Slow-bonding shear nail, steel-concrete composite beam and construction method thereof

Abstract

The present invention provides a slow-bonding shear nail, including a sleeve and a stud weld nail, the sleeve includes a cylinder and an upper cover, the cylinder and the upper cover enclose a receiving cavity, the receiving cavity is filled with a slow-bonding adhesive, the stud weld nail includes a welding portion welded to a steel structure and a covering portion extending into the cylinder and covered by the slow-bonding adhesive, the covering portion blocks the cylinder. The present invention also provides a steel-concrete composite beam, including a steel structure, a concrete slab, a plurality of prestressed steel strands and the aforementioned plurality of slow-bonding shear nails, each of the prestressed steel strands is tensioned in the concrete slab, the steel structure supports the concrete slab, each of the slow-bonding shear nails is welded to the steel structure and cast in the concrete slab. The present invention also provides a construction method for a steel-concrete composite beam, the steps are as follows: S1, erecting a steel structure; S2, welding stud weld nails on the steel structure, and installing a slow-bonding shear nail sleeve; S3, casting a concrete slab on the steel structure; S4, tensioning the prestress in the negative bending moment zone; S5, waiting for the slow-bonding adhesive to solidify.

Description

Technical Field

[0001] The invention relates to the field of steel-concrete composite beams, and in particular to a slow-bonding shear nail, a steel-concrete composite beam and a construction method thereof. Background Art

[0002] Shear connectors are key components that ensure that steel and concrete work together in steel-concrete composite beams. Shear studs are currently commonly used shear connectors, and their main function is to resist shear (shear force) and pullout (lifting) between steel beams and concrete beams. The concrete part in the negative bending zone may produce tensile stress, causing cracking of the concrete slab and affecting the durability of the bridge. Usually, measures such as applying prestress in the negative bending zone are used to control cracks, but the steel beam absorbs part of the prestress through combined action, reducing the introduction of prestress. Therefore, how to increase the introduction of prestress in the negative bending zone of the composite beam, thereby controlling the tensile stress of the concrete within the allowable range, has become the key to the design of steel-concrete composite beam bridges.

[0003] Currently, two technologies, post-combined prestressed concrete bridge deck and pull-out but not shear-resistant connectors, are used to solve the problem of prestressing efficiency.

[0004] Post-combined prestressed concrete bridge deck is a precast concrete bridge deck using the pre-tensioning method or post-tensioning method. After the prestressing is applied, the prestressed concrete bridge deck is combined with the steel beam. The flange bolt connectors on the steel beam adopt a novel clustered arrangement (the conventional arrangement is uniformly distributed). The precast bridge deck is hollowed out at the location of the steel beam shear nails (nail group) to form a reserved groove or post-cast joint. After the precast panel is installed, high-strength mortar is poured in the reserved holes or post-cast joints to combine the steel beam and the concrete precast panel. This method can effectively apply prestress to the negative moment concrete slab, but due to the large number of joints and complex construction procedures, the integrity of the bridge deck is not as good as the effect of one-time casting.

[0005] The pull-out-resistant but not shear-resistant connector is a special form of shear nail, which is composed of a screw and nut welded on the flange of the steel beam and an EVA foam jacket around it. Since the stiffness of foam plastics is negligible compared to steel and concrete, foam plastics allow the connector to slide in the longitudinal direction, and the nut (larger than the column head size of ordinary welded nails) can constrain the lower concrete in contact with the concrete to ensure a certain pull-out force, thereby forming a pull-out-resistant but not shear-resistant working mechanism within a certain sliding deformation range. When prestressing, the concrete is compressed, and this special shear nail ensures the introduction degree of prestressing. The concrete slab participates in cast-in-place construction and has good integrity. Due to the barrier effect of foam plastics, the concrete and steel beams in the negative moment zone cannot be combined to participate in the force. Compared with the use of conventional studs, the section stiffness in the negative moment zone is reduced to a certain extent, and the bending bearing capacity is weakened.

