Self-tapping anchor bolt wood-concrete composite beam anti-shear joint and construction method thereof

Abstract

The invention discloses a self-tapping anchor bolt wood-concrete composite beam anti-shear joint and a construction method thereof, and relates to the technical field of constructional engineering.The joint comprises a concrete plate, laminated wood, a perforated T-shaped steel plate and a self-tapping anchor bolt, the concrete plate and the laminated wood are each provided with a groove, and a flange and a web of the perforated T-shaped steel plate are embedded into the grooves correspondingly; the flanges are detachably connected with the concrete slab through self-tapping anchor bolts, and the web is bonded with the laminated wood through intrinsic flame-retardant structural adhesive; the web plate is provided with a hourglass-shaped reducing through structure hole and a spiral flow guide groove, and the glue solution is filled in the hole to form a mechanical interlocking structure. During construction, assembly is completed through the steps of groove treatment, steel plate connection, glue solution preparation and glue injection, curing and the like, full-assembly dry-type connection is achieved, the construction efficiency is improved, the problem that the glue injection quality of a traditional joint is difficult to control is solved, excellent shear resistance, pulling resistance and fireproof performance are achieved, reinforcement of a newly-built structure and an existing structure is adapted, and the application prospect is wide.

Description

A self-tapping anchored shear joint for timber-concrete composite beams and its construction method Technical Field

[0001] This invention relates to the field of prefabricated building engineering technology, specifically to a self-tapping anchored wood-concrete composite beam shear joint and its construction method. Background Technology

[0002] As a renewable, green, and low-carbon material, wood is increasingly widely used in modern mid-rise and high-rise buildings and large-span structures. However, pure wood structures are often limited by normal service limits such as deflection and vibration performance when meeting the demands of large spans. To overcome these bottlenecks, wood-concrete composite structures have emerged. This structural system combines concrete and wood beams through shear connectors, fully utilizing the high compressive strength and stiffness of concrete and the high tensile strength and light weight of wood. Furthermore, with the increasing development of industrialized, digitalized construction and prefabricated construction technologies, prefabricated wood-concrete structures have become a research hotspot in the field of modern green building.

[0003] In timber-concrete composite structural systems, the mechanical properties and construction techniques of shear connectors are crucial in determining the overall structural efficiency in terms of load-bearing capacity. However, traditional connection methods still suffer from problems such as heavy reliance on on-site wet work and long construction cycles during the transition to highly prefabricated systems. Although some connectors can be pre-assembled with concrete, their design flexibility and construction tolerance are relatively low.

[0004] Self-tapping anchors, as high-performance mechanical fasteners, are widely used in construction, bridges, tunnels, and equipment installation. my country's building materials industry standard, "Mechanical Anchors for Concrete" (JG / T160—2017), has formally incorporated them into its regulatory system. The working principle of these anchors is that their specially designed high-hardness threads directly cut into the concrete hole wall in a pre-drilled hole, forming a mechanical engagement and thus achieving anchoring. Compared to traditional expansion anchors, self-tapping anchors do not generate expansion stress during installation, making them suitable for applications with small edge distances and spacing. They offer advantages such as dry construction, convenient installation, immediate stress distribution, and the ability to be disassembled and adjusted. In terms of stress performance, qualified self-tapping anchors typically exhibit ductile concrete cone failure rather than brittle pull-out failure, providing reliable anchoring and, to some extent, replacing embedded parts or chemical anchoring techniques.

[0005] Traditionally, concealed joints in wood-concrete composite structures are often connected using ordinary cylindrical through-holes for adhesive injection. In actual construction, because the interior of the joint is an invisible "black box," the adhesive flows without guidance within the smooth, straight channels, easily leading to uneven flow rates, air bubbles, voids, or uneven adhesive distribution. Furthermore, relying solely on natural adhesive leveling makes it difficult to ensure consistent adhesive layer thickness; insufficient adhesive or an excessively thin layer significantly reduces the shear strength of the joint. This high dependence on manual experience and the difficulty of non-destructive testing make it challenging to control the adhesive injection quality of traditional concealed joints. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] Therefore, the purpose of this invention is to provide a self-tapping anchored wood-concrete composite beam shear joint and its construction method to solve the problems mentioned in the background art.

