Modular reinforcing device and method for forming large hole in concrete structural beam

Abstract

The invention provides a modular reinforcing device and method for forming a large hole in a concrete structural beam, the reinforcing device comprises a prefabricated split type steel sleeve assembly and a welding type U-shaped hoop plate module, the prefabricated split type steel sleeve assembly comprises four L-shaped steel plates, a convex rib is machined on the outer side of each L-shaped steel plate, and the welding type U-shaped hoop plate module is arranged on the outer side of each L-shaped steel plate; the four L-shaped steel plates are spliced through bolts to form an annular constraint sleeve; the welded U-shaped hoop plate module is a U-shaped frame formed by welding a bottom plate and two vertical plates, anchor bolt holes are formed in the vertical plates, and stiffening steel plates are symmetrically welded to the outer sides of the two vertical plates. And a preset glue injection hole is formed in the concrete beam. By means of the prefabricated assembly design and the standardized construction technology, efficient assembly and reliable stress of the reinforced structure are achieved, and the safety requirement of building transformation engineering is met.

Description

Technical Field

[0001] The present invention relates to the technical field of building structure reinforcement, and in particular to a modular reinforcement device and method for opening a large hole in a concrete structural beam, which is suitable for structural reinforcement of concrete beams in projects such as industrial and civil building renovation and pipeline crossing. Background Art

[0002] In building function renovation or pipeline laying projects, it is often necessary to open large-sized openings in concrete beams (the opening size usually exceeds 1 / 3 of the beam section height), such as Figure 1 However, randomly opening holes will significantly weaken the cross-sectional stiffness and bearing capacity of concrete beams, leading to crack expansion around the holes, increased deformation of the beam body, and even structural safety accidents. Existing reinforcement technologies mostly use on-site welding of steel casings combined with U-shaped hoop plates, but this has the following drawbacks:

[0003] 1. Low construction efficiency: Steel casing and U-shaped hoop plates need to be cut and welded on-site, with welding accounting for over 70% of the workload. Welding is significantly affected by ambient temperature and humidity, and welding quality is difficult to guarantee in low-temperature environments.

[0004] 2. Weak interface force transmission: The steel casing and concrete are only bonded by structural adhesive, and the shear stiffness is insufficient. The measured interface slip can reach 0.3mm, which can easily lead to stress concentration.

[0005] 3. Low degree of modularity: On-site operations rely on manual assembly, component dimensional accuracy is poor, adaptability to irregular openings is weak, and large-scale application is impossible.

[0006] Therefore, there is an urgent need for a prefabricated, modular reinforcement device and method to improve construction efficiency and structural safety. Summary of the Invention

[0007] In response to the problems of complex construction and poor interface force transmission in the existing technology for reinforcing concrete structural beams with large holes, the present invention provides a modular reinforcement device and method for reinforcing concrete structural beams with large holes. Through prefabricated component design and standardized construction technology, efficient assembly and reliable force bearing of the reinforced structure are achieved, meeting the safety requirements of building renovation projects.

[0008] The above-mentioned object of the present invention can be achieved by the following technical solutions:

[0009] A modular reinforcement device for large holes in concrete structural beams, comprising a prefabricated split steel casing assembly and a welded U-shaped hoop module. The prefabricated split steel casing assembly comprises four prefabricated L-shaped steel plates (8-12 mm thick), each with ribs spaced 50-150 mm apart and 3-8 mm high machined on the outside. The ribs enhance mechanical engagement with the concrete. The four L-shaped steel plates are bolted together to form an annular restraining casing.

[0010] The welded U-shaped hoop module is a U-shaped frame welded from a bottom plate (8-14mm thick) and two vertical plates (6-12mm thick). Anchor holes are opened on the vertical plates, and stiffening steel plates (6-10mm thick) are symmetrically welded on the outside of the two vertical plates.

[0011] Pre-set glue injection holes (10mm in diameter, 200mm in spacing) and exhaust holes (8mm in diameter) are opened on the concrete beam. If necessary, they can also be opened on the steel casing and U-shaped hoop plate to ensure that the glue is fully filled.

[0012] Furthermore, fixing pin inserts are provided on both sides of the L-shaped steel plate ends. The fixing pin inserts ensure assembly accuracy and prevent the expansion of cracks in the hole. Bolt connection holes are opened on the fixing pin inserts. The four L-shaped steel plates are connected and fixed with bolts through the fixing pin inserts. The pre-tightening force of the bolts is 100-160N·m.

