Hexagon bolts are actually called a variety of methods. For example, they can be called hexagonal screws. For example, they can be called hexagonal screws. It can also be called a hexagonal bolt. This is the same meaning. It’s just that personal habits are different. The following creation of the screw manager Zhu introduced the basic knowledge of the hexagonal screw standard.
1. Ordinary bolts are divided into three types: A, B, and C. The first two are refined bolts and are less used. Generally speaking, ordinary bolts refer to Class C ordinary bolts.
2. Common C-class bolts are commonly used in some temporary connections and connections that need to be removed. Common bolts commonly used in building structures are M16, M20, and M24. Some mechanical industry rough bolts may be large in diameter and special in use.
High-strength bolts
3. The material of the high-strength bolt is different from the ordinary bolt. High-strength bolts are generally used for permanent connections. Commonly used are M16~M30. The oversized high-strength bolts are unstable and should be used with caution.
4. The bolted joints of the main components of the building structure are generally connected by high-strength bolts.
5. The high-strength bolts shipped from the factory are not divided into pressure-bearing type or friction type.
6. What is the friction type high-strength hex bolt and the bearing type high-strength bolt? Actually, there are differences in design calculation methods:
(1) Friction type high-strength bolts are slipped between the plates as the limit state of load carrying capacity.
(2) The bearing type high-strength bolts are slipped between the plates as the normal use limit state, and the connection failure is taken as the limit state of the load capacity.
7. Friction type high strength bolts do not fully exploit the potential of bolts. In practical applications, friction-type high-strength screws should be used for important structures or structures subjected to dynamic loads, especially when the load causes reverse stress. In this case, the unutilized bolt potential can be used as a safety reserve. In addition to this, high-strength bolted connections should be used to reduce the cost.
High strength bolts are different from ordinary bolts
8. Ordinary bolts can be reused, and high-strength bolts cannot be reused.
9. High-strength bolts are generally made of high-strength steel (45 gauge steel (8.8s), 20MmTiB (10.9S), which is a pre-stressed bolt. The friction type uses a torque wrench to apply the specified pre-stress, and the pressure-type type twists off the plum head. Ordinary bolt Usually made of ordinary steel (Q235), just tighten it.
10. Ordinary bolts are generally 4.4, 4.8, 5.6 and 8.8. High-strength bolts are generally grades 8.8 and 10.9, with 10.9 grades.
11. The screw holes of ordinary bolts are not necessarily larger than those of high-strength bolts. In fact, ordinary bolt holes are relatively small.
12. Ordinary bolts A and B screw holes are generally only 0.3~0.5mm larger than bolts. Class C screw holes are generally 1.0 to 1.5 mm larger than bolts.
13. Friction type high strength bolts transmit load by friction, so the difference between screw and screw hole can reach 1.5~2.0mm.
14. The standard transmission force characteristic of the pressure-bearing high-strength hex bolt is to ensure that the shear force does not exceed the friction under normal use, which is the same as the friction type high-strength bolt. When the load is increased again, the relative slip will occur between the connecting plates. The connection relies on the shearing of the screw and the pressure of the hole wall to transmit the force, which is the same as the ordinary bolt, so the difference between the screw and the screw hole is slightly smaller, 1.0~1.5mm.
Column anchor
19. Anchor bolts have no grade, only material points: Q235 and Q345. The most anchor bolts on the building structure are the anchor bolts.
20. Column anchors are neither ordinary bolts nor high-strength bolts. Strictly speaking, it is not a bolt. Column anchors are generally M20 or M24.
21. The manufacturing standards for column anchors should be the same as those for ordinary bolts. The length of the column anchor should be related to the friction between it and the concrete, and also the form of the anchor.
Expansion bolts and chemical bolts
22. Whether it is an expansion anchor or a chemical anchor, it is not a connection form in the national standard. Avoid using such connections, especially in important connections. All pre-embedded parts should be used.
23. The expansion anchor is mainly pulled by the expansion of the expansion tube and the friction of the crucible. The size of the pull-out force has a great relationship with the construction process, and the human factor is large. It is useless to perform the tensile test.
24. The chemical anchor bolt is formed by punching with a punching machine, and the plug is placed, and then poured into a chemical slurry to form an anchoring action. Common brands such as Fischer and Heineken.
25. Expansion bolts and chemical bolts are actually anchored. In some cases, expansion bolts or chemical anchors are required because they are not pre-buried. But this situation should be avoided in the design. Because the anchors should be pre-buried. For example, column anchors. Because this is the only way to ensure the best bonding and stress. And after the hole punching, it often causes damage to the steel bars and the shackles in the shackles.
26. In the regulations, the components embedded in the concrete are called embedded parts. According to the Ministry of Construction documents, expansion bolts shall not be used for curtain walls. Generally, new construction projects are strictly prohibited, and expansion anchors are strictly forbidden.
The above is the basic knowledge of the hex screw, which is more comprehensive. If you are interested, you can take a look. Learning and learning
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