[0006] The current Chinese patent application number 201910483375.0 discloses a slow-bonding rivet, which is used as a shear connector in a steel-concrete composite beam. The slow-bonding rivet used in the patent is to wrap a layer of slow-bonding agent on the rivet after welding, and then sleeve a sheath divided into two halves longitudinally on each rivet. The structural type of the slow-bonding rivet cannot guarantee the problem of slow-bonding agent dripping and bottom leakage during on-site construction caused by the fluidity of the slow-bonding agent. The slow-bonding agent needs to be coated on the rivet at the construction site. The construction process is cumbersome and it is easy to have the phenomenon of incomplete slow-bonding agent. When the slow-bonding agent is incomplete, the force-bearing performance of the composite structure cannot be ultimately guaranteed. During the pouring of concrete, under the impact force of concrete, the relative position of the outer sheath of the slow-bonding rivet and the rivet will be misaligned, which will cause the slow-bonding function to fail and the quality of the project cannot be guaranteed. Summary of the invention

[0007] The purpose of the present invention is to overcome the defects of the prior art and provide a slow-bonding shear nail with reasonable structure, outstanding stress-bearing performance, wide adaptability, convenient and flexible operation, and excellent economy. The slow-bonding shear nail not only ensures the true combined stress of steel plate and concrete, but also solves the problem of reduced prestressing introduction degree of negative moment concrete of steel-concrete composite beams.

[0008] The present invention is achieved in that:

[0009] The present invention provides a slow-adhesion shear nail, comprising a sleeve and a stud weld, wherein the sleeve comprises a cylinder body and an upper cover, wherein the cylinder body and the upper cover enclose a receiving cavity, wherein the receiving cavity is filled with a slow-adhesion adhesive, and the stud weld comprises a welding portion welded to a steel structure and a covering portion extending into the cylinder body and covered by the slow-adhesion adhesive, wherein the covering portion blocks the cylinder body.

[0010] Preferably, the sleeve also includes a nut, which is fixedly installed in the cylinder. The stud weld includes a screw head welded to the steel structure and a screw column extending into the cylinder and sealing the cylinder. The screw column is threadedly connected to the nut, and the slow-adhesive adhesive covers the screw column.

[0011] Preferably, the cylinder is of T-shaped structure, comprising a cylinder head and a cylinder rod, the cylinder head being provided with an annular nut mounting plate, the nut being located at the cylinder head and fixedly supported on the nut mounting plate.

[0012] Preferably, the aperture of the barrel stem gradually decreases in a direction away from the barrel head.

[0013] Preferably, the outer wall of the cylinder rod is provided with concave-convex ribs or corrugations.

[0014] Preferably, the cylinder, upper cover and nut mounting plate are all injection molded parts of polyethylene, polypropylene or polyvinyl chloride.

[0015] Preferably, the upper cover is threadedly connected to the cylinder, and the upper cover is located at the top of the cylinder.

[0016] Preferably, the thickness of the end surface of the cylinder for the stud welding nail to extend into is smaller than the wall thickness of the cylinder, and the end surface of the cylinder for the stud welding nail to extend into is recessed toward the inside of the cylinder.

[0017] The present invention also provides a steel-concrete composite beam, comprising a steel structure, a concrete slab and a plurality of prestressed steel strands, each of the prestressed steel strands being tensioned in the concrete slab, the steel structure supporting the concrete slab, and the steel-concrete composite beam also comprising the aforementioned plurality of slow-bonding shear nails, each of the slow-bonding shear nails being welded to the steel structure and cast in the concrete slab.

[0018] The present invention also provides a construction method for a steel-concrete composite beam, comprising the following steps: S1, erecting a prefabricated steel structure; S2, welding studs and welds on the steel structure, and installing slow-bonding shear nail sleeves; S3, pouring a concrete slab on the steel structure; S4, when the concrete slab reaches a certain strength, starting to tension the prestress in the negative bending moment zone; S5, completing the construction, waiting for the slow-bonding adhesive to solidify, and then putting the steel-concrete composite beam into use.

