Concrete beam shear reinforcement structure based on through screw and u-shaped steel sleeve and construction method thereof

Abstract

Disclose a kind of concrete beam shear reinforcement structure based on through screw rod and U-shaped steel hoop and construction method, the method includes field detection and evaluation diagnosis, reinforcement scheme design and calculation, construction preparation and line positioning, drill through hole and upper anchor hole, floor hole opening (avoid reinforcing steel), hole cleaning and interface processing, install through screw rod and preliminary in position, install vertical steel plate, glue injection, fixed upper anchor bolt, final fastening through screw rod nut, weld top transverse connecting steel plate, steel wedge is punched into and contact surface is activated, hole and plate hole repair filling and post steel beam installation and protection treatment, the present application is suitable for the shear reinforcement reconstruction of various concrete beam components, especially suitable for important structural component reinforcement engineering with severe lack of bearing capacity and seismic performance needs to be greatly improved, with wide application prospect and significant economic benefit, social benefit.

Description

Technical Field

[0001] This invention relates to the field of building technology, and more specifically to a shear-strengthening structure for concrete beams based on through-type screws and U-shaped steel sleeves, and its construction method. Background Technology

[0002] Currently, the common method for reinforcing concrete beams with insufficient shear capacity is to attach external steel plates or U-shaped hoops and fix them with rear anchor bolts. However, this approach has the following drawbacks.

[0003] 1) Risk of brittle peeling at the edge is inherent

[0004] Traditional methods rely on the localized grip and load transfer of anchor bolts, leading to severe stress concentration at the bottom row of anchor bolts. Under combined tensile and shear stress, concrete is prone to inverted cone-shaped brittle spalling failure centered on the anchor bolts. This failure is sudden and without warning; once it occurs, it causes stress redistribution to the upper row of anchor bolts, potentially triggering a chain reaction of failures and causing the entire reinforcement system to collapse instantly, resulting in poor safety. This defect is rooted in the fundamental mechanical principles of traditional post-anchoring technology. Because the tensile strength of concrete is only about 1 / 10 of its compressive strength, and the failure strain is extremely small (only 0.01% to 0.02%), the concentrated shear force transmitted by the anchor bolts around the anchor bolt holes generates a complex three-dimensional stress field within the concrete. In particular, the peak principal tensile stress at the hole edge often exceeds the tensile strength of the concrete. Especially at the bottom row of anchor bolts, due to its proximity to the bottom reinforcing steel bars, the relatively thin concrete cover, and its location at the maximum shear surface of the beam's shear span, the stress concentration problem in this area is particularly prominent. Under ultimate load, oblique or radial microcracks first appear around the bottom row of anchor bolt holes. As the load increases, these microcracks rapidly expand and connect, forming splitting cracks around the anchor bolts, eventually leading to the complete peeling of the concrete cover. The anchor bolts and concrete completely lose their anchoring function, and the subsequent anchoring system fails instantly. This failure mode is characterized by its suddenness and brittleness, with no obvious warning signs before failure. The load-bearing capacity of the reinforced beam drops precipitously after reaching its peak, which contradicts the "strong shear, weak bending" ductile failure criterion of structural design. More seriously, once peeling failure occurs, the concrete substrate is already severely damaged, making effective anchoring repair impossible, leading to complete reinforcement failure and posing a serious threat to structural safety.

[0005] (2) Poor overall system integrity and weak collaborative performance.

[0006] Existing technologies mostly involve independent planar reinforcement on both sides, lacking effective spatial connections between steel plates and forming an "open" system. This leads to: a) prominent stress concentration, especially prone to fatigue under dynamic loads; b) easy slippage between the steel plate and concrete, reducing reinforcement efficiency; c) weak overall torsional restraint on the beam and failure to fully utilize the ductility of steel to improve structural failure modes, resulting in limited improvement in safety reserves. Traditional hoop reinforcement technology, as a variant of post-anchor bolt reinforcement, typically uses U-shaped or ring-shaped steel plates to wrap around concrete beams, forming closed hoops on the sides and bottom of the beam through anchor bolts or welding, hoping to achieve shear resistance similar to stirrups. However, this technology suffers from serious defects in practical applications, such as ambiguous force transmission paths and unreliable anchoring structures. First, the force mechanism of the U-shaped hoop plate essentially depends on the bond strength between the steel plate and concrete interface and the pull-out capacity of the end anchor bolts. However, under the influence of complex environmental factors such as long-term loads, temperature changes, and concrete shrinkage and creep, the interfacial bond performance will significantly degrade, leading to a continuous decrease in force transmission efficiency. Secondly, the anchor bolts at the ends of the stirrups are usually only installed in one or two rows, resulting in limited anchoring force. Under large shear forces, the anchor bolts are prone to pull-out or the concrete cone may fail, making it impossible to form a stable mechanical transmission path. Furthermore, traditional stirrups suffer from stress concentration and structural weakening in the corner areas of beams. Due to the deterioration of material properties caused by bending the steel plate and the lack of compaction in the corner concrete, this area often becomes a weak link in the reinforcement system.

