A construction method for modifying mispositioned embedded anchor bolts

Abstract

The application provides a pre-buried anchor bolt misalignment modification construction method, which solves the problem of long construction period and limited operation surface caused by the removal of the whole foundation after the misalignment of the pre-buried anchor bolt in the prior art. The method removes 500mm-800mm concrete on the top of the original reinforced concrete short column, retains the original steel bars and misaligned anchor bolts, cuts the original bolts without damage to retain 200mm exposed on the top, plants the steel bars on the top surface of the short column and processes the construction joint, fixes the new anchor bolts according to the new positioning size, uses the transverse and longitudinal reinforcing steel plates to melt and weld the new and old bolts, pours the concrete with one higher grade than the original to form the new short column, and pours the secondary pouring layer with one higher grade fine stone concrete after the installation of the steel column. The application is simple in construction, short in construction period, small in change of the original foundation, can meet the stress, installation precision of the upper steel structure and the construction period and operation surface requirements of the petrochemical device modification, and has little influence on production.

Description

Technical Field

[0001] This invention relates to the field of modifying embedded bolts in short columns of reinforced concrete foundations, specifically to a construction method for modifying misaligned embedded anchor bolts. Background Technology

[0002] Steel structures are a widely used structural load-bearing system across various industries. Steel structure systems are characterized by their inherent... Lightweight, easy to construct, and with a short construction period, steel structures are widely used in factories, stadiums, and residences. In the petrochemical industry, steel structures are widely used in various applications such as steel equipment frames, pipe corridors, and factory buildings, especially in the renovation of petrochemical plants. Steel structures are mainly composed of steel beams, steel columns, and steel trusses made of shaped steel and steel plates. The steel columns are connected to short concrete foundation columns via pre-embedded anchor bolts, forming a complete structural load-bearing system. Due to various reasons such as on-site construction errors, changes in the initial steel column dimensions, and subsequent plant modifications, the pre-embedded anchor bolts often become misaligned on the construction site, making it impossible to position and install the steel columns according to the design drawings.

[0003] To address this issue, existing technologies typically involve removing all existing concrete short columns and foundations, and then re-constructing concrete short columns and foundations according to the new positioning anchor bolts. This method can meet the connection, stress, and quality requirements of the superstructure steel columns for the pre-embedded anchor bolts. However, when re-casting concrete short columns and foundations and pre-embedding anchor bolts according to the new positioning dimensions, according to the requirements of the "Code for Design of Concrete Structures (GB / T50010-2024)" and the "Code for Acceptance of Construction Quality of Concrete Structures (GB50204-2015)," the actual bearing capacity of the re-cast concrete short columns and foundations must reach 100% of the design value, and the reinforced concrete curing time at room temperature needs to be approximately 28 days to meet the requirements. Due to the short construction period and heavy production tasks in the construction and renovation of petrochemical plants, the construction period often cannot meet the requirements. Furthermore, during the renovation construction process, the production unit is still in operation, and the construction work area is limited. Re-casting the foundation often lacks a mechanical work surface, making it impossible to meet the construction requirements for foundation demolition and re-excavation.

[0004] Therefore, we propose a construction method for correcting misaligned pre-embedded anchor bolts to solve the above problems. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a construction method for correcting misaligned pre-embedded anchor bolts. This method eliminates the need to remove the entire original foundation and allows for the repositioning of anchor bolts through only local modifications, significantly shortening the construction period and adapting to construction in confined spaces.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A construction method for modifying misaligned embedded anchor bolts is implemented based on the existing reinforced concrete short column, the existing misaligned anchor bolts, the newly added reinforced concrete short column, the secondary pouring layer, the newly added transverse reinforcing steel plate, the newly added longitudinal reinforcing steel plate, the newly positioned anchor bolts, welds, the steel column base plate, the steel column, and the connecting reinforcing bars. The specific steps are as follows: S1. Basic positioning and partial excavation First, a total station is used to accurately lay out the existing reinforced concrete short column, marking the area of ​​concrete to be removed. The planar dimensions of the removal area should be 50 mm larger than the design dimensions of the new reinforced concrete short column to facilitate subsequent formwork work. Removal is carried out manually with the aid of a small pneumatic hammer; the use of large crushing machinery is strictly prohibited to avoid excessive vibration to the existing foundation.