[0008] To solve the above-mentioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution: a shear joint for a self-tapping anchored timber-concrete composite beam, comprising: a concrete slab, glued laminated timber, a perforated T-shaped steel plate, and self-tapping anchors; both the concrete slab and the glued laminated timber are provided with grooves, and the flanges and webs of the perforated T-shaped steel plate are respectively embedded in the grooves of the concrete slab and the glued laminated timber; the webs of the perforated T-shaped steel plate are provided with a plurality of variable-diameter through-holes, and the inner walls of the variable-diameter through-holes are provided with guide grooves; the flanges of the concrete slab and the perforated T-shaped steel plate are detachably connected by self-tapping anchors, and the glued laminated timber and the webs of the perforated T-shaped steel plate are bonded by intrinsic flame-retardant structural adhesive, the intrinsic flame-retardant structural adhesive being filled in the variable-diameter through-holes and guide grooves to form a high-density solid wedge-shaped mechanical interlocking structure.

[0009] As a preferred embodiment of the self-tapping anchored wood-concrete composite beam shear joint described in this invention, the variable diameter through-hole is an hourglass-shaped bidirectional frustum structure, with the hole diameter gradually decreasing from the two sides of the web towards the inner center section, and the edge of the hole is rounded.

[0010] As a preferred embodiment of the self-tapping anchored wood-concrete composite beam shear joint described in this invention, the guide groove is spiral-shaped and distributed on the inner wall of the variable diameter through-hole structure.

[0011] As a preferred embodiment of the self-tapping anchor timber-concrete composite beam shear joint described in this invention, the concrete slab is pre-grooved with a groove, the groove size being 1mm larger than the perforated T-shaped steel plate; the glued laminated timber is pre-grooved with a groove, the length and width of which are 3mm larger than the perforated T-shaped steel plate, and the depth being 2mm larger than the perforated T-shaped steel plate, in order to form an adhesive layer to ensure adhesive strength.

[0012] As a preferred embodiment of the self-tapping anchor wood-concrete composite beam shear joint described in this invention, the intrinsic flame-retardant structural adhesive is a phosphorus / nitrogen modified epoxy resin structural adhesive, wherein the phosphorus and nitrogen flame-retardant elements are introduced into the resin molecular chain segments through chemical bonding.

[0013] As a preferred embodiment of the self-tapping anchored wood-concrete composite beam shear joint described in this invention, the phosphorus / nitrogen modified epoxy resin structural adhesive is composed of component A and component B. Component A is a DOPO graft-modified phosphorus-containing epoxy resin with a phosphorus content controlled at 2%-3%wt. Component B is a modified amine curing agent containing flexible long chains, and is compounded with 5%-10%wt of nitrogen-containing synergist.

[0014] A construction method for a shear joint of a self-tapping anchored timber-concrete composite beam includes the following steps: S1. Determine the type and size of the concrete slab, glued laminated timber, perforated T-shaped steel plate, and self-tapping anchors according to the usage requirements. Create grooves in the concrete slab and glued laminated timber according to the size of the perforated T-shaped steel plate, and grind and clean the grooves. S2. Determine the anchoring position of the self-tapping anchors on the concrete slab and drill holes. After cleaning the drilled holes, embed the flange of the perforated T-shaped steel plate into the groove of the concrete slab, aligning the anchor holes on the flange with the drilled holes in the concrete slab. S3. Pre-treat the web surface of the perforated T-shaped steel plate; S4. Prepare intrinsic flame-retardant structural adhesive and degas the adhesive; S5. Inject the degassed intrinsic flame-retardant structural adhesive into the groove of the glued laminated timber, and slowly insert the pre-treated web of the perforated T-shaped steel plate vertically into the center of the groove, so that the adhesive fills the variable diameter through-hole and guide groove; S6. Fix the position of the perforated T-shaped steel plate with positioning clamps, clean up the overflowing adhesive, and complete the node assembly after static curing.

