Jan. 14, 2020
As a China Modern Steel Structure Manufacturers, tell everyone.
(1) Structure of ordinary bolt connection
1. Forms and specifications of ordinary bolts
The general form of the steel structure is a large hexagon head, and its code is represented by the letter M and its nominal and diameter (mm). M18, M20, M22, M24 is commonly used in engineering. According to international standards, bolts are uniformly expressed by the performance level of the bolts, such as "grade 4.6" and "8.8 grade". The number before the decimal point indicates the minimum tensile strength of the bolt material. For example, "4" means 400N / mm2, and "8" means 800N / mm2. The numbers after the decimal point (0.6, 0.8) represent the yield ratio of the bolt material, that is, the ratio of the yield point to the lowest tensile strength. Our company has Industrial Building Steel Structure on sale.
Industrial Building Steel Structure
According to the machining accuracy of bolts, ordinary bolts are divided into three levels of A, B, and C.
Grade A and B bolts are made of grade 8.8 steel and machined by machine tools. The surface is smooth, the size is accurate, and they are equipped with class I holes (that is, the bolt holes are drilled or expanded into the assembled component, and the whole wall is smooth. , Accurate for holes). Because of its high processing accuracy, close contact with the hole wall, its connection deformation is small, and its force performance is good. It can be used for connections that bear large shear and tensile forces. However, it is labor-intensive and expensive to manufacture and install, so it is rarely used in steel structures.
Grade C bolts are made of grade 4.6 or 4.8 steel, with rough machining and inaccurate dimensions. Only type II holes are required (that is, bolt holes are punched on a single part at one time or without drilling dies. Generally, the hole diameter is larger than the diameter of the bolt shaft 2mm). When transmitting shear force, the connection deformation is large, but the performance of transmitting tensile force is good, no special equipment is required for operation, and the cost is low. Often used for bolted connections that bear tensile forces and secondary shear connections in structures that carry static or indirect dynamic loads.
2. Arrangement of ordinary bolted connections
The arrangement of the bolts should be simple, uniform and compact to meet the requirements of the force, and the structure should be reasonable and easy to install. There are two types of arrangements: side-by-side and staggered. Side by side is simpler and staggered is more compact.
(2) Force characteristics of ordinary bolted connections
1. Shear bolt connection
2. Tension bolt connection
3. Pull-shear bolt connection
(3) the stress characteristics of high-strength bolts
High-strength bolted connections can be divided into friction and pressure-bearing types according to design and stress requirements. When a frictional connection is subjected to shear, the maximum frictional resistance that can occur between the plates when the external shear force reaches the limit is the limit state; when it exceeds the relative slippage between the plates, the connection is considered to have failed and destroyed. When the pressure-bearing connection is sheared, the friction is allowed to be overcome and relative slippage occurs between the plates, and then the external force can continue to increase, and the subsequent screw shear or the ultimate failure of the hole wall pressure afterward is the ultimate state.
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