Concrete foundation beam made of composite carbon fiber reinforced material

Abstract

The invention discloses a concrete foundation beam made of a composite carbon fiber reinforced material, and belongs to the technical field of civil engineering structures. The beam comprises a concrete body, a plurality of rows of longitudinal load-bearing steel bar groups arranged up and down, a positioning bracket, a transverse constraint steel bar combination, an embedded anchoring connecting piece and an external composite carbon fiber reinforced layer, wherein the transverse constraint steel bar combination is composed of closed main stirrups and Z-shaped additional tie bars; the embedded anchoring connecting piece comprises an end metal anchor plate and radial lateral anchor bars; the external composite carbon fiber reinforced layer is formed by sticking a plurality of layers of unidirectional carbon fiber fabrics which are longitudinally arranged along the beam and impregnated with resin, completely wraps the edges of the bottom, the two sides and the top surface of the beam, and is in bolted connection with the anchor plate through a mechanical pressing sheet at the end part; longitudinal through reserved hole channels are further formed in the beams and used for allowing prestressed tendons or sensor cables to penetrate through. The anti-bending and anti-shearing capacity, ductility, durability and multifunctional adaptability of the structure are improved.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering structural technology, and in particular relates to a concrete foundation beam made of composite carbon fiber reinforced material. Background Technology

[0002] In modern civil engineering, reinforced concrete beams, as the most basic bending members in building and bridge structures, directly affect the safety, durability, and service life of the overall structure. Traditional reinforced concrete beams mainly rely on internal longitudinal reinforcing bars and stirrups to bear bending moments and shear forces. However, under high loads, large spans, or harsh environments, they often face problems such as insufficient bending stiffness, difficulty in crack control, bearing capacity degradation due to steel corrosion, and limited seismic ductility. To improve performance, the engineering community widely adopts reinforcement methods such as external steel cladding, increased cross-sections, external prestressing, or bonding fiber-reinforced composite materials.

[0003] However, existing carbon fiber reinforcement technologies generally suffer from defects such as weak end anchorage, easy peeling failure, and poor overall coordination due to only local reinforcement. At the same time, conventional beam internal steel reinforcement skeletons lack effective lateral ties when multiple rows of reinforcement are arranged, which can easily cause the steel reinforcement to scatter and slip during the stress process, weakening the bond with concrete.

[0004] To address these issues, we provide a concrete foundation beam made of composite carbon fiber reinforced material. Summary of the Invention

[0005] The purpose of this invention is to provide a concrete foundation beam reinforced with composite carbon fiber. By optimizing the configuration of multiple rows of longitudinal reinforcing bars, dense stirrups, and Z-shaped additional tie bars inside the concrete body to form a highly stable skeleton, and by fully wrapping the outer surface of the beam with multi-layer carbon fiber fabric arranged longitudinally, this invention solves the technical problems of existing reinforced concrete beams under high loads or harsh environments, such as insufficient bending and shear bearing capacity, easy peeling of carbon fiber reinforcement, poor integrity of the reinforcing bar skeleton, and low durability.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a concrete foundation beam reinforced with composite carbon fiber, comprising: Concrete body; The longitudinal reinforcing steel assembly includes an upper longitudinal reinforcing steel assembly installed on the upper part of the concrete body and a lower longitudinal reinforcing steel assembly installed on the lower part of the concrete body, with the two maintaining a fixed distance through positioning brackets; The transverse restraint reinforcement assembly includes main stirrups and additional tie bars. The main stirrups are closed ring structures that are installed around the longitudinal reinforcing reinforcement assembly. The additional tie bars are Z-shaped, with both ends hooked to non-adjacent bars in the longitudinal reinforcing reinforcement assembly, and fixed by spot welding at the intersection with the main stirrups in the middle. The pre-embedded anchoring connector includes an end metal anchor plate and a lateral anchor bar. The end metal anchor plate is vertically embedded in the end face of the concrete body and connected to the nearest main stirrup by a fillet weld. One end of the lateral anchor bar is welded to the outer side of the end metal anchor plate, and the other end extends into the concrete body and is lapped and welded to at least two longitudinal steel bars. The external composite carbon fiber reinforcement layer is made of multiple layers of unidirectional carbon fiber fabric bonded together by impregnation with resin. It completely covers the bottom, two sides and the top edge area of ​​the concrete body, and extends to the surface of the end metal anchor plate in the beam end area. It is connected to the end metal anchor plate by mechanical pressing and bolts. The fiber orientation of each layer of carbon fiber fabric is parallel to each other and arranged along the longitudinal axis of the concrete body.