[0007] Furthermore, traditional stirrup reinforcement is ill-suited to the complex boundary conditions commonly found in existing buildings, such as the presence of infill walls, pipelines, and decorative finishes on the sides of beams. Limited on-site construction space and difficulty in ensuring installation accuracy significantly reduce the actual reinforcement effectiveness. More critically, the core challenge of effectively transferring the shear stress within the beam to the external steel plate leads to a significant discrepancy between the theoretical calculation model of stirrup reinforcement and actual conditions. Designers often resort to excessively increasing material usage to ensure safety, resulting in unnecessary economic waste. Summary of the Invention

[0008] In view of this, this paper proposes a shear reinforcement structure and construction method for concrete beams based on through-type screws and U-shaped steel sleeves, aiming to at least partially solve the shortcomings of the existing technology.

[0009] More specifically, according to one aspect of the present invention, a shear-strengthening structure for concrete beams based on through-type screws and U-shaped steel sleeves is proposed, comprising: four vertical stiffening steel plates (5), two transverse connecting steel plates (6), steel wedges (11), and two screw anchoring structures (20).

[0010] Among them, the four vertical stiffening steel plates (5) are divided into two groups arranged in parallel at intervals. The two vertical stiffening steel plates in each group are symmetrically arranged on both sides of the concrete beam (1) to be reinforced. An anchor bolt hole is formed at the lower end of each vertical stiffening steel plate (5). A screw anchoring structure (20) passes through the anchor bolt hole of the two vertical stiffening steel plates in the group and the concrete beam (1) to fix the two vertical stiffening steel plates together with the concrete beam (1). The upper end of each vertical stiffening steel plate (5) extends through the floor slab (3). Each transverse connecting steel plate (6) is welded to the top of the two vertical stiffening steel plates in the group, thereby connecting the top of the two vertical stiffening steel plates together to form a closed U-shaped steel hoop.

[0011] Among them, the top surface of the transverse connecting steel plate (6) and the concrete beam (1) is separated by a certain gap, and the steel wedge (11) is wedged into the gap.

[0012] According to an embodiment of the present invention, the concrete beam shear reinforcement structure based on through-type screw and U-shaped steel sleeve further includes an anchor plate (4) and an anchor bolt (7). The anchor plate (4) is attached to one side of the concrete beam (1). Two vertical stiffening steel plates (5) on one side of the concrete beam (1) are provided on one side of the concrete beam (1) by being attached to the anchor plate (4). The screw anchoring structure (20) passes through the anchor plate (4). The two vertical stiffening steel plates (5) attached to the anchor plate (4) also include anchor bolt holes formed in the middle. The anchor bolt (7) is anchored in the concrete beam (1) through the anchor bolt holes in the middle and the anchor plate (4).

[0013] According to an embodiment of the present invention, the screw anchoring structure (20) includes a screw (8), a washer (9), and a nut (10).

[0014] According to an embodiment of the present invention, the gap is 2-4 mm.

[0015] According to an embodiment of the present invention, the concrete beam shear reinforcement structure based on through screw and U-shaped steel sleeve further includes a steel beam (2) disposed between two vertical stiffening steel plates (5) on one side of the concrete beam (1).

[0016] According to an embodiment of the present invention, the top of the transverse connecting steel plate (6) and the vertical stiffening steel plate are rigidly connected by a full penetration weld.

