Construction method for torsional shear type high-strength bolt of steel structure joint

Abstract

The invention relates to a construction method for a torsional shear type high-strength bolt of a steel structure node, which comprises the following steps of: 1, carrying out a high-strength bolt fastening axial force test and an anti-slip friction surface test, determining a torque coefficient control value, and checking a torque wrench; 2, after bolt joints with different plate thicknesses are treated, the friction face of the steel structural component is cleaned, the steel structural component is temporarily fixed through installation bolts after being hoisted in place, then the installation bolts are replaced with high-strength bolts, initial screwing is conducted, then final screwing is conducted on the high-strength bolts, and finally paint on the connecting face is coated in a supplementary mode; according to the method, fatigue crack propagation caused by stress overrun of the waterproof cloth due to sudden change of the plate thickness is avoided through pre-test verification, and after construction optimization treatment is carried out on bolt nodes with different plate thicknesses and the plate thickness difference is eliminated, friction surface cleaning is carried out, the micro-motion slippage amplitude is reduced, initial screwing and final screwing are carried out, and plate seam gaps are eliminated in stages, so that the reliability of the waterproof cloth is improved. And accurate torque transmission is ensured, so that the fatigue life of the steel structure joint is prolonged.

Description

Technical Field

[0001] This invention relates to the field of steel structure construction technology, and in particular to a method for constructing torsion-shear type high-strength bolts for steel structure nodes. Background Technology

[0002] Torque-shear type high-strength bolts for steel structure joints are permanent connection fasteners specifically designed for steel structure engineering. They achieve precise preload control through the physical characteristic of the tail end breaking off via a twist-off process, and are widely used in critical load-bearing joints in bridges, towers, masts, and high-rise buildings. However, when using torque-shear type high-strength bolts, if the two components of the steel structure joint have different plate thicknesses, directly installing high-strength bolts can easily lead to stress concentration and fatigue cracks. Furthermore, over long-term use, the tightly fitting friction surfaces are prone to relative sliding, promoting fretting wear on the contact surfaces, causing preload decay and resulting in loosening failure. They also exhibit relatively weak fatigue resistance. Therefore, this invention proposes a method for constructing torsion-shear type high-strength bolts for steel structure nodes to solve the above problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for constructing high-strength torsion-shear bolts for steel structure nodes, thereby improving the fatigue resistance of steel structure nodes.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for constructing torsion-shear type high-strength bolts for steel structure nodes, the innovation of which lies in: including the following steps: Step 1: Conduct axial force tests and anti-slip friction surface tests on high-strength bolts to determine the torque coefficient control value and calibrate the torque wrench; Step 2: After processing the bolt joints with different plate thicknesses, clean the friction surfaces of the steel structure components. After the steel structure components are hoisted into place, they are temporarily fixed with installation bolts. Then, high-strength bolts are used to replace the installation bolts and initial tightening is performed. Finally, the high-strength bolts are tightened for the final tightening, and the connection surfaces are painted.

[0005] Furthermore, the bolted joint includes: Single-sided pad bolt joint: includes two interlocking steel structural members and a pad. The pad is set on one side of the joint of the two interlocking steel structural members. When the two interlocking steel structural members have different plate thicknesses, the wall surfaces of the two steel structural members away from the pad are flush with each other. One side of the pad is attached to the wall surface of the steel structural member with larger plate thickness, and the other side creates a gap t with the wall surface of the steel structural member with smaller plate thickness. Double-sided pad bolt joint: includes two interlocking steel structural members and two pads. The two pads are respectively set on both sides of the joint of the two interlocking steel structural members. When the two interlocking steel structural members have different plate thicknesses, the two pads are respectively attached to the two side walls of the steel structural member with larger plate thickness, and are left with the same distance from the same side wall of the steel structural member with smaller plate thickness.