[0007] The present invention is further configured such that the upper longitudinal steel bar group and the lower longitudinal steel bar group each contain no less than two rows of parallel steel bars, and the steel bars in the same row are connected and fixed by transverse distribution bars.

[0008] The present invention is further configured such that the main stirrups are configured as a densified section in the beam end region, and the spacing of the main stirrups in the densified section is smaller than the spacing of the main stirrups in the undensified section in the middle.

[0009] The present invention is further configured such that the additional tie bars are arranged in an alternating manner in the cross section, and the spacing between adjacent additional tie bars in the longitudinal direction is not greater than twice the spacing of the main stirrups.

[0010] The invention is further configured such that the outer side of the end metal anchor plate is provided with a plurality of threaded holes, and the mechanical pressing plate is screwed into the threaded holes after passing through the composite carbon fiber reinforcement layer by a high-strength bolt.

[0011] The present invention is further configured such that the lateral anchor bars are ribbed steel bars, and each of the end metal anchor plates is connected to no less than four lateral anchor bars, and the lateral anchor bars are radially distributed inside the concrete body.

[0012] The present invention is further configured such that the composite carbon fiber reinforcement layer forms a folded-back wrapping structure at the edge of the top surface of the concrete body, and is bonded to the top carbon fiber layer by a resin adhesive layer.

[0013] The present invention is further configured such that a reserved channel is provided inside the concrete body, the reserved channel being longitudinally connected along the beam for subsequent installation of prestressed tendons or monitoring sensor cables.

[0014] The present invention has the following beneficial effects: 1. This invention effectively bears tensile stress by covering the outside of the beam with a composite carbon fiber reinforcement layer formed by multiple layers of unidirectional carbon fiber fabric arranged longitudinally, which is equivalent to adding high-performance external tension reinforcement; at the same time, the internal main stirrup reinforcement and Z-shaped additional tie bars work together to enhance the shear resistance of the beam and the overall skeleton stability.

[0015] 2. This invention improves the confinement of concrete and the integrity of the steel reinforcement skeleton through multiple measures such as increasing the density of stirrups at the beam ends, staggering additional tie bars, radial lateral anchor bars, and full carbon fiber wrapping restraint, effectively inhibiting crack development and improving plastic deformation capacity.

[0016] 3. In this invention, the upper and lower longitudinal steel bars are arranged in multiple rows and fixed by positioning brackets and transverse distribution bars. Additional tie bars tie non-adjacent longitudinal steel bars into a whole, effectively preventing construction disturbance and steel bars from scattering or slipping during stress, and ensuring the collaborative performance of steel bars and concrete.

[0017] 4. This invention solves the problem of end peeling and anchoring failure that easily occur when traditional carbon fiber bonding is used by setting pre-embedded end metal anchor plates and lateral anchor bars, and combining mechanical pressing plates and high-strength bolts to firmly connect the ends of the carbon fiber reinforcement layer to the anchor plates, thus ensuring that the carbon fiber material can give full play to its high strength characteristics.

[0018] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0020] Figure 1 This is a schematic diagram of the overall structure of a concrete foundation beam reinforced with composite carbon fiber.

[0021] Figure 2 For concrete foundation beams reinforced with composite carbon fiber Figure 1 Enlarged diagram of point A in the middle.

[0022] Figure 3 For concrete foundation beams reinforced with composite carbon fiber Figure 1 Enlarged diagram of point B in the middle.

[0023] Figure 4 For concrete foundation beams reinforced with composite carbon fiber Figure 1 Enlarged diagram of point C in the middle.