[0015] As a preferred embodiment of the construction method for a self-tapping anchored wood-concrete composite beam shear joint according to the present invention, in step S4, the preparation steps of the intrinsic flame-retardant structural adhesive are as follows: Component A is selected as DOPO graft-modified phosphorus-containing epoxy resin, with the phosphorus content controlled at 2%-3%wt; Component B is selected as a modified amine curing agent containing flexible long chains, and compounded with 5%-10%wt of nitrogen-containing synergist; Components A and B are mixed in a preset ratio and stirred at a speed of 300-500r / min for 2-3 minutes until uniform; the degassing treatment is performed under a negative pressure environment of -0.08MPa to -0.09MPa for 3-5 minutes until no visible bubbles are present in the adhesive.

[0016] As a preferred embodiment of the construction method for a self-tapping anchored wood-concrete composite beam shear joint described in this invention, in step S5, the amount of intrinsic flame-retardant structural adhesive injected is 10%-15% more than the volume of the gap between the groove and the web.

[0017] As a preferred embodiment of the construction method for the shear joint of the self-tapping anchor wood-concrete composite beam described in this invention, in step S6, the static curing conditions are: static curing at room temperature for 24-48 hours, and the filling rate of the adhesive to the variable diameter through structure hole and the guide groove is not less than 95%.

[0018] Compared with the prior art, the beneficial effects of this invention are as follows: by using the hourglass-shaped variable diameter through-structure holes and spiral guide channels in the web of the perforated T-shaped steel plate, combined with low viscosity intrinsic flame-retardant structural adhesive, a high filling rate of more than 95% of the adhesive is achieved. After curing, a solid wedge-shaped mechanical interlocking structure with macroscopic-mesoscopic-microscopic three-level linkage is formed, which greatly enhances the shear stiffness, pull-out bearing capacity and anti-slip performance of the joint. The failure mode is changed from the traditional brittle interface debonding to the ductile wood matrix splitting or steel plate yielding, making the stress more reliable.

[0019] Intrinsic phosphorus / nitrogen modified epoxy resin structural adhesive introduces flame-retardant elements into the resin molecular chain through chemical bonding, completely avoiding the risks of sedimentation, agglomeration, and interface peeling of traditional physically filled flame retardants. Under fire conditions, the synergistic effect of phosphorus / nitrogen elements achieves a dual effect of condensed phase char formation and gas phase quenching, generating a dense and expanded char layer in situ, effectively isolating heat transfer, protecting the mechanical properties of metal connectors, significantly improving the fire resistance limit of joints, and extending the structural support time during a fire.

[0020] Adopting a fully assembled dry connection process, the self-tapping anchors do not require on-site wet work, are easy to install, and are detachable and adjustable, significantly shortening the construction cycle. The adhesive is transparent before curing, and the quality of internal filling can be intuitively judged by the amount of adhesive overflow at the groove. This solves the quality problems such as air bubbles, hollow areas, and insufficient adhesive caused by the black box operation of traditional concealed node adhesive injection, reducing the cost of construction error tolerance and the difficulty of non-destructive testing. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Specifically: Figure 1 is a three-dimensional structural schematic diagram of a self-tapping anchor wood-concrete composite beam shear joint according to the present invention; Figure 2 is a right view of a self-tapping anchor wood-concrete composite beam shear joint according to the present invention; Figure 3 is a bottom view of a self-tapping anchor wood-concrete composite beam shear joint according to the present invention; Figure 4 is a structural schematic diagram of the perforated T-shaped steel plate of the self-tapping anchor wood-concrete composite beam shear joint according to the present invention; Figure 5 is a structural schematic diagram of the self-tapping anchor of the self-tapping anchor wood-concrete composite beam shear joint according to the present invention. Detailed Implementation

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] Figures 1-5 show a structural schematic diagram of one embodiment of the self-tapping anchor bolt of the shear joint of the wood-concrete composite beam according to the present invention. Referring to Figures 1-5, the shear joint of the wood-concrete composite beam with self-tapping anchor bolt of this embodiment includes a concrete slab 1, glued laminated timber 2, a perforated T-shaped steel plate 3 and a self-tapping anchor bolt 4.

