From the perspective of force characteristics: high-strength bolts apply pre-tightening force and transmit external force through friction. Ordinary bolted connections rely on the shear strength of the bolt shank and the pressure of the hole to transmit the front force, and the nuts
When tightening, the pre-tightening force is small, and its influence can be ignored. In addition to its high material strength, high-strength bolts also exert a large pre-tightening force on the bolts, so that there is extrusion between the connected components.Stainless Steel Screws
Pressure, so that the friction force perpendicular to the direction of the screw is greater. Ninth preload, anti-slip coefficient and steel type have a direct impact on the bearing capacity of high-strength bolts. According to the characteristics of force, it can be divided into pressure
type and rubbing type. Their calculation methods are different. The minimum specification of high-strength bolts is M12, and M16~M30 are commonly used. Too large bolts are unstable, so they should be used with caution in design.
The difference between group friction and pressure connection of high-strength bolts: high-strength bolt connection is to
Clamp the plate of the connecting plate by tightening the pre-tension in the bolt rod, which is enough to generate a large amount of friction, so that
Improves connection integrity and stiffness. When subjected to shear force, according to different design and force requirements, it can be divided into high-strength bolt friction connection and high-strength bolt bearing connection.
kind. The essential difference is in the dry limit state. Although they are the same bolt, they are very different in terms of calculation methods, requirements, scope of application, etc. In shear design, high-strength
The friction connection of high-strength bolts requires the external shear force to reach the limit state of the maximum possible friction force provided by the tightening force of the bolts between the contact surfaces of the plates, that is, to ensure that the internal and external shear forces of the connection are at the whole
(Security Screws) The maximum friction force is not exceeded within a service life. There is relatively no slippage between the plates (the original gap between the screw and the hole wall is always maintained), and the connected plates are stressed as a whole according to the elasticity. cutting
In the cutting design, when the allowable external shear force exceeds the maximum friction force of the high-strength bolt bearing connection, relative sliding deformation occurs between the connecting plates until the bolt rod contacts the hole. Then
According to the shearing of the bolt body in chapter 9, the force is transmitted by the pressure of the hole wall and the friction between the contact surface of the plate. Finally, the shearing of the rod body or the destruction of the pressure of the hole is taken as the limit of the fried state
In short, friction-type high-strength bolts and pressure-type high-strength bolts are actually the same kind of bolts, but slippage is considered or not considered during design. Friction-controlled high-strength bolts cannot slide, and bolts do not
Bearing shearing, sliding in one day, the design consideration reaches the failure state, and the technology is relatively mature: the bearing-type high-strength bolts can slide, and the bolts also bear the shearing force, and the final failure is quite common.
Through bolt failure (bolt shear failure or steel plate compression).Screw Series
From the perspective of use: the main components of the building structure are connected by bolts, and high-strength bolts are generally used. Ordinary bolts can be reused, but high-strength bolts cannot be reused. high
Strength bolts are generally used for permanent connections. High-strength bolts are prestressed bolts. The friction type uses a torque wrench to apply the specified prestress, and the pressure type screw has a torx head. Ordinary bolt resistance
The shear performance is poor and can be used for secondary structural parts.
