Torshear type high strength bolt connection

1 scope

This technology is applicable to steel structure installation for sets of torshear type high strength bolt construction technology.

2 construction preparation

2.1 materials and equipment:

2.1.1 bolts, nuts, washers should be accompanied by certificates of quality, and should comply with the design requirements and provisions of the national standard.

2.1.2 storage should be kept classified according to specifications of high strength bolt and rain-proof, moisture-proof. Case does not fit the bolt, nut, thread damage, shall not be used. Bolts, nuts, washers rust should be sampled fastening axial forces, to meet the requirements before use. Bolts may not be dyed by dirt, oil viscosity, kept clean and dry. Must be batch numbers, within the same batch used must not mix the mix.

2.1.3 equipment: electric torque wrenches and control instruments, hand torque wrench, hand wrenches, wire brushes, tool bags, and so on.

2.2 operating conditions:

2.2.1 friction: friction surface using sandblasting, grinding polishing method for processing, coefficient of friction, the design requirements (typically requires Q235 steel 0.45 per cent, 16 MN steel 0.55 per cent). Wooden iron oxide allowed residue of friction surface, the friction surfaces can be processed after you generate the rust-red surface mounting bolts (usually about open storage 10d), sandblasting treatment of friction surface mounting bolts without rust. When using grinding wheels grinding, grinding is not less than 4 times times the bolt diameter, polished direction perpendicular to the stress direction, the friction surface should be polished without obvious inequalities. Friction surfaces to prevent pollution by oil or paint, such as pollution should be thoroughly cleaned.

2.2.2 check bolt hole diameter, hole-edge burrs must be removed.

2.2.3 the same batch number, specification of bolts, nuts, washers, matching boxes for use.

2.2.4 electric wrenches and wrenches should be manually after calibration.

3 operational processes

3.1 process:

Ready → select bolt and supporting Joint Assembly → → → install temporary bolts bolt →

High-strength bolt fastening → checking

3.2 selection of bolt length: length of torshear type high strength bolt hexagon nut for the bolt head to bolt plum flower head cut the length of the roots. Choose the length of bolts for fastening the connecting plate thickness with a nut and a washer thickness and want to show at least two thread when fastening the remainder, generally based on connecting plate thickness and increasing the length of the table 5-2, and 5mm integer multiples.

Table 5-2

Nominal diameter of the bolt length (mm)

M16 25

M20 30

M22 35

M24 40

3.3 connector Assembly:

3.3.1 connection plate or steel should be formed, plate edge, no Burr hole; warping and distortion must be corrected at the joint, friction surfaces and prevent injury, ensure the friction surface cling.

3.3.2 before Assembly check the friction surface, friction coefficient whether the design meets the requirements of specimen, rust with a wire brush to remove, clean oil, paint.

3.3.3 plate surfaces should be flat, while when the contact gap, should be dealt with in accordance with the regulations, is shown in table 5-3.

Table 5-3

Gap processing method

1mm no

3mm side of the high ground to a 1:10 bevel grinding should be perpendicular to the force

3mm plus plate, plate friction surface treatment methods on both sides with the same components

3.4 Installing temporary bolts: joint use of ad hoc bolt, bolts more than 1/3 of the total number of bolts for joints and not less than two of each joint, drift pin penetration amount should not be more than temporary bolts 30%. Using a drift pin alignment hole at the Assembly, insert temporary bolts in place, using a wrench to tighten. No doubles as a temporary bolts with high strength bolts to avoid thread damage.

3.5 installing the high-strength bolts:

3.5.1 Installing high-strength bolts should be free to wear into the hole when, should not force to beat. Torshear type high strength bolt hexagon nut washer nut side gasket holes have chamfered side a voice contact nuts shall not be installed backwards (large Hexagon head bolt washer and nut on the bolt head side should be installed on one side, the gasket holes have chamfered side voice contact with the bolt head shall not be reversed).

3.5.2 when the bolts were not free to wear, not use gas cutting bore hole, use a reamer reaming, repair the holes required to make lamellar close in case of iron filings into the seams, hole cutter grinding machine to clear after Kong Bianmao Thorn, and to remove iron.