[0024] Both the concrete slab 1 and the glued laminated timber 2 have grooves. The flange 31 and web 32 of the perforated T-shaped steel plate 3 are respectively embedded into the grooves of the concrete slab 1 and the glued laminated timber 2. The web 32 of the perforated T-shaped steel plate 3 has several variable-diameter through-holes 33, and the inner wall of the variable-diameter through-holes 33 has a guide groove 34. The concrete slab 1 and the flange 31 of the perforated T-shaped steel plate 3 are detachably connected by self-tapping anchors 4. The glued laminated timber 2 and the web 32 of the perforated T-shaped steel plate 3 are bonded by intrinsic flame-retardant structural adhesive. The intrinsic flame-retardant structural adhesive is filled in the variable-diameter through-holes 33 and the guide groove 34 to form a high-density solid wedge-shaped mechanical interlocking structure.

[0025] In this embodiment, the variable diameter through-hole 33 is an hourglass-shaped bidirectional frustum structure. The diameter of the hole gradually decreases from the two sides of the web 32 towards the inner center section, and the edge of the hole is rounded. The guide groove 34 is spiral and distributed on the inner wall of the variable diameter through-hole 33. The surface of the web 32 of the perforated T-shaped steel plate 3 needs to be sandblasted to remove rust. The self-tapping anchor 4 is preferably a high-strength concrete screw with a special hardening treatment on its surface. It has a serrated cutting thread that can directly cut into the concrete substrate to form a mechanical interlock, providing excellent pull-out and shear bearing capacity, and has a certain degree of ductility.

[0026] The concrete slab 1 is pre-grooved with a groove, the groove size being 1mm larger than the perforated T-shaped steel plate 3; the glued laminated timber 2 is pre-grooved with a groove, the length and width of which are 3mm larger than the perforated T-shaped steel plate 3, and the depth is 2mm larger than the perforated T-shaped steel plate 3, in order to form an adhesive layer to ensure adhesive strength.

[0027] The intrinsic flame-retardant structural adhesive is a phosphorus / nitrogen modified epoxy resin structural adhesive. The phosphorus and nitrogen flame-retardant elements are introduced into the resin molecular chain segments through chemical bonding. The phosphorus / nitrogen modified epoxy resin structural adhesive consists of component A and component B. Component A is a phosphorus-containing epoxy resin grafted with DOPO, with the phosphorus content controlled at 2%-3%wt. The modified resin introduces flame-retardant elements into the molecular chain through chemical bonding, solving the problem of phase separation and interface peeling that is easy to occur when traditional physical flame retardants are added. Component B is a modified amine curing agent containing flexible long chains, and is compounded with 5%-10%wt of nitrogen-containing synergist. The phosphorus and nitrogen flame-retardant elements introduced by chemical bonding in this resin system have a significant dual effect of condensed phase char formation and gas phase quenching under high temperature conditions. When the node is exposed to fire, the resin molecular chains permeating the spiral guide groove 34 rapidly undergo directional dehydration and carbonization, generating a dense, expanded carbon layer rich in phosphate ester bonds in situ. Unlike the interface peeling that easily occurs with traditional physical addition of microcapsules, this intrinsic carbon layer, as a transformation product of the resin matrix, can completely retain the macroscopic morphology of the variable-diameter through-holes and spiral guide grooves, forming a robust carbonaceous mechanical interlocking structure at high temperatures. This high-temperature resistant carbonaceous skeleton not only effectively isolates the transfer of external heat flow to the interior of the steel plate, protecting the mechanical properties of the metal connectors, but also, even after the decomposition of the colloidal organic components, still restricts the slippage and pull-out of the T-shaped steel plate 3 through physical interlocking, thus significantly improving the safety of the node throughout the entire fire process.

[0028] Referring to Figures 1-5, the specific construction method of the self-tapping anchored timber-concrete composite beam shear joint described in this embodiment is as follows: Determine the type and size of concrete slab 1, glued laminated timber 2, perforated T-shaped steel plate 3, and self-tapping anchor 4 according to the requirements. According to the size of the perforated T-shaped steel plate 3, grooves are made in concrete slab 1 and glued laminated timber 2. The grooves are ground and cleaned to ensure that the groove openings are clean and flat.

[0029] Connecting concrete slab 1 and perforated T-shaped steel plate 3: Confirm the anchoring position of self-tapping anchor 4 on concrete slab 1, drill holes at the corresponding positions, clean the drilled holes, and then embed the flange 31 of perforated T-shaped steel plate 3 into the groove of concrete slab 1. The anchor hole of flange 31 should be aligned with the drilled hole of concrete slab 1. Use an impact wrench to screw in the self-tapping anchor 4 to complete the connection between perforated T-shaped steel plate 3 and concrete slab 1.