[0017] According to another aspect of the present invention, a construction method for a shear-strengthening structure of a concrete beam based on a through-type screw and a U-shaped steel sleeve is also provided, comprising:

[0018] Step 1): On-site inspection and assessment, including comprehensive on-site inspection of the concrete beams requiring reinforcement and assessment of bearing capacity requirements through calculation;

[0019] Step 2): Reinforcement scheme design and calculation, including the design of a special reinforcement structure based on test data and load-bearing capacity requirements;

[0020] Step 3): Construction preparation and layout positioning, including accurate measurement and layout on site according to the design drawings, marking the positions of through holes, anchor bolt holes, floor slab openings and steel plate installation edges, and preparing construction equipment and materials;

[0021] Step 4): Drill through holes and upper anchor bolt holes;

[0022] Step 5): Opening a hole in the floor slab;

[0023] Step 6): Hole cleaning and interface treatment, including cleaning through holes, anchor bolt holes and floor slab openings, removing dust, debris and oil stains; grinding and brushing the concrete surface to enhance its adhesion to adhesives and steel plates.

[0024] Step 7): Install the through bolt, including inserting the high-strength bolt into the through hole, temporarily installing washers and nuts at both ends, and adjusting the position of the bolt to center it;

[0025] Step 8): Install the vertical steel plate, inject adhesive, and fix the upper anchor bolts, including passing the anchor plate and the prefabricated vertical stiffening steel plate through the floor slab opening, positioning them tightly against the side of the beam, aligning the bottom row of holes with the through bolts; then install the upper anchor bolts;

[0026] Step 9): Tighten the through bolt nut to achieve the designed preload;

[0027] Step 10): Weld the top transverse connecting steel plate; and

[0028] Step 11): Drive in the steel wedge and activate the contact surface. After the middle weld is inspected and approved, drive in the wedge-shaped steel wedges from the side at intervals of 300~500mm along the length of the beam.

[0029] According to an embodiment of the present invention, step 10) includes placing a 2mm thick temporary shim between the bottom surface of the steel plate and the top surface of the concrete beam before welding to ensure uniform gap and isolate the heat effect of welding.

[0030] According to an embodiment of the present invention, in step 11), the wedge angle of the steel wedge is 8°~12° and the driving depth is not less than 30mm.

[0031] According to an embodiment of the present invention, the construction method further includes: step 12): repairing and filling holes and slab openings, and step 13): installing and protecting the added steel beams.

[0032] The technical functional effects of this invention are mainly reflected in the following aspects: First, by using the through-bolt and the top connecting steel plate, the shear force originally borne by the local anchor bolts is effectively transferred and diffused to the entire cross-sectional height of the concrete beam, forcing the entire cross-section of the concrete beam to participate in shear resistance, greatly reducing the local bearing pressure and shear stress of the concrete at the bottom row of anchor bolts. Second, this structure forms an efficient internal force redistribution path. The shear force is first transferred from the beam to the stiffening steel plate surrounding it, and then redistributed through the closed force transmission ring formed by the top connecting steel plate and the through-bolt, avoiding stress concentration in the corner area. The reserved gap in the top steel plate and the post-weld wedging process, through a staged force transmission mechanism, not only avoids welding heat damage to the concrete, but also achieves micro-interlocking and pre-compression contact between the steel plate and concrete through the lateral squeezing of the steel wedge, optimizing the force transmission performance of the contact surface and ensuring the coordinated deformation of the bolt and the vertical stiffening steel plate. Finally, this reinforcement system significantly improves the ductility and safety reserve of the structure. The steel plate and concrete beam work together through chemical adhesives and mechanical anchoring, utilizing both the ductility of steel and the compressive strength of concrete. This allows the reinforced beam to undergo greater deformation and provide early warning before reaching its ultimate load. The failure mode shifts from brittle concrete splitting to the yielding of the more ductile steel plate or the progressive failure of the anchoring system, providing dual protection for structural safety. In summary, this invention, through ingenious structural design and relatively simple construction process, achieves a fundamental improvement in shear reinforcement effectiveness and has significant engineering application value. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a shear-strengthening structure for concrete beams based on a through-type screw and a U-shaped steel sleeve according to an embodiment of the present invention.

[0034] Figure 2 for Figure 1 The diagram shows a cross-sectional view along line AA of a concrete beam shear strengthening structure based on a through-type screw and a U-shaped steel sleeve.