[0013] Furthermore, the middle sleeve of the bolt is provided with a plurality of steel washers, through which the length and width of the steel sleeve can be adjusted to meet the needs of holes of different sizes.

[0014] Furthermore, the height of the vertical plate is 1.2-1.8 times higher than the height of the opening.

[0015] Furthermore, the spacing of the anchor holes is 100-150mm, the diameter d of the chemical anchor is 12-18mm, and a modified epoxy resin structural hose is used. The anchoring depth is ≥10d (d is the diameter of the chemical anchor), and the design value of the single-bolt pull-out bearing capacity is ≥10kN.

[0016] Furthermore, a modified epoxy resin structural adhesive is injected into the preset glue injection hole, with a bonding strength of ≥10MPa, and can be cured in an environment above 5°C.

[0017] Another object of the present invention is to provide a modular reinforcement method for a concrete structural beam with a large hole, comprising the following steps:

[0018] Finite element analysis was used to determine that the unloading capacity was 30%-50% of the design load. The unloading was carried out in stages using hydraulic jacks, with each stage holding the load for 20 minutes and the displacement deviation controlled to be ≤3mm. The split steel casing components and welded U-shaped hoop plate modules were prefabricated in the factory, with a pre-assembly error of ≤2mm.

[0019] Insert four L-shaped steel plates into the hole, temporarily fix them with fixing pins, and tighten the bolts in diagonal order to form a ring-shaped constraint sleeve. Set several steel washers in the middle as needed. Use these steel washers to adjust the length and width of the steel sleeve to meet the needs of holes of different sizes.

[0020] Fit the bottom plate to the bottom surface of the beam, weld the vertical plate to the bottom plate, and ensure the weld height is ≥6mm; symmetrically weld stiffening steel plates on the outside of the vertical plate with a spacing of 200mm to form a three-dimensional force system;

[0021] Drill holes at the corresponding locations of the anchor holes, clean the holes and implant chemical anchors. After curing for 24 hours, perform a pull-out test. The design value of the pull-out bearing capacity of a single bolt is ≥10kN.

[0022] Inject modified epoxy resin structural adhesive from the lowest preset injection hole, control the pressure at 0.2-0.3MPa, until the air vent overflows with bubble-free adhesive, maintain the pressure for 5 minutes and then seal the hole. The adhesive layer thickness should be 2-3mm.

[0023] The load on the upper part of the beam was restored in stages (30%→70%→100%), with each stage holding the load for 1 hour. The strain increment was monitored to be ≤30με and the mid-span deflection ≤L / 400. Finally, a 1.2 times overload test was carried out, and no structural abnormalities were found after holding the load for 2 hours.

[0024] Furthermore, the pre-tightening force of the bolt is 100-160N·m.

[0025] Furthermore, the height of the vertical plate is 1.2-1.8 times higher than the height of the opening.

[0026] Furthermore, the diameter d of the chemical anchor is 12-18 mm, the anchoring depth is ≥10 d, and the design value of the pull-out bearing capacity of a single bolt is ≥10 kN.

[0027] The beneficial effects of the present invention are:

[0028] 1. Prefabricated design: Steel casing and U-shaped hoop plates are prefabricated in the factory, with an on-site assembly rate of 85%, reducing welding workload by 60% and increasing construction efficiency by 50%;

[0029] 2. Combined force transmission system: The steel casing ribs and structural adhesive form a "mechanical bite + bonding" dual force transmission system, which increases the interface shear strength by 35%;

[0030] 3. Dimensional reinforcement structure: The U-shaped hoop plate forms a spatial force system through the reinforced steel plate, and the shear bearing capacity is increased by 30% compared with the traditional process.

[0031] 4. Performance improvement: flexural bearing capacity is increased by 35%-45%, shear bearing capacity is increased by 25%-35%, and crack width is controlled within 0.1mm;

[0032] 5. Shortened cycle: 30% shorter than traditional process, and overall cost reduced by 20%;

[0033] 6. Strong adaptability: It can be used in environments above 5°C, and welding fume emissions are reduced by 50%, meeting the requirements of green construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of a large hole in a concrete beam;

[0035] Figure 2 It is a schematic diagram of the prefabricated split steel casing assembly of the present invention;

[0036] Figure 3 This is a diagram of the assembly nodes of the prefabricated split steel casing assembly of the present invention;

[0037] Figure 4 This is a schematic diagram of a welded U-shaped hoop module of the present invention;

[0038] Figure 5 It is a schematic diagram of the overall structure of the modular reinforcement device of the present invention;