[0030] The surface of the web 32 of the perforated T-shaped steel plate 3 is sandblasted to remove oxide scale and rust. The surface cleanliness reaches Sa2.5 level, and the surface roughness Ra≥12.5μm. The sandblasted surface is then cleaned with acetone or anhydrous ethanol to remove oil and dust, and then dried for later use.

[0031] To prepare the intrinsic flame-retardant structural adhesive, component A (modified resin matrix) is a phosphorus-containing epoxy resin grafted with DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), with a phosphorus content controlled at 2%-3%wt. This modified resin introduces flame-retardant elements into the molecular chain through chemical bonding, solving the problems of phase separation and interfacial delamination that easily occur with traditional physically added flame retardants. Component B (curing agent) is a modified amine curing agent containing flexible long chains, compounded with 5%-10%wt of a nitrogen-containing synergist (such as melamine cyanurate) to enhance the gas source synergistic effect. Components A and B are mixed in a specified ratio and stirred at medium speed (300-500 r / min) using a mechanical stirrer for 2-3 minutes until homogeneous. The adhesive solution is then placed in a vacuum chamber and degassed for 3-5 minutes under a negative pressure of -0.08 MPa to -0.09 MPa until no visible bubbles escape from the adhesive solution.

[0032] Inject an appropriate amount of the aforementioned degassed intrinsic structural adhesive into the bottom and side walls of the precast groove of the glued laminated timber 2. The amount of adhesive injected should be slightly more than the calculated gap volume (usually 10% to 15% surplus) to ensure that air can be carried out during subsequent extrusion. Align the web 32 of the prepared perforated T-shaped steel plate 3 vertically with the center of the groove and insert it slowly and uniformly. During this process, the low-viscosity adhesive generates hydraulic pressure under the extrusion action of the perforated T-shaped steel plate 3, forcing the adhesive to flow into the variable-diameter through-hole 33 on the web 32. As the perforated T-shaped steel plate 3 continues to penetrate, the adhesive, driven by the pressure difference, generates a swirling flow along the spiral guide groove 34 on the inner wall of the variable-diameter through-hole 33. This flow pattern can effectively overcome surface tension and discharge air from the depth of the channel and the dead corner of the spiral groove along the guide groove 34, ensuring that the adhesive fills more than 95% of the complex hole shape.

[0033] After the perforated T-shaped steel plate 3 is fully inserted, observe whether there is continuous transparent glue overflowing from the edge of the groove of the glued laminated wood 2 (to determine whether the interior is filled). Use positioning clamps to fix the position of the T-shaped steel plate 3, clean up the excess glue, and let it stand at room temperature to cure for 24-48 hours. During this period, the glue undergoes a cross-linking reaction and transforms into a high-strength thermosetting entity. At this time, the cured glue macroscopically fills the hourglass-shaped variable-diameter through hole 33 to form a bidirectional wedge-shaped pin, mesoscopically completely replicates the texture of the spiral guide groove to form an anti-torsion thread, and microscopically penetrates into the sandblasted pits of the steel plate and the cell cavities of the wood, thus forming a highly dense mechanical interlocking structure with macroscopic-mesoscopic-microscopic three-level linkage.

[0034] To further illustrate the synergistic effect mechanism of the intrinsic flame-retardant epoxy resin and the spiral guide groove structure with variable diameter through holes described in this invention, the expected performance of the embodiments of this invention is described in detail, and a theoretical comparison is made with the traditional microcapsule physical filling scheme.

[0035] 1) Example Setup Example 1 (Preferred embodiment of the present invention): An intrinsic phosphorus / nitrogen modified epoxy resin system is used. This system incorporates flame-retardant groups into the resin skeleton through chemical grafting technology. The initial mixing viscosity is designed to be controlled at 500~800 MPa·s (25℃). The system is a homogeneous transparent fluid and does not contain solid particles.

[0036] Comparative Example 1 (Traditional Physical Modification Scheme): The same epoxy resin as in Example 1 was used, with 15% wt% intumescent flame-retardant microcapsules with a particle size of 50-100 μm physically doped. Based on Einstein's suspension viscosity equation, the mixed viscosity of this system is expected to exceed 5000 MPa·s and exhibit non-Newtonian fluid characteristics.

