How to construct the connection of high-strength bolts?

1. Management of high-strength bolt connectors (1) Suppliers who purchase high-strength bolts for use must be experienced* * Professional manufacturers recognized by relevant departments must select bolt grades in strict accordance with the requirements of steel structure design drawings when purchasing. (2) High-strength bolt connection pairs must be supplied together. Each set of torsion-shear type high-strength bolt connection pairs includes one bolt, one nut and one washer. ； Each set of high-strength large hexagonal head bolt connection pairs includes one bolt, one nut and two washers. (3) Pay attention to the storage of high-strength bolts before use. Improper storage will cause the bolts to rust and become contaminated with dirt, which will change the torque coefficient and performance of the bolts. Please pay attention to the following points during storage: a. Bolts should be stored in a moisture-proof, rain-proof, dust-proof place and classified according to type and specification. b. Bolts should be handled with care to prevent impact, damage to packaging and damage to bolts. Before tightening, it should be kept in its factory condition as much as possible to avoid changes in the torque coefficient and standard deviation or the fastening axial force variation coefficient. c. Bolts should be opened in the packaging box only when used, and the quantity used on that day should be collected. The remaining bolts should be recycled on the same day and kept according to the batch number and specification. They should be stored and used strictly according to the batch number. Bolts, nuts, and washers of different batch numbers must not be mixed. 2. Structural assembly Before assembling the structure, clean the friction surface, use a wire brush to remove floating rust, and use a grinder to remove the hole edges, plate edge burrs, curling edges, cutting burrs, etc. that affect the close contact between the plates. The friction surface stained by paint or oil must be strictly cleaned before lifting. During assembly, steel drills, punches, etc. should be used to correct the hole positions. In order to ensure that the friction surfaces between the joint steel plates are close to each other and the connection is good, temporary ordinary installation bolts and manual wrenches should be used to tighten them until they are tight. After the structure is adjusted in place, insert the high-strength bolts and tighten them appropriately with a handle wrench. Then replace the high-strength bolts with high-strength bolts one by one. In order to prevent the positional deviation of the components after connection and for effective clamping between steel plates, try to eliminate gaps as much as possible. Therefore, when installing, you must control the following points: (1) The number of temporary bolts and punch nails required for each node should be calculated and determined based on the load that may occur during installation, and should meet the following requirements. A. The sum of temporary bolts and punch nails should not be less than 1/3 of the total number of bolts at this node, in order to prevent component deviation. B. The number of temporary bolts should not be less than 2. C. The number of punch nails used should not be more than 30% of the temporary bolts. The purpose is to increase the pressing force on the plate stack. D. High-strength bolts used for connection must not also serve as temporary bolts to prevent thread damage and bending of the surface condition of the connection pair, causing changes in the torque coefficient. (2) Precautions when installing and replacing high-strength bolts: A. The bolt insertion direction should be easy to operate and should be consistent. 3. Calibration of construction tools. Due to the actual joint operation of high-strength bolt connections, the pretension force of high-strength bolts cannot be directly measured. To do this, it is necessary to start from the torque coefficient relationship of the bolt (T=K * P * In d), the pretension force is estimated based on the torque value. Therefore, the inspection control after bolt tightening must confirm the torque value instead of the measurement of the pretension force. For this reason, the wrench used for tightening must be measured to determine the torque indication value. Commonly used wrench calibration methods are as follows:: (1) Calibration steps for torque wrenches with noise: (2) Calibration method of electric wrench: Most electric wrenches are double-fixed, which can be used for both torque and rotation angle. When calibrating torque, first turn the "Control Selection" knob to the "Torque Position", and then turn the "Torque Selection" knob to the indicated value corresponding to the torque value to be calibrated. There are two calibration methods.: ② Steps of scale calibration method: A. Insert the bolts into the fixed connecting plate, screw on the hexagonal nuts, and tighten with a wrench. B. Extend the short handle of the outer sleeve of the electric wrench, and put the inner sleeve on the hexagonal nut.