What are the main differences in appearance between steel structure bolts and torsional shear bolts?

(1) Shape differences: The head of a steel structure bolt is designed in a hexagonal shape, while the head of a torsional shear bolt is semi-circular, and it also has a unique plum blossom head at the tail.

(2) Different installation methods: Large hexagonal bolts are usually installed with a torque wrench, while shear-torsion bolts, during the installation process, utilize the reaction force between the star-shaped head at the tail and the torque to tighten the bolt in the opposite direction until its straight toothed tail end breaks.

(3) Differences in matching components: Each set of large hexagon bolts consists of one bolt, one nut and two flat washers, while torsion shear bolts are only equipped with one bolt, one nut and one flat washer.

What is the function of the plum blossom head at the tail of the torsional shear bolt?

When installing shear-type high-strength bolts, an electric torque wrench must be used. When the torque reaches the preset value, the plum blossom head at the tail of the bolt will be automatically unscrewed, which ensures that the bolt has reached the necessary preload, thereby guaranteeing its performance. Therefore, in engineering practice, the effectiveness of high-strength bolts is judged by checking whether the star-shaped heads are retained. In addition, shear-type high-strength bolts are usually for single use and cannot be reused after use.