[0037] 2) Construction Process and Filling Effect Prediction: Based on fluid mechanics principles, during the injection process, the expected performance of Comparative Example 1 is as follows: When the high-viscosity adhesive containing microcapsules flows through the spiral guide groove 34 at the web of the perforated T-shaped steel plate, due to the small cross-sectional size and complex path of the flow channel, the microcapsule particles are prone to accumulate and bridge at the groove opening, resulting in a filter cake effect. This will lead to insufficient adhesive or air pocket defects deep in the spiral groove, and the filling rate is expected to be difficult to exceed 65%.

[0038] Expected performance of Example 1: The intrinsic adhesive of the present invention has low viscosity and high wettability similar to engine oil. Driven by gravity and capillary action, the adhesive is expected to smoothly expel air from the "variable diameter through hole 33" and completely wet the inner wall of the "spiral guide groove 34", with a filling rate expected to reach more than 95%, thereby forming a complete solid mechanical interlocking structure.

[0039] 3) Mechanical Properties and Fire Resistance Mechanism Prediction: Based on the interfacial mechanics theory of composite materials and the flame-retardant chemical mechanism, the predicted joint performance is as follows: Pull-out load capacity prediction: Thanks to the expected filling rate of over 95%, in Example 1, after curing, the colloid will form a high-density cast-in-place wedge-shaped pin with the variable-diameter hole of the steel plate. Compared with Comparative Example 1, which suffers from stress concentration and early interface delamination due to internal defects, the single-pin pull-out ultimate load capacity of the joint of this invention is expected to increase by 20%~40%, and the failure mode will change from brittle colloid-steel plate interface debonding to ductile wood matrix splitting or steel plate yielding.

[0040] 4) Fire resistance performance prediction: Under high temperature conditions in a fire (ISO 834 standard temperature rise curve): Although Comparative Example 1 contains microcapsules, due to the lack of tightness in the glue injection, there are internal cavities. At high temperatures, gas expansion may accelerate interface peeling, leading to premature detachment of the insulation layer.

[0041] In Example 1, the intrinsic flame-retardant system, when heated, utilizes phosphorus / nitrogen elements in its molecular chains to catalyze the in-situ dehydration of the resin into char, forming a continuous, dense, and strongly adherent expanded char layer. The fire resistance limit of this node (with a slippage of 15 mm as the failure criterion) is expected to be significantly better than that of Comparative Example 1, effectively delaying heat transfer to the interior of the steel plate and ensuring the remaining load-bearing capacity of the connector during a fire.

[0042] In summary, the use of intrinsic phosphorus / nitrogen modified epoxy resin can fundamentally solve the injection process problems faced by the complex and precise hole structures (variable diameter holes, spiral grooves) described in this invention. Compared with traditional microcapsule physical filling technology, this solution is expected to have significant technical advantages in terms of construction feasibility, interface bonding quality, pull-out bearing capacity, and fire resistance safety.

[0043] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A shear joint for a self-tapping anchored timber-concrete composite beam, characterized in that, include: The concrete slab (1), glued laminated timber (2), perforated T-shaped steel plate (3), and self-tapping anchors (4) are provided. Both the concrete slab (1) and the glued laminated timber (2) have grooves. The flange (31) and web (32) of the perforated T-shaped steel plate (3) are respectively embedded into the grooves of the concrete slab (1) and the glued laminated timber (2). The web (32) of the perforated T-shaped steel plate (3) has several through-holes (33) with varying diameters. The inner wall of the hole (33) is provided with a guide groove (34); the flange (31) of the concrete slab (1) and the perforated T-shaped steel plate (3) are detachably connected by self-tapping anchors (4); the glued laminated timber (2) and the web plate (32) of the perforated T-shaped steel plate (3) are bonded by intrinsic flame-retardant structural adhesive; the intrinsic flame-retardant structural adhesive is filled in the variable diameter through structural hole (33) and the guide groove (34) to form a high-density solid wedge mechanical interlocking structure.

2. The shear joint of a self-tapping anchored wood-concrete composite beam according to claim 1, characterized in that, The variable diameter through structure hole (33) is an hourglass-shaped bidirectional frustum structure. The hole diameter gradually decreases from the two sides of the web plate (32) towards the inner center section, and the edge of the hole is rounded.