[0039] In the figure: 1-L-shaped steel plate, 2-convex rib, 3-bolt, 4-base plate, 5-vertical plate, 6-anchor hole, 7-stiffening steel plate, 8-preset glue injection hole, 9-fixing pin plug-in, 10-bolt connection hole, 11-steel gasket, 12-chemical anchor, 13-vent hole. DETAILED DESCRIPTION

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Specific details such as specific system structures and technologies are provided to provide a more thorough understanding of the embodiments of the present invention. The described embodiments are part of the embodiments of the present disclosure, not all of them. However, it should be clear to those skilled in the art that the present invention can also be implemented in other embodiments without these specific details. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present disclosure.

[0041] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0042] Taking the reconstruction of a frame beam as an example, the beam cross-section is 300mm×600mm, with a 400mm×400mm rectangular opening, and the original beam concrete strength is C30.

[0043] 1. Device parameters:

[0044] Prefabricated split steel casing assembly: four L-shaped steel plates 1, 10 mm thick, and ribs 2 5 mm high;

[0045] Welded U-shaped hoop plate module: bottom plate 4 is 300mm wide, vertical plate 5 is 650mm high, and the spacing between stiffening steel plates 7 is 200mm;

[0046] Chemical anchor bolt 12: Φ12mm, anchoring depth 160mm, eight bolts arranged on each side of the vertical plate 5.

[0047] 2. Device composition:

[0048] like Figure 2 As shown, the prefabricated split steel casing assembly includes four prefabricated L-shaped steel plates 1 (thickness 10mm), each L-shaped steel plate 1 is processed with a 5mm high rib 2 on the outside, and the rib 2 enhances the mechanical bite with the concrete. The two sides of the L-shaped steel plate 1 are provided with fixing pin inserts 9, which ensure the assembly accuracy and prevent the expansion of the hole crack. The fixing pin inserts 9 are provided with bolt connection holes 10; Figure 3 As shown, four L-shaped steel plates are connected and assembled with bolts 3 through a fixing pin plug-in 9 to form an annular constraint sleeve. A number of steel washers 11 are sleeved in the middle of the bolts 3 as needed. The length and width of the steel sleeve are adjusted by these steel washers 11 to meet the needs of holes of different sizes.

[0049] like Figure 4 As shown, the welded U-shaped hoop module is a U-shaped frame welded by a bottom plate 4 (300mm wide) and two vertical plates 5 (650mm high). Each vertical plate 5 has eight anchor holes 6. Chemical anchors 12 with a diameter d of 12mm and an anchoring depth of 160mm are used. Reinforcing steel plates 7 are symmetrically welded to the outside of the two vertical plates 5.

[0050] like Figure 5 As shown, a preset glue injection hole 8 and an exhaust hole 13 are opened on the concrete beam, and the preset glue injection hole 8 is injected with modified epoxy resin structural glue.

[0051] 3. Construction parameters:

[0052] Unloading to 25kN, steel casing assembly gap 1.2mm, bolt final tightening torque 120N·m;

[0053] The injection pressure is 0.25MPa, and the effective bonding area of ​​the adhesive layer is 96%;

[0054] When the load recovers to 100%, the mid-span strain is 185με and the deflection is 12mm, which meets the specification requirements.

[0055] 4. Process flow of modular processing method

[0056] Finite element analysis was used to determine the load to be unloaded to 25kN, and the load was unloaded in stages using hydraulic jacks, with each stage holding the load for 20 minutes. The split steel casing components and welded U-shaped hoop plate modules were prefabricated in the factory, with a pre-assembly tolerance of 1.2mm.

[0057] Insert four L-shaped steel plates 1 into the hole and temporarily fix them with fixing pin inserts 9. Tighten the bolts 3 in diagonal order with a final tightening torque of 120 N·m to form an annular restraining sleeve. Set several steel washers 12 in the middle as needed.

[0058] Fit the bottom plate 4 to the bottom surface of the beam, weld the vertical plate 5 to the bottom plate 4, and symmetrically weld the stiffening steel plates 7 on the outside of the vertical plate 5 with a spacing of 200mm to form a three-dimensional force system;

[0059] Drill holes at the corresponding positions of the anchor holes 6, clean the holes and then implant the chemical anchors 12;

[0060] Inject modified epoxy resin structural adhesive from the lowest preset adhesive injection hole 8, controlling the pressure at 0.25 MPa, until the air vent 13 overflows with bubble-free adhesive. Maintain the pressure for 5 minutes and then close the hole. The effective bonding area of ​​the adhesive layer is 96%;

[0061] The graded recovery load was 100%, with each level holding the load for 1 hour. The mid-span strain was 185με and the deflection was 12mm. Finally, a 1.2 times overload test was carried out, and there was no abnormality in the structure after holding the load for 2 hours.

