Details of High Strength Bolts
According to the stress state, it can be divided into friction type and pressure type: Actually, there are differences in the design and calculation methods. The friction type high-strength bolts take the slip between the plates as the limit state of bearing capacity. Type-I high-strength bolts take the slip between slabs as the normal limit state, and the connection failure as the limit state of bearing capacity. Friction high-strength bolts can't give full play to the potential of bolts. In practical application, friction type high-strength bolts should be used for very important structures or structures bearing dynamic loads, especially when the loads cause reverse stress. At this time, the unexploited bolt potential can be used as a safety reserve. In addition, pressure-bearing high-strength bolts should be used to reduce the cost.
According to the construction technology, it is divided into: torsional shear type high-strength bolt and big hexagonal high-strength bolt. The hexagonal high-strength bolt belongs to the high-strength grade of ordinary screws, while the torsional shear type high-strength bolt is an improved type of hexagonal high-strength bolt, in order to better construct. The construction of high-strength bolts must be screwed first and then finally, and the impact type electric wrench or torque-adjustable electric wrench should be used for the initial screwing of high-strength bolts; However, there are strict requirements for the final tightening of high-strength bolts. The final tightening of torsional shear type high-strength bolts must use a torsional shear type electric wrench, and the final tightening of torque type high-strength bolts must use a torque type electric wrench. The hexagonal bolt consists of a bolt, a nut and two washers. The shear-type high-strength bolt consists of a bolt, a nut and a washer.
1. Pressure-bearing high-strength bolt: This type of high-strength bolt is mainly used for the connection between static or slightly sliding structural components. It is required that the high-strength bolt be used for strong pressure-bearing capacity and strong shear resistance.
2. Friction-type high-strength bolt: This type of high-strength bolt is mainly used for the connection between the braking system and important structures bearing dynamic loads, such as the connection of heavy crane beams and solid web beams.
3. Tensile-type high-strength bolts: The basic requirement of this type of high-strength bolts is that the bolts are not easy to deform, break or fall off under strong tension, etc. They are often used for flange connection of pressure parts.
High-strength bolts are suitable for large-span houses, steel structures of industrial plants, steel frame structures of high-rise buildings, bridge structures, heavy lifting machinery and other important structures.
According to the connection type, there are the following three types:
(1) Installation and wiping type high-strength bolts are suitable for beam-column connections in steel frame structures, heavy crane beam connections in industrial plants, solid web beam connections, braking systems and important structures bearing dynamic loads.
(2) Pressure-bearing high-strength bolts can be used for shear connection in static load structures that allow a small amount of sliding or in components that indirectly bear dynamic loads.
(3) Tensile high-strength bolts have low fatigue strength in tension, and their bearing capacity cannot easily exceed 0.6P(P under dynamic load (P is the allowable axial force of bolts). Therefore, it is only suitable for use under static load, such as flange butt joint and T-joint of compression bar.
Post time: Jun-27-2022