[0007] The removal process employs a layered removal method, with each layer's thickness controlled within 100 mm. Manual removal is mandatory within 30 mm of the existing reinforcing bars and misaligned anchor bolts; damage to these materials is strictly prohibited. After removal, use a wire brush to clean the surface of the existing reinforcing bars of concrete debris. Inspect the existing reinforcing bars and misaligned anchor bolts for damage; if any damage is found, reinforcement measures should be taken immediately. The flatness deviation of the removed surface should be controlled within ±10 mm. The preferred removal depth is 500 mm to 800 mm. This depth ensures the required anchorage length for the connection between the old and new anchor bolts while minimizing damage to the existing foundation.

[0008] S2. Treatment of existing bolts and construction joints The misaligned anchor bolts were cut non-destructively using a diamond saw blade. Cooling water was used during cutting to prevent deformation and material changes caused by heat. A length of 200 mm ± 5 mm was left exposed above the cut surface. This length provides sufficient operating space for subsequent welding operations while ensuring the strength of the welded connection. After cutting, the cut was smoothed with an angle grinder to remove burrs and oxide scale, revealing the metallic luster.

[0009] The construction joint of the original reinforced concrete short column top surface after removal is treated as follows: The concrete surface is manually roughened until the coarse aggregate is exposed. The roughening depth is controlled at 5 mm to 8 mm, and the roughening points are evenly distributed, with no less than 300 points per square meter. Then, the surface is blown away with compressed air at 0.5 MPa to 0.7 MPa to ensure that there are no loose concrete particles or dust. Finally, a cement-based interface agent is evenly applied, with a water-cement ratio controlled at 0.4 to 0.5, and a dosage of 0.3 kg / m² to 0.5 kg / m². The next construction step should be carried out within 30 minutes after application to prevent the interface agent from drying and becoming ineffective.

[0010] S3, Chemical Rebar Installation On the treated top surface of the existing reinforced concrete short column, drill holes for connecting reinforcing bars are arranged in a quincunx pattern at 250 mm intervals, and the center point of each hole is marked with chalk. Drill the holes using an impact drill with a diameter of 16 mm and a depth of 180 mm (i.e., 15 times the diameter of the connecting reinforcing bar). When drilling, the drill bit should be kept perpendicular to the top surface, with a deviation of no more than 2 degrees.

[0011] After drilling is completed, a hole cleaning operation should be performed: First, use a brush to brush back and forth inside the hole to remove dust from the hole wall. Then, use compressed air to blow air from the bottom of the hole to the opening to blow out the dust. Repeat this process at least three times to ensure that there is no dust, water, or oil in the hole. After cleaning, temporarily seal the hole opening with cotton thread to prevent debris from falling in.

[0012] Injecting the anchoring adhesive: Use modified epoxy resin anchoring adhesive. Mix components A and B evenly according to the product instructions. Use a special syringe to inject the anchoring adhesive into the hole, filling it to 2 / 3 of the hole depth. Then, slowly rotate and insert the HPB300 hot-rolled plain round connecting steel bar into the hole until the connecting steel bar reaches the bottom of the hole, ensuring that the adhesive evenly coats the surface of the connecting steel bar. Clean up any excess adhesive that overflows from the hole promptly.

[0013] During the curing period of the anchoring adhesive, it is strictly forbidden to touch the connecting steel bars. The curing time shall not be less than 72 hours (ambient temperature 20 degrees Celsius ± 5 degrees Celsius). After curing, a non-destructive pull-out test shall be conducted in accordance with the requirements of the "Technical Specification for Post-Anchoring of Concrete Structures". The number of samples tested shall be 1% of the number of anchored steel bars in each batch, and not less than 3 bars. The pull-out force of a single connecting steel bar shall not be less than 12 kN. Only after the test is passed can the next step of construction be carried out.