[0019] The present invention has the following beneficial effects:

[0020] 1. The material properties of the slow-bonding adhesive and sleeve in the present invention, as well as the structural form of the slow-bonding shear nails in the present invention, effectively ensure that the steel plate and concrete are truly combined to bear force, and at the same time solve the problem of reduced prestressing degree of negative moment concrete in steel-concrete composite beams.

[0021] 2. The slow-bonding shear nail provided by the present invention does not require the slow-bonding adhesive to be coated on site, thus avoiding the cumbersome on-site construction process. The slow-bonding shear nail provided by the present invention has good sealing performance, and there will be no problem of the slow-bonding adhesive flowing or dripping. The slow-bonding adhesive is filled sufficiently full and dense in the sleeve, which can ensure that the prestress is effectively applied before the slow-bonding adhesive is cured, and can also ensure the force-bearing performance of the steel-concrete composite structure after the slow-bonding adhesive is cured.

[0022] 3. This slow-bonding shear nail adopts a structure in which stud welding nails and nuts are assembled through threaded connection (the common cylindrical head welding nail structure is not adopted), which reduces the manual operation steps of on-site construction, making it convenient and fast in engineering applications, and making large-scale use possible. This slow-bonding shear nail has a novel structure, convenient and simple construction, and reliable construction quality. The stud welding nails and nuts are connected by threads, which can effectively prevent the impact force of concrete during pouring concrete from causing the slow-setting shear nail sleeve to be dislocated.

[0023] 4. The inner cavity of the cylinder is tapered, and the plastic outside the cone has solid ribs. After the slow-adhesive adhesive is cured, the taper, ribs and nuts together provide pull-out resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A cross-sectional view of a slow-bonding shear stud provided in an embodiment of the present invention;

[0026] Figure 2 A cross-sectional view of a sleeve provided in an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the arrangement of the slow-bonding shear studs provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figure 1-Figure 3, Embodiment 1 of the present invention provides a slow-bonding shear nail, including a sleeve 1 and a stud weld 2, wherein the sleeve 1 includes a cylinder 3 and an upper cover 4, wherein the upper cover 4 is threadedly connected to the cylinder 3, and the upper cover 4 is located at the top of the cylinder 3, wherein the cylinder 3 and the upper cover 4 enclose a receiving cavity, wherein the receiving cavity is filled with a slow-bonding adhesive 5, and the stud weld 2 includes a welding portion welded to a steel structure 6 and a covering portion extending into the cylinder 3 and covered by the slow-bonding adhesive 5, wherein the covering portion blocks the cylinder 3. The slow-bonding shear nail provided by the present invention does not require coating the stud with a slow-bonding adhesive on site, thereby avoiding the cumbersome procedures of on-site construction. The slow-bonding shear nail provided by the present invention has good sealing performance, and will not have the problem of the slow-bonding adhesive flowing or dripping. The slow-bonding adhesive is filled sufficiently full and densely in the sleeve, which can not only ensure the effective application of prestress before the slow-bonding adhesive is cured, but also ensure the stress-bearing performance of the steel-concrete composite structure after the slow-bonding adhesive is cured. The sleeve also includes a nut 7, which is a steel part. The nut 7 is fixedly installed in the cylinder 3. The stud welding nail 2 includes a screw head welded to the steel structure 6 and a screw column extending into the cylinder 3 and blocking the cylinder 3. The screw column is threadedly connected to the nut 7, and the slow-adhesion adhesive 5 covers the screw column. The cylinder 3 is a T-shaped structure. The cylinder 3 includes a cylinder head and a cylinder rod. The cylinder head is provided with an annular nut mounting plate 8. The nut 7 is located at the cylinder head and fixedly supported on the nut mounting plate 8. The slow-adhesion shear nail adopts a structure in which the stud welding nail 2 and the nut 7 are assembled by threaded connection (the common cylindrical head welding nail structure is not adopted), which reduces the manual operation steps of on-site construction, makes it convenient and fast in engineering applications, and makes large-scale use possible. The slow-adhesion shear nail has a novel structure, is convenient and simple to construct, and has reliable construction quality. The stud welding nail 2 and the nut 7 are threadedly connected, which can effectively prevent the impact force of concrete during pouring concrete from causing the slow-setting shear nail sleeve to be dislocated. The stud welding nail 2 and the nut 7 are connected by threads, and the nut 7 of corresponding size can be designed according to different pull-out resistances.