3. The shear joint of a self-tapping anchored wood-concrete composite beam according to claim 1, characterized in that, The guide groove (34) is spiral-shaped and distributed on the inner wall of the variable diameter through structure hole (33).

4. A self-tapping anchored timber-concrete composite beam shear joint according to claim 1, characterized in that, The concrete slab (1) is pre-grouted during prefabrication, and the groove size is 1mm larger than the perforated T-shaped steel plate (3); the glued laminated timber (2) is pre-grouted during prefabrication, and the groove length and width are 3mm larger than the perforated T-shaped steel plate (3), and the depth is 2mm larger than the perforated T-shaped steel plate (3), so as to form an adhesive layer to ensure adhesive strength.

5. A shear joint for a self-tapping anchored timber-concrete composite beam according to claim 1, characterized in that, The intrinsic flame-retardant structural adhesive is a phosphorus / nitrogen modified epoxy resin structural adhesive, wherein the phosphorus and nitrogen flame-retardant elements are introduced into the resin molecular chain segments through chemical bonding.

6. A self-tapping anchored timber-concrete composite beam shear joint according to claim 5, characterized in that, The phosphorus / nitrogen modified epoxy resin structural adhesive is composed of component A and component B. Component A is a phosphorus-containing epoxy resin grafted with DOPO and the phosphorus content is controlled at 2%-3%wt. Component B is a modified amine curing agent containing flexible long chains and is compounded with 5%-10%wt of nitrogen-containing synergist.

7. A construction method for a shear joint of a self-tapping anchored timber-concrete composite beam as described in any one of claims 1-6, characterized in that, The steps are as follows: S1. Determine the type and size of the concrete slab (1), glued laminated timber (2), perforated T-shaped steel plate (3), and self-tapping anchors (4) according to the usage requirements. According to the size of the perforated T-shaped steel plate (3), grooves are made on the concrete slab (1) and glued laminated timber (2). The grooves are then ground and cleaned. S2. Determine the anchoring position of the self-tapping anchors (4) on the concrete slab (1) and drill holes. After cleaning the drilled holes, embed the flange (31) of the perforated T-shaped steel plate (3) into the groove of the concrete slab (1), aligning the anchor holes on the flange (31) with the drilled holes in the concrete slab (1). S3. Pre-treat the web surface of the perforated T-shaped steel plate (3); S4. Prepare intrinsic flame-retardant structural adhesive and degas the adhesive; S5. Inject the degassed intrinsic flame-retardant structural adhesive into the groove of the glued laminated timber (2), and slowly insert the pre-treated web of the perforated T-shaped steel plate (3) vertically aligned with the center of the groove, so that the adhesive fills the variable diameter through-hole (33) and the guide groove (34); S6. Fix the position of the perforated T-shaped steel plate (3) with the positioning clamp, clean up the overflowing adhesive, and complete the node assembly after static curing.

8. A construction method for a shear joint of a self-tapping anchored timber-concrete composite beam according to claim 7, characterized in that, In step S4, the preparation steps of the intrinsic flame-retardant structural adhesive are as follows: Component A is selected from DOPO graft-modified phosphorus-containing epoxy resin, with the phosphorus content controlled at 2%-3%wt; Component B is selected from modified amine curing agent containing flexible long chains, and compounded with 5%-10%wt nitrogen-containing synergist; Components A and B are mixed in a preset ratio and stirred at 300-500r / min for 2-3 minutes until uniform; The degassing treatment is performed under a negative pressure environment of -0.08MPa to -0.09MPa for 3-5 minutes until no visible bubbles are found in the adhesive.

9. A construction method for a shear joint of a self-tapping anchored timber-concrete composite beam according to claim 1, characterized in that, In step S5, the amount of intrinsic flame-retardant structural adhesive injected is 10%-15% more than the volume of the gap between the groove and the web (32).

10. A construction method for a shear joint of a self-tapping anchored timber-concrete composite beam according to claim 1, characterized in that, In step S6, the static curing conditions are: standing at room temperature for 24-48 hours, and the filling rate of the adhesive to the variable diameter through structure hole (33) and the guide groove (34) is not less than 95%.

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