[0014] S4. New bolt positioning and reinforcement welding The newly positioned anchor bolts are secured using a three-dimensional adjustable bracket. The bracket should possess sufficient rigidity and stability to prevent displacement of the anchor bolts during welding and concrete pouring. By adjusting the adjusting bolts on the bracket, the planar position, verticality, and elevation of the newly positioned anchor bolts are precisely adjusted: planar position deviation ≤ 2 mm, verticality deviation ≤ 1 / 1000, and elevation deviation ≤ +5 mm. After adjustment, the bracket is temporarily welded and fixed to the reinforcing steel of the existing reinforced concrete short column.

[0015] A Q235-B carbon structural steel plate with the same diameter and thickness as the newly positioned anchor bolts is cut and processed into additional transverse and longitudinal reinforcing steel plates. The width of the steel plate is 3 to 4 times the diameter of the newly positioned anchor bolts, and the length is determined according to the spacing between the old and new anchor bolts. The length extending beyond the center line of the bolts at both ends is not less than twice the diameter of the newly positioned anchor bolts. For example, when the diameter of the newly positioned anchor bolts is 30 mm, the steel plate thickness is 30 mm, the width is 100 mm, the length is determined according to the actual spacing, and each end extends 60 mm beyond the center line of the bolts.

[0016] Before welding, grind the welding areas of the existing misaligned anchor bolts, newly positioned anchor bolts, and newly added transverse and longitudinal reinforcing steel plates with an angle grinder until the metal luster is exposed, removing oil, rust, and scale. Use E43 series carbon steel welding rods for bevel penetration welding, controlling the welding current at 160-200 amps and the welding speed at 150-200 mm / min. Employ a symmetrical welding method to avoid welding deformation. The weld height should be no less than 0.7 times the diameter of the newly positioned anchor bolts and no less than 8 mm. After welding, gently tap the weld with a small hammer to remove slag and perform a visual inspection. The weld surface must be free of defects such as cracks, porosity, slag inclusions, and incomplete penetration. For welds in critical areas, ultrasonic testing should be performed. The weld quality level should be no lower than level two. The top of the original misaligned anchor bolts should be welded and fixed to one side of the newly added transverse reinforcing steel plate near the bottom. The newly positioned anchor bolts should be welded and fixed to the other side of the newly added transverse reinforcing steel plate near the top. The newly added transverse reinforcing steel plate and the newly added longitudinal reinforcing steel plate are welded to form a T-shaped structure.

[0017] S5, New short column concrete pouring For the erection of new reinforced concrete short columns, steel formwork with a thickness of not less than 15 mm should be used. The formwork should be bolted together, and sponge strips should be pasted at the joints to prevent grout leakage. The outside of the formwork should be reinforced with steel pipe scaffolding and tie bolts, with the spacing of the tie bolts not exceeding 600 mm, to ensure the rigidity and stability of the formwork. The verticality deviation of the formwork should be ≤3 mm.

[0018] Concrete pouring: Use concrete of a higher strength grade than the existing reinforced concrete short column. For example, if the existing reinforced concrete short column is of strength grade C30, then the new reinforced concrete short column should use concrete of strength grade C35. The concrete should have good workability, and the slump should be controlled within 120 mm ± 20 mm. Use a layered pouring method, with each layer ≤ 300 mm thick. Use an immersion vibrator for compaction, inserting the vibrator at least 50 mm into the lower layer of concrete. Vibrate until the concrete surface is smooth and no air bubbles emerge. Under-vibration and over-vibration are strictly prohibited.

[0019] The top surface elevation of the newly added reinforced concrete short column should be 20 mm to 30 mm higher than the design elevation. After the concrete has initially set, it should be smoothed with a wooden trowel to ensure that the flatness deviation of the top surface is ≤5 mm. After pouring, geotextile should be covered in a timely manner for moisture retention and curing. The curing time should not be less than 14 days. During the curing period, it is strictly forbidden to pile heavy objects on the concrete surface or to carry out impact operations.

