45 mm) and the embedment depth is too deep, a square plate can be welded to the bolt end to create a larger head.  
(However, there are certain requirements for this.) The embedment depth and hook are designed to ensure sufficient friction between the bolt and the foundation, preventing the bolt from being pulled out and causing failure.