[0030] The slow-adhesive adhesive 5 is a paste-like non-Newtonian fluid in the early stage, with good thixotropy and impact resistance, which ensures the efficiency of applying prestress in the negative bending moment zone during prestressing; after curing, the slow-adhesive adhesive 5 has high bonding strength and tensile shear strength, which firmly bonds the nut 7, stud weld 2, and sleeve 1 into one, has good pull-out and shear resistance, improves the integrity of the steel-concrete composite beam, and makes the composite structure bear force reasonably; after curing, the slow-adhesive adhesive 5 has high strength and a certain micro-expansion, so it has good construction performance and mechanical properties.

[0031] The slow-bonding shear nail structure has good versatility, and the size of the nut 7 and the corresponding cylinder 3 can be changed according to the requirements of pull-out resistance. Therefore, the structure of the slow-bonding shear nail can be used not only in the negative bending moment zone of the steel-concrete composite beam, but also in other steel-concrete composite structures.

[0032] The aperture of the cylinder rod gradually decreases in the direction away from the cylinder head, and the outer wall of the cylinder rod is provided with concave-convex ribs or corrugations. The cone design of the cylinder 3, which is small at the bottom and large at the top, can effectively improve the pull-out resistance of the shear nail. The concave-convex ribs enhance the bonding force between the slow-bonding shear nail and the concrete slab 9 after the slow-bonding adhesive is cured. The internal cavity of the cylinder 3 is tapered, and the plastic outside the cone is provided with solid ribs. After the slow-bonding adhesive 5 is cured, the taper, ribs and nuts together provide pull-out resistance.

[0033] The upper cover 4, nut mounting plate 8, and cylinder 3 can be made of high-density polyethylene, polypropylene, polyvinyl chloride materials through injection molding process, which have high tensile yield strength and elongation at break. The components of the slow-bonding shear nail cylinder are easy to produce and process, with mature technology, high production efficiency, low production cost, and suitable for mass production. The slow-bonding shear nail sleeve has good sealing performance and is easy to produce and assemble, which can effectively ensure that the slow-bonding adhesive 5 will not flow or drip during on-site construction.

[0034] The thickness of the end surface of the cylinder 3 for the stud welding nail 2 to extend into is smaller than the wall thickness of the cylinder 3, and the end surface of the cylinder 3 for the stud welding nail 2 to extend into is recessed toward the inside of the cylinder 3. The bottom of the cylinder 3 is designed with a thin wall, which is convenient for the stud welding nail 2 to pierce the bottom of the sleeve and tighten the nut 7.

[0035] Embodiment 2 of the present invention provides a steel-concrete composite beam including a steel structure 6, a concrete slab 9 and a plurality of prestressed steel strands (not shown), each of the prestressed steel strands is tensioned in the concrete slab 9, the steel structure 6 supports the concrete slab 9, and the steel-concrete composite beam also includes the aforementioned plurality of slow-bonding shear nails, each of the slow-bonding shear nails is welded to the steel structure 6 and cast in the concrete slab 9.