[0020] S6. Steel column installation and leveling Once the concrete strength of the newly added reinforced concrete short column reaches more than 75% of the design strength, remove the formwork and clean up any debris and water on the top surface of the column. Use a truck crane or manual hoist to lift the steel column base plate and steel column, align the bolt holes on the base plate with the newly positioned anchor bolts, and slowly lower the column.

[0021] The verticality and elevation of the steel columns were adjusted using a theodolite and a level: Verticality was observed by setting up a theodolite on two mutually perpendicular sides of the steel column, and the shims at the bottom of the steel column were adjusted to ensure a verticality deviation ≤ 1 / 1000; Elevation was determined by observing the elevation baseline at the top of the steel column using a level, and the nuts of the newly positioned anchor bolts were adjusted to ensure an elevation deviation ≤ ±3 mm. After adjustment, flat washers, spring washers, and double nuts were installed in sequence, and the nuts were tightened to the torque required by the design, which should comply with the provisions of the "Standard for Acceptance of Construction Quality of Steel Structures".

[0022] S7, Secondary pouring layer construction Erect perimeter grout-blocking formwork in the gap between the steel column base plate and the newly added reinforced concrete short column. The formwork should be 50 mm higher than the bottom surface of the steel column base plate. Use cement mortar to seal the gap between the formwork and the foundation to prevent grout leakage.

[0023] The secondary grouting layer is constructed using non-shrink fine-aggregate concrete of a higher strength grade than that used in the newly added reinforced concrete short columns. The slump of the concrete is controlled at 180 mm ± 20 mm, and an appropriate amount of expansion agent is added to compensate for concrete shrinkage. During pouring, the concrete is continuously poured from one side of the steel column base plate until it overflows from the other side. A small vibrator is used to assist in air removal during the pouring process to ensure that all voids are completely filled and no voids are left. The thickness of the secondary grouting layer is 50 mm to 100 mm, and its top surface should be flush with the bottom surface of the steel column base plate.

[0024] After the concrete pouring is completed, cover it with geotextile fabric for timely moisture retention and curing, which should last for no less than 7 days. During the curing period, it is strictly forbidden to bump into the steel columns, and welding, cutting, and hoisting operations are prohibited on the steel columns. Once the secondary concrete pouring layer has reached 100% of its design strength, the installation of the upper steel structure can begin. Beneficial effects

[0025] Compared with the prior art, the present invention has the following advantages: This invention can meet the connection, stress, and quality requirements of the pre-embedded anchor bolts for the upper structural steel columns, while also satisfying the construction work area, schedule, and production requirements during the renovation of petrochemical plants. It minimizes the impact on plant production. The pre-embedded anchor bolt misalignment modification construction method of this invention is characterized by simple construction, short construction period, and minimal impact on plant production. Attached Figure Description

[0026] Figure 1 This is a construction flowchart of the present invention; Figure 2 This is a front elevation view of the construction method for correcting misaligned anchor bolts according to the present invention.

[0027] Figure 3 This is a plan view of the construction method for correcting misaligned anchor bolts according to the present invention.

[0028] Figure 4 This is a schematic diagram of the connection between the old and new anchor bolts in the pre-embedded anchor bolt misalignment modification construction method of the present invention.

[0029] Figure 5 This is a schematic diagram of the original anchor bolts in the construction method for modifying the misalignment of the pre-embedded anchor bolts according to the present invention.