[0035] Figure 3 A partial top view along the extension direction of the concrete beam of a concrete beam shear strengthening structure based on a through-bolt and a U-shaped steel sleeve according to an embodiment of the present invention; and

[0036] Figure 4 This is a flowchart illustrating a construction method for a concrete beam shear reinforcement structure based on a through-type screw and a U-shaped steel sleeve according to an embodiment of the present invention. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The content shown is intended to fully illustrate the content of the present invention, but is not intended to limit the present invention.

[0038] Figure 1This is a schematic diagram of a shear-strengthening structure for concrete beams based on a through-type screw and a U-shaped steel sleeve according to an embodiment of the present invention. Figure 2 for Figure 1 The diagram shows a cross-sectional view along line AA of a concrete beam shear strengthening structure based on a through-type screw and a U-shaped steel sleeve. Figure 3 This is a partial top view along the extension direction of the concrete beam of the concrete beam according to an embodiment of the present invention, which is a shear strengthening structure for concrete beams based on through-bolts and U-shaped steel sleeves.

[0039] Referring to the accompanying drawings, the concrete beam shear reinforcement structure based on through-type screws and U-shaped steel sleeves according to the embodiments of the present invention may include: a steel beam (2), an anchor plate (4), four vertical stiffening steel plates (5), two transverse connecting steel plates (6), an anchor bolt (7), a steel wedge (11), and two screw anchoring structures (20).

[0040] As shown in the figure, the four vertical stiffening steel plates (5) can be divided into two groups arranged in parallel at intervals. The two vertical stiffening steel plates in each group are symmetrically arranged on both sides of the concrete beam (1) to be reinforced. An anchor bolt hole matching the anchor bolt (7) can be pre-set in the middle of each stiffening steel plate and an anchor bolt hole for the screw anchoring structure (20) can be pre-set in the lower part. The anchor plate (4) is attached to one side of the concrete beam (1). For example, the anchor bolt (7) (such as a chemical anchor bolt) passes through the anchor bolt hole in the middle and the anchor plate (4) to anchor the anchor plate (4) to the side of the concrete beam (1). The two vertical stiffening steel plates (5) on one side of the concrete beam (1) are set on one side of the concrete beam (1) by attaching to the anchor plate (4). The screw anchoring structure (20) can include a screw (8), a washer (9) and a nut (10). More specifically, a high-strength bolt that penetrates the concrete beam section, anchor plate (4) and lower anchor bolt hole can be used, along with a large-size pad (9) and a high-strength nut (10), to fasten the stiffening steel plates on both sides to the concrete beam.

[0041] The upper end of each vertical stiffening steel plate (5) extends through the floor slab (3); each horizontal connecting steel plate (6) is welded to the top of two vertical stiffening steel plates in a set, thereby connecting the tops of the two vertical stiffening steel plates together to form a closed U-shaped steel hoop. More specifically, the top of the horizontal connecting steel plate is connected to the top of the vertical stiffening steel plates on both sides by a full penetration weld. During construction, a certain gap, such as 2mm-4mm, is reserved between the horizontal connecting steel plate and the top surface of the concrete beam. After the weld is inspected and qualified, steel wedges (11) are driven into the gap to form a tight force transmission, thereby connecting the vertical stiffening steel plates on both sides into a closed U-shaped steel hoop, which significantly improves the integrity and spatial stiffness of the reinforcement system.

[0042] In addition, the reinforced concrete beam of the present invention can serve as a reliable additional support for the installation of new components such as post-installed steel beams, thereby expanding the structural function. Referring to the accompanying drawings, for example, the concrete beam shear reinforcement structure based on through-bolts and U-shaped steel sleeves in the embodiment also includes a steel beam (2) disposed between two vertical stiffening steel plates (5) on one side of the concrete beam (1).

[0043] The structure, working mechanism, and effects of each component of the structure will be explained in more detail below.