[0036] Embodiment 3 of the present invention provides a construction method for a steel-concrete composite beam, comprising the following steps: S1, erecting a prefabricated steel structure 6; S2, welding stud welds 2 on the steel beam flange 10, and installing a slow-bonding shear nail sleeve 1; S3, applying a release agent on the upper surface 11 of the steel beam flange, and pouring a concrete slab 9 on the steel structure 6; S4, when the concrete slab 9 reaches a certain strength, starting to tension the prestress in the negative bending moment zone; S5, completing the construction, waiting for the slow-bonding adhesive 5 to solidify, and then putting the steel-concrete composite beam into use.

[0037] After the steel beam is poured with concrete and the prestressing requirements are met, the concrete is prestressed, and the stud welds 2 and nuts 7 can freely slide with the concrete in the horizontal direction without affecting the introduction of prestress in the concrete.

[0038] The present invention provides a slow-bonding shear nail and a construction method thereof suitable for use in negative moment intervals of bridges or other steel-concrete composite structures. Figure 1As shown, the slow-bonding shear nail provided by the present invention consists of a stud welding nail 2 and a sleeve 1. The construction method provided by the present invention mainly relates to the operation of the combined structure of the steel beam flange plate and the slow-bonding shear nail in the negative bending moment area. The material and performance of the stud welding nail 2 are the same as those of the "cylindrical head welding nail for arc stud welding". The stud welding nail 2 needs to be welded on the steel beam flange plate according to the design requirements of the drawing.

[0039] like Figure 2 As shown, the sleeve 1 is composed of a cylinder, a slow-adhesive adhesive 5, an upper cover 4, a nut 7, and a nut mounting plate 8, wherein: the slow-adhesive adhesive 5 is placed inside the sleeve 1, and after the stud welding nail 2 is inserted, it is tightly wrapped and the sleeve 1 is filled densely. The slow-adhesive adhesive 5 is a paste-like non-Newtonian fluid before the prestressed tensioning construction is completed. Its material form effectively ensures that there is no bonding force between the shear nail and the concrete, but it also has a certain impact resistance, which can fully resist and release the tension force to ensure that the shear nail is not subjected to the force during tensioning; after the tensioning is completed, the slow-adhesive adhesive 5 gradually solidifies with the passage of time (the curing time of the slow-adhesive adhesive 5 can be controlled by adjusting the formula of the slow-adhesive adhesive 5), so that the shear nail and the concrete are effectively combined, and its pull-out and shear-resistant functions are truly exerted, so that the steel plate and concrete are truly combined to bear force.

[0040] Post-bonded prestressed concrete bridge deck is only suitable for prefabricated bridge deck structures, which have many blocks, many wet joints, and poor integrity of the bridge deck. The slow-bonding shear nails provided by the present invention can be used for both prefabricated structures and cast-in-place structures. When cast-in-place construction is adopted, the integrity is good and the adaptability is strong.

[0041] For pull-out resistant but not shear resistant connectors, when prestress is applied to concrete, a layer of EVA foam is set between the shear nails and the concrete, and the prestress cannot be transmitted to the steel beam through the shear nails, thereby ensuring the introduction degree of the prestress. However, after the prestressing is completed, the shear nails and concrete are still in a separated state, the steel plate and concrete cannot be combined to bear the force, the section stiffness under the later load is reduced, and the mid-span bending moment increases.

[0042] The slow-bonding shear nail provided by the present invention adopts a combination structure of a stud weld 2 and a nut 7 to replace the common cylindrical head weld nail, fixes the nut 7 in the sleeve 1, and then encapsulates the slow-bonding adhesive 5 in the sleeve 1. During construction, the stud weld 2 is first welded to the steel beam, and then the sleeve 1 encapsulating the nut 7 and the slow-bonding adhesive 5 is installed on the stud weld 2 through the nut 7. This structural type avoids the problem of coating the slow-bonding adhesive on the weld nail on site and the problem of leakage of the slow-bonding adhesive. The sleeve 1 and the stud weld 2 can be relatively positioned to avoid the problem of misalignment under the impact force of pouring concrete. The stud weld 2 and the nut 7 are connected by threads, and the nut 7 of corresponding size can be designed according to the different pull-out resistance. The slow-bonding shear nail proposed in this patent is a connecting part of a steel structure and a concrete slab with a reasonable structural type, outstanding force performance, wide adaptability, convenient and flexible operation, and excellent economy.