[0030] Numbering in the diagram: 1-Existing reinforced concrete short column; 2-Existing misaligned anchor bolts; 3-Newly added reinforced concrete short column; 4-Secondary pouring layer; 5-Newly added transverse reinforcing steel plate; 6-Newly added longitudinal reinforcing steel plate; 7-Newly positioned anchor bolts; 8-Weld; 9-Steel column base plate; 10-Steel column; 11-Connecting reinforcing bars. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Implementation like Figure 1-5 As shown, a construction method for modifying misaligned pre-embedded anchor bolts is implemented based on the existing reinforced concrete short column 1, the existing misaligned anchor bolts 2, the newly added reinforced concrete short column 3, the secondary pouring layer 4, the newly added transverse reinforcing steel plate 5, the newly added longitudinal reinforcing steel plate 6, the newly positioned anchor bolts 7, the weld 8, the steel column base plate 9, the steel column 10, and the connecting steel bars 11. The specific steps are as follows: S1. Basic positioning and partial excavation First, a total station is used to accurately lay out the existing reinforced concrete short column 1, marking the area of ​​concrete to be removed. The planar dimensions of the removal area should be 50 mm larger than the design dimensions of the new reinforced concrete short column 3 to facilitate subsequent formwork work. Removal is carried out manually with the aid of a small pneumatic hammer; the use of large crushing machinery is strictly prohibited to avoid excessive vibration to the existing foundation.

[0033] The removal process employs a layered removal method, with each layer's thickness controlled within 100 mm. Within 230 mm of the original reinforcing bars and misaligned anchor bolts, manual removal is mandatory, and damage to the original reinforcing bars and misaligned anchor bolts is strictly prohibited. After removal, use a wire brush to clean the concrete debris from the surface of the original reinforcing bars and inspect the original reinforcing bars and misaligned anchor bolts for damage. If damage is found, reinforcement measures should be taken immediately. The flatness deviation of the removed surface should be controlled within ±10 mm. The preferred removal depth is 500 mm to 800 mm, which ensures the required anchorage length for the connection between the old and new anchor bolts while minimizing damage to the original foundation.

[0034] S2. Treatment of existing bolts and construction joints The misaligned anchor bolt 2 was cut non-destructively using a diamond saw blade. Cooling water was used during the cutting process to prevent deformation and material changes caused by heat. A length of 200 mm ± 5 mm was left exposed above the cut surface. This length provides sufficient operating space for subsequent welding operations while ensuring the strength of the welded connection. After cutting, the cut was smoothed with an angle grinder to remove burrs and oxide scale, revealing the metallic luster.

[0035] The construction joint of the original reinforced concrete short column 1 after removal is treated as follows: The concrete surface is manually roughened until the coarse aggregate is exposed. The roughening depth is controlled at 5 mm to 8 mm, and the roughening points are evenly distributed, with no less than 300 points per square meter. Then, the surface is blown away with compressed air at 0.5 MPa to 0.7 MPa to ensure that there are no loose concrete particles or dust. Finally, a cement-based interface agent is evenly applied. The water-cement ratio of the interface agent is controlled at 0.4 to 0.5, and the dosage is 0.3 kg / m² to 0.5 kg / m². The next construction step should be carried out within 30 minutes after application to prevent the interface agent from drying and becoming ineffective.

[0036] S3, Chemical Rebar Installation On the top surface of the existing reinforced concrete short column 1, drill holes for connecting reinforcing bars 11 are arranged in a quincunx pattern at 250 mm intervals, and the center point of each hole is marked with chalk. Drilling is carried out using an impact drill with a diameter of 16 mm and a depth of 180 mm (i.e., 15 times the diameter of the connecting reinforcing bar). When drilling, the drill bit should be kept perpendicular to the top surface, with a deviation of no more than 2 degrees.

[0037] After drilling is completed, a hole cleaning operation should be performed: First, use a brush to brush back and forth inside the hole to remove dust from the hole wall. Then, use compressed air to blow air from the bottom of the hole to the opening to blow out the dust. Repeat this process at least three times to ensure that there is no dust, water, or oil in the hole. After cleaning, temporarily seal the hole opening with cotton thread to prevent debris from falling in.

[0038] Injecting the anchoring adhesive: Use modified epoxy resin anchoring adhesive. Mix components A and B evenly according to the product instructions. Use a special syringe to inject the anchoring adhesive into the hole, filling it to 2 / 3 of the hole depth. Then, slowly rotate and insert the HPB300 hot-rolled plain round connecting steel bar 11 into the hole until the connecting steel bar 11 reaches the bottom of the hole, ensuring that the adhesive evenly coats the surface of the connecting steel bar 11. Clean up any excess adhesive that overflows from the hole promptly.