[0006] Furthermore, the method for handling bolted joints in steel structures with different plate thicknesses includes: No treatment is required for single-sided pad bolt joints with t < 1 mm; For single-sided pad bolt joints with 1mm≤t<3mm, the wall surface of the steel structure member with thicker plate that is in contact with the pad is ground to a slope of 1:10, so that the gap between the pad and the wall surface of the steel structure member with thinner plate is less than 1mm. For single-sided pad bolt nodes with t≥3mm, a clamping plate is added between the pad and the steel structural member with a small plate thickness. The thickness of the clamping plate is d, d≥3mm and t-1mm<d<t+1mm. The material of the clamping plate and the friction surface treatment method are the same as those of the steel structural member. For double-sided plate bolt joints, a clamping plate is added between each of the two plates and the steel structural member with the smaller plate thickness. The material and friction surface treatment of the clamping plate are the same as those of the steel structural member.

[0007] Furthermore, when using mounting bolts for temporary fixing in step 2, no foreign matter should be allowed to enter the connection surface, and the number of mounting bolts should not be less than 30% of the number of bolts in the corresponding bolt node, and not less than 2 bolts.

[0008] Furthermore, when initially tightening the high-strength bolts in step 2, start installation from the middle of the bolt group and tighten them one by one outwards. If the high-strength bolt cannot be freely inserted into the bolt hole, it must not be forcibly hammered in. Instead, use an electric milling machine to correct and enlarge the hole before inserting it. The maximum diameter of the bolt hole after correction and enlargement must not exceed 1.2 times the nominal diameter of the bolt.

[0009] Furthermore, in step 2, the final tightening of the high-strength bolt is completed within 24 hours after the initial tightening. The final tightening sequence is the same as the initial tightening. The final tightening of the high-strength bolt is considered qualified when the tail is unscrewed, while ensuring that 2 to 3 threads remain exposed outside the nut.

[0010] Furthermore, in step 2, after the high-strength bolts are finally tightened and before the paint is applied to the connection surface, a construction inspection of the high-strength bolts is carried out in accordance with the specifications. Inspection of high-strength bolts during construction must be completed 1 hour after final tightening and 24 hours before final tightening. If the inspection reveals that the fastening strength of the high-strength bolt does not meet the requirements, the tightening torque of the torque wrench used to tighten the high-strength bolt needs to be checked. If the inspection operation does not meet the specifications, the inspection must be expanded by 10%. If the inspection operation still does not meet the specifications, the high-strength bolts of the entire bolt joint must be retightened.

[0011] Furthermore, the initial tightening, final tightening, and inspection of the high-strength bolts are all performed using a torque wrench. The torque wrench is calibrated before and after operation. Before operation, the torque wrench is calibrated according to the calculated construction torque value. The calibrated torque error shall not exceed ±5% of the calculated construction torque value. After operation, the torque error of the torque wrench shall not exceed ±3% of the operation construction torque.

[0012] The advantages of this invention are: The construction method of this invention is verified through pre-testing. High-strength bolt tightening axial force test and anti-slip friction surface test are used to ensure that the bearing capacity of the connection surface meets the standard, avoiding fatigue crack propagation caused by excessive stress in the rain cover due to sudden changes in plate thickness. Furthermore, by optimizing the structure of bolt joints with different plate thicknesses, the thickness difference is eliminated, and the friction surface is cleaned to reduce the amplitude of fretting and slippage. After the steel structure components are hoisted into place, they are temporarily fixed with installation bolts. This process can adjust the position of the components and reduce the scraping of the friction surface when the high-strength bolts are inserted, thereby improving the anti-slip performance. Then, initial tightening and final tightening are performed to eliminate the gap between the plate joints in stages, ensuring accurate torque transmission, thereby improving the fatigue life of the steel structure joints.