[0024] The attached diagram lists the components represented by each number as follows: 1. Concrete body; 2. Longitudinal reinforcing steel reinforcement assembly; 21. Upper longitudinal reinforcing steel reinforcement assembly; 22. Lower longitudinal reinforcing steel reinforcement assembly; 3. Positioning bracket; 4. Transverse restraint reinforcing steel reinforcement assembly; 41. Main stirrups; 42. Additional tie bars; 5. Embedded anchorage connectors; 51. End metal anchor plates; 52. Lateral anchor bars; 6. External composite carbon fiber reinforcement layer; 61. Unidirectional carbon fiber fabric; 7. Reserved ducts. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] Example Please see Figure 1-4 This invention relates to a concrete foundation beam reinforced with composite carbon fiber, comprising: Concrete body 1, as the main load-bearing structure of the beam, provides basic compressive strength and serves as a bonding matrix for the internal steel reinforcement skeleton and the external reinforcement layer; The longitudinal reinforcing steel assembly 2 includes an upper longitudinal reinforcing steel assembly 21 installed on the upper part of the concrete body 1 and a lower longitudinal reinforcing steel assembly 22 installed on the lower part of the concrete body 1. The two are kept at a fixed distance by a positioning bracket 3. The upper longitudinal reinforcing steel assembly 21 is mainly used to resist negative bending moment, while the lower longitudinal reinforcing steel assembly 22 mainly bears the tensile stress caused by positive bending moment. By setting them up separately at the top and bottom and precisely controlling the distance by the positioning bracket 3, the internal force couple arm required for the bending member can be effectively formed, thereby improving the bending bearing capacity of the beam. At the same time, the positioning bracket 3 also plays a role in preventing the reinforcing steel from shifting during the pouring process. The transverse restraint reinforcement assembly 4 includes main stirrups 41 and additional tie bars 42. The main stirrups 41 are closed ring structures installed around the longitudinal reinforcing reinforcement assembly 2. The additional tie bars 42 are Z-shaped, with both ends hooked to non-adjacent reinforcing bars in the longitudinal reinforcing reinforcement assembly 2, and fixed by spot welding at the intersection with the main stirrups 41 in the middle. The main stirrups 41 constitute the core shear skeleton of the beam, which significantly improves the shear performance and ductility of the beam by restraining the transverse deformation of the concrete and preventing the propagation of diagonal cracks. The additional tie bars 42 tie the upper and lower rows of longitudinal reinforcing bars into a whole, effectively suppressing the relative slippage or scattering of the reinforcing skeleton during the stress process. The spot welding method ensures that the additional tie bars 42 and the main stirrups 41 form a stable spatial network system. The pre-embedded anchoring connector 5 includes an end metal anchor plate 51 and a lateral anchor bar 52. The end metal anchor plate 51 is vertically embedded inside the end face of the concrete body 1 and connected to the nearest main stirrup 41 by a fillet weld. One end of the lateral anchor bar 52 is welded to the outer side of the end metal anchor plate 51, and the other end extends into the concrete body 1 and is lap-welded to at least two longitudinal steel bars. The end metal anchor plate 51 serves as a key anchoring point for the external composite carbon fiber reinforcement layer 6. It is embedded in the concrete and connected to the main stirrup 41 by a fillet weld to form a reliable force transmission path, preventing the carbon fiber layer from peeling off under tension. The lateral anchor bar 52 uses ribbed steel bars and is radially distributed. It not only enhances the anchoring force between the anchor plate and the concrete, but also achieves effective force transmission through lap welding with the longitudinal steel bars. It guides part of the tensile force borne by the carbon fiber layer into the internal steel reinforcement skeleton of the beam through the anchor plate and the lateral anchor bar, thereby improving the ultimate bearing capacity and ductility of the overall structure. The external composite carbon fiber reinforcement layer 6 is made of multiple layers of unidirectional carbon fiber fabric 61 bonded layer by layer through resin impregnation. It completely covers the bottom, two sides and top edge areas of the concrete body 1, and extends to the surface of the end metal anchor plate 51 at the beam end area. It is bolted to the end metal anchor plate 51 by mechanical pressing. The fiber directions of each layer of carbon fiber fabric are parallel to each other and are arranged along the longitudinal axis of the concrete body 1. The composite carbon fiber reinforcement layer 6 is arranged along the longitudinal direction of the beam and mainly bears the bending tensile stress. The full wrapping not only improves the bending resistance, but also effectively restrains the concrete, delays crack propagation, and improves stiffness and durability. The mechanical pressing and bolted connection to the anchor plate 51 at the beam end solves the problem of easy peeling of carbon fiber material at the end, realizes reliable anchoring boundary conditions, and allows the carbon fiber layer to fully exert its tensile potential.