[0039] During the curing period of the anchoring adhesive, it is strictly forbidden to touch the connecting rebar 11. The curing time shall not be less than 72 hours (ambient temperature 20 degrees Celsius ± 5 degrees Celsius). After curing, a non-destructive pull-out test shall be conducted in accordance with the requirements of the "Technical Specification for Post-Anchoring of Concrete Structures". The number of samples tested shall be 1% of the number of anchored rebars in each batch, and not less than 3. The pull-out force of a single connecting rebar 11 shall not be less than 12 kN. Only after the test is passed can the next step of construction be carried out.

[0040] S4. New bolt positioning and reinforcement welding The newly positioned anchor bolts 7 are fixed using a three-dimensional adjustable bracket. The bracket should have sufficient rigidity and stability to prevent displacement of the anchor bolts during welding and concrete pouring. The planar position, verticality, and elevation of the newly positioned anchor bolts 7 are precisely adjusted by adjusting the adjusting bolts on the bracket: planar position deviation ≤ 2 mm, verticality deviation ≤ 1 / 1000, and elevation deviation ≤ +5 mm. After adjustment, the bracket is temporarily welded and fixed to the reinforcing bars of the existing reinforced concrete short column 1.

[0041] A carbon structural steel plate of grade Q235-B with the same diameter and thickness as the newly positioned anchor bolt 7 is cut and processed into a new transverse reinforcing steel plate 5 and a new longitudinal reinforcing steel plate 6. The width of the steel plate is 3 to 4 times the diameter of the newly positioned anchor bolt 7, and the length is determined according to the spacing between the old and new anchor bolts. The length extending beyond the center line of the bolts at both ends is not less than twice the diameter of the newly positioned anchor bolt 7. For example, when the diameter of the newly positioned anchor bolt 7 is 30 mm, the thickness of the steel plate is 30 mm, the width is 100 mm, the length is determined according to the actual spacing, and each end extends 60 mm beyond the center line of the bolt.

[0042] Before welding, grind the welding areas of the original misaligned anchor bolts 2, the newly positioned anchor bolts 7, the newly added transverse reinforcing steel plates 5 and 6 with an angle grinder until the metal luster is exposed, removing oil, rust, and scale. Use E43 series carbon steel welding rods for bevel penetration welding, controlling the welding current at 160-200 amps and the welding speed at 150-200 mm / min. Use a symmetrical welding method to avoid welding deformation. The height of weld 8 should be no less than 0.7 times the diameter of the newly positioned anchor bolts 7, and no less than 8 mm. After welding, gently tap weld 8 with a small hammer to remove slag and perform a visual inspection. The surface of weld 8 should be free of defects such as cracks, porosity, slag inclusions, and incomplete penetration. For welds 8 in critical areas, ultrasonic testing should also be performed. The quality grade of weld 8 should not be lower than level 2. The top of the original misaligned anchor bolts 2 is welded and fixed to one side of the newly added transverse reinforcing steel plate 5 near the bottom. The newly positioned anchor bolts 7 are welded and fixed to the other side of the newly added transverse reinforcing steel plate 5 near the top. The newly added transverse reinforcing steel plate 5 and the newly added longitudinal reinforcing steel plate 6 are welded to form a T-shaped structure.

[0043] S5, New short column concrete pouring Erect formwork for the newly added reinforced concrete short column 3. The formwork should be made of steel with a thickness of not less than 15 mm. The formwork should be bolted together, and sponge strips should be pasted at the joints to prevent grout leakage. The outside of the formwork should be reinforced with steel pipe scaffolding and tie bolts. The spacing of the tie bolts should not exceed 600 mm to ensure the rigidity and stability of the formwork. The verticality deviation of the formwork should be ≤3 mm.

[0044] Concrete pouring: Use concrete of a higher strength grade than the existing reinforced concrete short column 1. For example, if the existing reinforced concrete short column 1 is C30 grade concrete, then the new reinforced concrete short column 3 should be C35 grade concrete. The concrete should have good workability, and the slump should be controlled within 120 mm ± 20 mm. Use a layered pouring method, with each layer ≤ 300 mm thick. Use an immersion vibrator for compaction, inserting the vibrator at least 50 mm into the lower layer of concrete. Vibrate until the concrete surface is smooth and no air bubbles emerge. Under-vibration and over-vibration are strictly prohibited.