[0013] The construction method of this invention adopts different treatments for different plate thickness differences in single-sided plate bolt joints. When the plate thickness difference is small (t < 1 mm), the stress concentration effect is negligible, and no additional treatment is required to avoid excessive processing and resource waste. For moderate plate thickness differences of 1 mm ≤ t < 3 mm, the thicker plate is ground with a slope to achieve a smooth transition in plate thickness, reducing stress concentration caused by sudden thickness changes and preventing fatigue cracks. For severe plate thickness differences of t ≥ 3 mm, a clamping plate of the same material as the component is added to fill the gap formed by the plate thickness difference. The friction surface of the clamping plate and the component are treated in the same way to ensure uniform contact and load distribution, avoiding local extrusion deformation or hole wall tearing. For double-sided plate bolt joints, clamping plates are added symmetrically to maintain the bolt axis perpendicular to the force, avoid eccentric bending moment caused by unilateral gaps, and reduce additional shear force on the bolt. Attached Figure Description

[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0015] Figure 1 This is a schematic diagram of the single-sided pad bolt joint treatment of the present invention with t < 1 mm.

[0016] Figure 2 This is a schematic diagram of the single-sided pad bolt joint treatment of 1mm≤t<3mm according to the present invention.

[0017] Figure 3 This is a schematic diagram of the bolt joint treatment of a single-sided pad plate with a diameter of t≥3mm according to the present invention.

[0018] Figure 4 This is a schematic diagram of the double-sided pad bolt joint treatment of the present invention. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] Example This embodiment provides a method for constructing torsion-shear type high-strength bolts for steel structure nodes, including the following steps: Step 1: Conduct axial force tests and anti-slip friction surface tests on high-strength bolts to determine the torque coefficient control value and calibrate the torque wrench; The torque coefficient of high-strength bolts is tested before assembly, based on the changes in ambient temperature and relative humidity during the construction period. This allows for the selection of the appropriate torque coefficient during the assembly of steel structure components, ensuring that the high-strength bolts accurately reach the designed preload.

[0021] Step 2: After processing the bolt joints with different plate thicknesses, clean the friction surfaces of the steel structure components. After the steel structure components are hoisted into place, they are temporarily fixed with installation bolts. Then, high-strength bolts are used to replace the installation bolts and initial tightening is performed. Finally, the high-strength bolts are tightened for the final tightening, and the connection surfaces are painted.

[0022] Bolted nodes include: Single-sided pad bolt joint: includes two interlocking steel structural members and a pad. The pad is set on one side of the joint of the two interlocking steel structural members. When the two interlocking steel structural members have different plate thicknesses, the wall surfaces of the two steel structural members away from the pad are flush with each other. One side of the pad is attached to the wall surface of the steel structural member with larger plate thickness, and the other side creates a gap t with the wall surface of the steel structural member with smaller plate thickness. Double-sided pad bolt joint: includes two interlocking steel structural members and two pads. The two pads are respectively set on both sides of the joint of the two interlocking steel structural members. When the two interlocking steel structural members have different plate thicknesses, the two pads are respectively attached to the two side walls of the steel structural member with larger plate thickness, and are left with the same distance from the same side wall of the steel structural member with smaller plate thickness. Methods for handling bolted joints in steel structures with different plate thicknesses include: like Figure 1As shown, for single-sided pad bolt nodes with t < 1 mm, the stress concentration effect can be ignored and no treatment is required to avoid excessive processing and waste of resources. like Figure 2 As shown, for single-sided pad bolt nodes with 1mm≤t<3mm, the wall surface of the steel structure member with thicker plate and the pad is ground to a slope of 1:10, so that the gap between the pad and the wall surface of the steel structure member with thinner plate is less than 1mm, so as to achieve a smooth transition of plate thickness, reduce stress concentration caused by sudden thickness change, and prevent fatigue cracks. like Figure 3 As shown, for single-sided pad bolt nodes with t≥3mm, a clamping plate is added between the pad and the steel structural member with a smaller plate thickness to fill the gap formed by the difference in plate thickness. The thickness of the clamping plate is d, d≥3mm and t-1mm<d<t+1mm. The material of the clamping plate and the friction surface treatment method are the same as those of the steel structural member to ensure uniform contact and load distribution, and avoid local extrusion deformation or hole wall tearing. like Figure 4 As shown, for double-sided plate bolt joints, a clamping plate is added between each of the two plates and the steel structural member with a smaller plate thickness to maintain the bolt axis perpendicular to the force, avoid eccentric bending moment caused by unilateral gap, and reduce additional shear force on the bolt. The material and friction surface treatment of the clamping plate are the same as those of the steel structural member.