[0062] This method utilizes on-site assembly of prefabricated split steel casing components and welded U-shaped hoop modules, reinforced with stiffening steel plates, and anchored with chemical anchor bolts, combined with a pressure injection process to create a composite load-bearing system. This method boasts high efficiency and reliable load-bearing, making it suitable for reinforcing concrete beams in building renovations and offering significant economic and social benefits.

[0063] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the scope of the claims should be included in the scope of protection of the present invention.

Claims

1. A modular reinforcement device for large holes in concrete structural beams, characterized by: The invention comprises a prefabricated split steel casing assembly and a welded U-shaped hoop plate module, wherein the prefabricated split steel casing assembly comprises four L-shaped steel plates (1), each L-shaped steel plate (1) having a convex rib (2) processed on the outer side, and the four L-shaped steel plates (1) are spliced ​​together by bolts (3) to form an annular constraint casing; the welded U-shaped hoop plate module is a U-shaped frame welded by a bottom plate (4) and two vertical plates (5), the vertical plates (5) are provided with anchor bolt holes (6), and the outer sides of the two vertical plates (5) are symmetrically welded with reinforcing steel plates (7); and the concrete beam is provided with a preset glue injection hole (8).

2. A modular reinforcement device for large holes in concrete structural beams according to claim 1, characterized in that: The L-shaped steel plates (1) are provided with fixing pin inserts (9) on both sides of the ends thereof, and the fixing pin inserts (9) are provided with bolt connection holes (10). The four L-shaped steel plates (1) are connected and fixed by bolts (3) through the fixing pin inserts (9), and the pre-tightening force of the bolts (3) is 100-160 N·m.

3. A modular reinforcement device for large holes in concrete structural beams according to claim 2, characterized in that: The middle sleeve of the bolt (3) is provided with a plurality of steel washers (11), and the length and width of the steel sleeve are adjusted by these steel washers (11) to meet the needs of holes of different sizes.

4. The modular reinforcement device for large holes in concrete structural beams according to claim 1, characterized in that: The height of the vertical plate (5) is 1.2-1.8 times higher than the height of the hole.

5. The modular reinforcement device for large holes in concrete structural beams according to claim 1, characterized in that: The spacing between the anchor holes (6) is 100-150 mm, the diameter d of the chemical anchor bolts (12) used is 12-18 mm, the anchoring depth is ≥10 d, and the design value of the single bolt pull-out bearing capacity is ≥10 kN.

6. The modular reinforcement device for large holes in concrete structural beams according to claim 1, characterized in that: The preset glue injection hole (8) is injected with modified epoxy resin structural glue, with a bonding strength of ≥10MPa, and can be cured in an environment above 5°C.

7. A modular reinforcement method for large holes in concrete structural beams, characterized in that: The following steps are involved: Unload the upper load of the beam in stages; Insert four L-shaped steel plates (1) into the hole, temporarily fix them with fixing pin inserts (9), tighten the bolts (3) in diagonal order to form an annular constraint sleeve, and set a number of steel washers (12) in the middle as needed; Lay the bottom plate (4) on the bottom surface of the beam, weld the vertical plate (5) to the bottom plate (4), and symmetrically weld the stiffening steel plate (7) on the outside of the vertical plate (5); Drill holes at positions corresponding to the anchor holes (6), clean the holes, and then implant chemical anchors (12); Injecting modified epoxy resin structural adhesive from the lowest preset adhesive injection hole (8) to form a composite force-bearing system; Restore the upper load of the beam in stages.

8. The modular reinforcement method for a large hole in a concrete structural beam according to claim 7, characterized in that: The pre-tightening force of the bolt (3) is 100-160N·m.

9. The modular reinforcement method for a large hole in a concrete structural beam according to claim 7, characterized in that: The height of the vertical plate (5) is 1.2-1.8 times higher than the height of the hole.

10. The modular reinforcement method for a large hole in a concrete structural beam according to claim 7, characterized in that: The diameter d of the chemical anchor bolt (12) is 12-18 mm, the anchoring depth is ≥10 d, and the design value of the single bolt pull-out bearing capacity is ≥10 kN.

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