[0043] Compared with the prior art, the material properties of the slow-bonding adhesive 5 and the sleeve 1 in the present invention, as well as the structural form of the slow-bonding shear nails in the present invention effectively ensure the establishment of a true combined force of the steel plate and concrete, and solve the problem of reduced prestressing introduction degree of negative moment concrete in steel-concrete composite beams.

[0044] The patented slow-bonding shear nail has a reasonable force pattern, is easy to produce and manufacture, has a low manufacturing cost, is convenient to construct, has flexible layout, and has reliable construction quality in the engineering application link. It is a product that can be used on a large scale in engineering.

[0045] The present invention provides a slow-bonding shear nail and a construction method thereof for effectively combining a steel structure and a concrete slab in a steel-concrete composite beam. The present invention can ensure the efficiency of applying prestress in the negative moment zone, ensure the overall stiffness of the composite beam, improve the strength utilization rate, and have good construction performance.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A slow-bonding shear nail, characterized in that: It includes a sleeve and a stud weld, the sleeve includes a cylinder and an upper cover, the cylinder and the upper cover enclose a receiving cavity, the receiving cavity is filled with a slow-adhesion adhesive, the stud weld includes a welding portion welded to the steel structure and a covering portion extending into the cylinder and covered by the slow-adhesion adhesive, the covering portion blocks the cylinder; the sleeve also includes a nut, the nut is fixedly installed in the cylinder, the stud weld includes a screw head welded to the steel structure and a screw column extending into the cylinder and blocking the cylinder, the screw column is threadedly connected to the nut, and the slow-adhesion adhesive covers the screw column; the upper cover is threadedly connected to the cylinder, and the upper cover is located at the top of the cylinder.

2. The slow-bonding shear nail according to claim 1, characterized in that: The cylinder is in a T-shaped structure and comprises a cylinder head and a cylinder rod. The cylinder head is provided with an annular nut mounting plate. The nut is located at the cylinder head and fixedly supported on the nut mounting plate.

3. The slow-bonding shear nail according to claim 2, characterized in that: The aperture of the barrel stem gradually decreases in a direction away from the barrel head.

4. The slow-bonding shear nail according to claim 2, characterized in that: The outer wall of the cylinder rod is provided with concave-convex ribs or corrugations.

5. The slow-bonding shear nail according to claim 2, characterized in that: The cylinder, the upper cover and the nut mounting plate are all injection-molded parts made of polyethylene, polypropylene or polyvinyl chloride.

6. The slow-bonding shear nail according to claim 1, characterized in that: The thickness of the end surface of the cylinder for the stud welding nail to extend into is smaller than the wall thickness of the cylinder, and the end surface of the cylinder for the stud welding nail to extend into is concave toward the inside of the cylinder.

7. A steel-concrete composite beam, comprising a steel structure, a concrete slab and a plurality of prestressed steel strands, each of the prestressed steel strands being tensioned in the concrete slab, the steel structure supporting the concrete slab, characterized in that: The steel-concrete composite beam also includes a plurality of slow-bonding shear nails as described in any one of claims 1 to 6, each of which is welded to the steel structure and cast in the concrete slab.

8. A construction method for a steel-concrete composite beam, characterized in that: The method comprises the following steps: S1, erecting a prefabricated steel structure; S2, welding studs and weld nails on the steel structure, and installing slow-bonding shear nail sleeves; S3, pouring a concrete slab on the steel structure; S4, when the concrete slab reaches a certain strength, starting to tension the prestress in the negative bending moment zone; S5, completing the construction, waiting for the slow-bonding adhesive to solidify, and then putting the steel-concrete composite beam into use.

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