[0044] 1) Vertical stiffening steel plate

[0045] The vertical stiffening steel plate (5) serves as the core force transmission component for shear reinforcement. Its width and thickness can be designed according to the shear force design value required by the subsequent steel beam (2). The stiffening steel plate has pre-set array holes (anchor bolt holes) on the side connected to the anchor plate. The upper holes are matched with conventional anchor bolts (7), and the lowermost holes are matched with high-strength bolts (8). During installation, it passes through the floor slab (3) and is tightly attached to the anchor plate on one side and the side of the concrete beam (1) on the other side. It works together with the beam through the adhesive bolts. The steel plate stiffness design meets the following requirements: shear bearing capacity ≥ 1.2~1.35 times the shear force to be reinforced, and its vertical stiffness meets the requirement that the strain of the steel plate under shear force should be less than 80% of the ultimate tensile failure strain of the concrete. The preferred material is Q355B, and Q420 or Q690 can be used for heavy-duty beams. The hole diameter deviation is +0.5 to +1.5 mm, and the hole position deviation is ±1 mm. The weld between the top of the steel plate and the transverse connecting steel plate needs to be beveled, and the bevel depth is considered to leave a 2 mm gap.

[0046] 2) Through-type screw anchoring structure (20) (8, 9, 10)

[0047] The through-type screw anchoring structure is another innovation in this design to solve the core defects. A through hole is drilled at the most unfavorable position at the bottom of the concrete beam, and a high-strength screw (8) is inserted. Large-size pads (9) and high-strength nuts (10) are set at both ends. The pads are preferably arc-shaped or used with epoxy pads. The system clamps the stiffening steel plates (5) on both sides to the beam body, and converts the local shear force into full-section pressure and friction. Design parameters: screw material is 10.9 grade or 12.9 grade alloy structural steel, tensile strength ≥1000MPa; diameter M20-M36; pad thickness ≥0.6 times the screw diameter, side length ≥3 times the screw diameter; nut performance grade matches the screw, and the construction pre-tension is 1.1 times the design value, forming a compressive stress field in the bottom area of ​​the beam to suppress cracking.

[0048] 3) The transverse connecting steel plate (6) and the steel wedge system (11)

[0049] The transverse connecting steel plate (6) is located on the top surface of the beam. Its width is the same as that of the vertical stiffening steel plate (5). It is rigidly connected to the two sides of the through-height steel plate through a full penetration weld. After the reserved gap welding and steel wedge wedging process, it forms a closed U-shaped sleeve with the bottom through screw system.

[0050] Technical details: The thickness is equal to or slightly thicker than the vertical steel plate; the weld is a full penetration groove weld, quality grade II, 100% non-destructive testing; a 2.0±0.5mm vertical gap is reserved between the bottom surface of the steel plate and the top surface of the concrete. If the tolerance is too large, the force transmission efficiency of the steel wedge will decrease; if it is too small, it will not provide effective heat insulation. The steel wedge is made of Q355B, with a wedge angle of 8°~12°; the surface can be provided with transverse teeth to enhance the interlocking, arranged at intervals of 300-500mm along the beam length, and must be set at the mid-span and both ends, with a wedge depth ≥30mm.

[0051] Mechanical Mechanism: After the steel wedge is driven in, it forms a self-locking system, generating a horizontal component force Fh and a vertical component force Fv. Fv causes the steel plate to press down, forming initial contact prestress, while Fh anchors the steel wedge itself in the gap to prevent loosening. This prestress increases the interfacial friction coefficient, significantly enhancing the shear force transmission efficiency.

[0052] 4) Upper anchor system (4, 7)

[0053] The upper part of the vertical stiffening steel plate (5) is fixed with anchor bolts (7) and anchor plate (4). Its main function is to temporarily fix the steel plate during construction and to assist in the transfer of some shear force during use, forming a graded and coordinated anchoring mechanism with the through bolt system. Design parameters: The anchor bolt type is selected according to the condition of the concrete substrate. For cracked concrete, the expanded bottom mechanical anchor bolt or special chemical anchor bolt should be selected; the performance grade is ≥8.8, the effective anchoring depth is ≥10 times the anchor bolt diameter; the spacing is ≥5 times the anchor bolt diameter, the edge distance is ≥3 times the anchor bolt diameter; the thickness of the anchor plate 4 is ≥10mm, and the size is determined according to the anchor bolt arrangement. The design value of the anchoring force of the system is taken as 0.7 times the calculated value. Considering the long-term load and interface degradation, it is ensured that it will not fail within the service life (usually 50 years).

[0054] 5) Add steel beams later (2)

[0055] The reinforced concrete beam of this invention can serve as a reliable additional support for installing new components such as the added steel beam (2), thereby expanding the structural function. The steel beam is connected to the reinforcing steel plate by high-strength bolts or welds, and the connection nodes need to be specially designed to ensure effective load transfer. This expanded function reflects the engineering application value of this invention; the reinforcement not only improves shear resistance but also provides conditions for structural modification.

