The tensile strength of an anchor bolt is the inherent tensile strength of the round steel itself, equal to the cross-sectional area multiplied by the allowable stress value (Q235B: 140MPa, 16Mn or Q345: 170MPa), which is the allowable tensile bearing capacity in the design.
Anchor bolts are generally made of Q235 steel, i.e., plain round steel. Threaded steel (Q345) has higher strength, but the threads for making nuts are not as easy to work with as plain round steel. For plain round anchor bolts, the embedment depth is generally 25 times its diameter, followed by a 90-degree hook about 120mm long. If the bolt diameter is very large (e.g., 45mm) and the embedment depth is too deep, a square plate can be welded to the end of the bolt, creating a large head (however, there are certain requirements). The embedment depth and hook are both to ensure sufficient friction between the bolt and the foundation, preventing the bolt from being pulled out.