[0023] In this embodiment, when using mounting bolts for temporary fixation, debris must not be allowed to enter the connection surface. The number of mounting bolts must not be less than 30% of the number of bolts in the corresponding bolt node, and must not be less than 2 bolts, forming multi-point constraints to prevent the component from slipping or overturning during hoisting and to avoid chain collapse caused by the failure of a single bolt.

[0024] When initially tightening high-strength bolts, start installation from the middle of the bolt group and tighten them one by one outwards. If the high-strength bolt cannot be freely inserted into the bolt hole, do not force it in to prevent thread deformation from causing preload failure or abnormal torque coefficient. Use an electric milling machine to correct and enlarge the hole before inserting it. The maximum diameter of the bolt hole after correction and enlargement should not exceed 1.2 times the nominal diameter of the bolt.

[0025] Complete the final tightening of the high-strength bolt within 24 hours after the initial tightening. The final tightening sequence is the same as the initial tightening. The final tightening of the high-strength bolt is considered qualified when the tail is unscrewed, while ensuring that 2 to 3 threads remain exposed outside the nut.

[0026] After the high-strength bolts are finally tightened and before the joint surfaces are painted, a construction inspection of the high-strength bolts should be carried out according to the specifications. The construction inspection of high-strength bolts should be completed 1 hour after the final tightening and 24 hours before the final tightening. During this 1-24 hour window, the preload loss of the high-strength bolts will gradually decrease, which will allow for better control of residual torque error and prevent over-tightening or under-tightening failure.

[0027] If the inspection reveals that the tightening strength of the high-strength bolt does not meet the requirements, it is necessary to check the tightening torque of the torque wrench used to tighten the high-strength bolt, quickly distinguish whether it is a tool failure or human error, and then address the source of the problem accordingly.

[0028] For each bolt group inspected, the number of unqualified bolts should not exceed 20% of the total number of bolts sampled. If it exceeds this, the sampling should continue until the cumulative sampling rate reaches 80%. Then, the bolts that are under-tightened should be tightened, and the bolts that are over-tightened should be replaced and retightened. If the inspection operation does not meet the specifications, the inspection should be expanded by 10%. If the inspection operation still does not meet the specifications, the high-strength bolts of the entire bolt group must be retightened to prevent the spread of systemic quality risks.

[0029] A torque wrench is used for initial tightening, final tightening, and inspection of high-strength bolts. The torque wrench is calibrated before and after operation. Before operation, the torque wrench is calibrated according to the calculated construction torque value. The calibrated torque error shall not exceed ±5% of the calculated construction torque value to avoid group under-tightening or over-tightening due to initial wrench deviation. The torque error after operation shall not exceed ±3% of the operation construction torque to detect hidden faults such as torque wrench gear wear and prevent the risk of loss of control due to excessive torque attenuation or deviation during construction.

[0030] The construction method is verified through pre-construction testing. High-strength bolt tightening axial force tests and anti-slip friction surface tests are used to ensure that the bearing capacity of the connection surface meets the standards, avoiding fatigue crack propagation caused by excessive stress in the rain cover due to sudden changes in plate thickness. Furthermore, the construction of bolt joints with different plate thicknesses is optimized to eliminate the thickness difference. After cleaning the friction surface, the amplitude of fretting and slippage is reduced. After the steel structure components are hoisted into place, they are temporarily fixed with installation bolts. This process can adjust the position of the components and reduce the scraping of the friction surface when the high-strength bolts are inserted, thereby improving the anti-slip performance. Then, initial tightening and final tightening are carried out in stages to eliminate the gap between the plate joints, ensuring accurate torque transmission and thus improving the fatigue life of the steel structure joints.

[0031] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for constructing torsion-shear type high-strength bolts for steel structure nodes, characterized in that: Includes the following steps: Step 1: Conduct axial force tests and anti-slip friction surface tests on high-strength bolts to determine the torque coefficient control value and calibrate the torque wrench; Step 2: After processing the bolt joints with different plate thicknesses, clean the friction surfaces of the steel structure components. After the steel structure components are hoisted into place, they are temporarily fixed with installation bolts. Then, high-strength bolts are used to replace the installation bolts and initial tightening is performed. Finally, the high-strength bolts are tightened for the final tightening, and the connection surfaces are painted.

2. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 1, characterized in that: The bolted joint includes: Single-sided pad bolt joint: includes two interlocking steel structural members and a pad. The pad is set on one side of the joint of the two interlocking steel structural members. When the two interlocking steel structural members have different plate thicknesses, the wall surfaces of the two steel structural members away from the pad are flush with each other. One side of the pad is attached to the wall surface of the steel structural member with larger plate thickness, and the other side creates a gap t with the wall surface of the steel structural member with smaller plate thickness. Double-sided pad bolt joint: includes two interlocking steel structural members and two pads. The two pads are respectively set on both sides of the joint of the two interlocking steel structural members. When the two interlocking steel structural members have different plate thicknesses, the two pads are respectively attached to the two side walls of the steel structural member with larger plate thickness, and are left with the same distance from the same side wall of the steel structural member with smaller plate thickness. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 2 is characterized in that: the method for treating steel structure bolt nodes with different plate thicknesses includes: No treatment is required for single-sided pad bolt joints with t < 1 mm; For single-sided pad bolt joints with 1mm≤t<3mm, the wall surface of the steel structure member with thicker plate that is in contact with the pad is ground to a slope of 1:10, so that the gap between the pad and the wall surface of the steel structure member with thinner plate is less than 1mm. For single-sided pad bolt nodes with t≥3mm, a clamping plate is added between the pad and the steel structural member with a small plate thickness. The thickness of the clamping plate is d, d≥3mm and t-1mm<d<t+1mm. The material of the clamping plate and the friction surface treatment method are the same as those of the steel structural member. For double-sided plate bolt joints, a clamping plate is added between each of the two plates and the steel structural member with the smaller plate thickness. The material and friction surface treatment of the clamping plate are the same as those of the steel structural member.

3. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 1, characterized in that: When using mounting bolts for temporary fixing in step 2, no foreign objects should be allowed to enter the connection surface. The number of mounting bolts should not be less than 30% of the number of bolts in the corresponding bolt node, and should not be less than 2.

4. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 1, characterized in that: When initially tightening the high-strength bolts in step 2, start installation from the middle of the bolt group and tighten them one by one outwards. If the high-strength bolts cannot be freely inserted into the bolt holes, do not force them in. Use an electric milling machine to correct and enlarge the holes before inserting them. The maximum diameter of the bolt holes after correction and enlargement should not exceed 1.2 times the nominal diameter of the bolts.

5. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 1, characterized in that: In step 2, the final tightening of the high-strength bolt is completed within 24 hours after the initial tightening. The final tightening sequence is the same as the initial tightening. The final tightening of the high-strength bolt is considered qualified when the tail is unscrewed, while ensuring that 2 to 3 threads remain exposed outside the nut.

6. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 1, characterized in that: In step 2, after the high-strength bolts are finally tightened and before the paint is applied to the joint surface, a construction inspection of the high-strength bolts is carried out in accordance with the specifications. Inspection of high-strength bolts during construction must be completed 1 hour after final tightening and 24 hours before final tightening. If the inspection reveals that the fastening strength of the high-strength bolt does not meet the requirements, the tightening torque of the torque wrench used to tighten the high-strength bolt needs to be checked. If the inspection operation does not meet the specifications, the inspection must be expanded by 10%. If the inspection operation still does not meet the specifications, the high-strength bolts of the entire bolt joint must be retightened.

7. The method for constructing torsion-shear type high-strength bolts for steel structure nodes according to claim 7, characterized in that: The initial tightening, final tightening, and inspection of the high-strength bolts are all performed using a torque wrench. The torque wrench is calibrated before and after operation. Before operation, the torque wrench is calibrated according to the calculated construction torque value. The calibrated torque error shall not exceed ±5% of the calculated construction torque value. After operation, the torque error of the torque wrench shall not exceed ±3% of the operation construction torque.

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