3.5.3 bolts into the appropriate agreement, put into high strength bolts with a wrench after fastening, remove temporary bolts with high strength bolts replaced. High-strength bolts shall not be installed on a rainy day, and the friction surface should be in a dry state.

3.6 high-strength bolt fastening: must be carried out in two stages, for the first time beginning to twist. Tighten the fixing bolt standard axial force (design pretension) 60%~80%, first screw Torque values shall be not less than final twisting by torque value 30%. The second fastening to final twisting, when final twisting by sets of torshear type high strength bolt plum flower heads should be unscrewed. For bolts all bolts uniformly in force, twist, twist at the beginning should be in a certain order.

3.6.1 General joints: lateral fastening bolts order.

3.6.2 from joint stiffness much place to the free end of the out of control.

3.6.3 from bolts to diffuse manner from the Center.

Twist the wrench should torque can be controlled at the beginning, completed early twist of the bolts should be marked for confirmation. To prevent leakage screw, installation of high-strength bolts on the day, should be screwed on the day complete.

Final twisting dedicated wrench should be used, such as certain jobs where there is difficulty or hand torque wrench, final twisting by torque shall be conducted according to the design requirements. When using the wrench, bolt tail shoots up after the show finished final twisting card, check the exposed threads of not less than 2 buckle, breaking down the Chuck should be collected together into a tool bag to prevent accidents caused by falling from a height.

3.7 check acceptance:

3.7.1 sets of torshear type high strength bolt should be twist off tail plum twist to an end card is no omission.

3.7.2 individual cannot use special wrench when torshear type high strength bolt Hexagon head bolt torque method. Screwed over, check for leaks turn, under screw should be used 0.3~0.5kg hammers one by one to check if is not screwed, screwed spills the number of twist; Super twist should be replaced. Checks should be nuts to go back 30 ° ~50 °, then screwed to the in-situ determination final twisting by torque, the deviation shall not exceed ± 10%, twist the qualifying mark.

3.7.3 high strength bolts and inspection record, collated and included in the technical file.

4 quality criteria

4.1 project:

4.1.1 high-strength bolt type, specifications and must comply with the design requirements and the relevant provisions of the standard, check the quality certificates and inspection reports. Reinspect the rear bolt pretension in accordance with provisions allowing the use of.

4.1.2 connection surface coefficient of friction (coefficient of creep resistance) must comply with the design requirements. Clamp down on iron oxide scale, burrs, splashes, paint and dirt, welding scar, check friction coefficient test experiment reports and field sample reinspection report.

4.1.3 first screw Torque wrench should be calibrated on a regular basis. Early high strength bolt screw, screw must conform to the specifications and requirements, check for calibration records and construction records.

4.2 Basic project:

4.2.1 Visual inspection: bolt into the direction should be consistent, length not less than 2 threads exposed button.

4.2.2 sets of torshear type high strength bolt tail-head screw should be screwed off.

4.2.3 friction and clearance in accordance with code requirements.

5 finished product protection

5.1 structure corrosion section (such as pickling shop), connection joints, screws, nuts, gaskets around the paint anticorrosion PuTTY (such as perchloroethylene PuTTY) closed surface treated the same as steel structures in the area.

5.2 structure rust-proof sector, connection joints and screw heads, nuts, washers quick drying red lead paint around the closed surface rust with steel structure the same.

6 quality problems to be noticed

6.1 mounting surfaces does not meet the requirements: surface rust, greasy dirt, burrs, welding the bolt bore such as, should be cleaned up.

6.2 connection Board Assembly is not strict: connecting plate, gap, should be corrected before use.

6.3 bolt thread damage: bolt should be free to wear into the screw hole, do not allow forced into.

6.4 torque allowed: should be periodically calibrated wrench torque values, the deviation is less than 5%, strictly according to the tightening sequence.

7 quality records

This standard shall meet the following quality records:

7.1 high-strength bolts, nuts, washers, continuous Vice-certificate of quality, factory inspection report.

7.2 high-strength bolt pretension reinspection report.

7.3 anti-slip coefficient of friction (friction coefficient) testing and reinspection report.

7.4 torque wrench calibration record.

7.5 design changes, record of negotiation.

7.6 the construction inspection records.