[0056] Figure 4 The following is a flowchart illustrating the construction method of a concrete beam shear reinforcement structure based on a through-type screw and a U-shaped steel sleeve according to an embodiment of the present invention. The construction method of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] As shown in the figure, the construction method includes the following steps:

[0058] Step 1: On-site testing and assessment diagnosis

[0059] A comprehensive on-site inspection was conducted on the concrete beams requiring reinforcement, including a detailed investigation of beam dimensions, concrete strength, existing damage (cracks, spalling, etc.), reinforcement layout, and floor slab construction. Mechanical calculations were used to identify the shear capacity shortfall, assess the reinforcement scope and stress requirements, and determine the steel plate dimensions, anchor bolt placement, and through-hole locations. Simultaneously, the construction environment was inspected to ensure sufficient operating space, and a specific plan was developed to avoid existing pipelines and reinforcement, providing an accurate basis for subsequent construction.

[0060] Step Two: Reinforcement Scheme Design and Calculation

[0061] Based on the test data and load-bearing capacity requirements, a specialized design for the reinforcement structure is carried out. The width, thickness, and material of the vertical stiffening steel plates are calculated and determined; the diameter, length, and placement of the through bolts are planned; and the type, spacing, and anchoring depth of the upper anchor bolts are designed. Simultaneously, the structural design of the transverse connecting steel plates and wedges is completed, detailed construction parameters and control standards are established, and complete construction drawings and process documents are generated to ensure the reinforcement scheme is safe, reliable, economical, and reasonable.

[0062] Step 3: Construction preparation and layout positioning

[0063] Based on the design drawings, precise measurements and layout were conducted on-site, marking the locations of through holes, anchor bolt holes, floor slab openings, and steel plate installation edges. Drilling equipment, welding tools, grouting materials, and other construction equipment were inspected, and high-strength bolts, steel plates, anchor bolts, steel wedges, and repair materials were prepared. Technical briefings were conducted for construction personnel, clarifying the process requirements and quality control points for each stage to ensure the orderly progress of construction.

[0064] Step 4: Drill through holes and upper anchor bolt holes

[0065] Using a specialized drilling rig, drill through holes at the designated locations. These holes must penetrate the beam, with a diameter 1.5–2 times the bolt diameter. Maintain verticality and clean debris regularly during drilling. Next, drill the upper anchor bolt holes according to the designed spacing and depth, ensuring the hole walls are intact and clean. After drilling, verify the hole positions, controlling deviations within ±2mm to lay the foundation for subsequent installation.

[0066] Step 5: Create openings in the floor slab (avoiding reinforcing steel bars)

[0067] At the location corresponding to the through hole in the floor slab, a vertical groove is chiseled, slightly larger than the width of the steel plate, to allow the steel plate to pass through. During the drilling process, a detection instrument is used to identify and avoid the reinforcing bars within the slab, and local adjustments are made as necessary to ensure that the original structural reinforcing bars are not damaged. After drilling, debris is cleaned up, and the flatness of the opening edges is checked to create suitable space for the installation of the steel plate.

[0068] Step Six: Hole Cleaning and Interface Treatment

[0069] Thoroughly clean through holes, anchor bolt holes, and floor openings using pressurized air and specialized brushes to remove dust, debris, and oil. Grind the concrete surface to enhance its adhesion to the adhesive and steel plate. Apply a bonding agent if necessary to ensure synergistic effects between the new and old materials, improving load transfer efficiency and durability.

[0070] Step 7: Install the through bolt and initially position it.

[0071] Insert the high-strength bolt into the through hole, temporarily install washers and nuts at both ends, and adjust the bolt position to center it. Pour high-performance chemical adhesive into the hole, ensuring it fills the gaps and wraps around the bolt. Initially tighten the nuts to apply initial force to the bolt, creating a slight clamping effect on the beam and providing a positioning reference for subsequent steel plate installation.

[0072] Step 8: Install vertical steel plates, apply adhesive, and secure the upper anchor bolts.