[0027] Specifically, the upper longitudinal reinforcement group 21 and the lower longitudinal reinforcement group 22 each contain no less than two rows of parallel reinforcement bars. The reinforcement bars in the same row are connected and fixed by transverse distribution bars 23. The multiple rows of reinforcement bars can adapt to the requirements of large cross sections or high loads. The transverse distribution bars 23 are used to maintain the uniform spacing of the reinforcement bars in the same row, prevent construction disturbance, and participate in crack resistance and local restraint to a certain extent, thereby improving the overall stability of the reinforcement cage. The main stirrups 41 are set as a densified section in the beam end area. The spacing of the main stirrups 41 in the densified section is smaller than that of the main stirrups 41 in the middle non-densified section. The densification of stirrups can significantly improve the shear resistance of this area, restrain the concrete, prevent brittle shear failure, and enhance ductility. The additional tie bars 42 are arranged in an alternating manner in the cross section. The longitudinal spacing of adjacent additional tie bars 42 is no more than twice the spacing of the main stirrups 41. The outer surface of the end metal anchor plate 51 is provided with multiple threaded holes. The mechanical clamping plate is screwed into the threaded holes after passing through the composite carbon fiber reinforcement layer 6 with a high-strength bolt. The threaded holes and the high-strength bolt constitute a detachable but highly reliable mechanical anchoring system, which can transmit huge tensile forces and facilitate construction, installation and subsequent maintenance, avoiding the risk of long-term creep or interface failure that may occur if only adhesives are used. The lateral anchor bars 52 are ribbed steel bars, and each end metal anchor plate 51 is connected with no less than four lateral anchor bars 52. The lateral anchor bars 52 are radially distributed inside the concrete body 1.

[0028] Furthermore, the composite carbon fiber reinforcement layer forms a folded-back wrapping structure at the top edge of the concrete body 1, and is bonded to the top carbon fiber layer by a resin adhesive layer. The folded-back wrapping structure effectively seals the corner of the beam, preventing the ends of the carbon fibers from warping or peeling off, while enhancing the constraint on the top concrete, inhibiting the development of cracks in the top compression zone, and improving the overall integrity and bending stiffness of the section. The concrete body 1 is provided with a reserved channel 7, which runs longitudinally along the beam and is used to implant intelligent sensing elements such as fiber optic gratings and strain gauges to realize structural health monitoring.

[0029] The operation process of this embodiment is as follows: First, in the prefabrication stage at the factory or on site, the steel reinforcement cage is tied according to the design drawings, including the installation of the upper longitudinal steel reinforcement group 21 and the lower longitudinal steel reinforcement group 22, and the vertical spacing between the two is precisely controlled by the positioning bracket 3; the longitudinal steel reinforcement in the same row is fixed by the transverse distribution reinforcement 23 to ensure the stability of the steel reinforcement position; Subsequently, closed-loop main stirrups 41 are arranged around the longitudinal reinforcing steel assembly 2, and the arrangement is denser at the beam end area; at the same time, the two ends of the Z-shaped additional tie bars 42 are hooked to the non-adjacent longitudinal steel bars respectively, and the middle part is firmly connected to the main stirrups 41 at the intersection point by spot welding to form a spatially stable transverse constraint system. Next, install the pre-embedded anchoring connector 5: vertically embed the end metal anchor plate 51 into the designated position inside the beam end formwork, and weld it to the adjacent main stirrup 41 through fillet weld; weld no less than four radially distributed ribbed lateral anchor bars 52 on its outer side, with the other end of each lateral anchor bar 52 extending into the beam body and lap-welded to at least two longitudinal steel bars to ensure effective force transmission. Simultaneously pre-embed a reserved duct 7 running longitudinally along the beam for subsequent installation of prestressed tendons or monitoring sensor cables; After the steel reinforcement cage and embedded parts are installed, formwork is erected and concrete that meets the strength and durability requirements is poured. The concrete is then vibrated to compact and cured to form the concrete body 1. After the concrete reaches the specified age, a base treatment is carried out on the outer surface of the beam. Then, unidirectional carbon fiber fabric 61 impregnated with resin is pasted layer by layer on the bottom, two sides and the top edge area. The fiber direction of each layer is along the longitudinal axis of the beam to ensure that the stress direction is consistent. The carbon fiber fabric is folded back and wrapped at the top edge and bonded to the top layer with a resin adhesive layer to form a closed reinforcement system. Finally, in the beam end region, the composite carbon fiber reinforcement layer 6 is extended to cover the surface of the end metal anchor plate 51, a mechanical pressure plate is placed, and a high-strength bolt is screwed through the carbon fiber layer into the threaded hole on the anchor plate to achieve reliable mechanical anchoring. Subsequently, as needed, prestressed tendons can be inserted through the reserved channel 7 for tensioning, or sensor cables can be laid to implement structural health monitoring.