[0045] The top surface elevation of the newly added reinforced concrete short column 3 should be 20 mm to 30 mm higher than the design elevation. After the concrete has initially set, it should be smoothed with a wooden trowel to ensure that the flatness deviation of the top surface is ≤5 mm. After pouring, geotextile should be covered in time for moisture retention and curing. The curing time should not be less than 14 days. During the curing period, it is strictly forbidden to pile heavy objects on the concrete surface or to carry out impact operations.

[0046] S6. Steel column installation and leveling Once the concrete strength of the newly added reinforced concrete short column 3 reaches more than 75% of the design strength, remove the formwork and clean up any debris and water on the top surface of the new reinforced concrete short column 3. Use a truck crane or manual hoist to lift the steel column base plate 9 and steel column 10, align the bolt holes on the steel column base plate 9 with the newly positioned anchor bolts 7, and slowly lower the steel column 10.

[0047] The verticality and elevation of steel column 10 were adjusted using a theodolite and a level: Verticality was observed by setting up a theodolite on two mutually perpendicular sides of steel column 10, and the shims at the bottom of steel column 10 were adjusted to ensure a verticality deviation ≤ 1 / 1000; elevation was observed using a level to determine the elevation baseline at the top of steel column 10, and the nuts of the newly positioned anchor bolts 7 were adjusted to ensure an elevation deviation ≤ ±3 mm. After adjustment, flat washers, spring washers, and double nuts were installed sequentially, and the nuts were tightened to the torque required by the design. The tightening torque should comply with the provisions of the "Standard for Acceptance of Construction Quality of Steel Structures".

[0048] S7, Secondary pouring layer construction A perimeter grout-blocking formwork is erected in the gap between the steel column base plate 9 and the newly added reinforced concrete short column 3. The formwork should be 50 mm higher than the bottom surface of the steel column base plate 9. Cement mortar is used to seal the gap between the formwork and the foundation to prevent grout leakage.

[0049] The secondary grouting layer 4 is constructed using non-shrink fine-aggregate concrete of a higher strength grade than that used in the newly added reinforced concrete short column 3. The slump of the concrete is controlled at 180 mm ± 20 mm, and an appropriate amount of expansion agent is added to compensate for concrete shrinkage. During pouring, the concrete is continuously poured from one side of the steel column base plate 9 until it overflows from the other side. A small vibrator is used to assist in air removal during the pouring process to ensure that all gaps are completely filled and no voids are left. The thickness of the secondary grouting layer 4 is 50 mm to 100 mm, and its top surface should be flush with the bottom surface of the steel column base plate 9.

[0050] After pouring, cover with geotextile fabric promptly for moisture retention and curing for no less than 7 days. During the curing period, collisions with steel column 10 are strictly prohibited, as are welding, cutting, and hoisting operations on steel column 10. Once the concrete strength of the secondary pouring layer 4 reaches 100% of the design strength, the installation of the upper steel structure can commence.