[0073] The anchor plate and prefabricated vertical stiffening steel plate are inserted through the opening in the floor slab and positioned close to the side of the beam, aligning the bottom row of holes with the through bolts. Structural adhesive is applied to the interface between the anchor plate, vertical stiffening steel plate, and concrete to enhance adhesion. The upper anchor bolts are then installed and tightened in batches according to the design torque, initially fixing the steel plates to the beam and forming a preliminary shear-resistant load-bearing system.

[0074] Step 9: Final tightening of the through bolt and nut

[0075] After the adhesive has initially cured, use a torque wrench to finally tighten the nuts at both ends of the threaded rod to achieve the design preload (usually 1.1 times the design value). During the tightening process, monitor the adhesion between the steel plate and the concrete to ensure uniform pressure distribution and create a favorable compressive stress field at the bottom of the beam.

[0076] Step 10: Weld the top horizontal connecting steel plate

[0077] A transverse connecting steel plate is installed on top of the beam, aligned with the top of the vertical steel plates on both sides, and welded using a bevel full penetration weld. Before welding, a 2mm thick temporary shim is placed between the bottom surface of the steel plate and the top surface of the concrete to ensure uniform gap and isolate the heat-affected zone during welding. After welding, non-destructive testing is performed to ensure that the weld quality meets the secondary standard.

[0078] Step 11: Drive in the steel wedge and activate the contact surface

[0079] After the weld inspection is passed, remove the temporary shims and drive wedge-shaped steel wedges into the beam from the side at intervals of 300-500mm along the beam length. The wedge angle should be 8°-12° and the driving depth should be no less than 30mm. The steel plate is brought into close contact with the concrete top surface through lateral compression, forming mechanical interlocking and pre-stress, thus activating the force transmission interface.

[0080] Step 12: Repair and filling holes and cavities

[0081] For through holes, floor openings, and gaps around steel wedges, use micro-expansion high-strength mortar or epoxy resin mortar for dense filling. The filling material must have low shrinkage and high adhesion properties to ensure that it can work together with the original structure to restore the integrity and aesthetics of the floor slab, while protecting the steel components from corrosion.

[0082] Step Thirteen: Installation and Protective Treatment of the Added Steel Beams

[0083] If required by the design, a secondary steel beam can be installed on the reinforced beam and connected to the reinforcing steel plate using high-strength bolts or welding. After the steel beam is installed, it should be treated with an anti-rust and fire-retardant coating to ensure its long-term durability. Finally, an overall acceptance test and load test should be conducted to verify whether the reinforcement effect meets the design requirements.

[0084] The technical solution of this invention achieves a fundamental transformation in the force transmission mechanism and innovatively introduces spatial separation between the welding process and the final stress state: through the combined structure of the through-bolt and the full-height steel plate, the shear force borne by the concrete beam is transformed into axial tensile and compressive forces distributed along the beam height, thus acting on the beam as a surface load; simultaneously, the post-weld wedging technology of the top connecting steel plate achieves spatial separation between the welding process and the final stress state, ensuring both weld quality and the safety of the concrete substrate, while also ensuring the complete force transmission function of the closed sleeve. This reinforcement method has significant technical advantages such as a clear and defined force transmission path, uniform and reasonable stress distribution, a change in failure mode from brittle to ductile, a large increase in bearing capacity, high structural reliability, and strong construction tolerance and process controllability. The geometric dimensions (width and thickness) of the steel plate can be flexibly adjusted according to the actual engineering calculation results without changing the overall structural form, exhibiting good engineering adaptability. This invention is applicable to the shear reinforcement and retrofitting of various concrete beam components, especially to the reinforcement of important structural components with severely insufficient bearing capacity and a need for significant improvement in seismic performance. It has broad application prospects and significant economic and social benefits.

[0085] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A shear-strengthening structure for concrete beams based on through-type screws and U-shaped steel sleeves, characterized in that, include: Four vertical stiffening steel plates (5), two horizontal connecting steel plates (6), steel wedges (11) and two screw anchoring structures (20); Among them, the four vertical stiffening steel plates (5) are divided into two groups arranged in parallel at intervals. The two vertical stiffening steel plates in each group are symmetrically arranged on both sides of the concrete beam (1) to be reinforced. An anchor bolt hole is formed at the lower end of each vertical stiffening steel plate (5). A screw anchoring structure (20) passes through the anchor bolt hole of the two vertical stiffening steel plates in the group and the concrete beam (1) to fix the two vertical stiffening steel plates together with the concrete beam (1). The upper end of each vertical stiffening steel plate (5) extends through the floor slab (3). Each transverse connecting steel plate (6) is welded to the top of the two vertical stiffening steel plates in the group, thereby connecting the top of the two vertical stiffening steel plates together to form a closed U-shaped steel hoop. Among them, the top surface of the transverse connecting steel plate (6) and the concrete beam (1) is separated by a certain gap, and the steel wedge (11) is wedged into the gap.

