Hexagon Socket Head Bolt is the most common construction content in steel structure construction. All steel structure engineers will feel that they are too familiar. However, this may not be the case. Today, we start with the most basic concepts and take everyone to re-understand high-strength bolts. This may subvert everyone's most basic understanding.

          01What is a high-strength bolt

          High-strength friction clamping bolt (hsfg for short). It can be seen that the high-strength bolts in my country's construction are short for high-strength friction pre-tightening bolts. In daily communication, only the two words "friction" and "grip strength" are abbreviated, but many engineers and technicians misunderstand the basic definition of high-strength bolts.

          Misunderstanding 1: Bolts with a material grade of more than 8.8 are "high-strength bolts"?

          The core difference between high-strength bolts and ordinary bolts is not the strength of the materials used, but the form of stress. The essence is whether to apply pre-compression and use static friction to resist shear.

          In fact, the hsfg bolts (BS EN 14399/astm-a325&astm-490) mentioned in the British Standard and the American Standard are only 8.8 and 10.9, while ordinary bolts include 4.6, 5.6, 8.8, 10.9, 12.9, etc., so the material Strength is not the key to distinguish high-strength bolts from ordinary bolts.

          Misunderstanding 2: The bearing capacity of high-strength bolts is higher than that of ordinary bolts. Which one is "high-strength"?

          It can be seen from the calculation of a single bolt that the design strength of high-strength bolts in tension and shear is lower than that of ordinary bolts. The essence of its high strength is that relative sliding is not allowed during normal operation, that is, the elasto-plastic deformation is small and the joint stiffness is large.

          It can be seen that, under a given design node load, although nodes designed with high-strength bolts may not necessarily save the number of bolts, they have small deformation, large rigidity and high safety reserves. It is suitable for high rigidity parts such as the main beam and conforms to the basic seismic design principle of "strong joints and weak members".

          The strength of China Stud Supplier's high-strength bolts is not due to the design value of its load-bearing capacity, but due to its high rigidity, high safety performance and strong damage resistance.