[0051] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A construction method for correcting misaligned pre-embedded anchor bolts, characterized in that, Includes the following steps: S1. Foundation positioning and partial removal: Mark the removal area on the top surface of the original reinforced concrete short column (1), and remove the top part of the concrete by manual labor and small construction tools, while retaining the main reinforcement, stirrups and original misaligned anchor bolts (2) of the original reinforced concrete short column (1). S2. Treatment of existing bolts and construction joints: Non-destructive cutting of existing misaligned anchor bolts (2) is carried out, leaving an appropriate length of exposed surface; the top surface of the excavation is roughened manually, and after blowing away the slag, an interface agent is applied. S3, Chemical anchoring construction: Drill holes in a quincunx pattern on the top surface after chiseling, clean the holes and inject anchoring adhesive, then insert connecting steel bars (11), and conduct a pull-out test after the anchoring adhesive has cured. S4. Positioning and reinforcement welding of new bolts: The new anchor bolts (7) are fixed with adjustable brackets, and their plane position, verticality and elevation are adjusted to meet the requirements; the original misaligned anchor bolts (2) and the new anchor bolts (7) are welded together with the newly added transverse reinforcement steel plates (5) and longitudinal reinforcement steel plates (6); S5. Concrete pouring of new short columns: Set up and reinforce the formwork, pour concrete with a strength grade one level higher than the original reinforced concrete short column (1), compact it in layers and then carry out moisture curing to form new reinforced concrete short columns (3). S6. Steel column installation and leveling: After the concrete strength of the newly added reinforced concrete short column (3) reaches the design requirements, hoist the steel column base plate (9) and steel column (10), adjust the verticality and elevation of the steel column (10) to meet the requirements, and tighten the nuts of the newly positioned anchor bolts (7). S7. Construction of the secondary grouting layer: Set up the surrounding grouting formwork, and use fine stone concrete with a strength grade one level higher than that of the newly added reinforced concrete short column (3) to pour the secondary grouting layer (4). After the pouring is completed, carry out curing.

2. The construction method for correcting misaligned embedded anchor bolts according to claim 1, characterized in that, In step S1, when removing concrete, a layered removal method is used. Within a certain range from the original reinforcing bars and the original misaligned anchor bolts (2), manual removal is used. Damage to the original reinforcing bars and the original misaligned anchor bolts (2) is strictly prohibited.

3. The construction method for modifying misaligned embedded anchor bolts according to claim 1, characterized in that, In step S2, after the original misaligned anchor bolt (2) is cut, the cut is ground flat to remove burrs and oxide scale.

4. The construction method for modifying misaligned embedded anchor bolts according to claim 1, characterized in that, In step S3, the hole is cleaned repeatedly with a brush and compressed air to ensure that there is no dust, water or oil in the hole; the amount of adhesive injected is moderate, and the connecting steel bar (11) is slowly rotated when inserted to ensure that the adhesive evenly coats the surface of the connecting steel bar (11).

5. The construction method for correcting misaligned embedded anchor bolts according to claim 1, characterized in that, In step S4, the dimensions of the newly added transverse reinforcing steel plate (5) and the newly added longitudinal reinforcing steel plate (6) are determined according to the diameter of the newly positioned anchor bolt (7) and the distance between the old and new bolts, with both ends extending an appropriate length beyond the bolt centerline.

6. The construction method for correcting misaligned embedded anchor bolts according to claim 1, characterized in that, In step S4, before welding, the welding areas of the original misaligned anchor bolts (2), the newly positioned anchor bolts (7), the newly added transverse reinforcing steel plates (5), and the newly added longitudinal reinforcing steel plates (6) are ground until the metal luster is exposed, and the weld (8) is formed by full penetration welding. After welding, the welding slag is removed and the quality of the weld (8) is inspected.

7. The construction method for modifying misaligned embedded anchor bolts according to claim 1, characterized in that, In step S5, the top surface elevation of the newly added reinforced concrete short column (3) is appropriately higher than the design elevation, and after the concrete has initially set, it is smoothed by troweling.

8. The construction method for correcting misaligned embedded anchor bolts according to claim 1, characterized in that, In step S7, the secondary grouting layer (4) is poured continuously from one side of the steel column base plate (9) until it overflows from the other side. During the pouring process, venting is assisted. During the curing period, collisions with the steel column (10) and work on the steel column (10) are prohibited.

9. The construction method for correcting misaligned embedded anchor bolts according to claim 1, characterized in that, In step S4, the top of the original misaligned anchor bolt (2) is welded and fixed to one side of the newly added transverse reinforcing steel plate (5) near the bottom, and the newly positioned anchor bolt (7) is welded and fixed to the other side of the newly added transverse reinforcing steel plate (5) near the top. The newly added transverse reinforcing steel plate (5) and the newly added longitudinal reinforcing steel plate (6) are welded to form a T-shaped structure.

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