2. The concrete beam shear strengthening structure based on through-type screw and U-shaped steel sleeve according to claim 1, characterized in that: It also includes an anchor plate (4) and an anchor bolt (7). The anchor plate (4) is attached to one side of the concrete beam (1). Two vertical stiffening steel plates (5) on one side of the concrete beam (1) are set on one side of the concrete beam (1) by being attached to the anchor plate (4). The screw anchoring structure (20) passes through the anchor plate (4). The two vertical stiffening steel plates (5) attached to the anchor plate (4) also include anchor bolt holes formed in the middle. The anchor bolt (7) is anchored in the concrete beam (1) through the anchor bolt holes in the middle and the anchor plate (4).

3. The concrete beam shear strengthening structure based on through-type screw and U-shaped steel sleeve according to claim 1, characterized in that: The screw anchoring structure (20) includes a screw (8), a washer (9), and a nut (10).

4. The concrete beam shear strengthening structure based on through-type screw and U-shaped steel sleeve according to claim 1, characterized in that: The gap is 2-4mm.

5. The concrete beam shear strengthening structure based on through-type screw and U-shaped steel sleeve according to claim 2, characterized in that: It also includes a steel beam (2) set between two vertical stiffening steel plates (5) on one side of the concrete beam (1).

6. The concrete beam shear strengthening structure based on through-type screw and U-shaped steel sleeve according to claim 1, characterized in that: The top of the transverse connecting steel plate (6) and the vertical stiffening steel plate are rigidly connected by a full penetration weld.

7. The construction method of the concrete beam shear reinforcement structure based on through-type screws and U-shaped steel sleeves according to any one of claims 1-6, characterized in that, include: Step 1): On-site inspection and assessment, including comprehensive on-site inspection of the concrete beams requiring reinforcement and assessment of bearing capacity requirements through calculation; Step 2): Reinforcement scheme design and calculation, including the design of a special reinforcement structure based on test data and load-bearing capacity requirements; Step 3): Construction preparation and layout positioning, including accurate measurement and layout on site according to the design drawings, marking the positions of through holes, anchor bolt holes, floor slab openings and steel plate installation edges, and preparing construction equipment and materials; Step 4): Drill through holes and upper anchor bolt holes; Step 5): Opening a hole in the floor slab; Step 6): Hole cleaning and interface treatment, including cleaning through holes, anchor bolt holes and floor slab openings, removing dust, debris and oil stains; grinding and brushing the concrete surface to enhance its adhesion to adhesives and steel plates. Step 7): Install the through bolt, including inserting the high-strength bolt into the through hole, temporarily installing washers and nuts at both ends, and adjusting the position of the bolt to center it; Step 8): Install the vertical steel plate, inject adhesive, and fix the upper anchor bolts, including passing the anchor plate and the prefabricated vertical stiffening steel plate through the floor slab opening, positioning them tightly against the side of the beam, aligning the bottom row of holes with the through bolts; then install the upper anchor bolts; Step 9): Tighten the through bolt nut to achieve the designed preload; Step 10): Weld the top horizontal connecting steel plate; as well as Step 11): Drive in the steel wedge and activate the contact surface. After the middle weld is inspected and approved, drive in the wedge-shaped steel wedges from the side at intervals of 300~500mm along the length of the beam.

8. The construction method according to claim 7, characterized in that, Step 10) includes placing a 2mm thick temporary shim between the bottom surface of the steel plate and the top surface of the concrete beam before welding to ensure a uniform gap and isolate the heat effect of welding.

9. The construction method according to claim 7, characterized in that, In step 11), the wedge angle of the steel wedge is 8°~12°, and the wedge depth is not less than 30mm.

10. The construction method according to claim 7, characterized in that, Also includes: Step 12): Repair and filling of holes and cavities, and Step 13): Installation and protection of the added steel beams.

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