steel structure manufacturer introduces the structure of common bolt connection

steel structure manufacturer introduces the structure with common bolt connection. The common form adopted for steel layout is large hexagon head type, and its code is represented by letter M and nominal diameter (sister).M18, M20, M22 and M24 are rarely used in the project.According to international standards, bolts are the same as the functional grade of bolts, such as “4.6 grade”, “8.8 grade”, etc.

       According to the machining accuracy of the bolt, the simple bolt is divided into a, B, C three levels.

A. Grade B bolt (refined bolt) is made of grade 8.8 steel and turned by machine tool. It is greasy on the outside and accurate in scale, and it is equipped with class I hole (that is, bolt hole is drilled or expanded on the component with good equipment, the hole wall is greasy and accurate for hole).Because of its high machining accuracy, close combat with the hole wall, small deformation and good mechanical function, it can be used for connection subject to large shear and tension.However, production and equipment are more labor-intensive and cost-effective, so they are less used in steel layout.

Grade C bolt (Rough bolt) is made of grade 4.6 or 4.8 steel, which is rough in processing and inaccurate in scale. Only class II holes (i.e. bolt holes are punched on a single machine or drilled without drilling die) are required.As usual, the hole diameter is 1-2 larger than the bolt rod diameter.When the shear force is announced, the connection deformation is large, but the function of the tension force is good, the operation does not need special equipment, and the cost is low.It is rarely used for bolt connection under tension and main shear connection under static load or direct dynamic load.Guiyang steel structure

      2, simple breakdown of bolt connection

      The bolts shall be simple, uniform and compact, meet the requirements of stress, and have reasonable structure and convenient equipment.There are two ways to separate them (as shown in the figure).The side-by-side arrangement is simpler and the wrong column is more compact.

      Stress characteristics of bolt connection

      1. shear bolt connection

      2. tension bolt connection

      3. tension shear bolt connection

      High strength bolt connection can be divided into conflict type and pressure type according to plan and stress demand.When the conflict type connection is subjected to shear, the maximum friction resistance that can occur when the external shear reaches between the plates is the limit case; when there is a certain slip between the overdue plates, that is to say, the connection is considered to be effective and damaged.When the pressure bearing type connection is in shear, the allowable conflict force is subdued and the plates must slip, and then the external force can continue to grow, and the ultimate damage of the screw shear or hole wall pressure bearing occurred later is the limit case.