[0030] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A concrete foundation beam reinforced with composite carbon fiber, characterized in that, include: Concrete body (1); The longitudinal reinforcing steel assembly (2) includes an upper longitudinal reinforcing steel assembly (21) installed on the upper part of the concrete body (1) and a lower longitudinal reinforcing steel assembly (22) installed on the lower part of the concrete body (1), and the two are kept at a fixed distance by a positioning bracket (3); The transverse restraint reinforcement assembly (4) includes a main stirrup (41) and an additional tie bar (42). The main stirrup (41) is a closed ring structure and is installed around the longitudinal reinforcing reinforcement assembly (2). The additional tie bar (42) is Z-shaped, with its two ends hooked onto non-adjacent reinforcing bars in the longitudinal reinforcing reinforcement assembly (2), and its middle part is fixed by spot welding at the intersection with the main stirrup (41). The pre-embedded anchoring connector (5) includes an end metal anchor plate (51) and a lateral anchor bar (52). The end metal anchor plate (51) is vertically embedded in the end face of the concrete body (1) and connected to the nearest main stirrup (41) by a fillet weld. One end of the lateral anchor bar (52) is welded to the outer side of the end metal anchor plate (51), and the other end extends into the concrete body (1) and is lap-welded to at least two longitudinal steel bars. The external composite carbon fiber reinforcement layer (6) is made of multiple layers of unidirectional carbon fiber fabric (61) bonded layer by layer by impregnation with resin. It completely covers the bottom, two sides and top edge areas of the concrete body (1) and extends to the surface of the end metal anchor plate (51) in the beam end area. It is connected to the end metal anchor plate (51) by mechanical pressing and bolting. The fiber directions of each layer of carbon fiber fabric are parallel to each other and are arranged along the longitudinal axis of the concrete body (1).

2. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The upper longitudinal steel bar group (21) and the lower longitudinal steel bar group (22) each contain no less than two rows of parallel steel bars, and the steel bars in the same row are connected and fixed by transverse distribution bars (23).

3. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The main stirrups (41) are set as a densified section in the beam end area, and the spacing of the main stirrups (41) in the densified section is smaller than the spacing of the main stirrups (41) in the middle non-densified section.

4. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The additional tie bars (42) are arranged in an alternating manner in the cross section, and the longitudinal spacing between adjacent additional tie bars (42) is no greater than twice the spacing of the main stirrups (41).

5. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The outer side of the end metal anchor plate (51) is provided with multiple threaded holes. The mechanical pressing plate is screwed into the threaded holes after passing through the composite carbon fiber reinforcement layer (6) with a high-strength bolt.

6. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The lateral anchor bars (52) are ribbed steel bars, and each end metal anchor plate (51) is connected to no less than four lateral anchor bars (52). The lateral anchor bars (52) are radially distributed inside the concrete body (1).

7. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The composite carbon fiber reinforcement layer forms a folded wrapping structure at the top edge of the concrete body (1) and is bonded to the top carbon fiber layer by a resin adhesive layer.

8. The concrete foundation beam of the composite carbon fiber reinforced material according to claim 1, characterized in that, The concrete body (1) has a reserved channel (7) inside, which runs through the beam longitudinally and is used for the subsequent installation of prestressed tendons or monitoring sensor cables.

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