If stored for a long period of time, a full quality inspection should be performed before use. The procurement and inspection management of high-strength bolts must be strictly managed for the procurement and inspection of high-strength bolts. The main purpose is to control the torque coefficient of the connecting pairs composed of bolts, nuts and washers. It is required to have a small dispersion, otherwise it is impossible to control the axial force of the bolt. In order to prevent the torque coefficient from being high, the strength of the bolt friction surface is managed. The high-strength bolt-connected friction surface directly affects the strength of the bolted joint. High-strength bolted joints generally refer to frictional joints, and their load-carrying capacity is one, only, and, in addition, one sliding ultimate bearing capacity, one bolting force, one friction surface, one friction coefficient The corpse is pre-tensioned with a bolt.
It can be seen that it is proportional to the friction coefficient of the plate bundle, and the state of the friction surface and the surface treatment condition will all have a coefficient of friction. It must be noted that the rubbing surface is prohibited from painting and contamination. Before the construction of high-strength bolts, the anti-slip coefficient of the friction surface must be re-examined to ensure the construction quality of the high-strength bolts.
The test piece shall be provided by the manufacturer and the steel structure test plate made of the same material, the same friction surface treatment method and the high-strength bolt of the same condition shall be provided by the manufacturer. The friction pair shall conform to the steel structure construction and The provisions of the acceptance specification. Fastening management of high-strength bolts The tightening management of high-strength bolts should include a series of work such as confirmation of the hole making, confirmation of the quality of the friction surface, selection of the fastening method, determination of the tightening torque and fastening construction.
The installation direction of the high-strength bolts is required to be consistent, and the large hexagonal high-strength bolt connection pair should be oriented toward the bolt head on the side of the root of the washer when the chamfer is installed. The side of the nut with the countertop should be turned toward the washer. One side of the corner faces the tail of the bolt. The manual fastening of large hexagonal high-strength bolts is usually carried out by manual torque wrenches. Due to the warpage in the manufacture and installation of the steel structure, the layers are not tightly attached. Therefore, in order to ensure the accuracy of the axial force in the fastening, it is required. In the case of high-strength bolt tightening, the initial tightening and final screwing must be performed in stages. For large nodes, it can be divided into initial screwing, double screwing and final screwing.
In the final tightening construction using the torque method and the corner method, the final tightening torque should be strictly controlled. The final tightening construction torque value is generally calculated according to the following formula. The corpse is designed to pre-tension, and the corpse is pre-tension loss value. The torque coefficient of the tension is the nominal diameter of the bolt. In the fastening construction, it should be noted that the high-strength bolt fastening sequence of each column and beam is the first top layer, the back bottom layer, the last intermediate layer, and the initial and final twisting should be in one day. Completed within.
For the amount of work completed every day, it should be re-examined. The number of unacceptables should be less than the number of samples to be inspected, and should be less than one. The under-spinning and the missing-spinning must be fully replenished, and the over-tightening should be replaced. After the construction unit completes the fastening construction, the construction party shall also check the torque coefficient.
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