A prefabricated road slab bidirectional pre-tightened steel bar connection structure and its rapid construction method

Abstract

This invention provides a bidirectional pre-tensioned rebar connection structure for prefabricated pavement panels and its rapid construction method, belonging to the field of road engineering technology, and particularly suitable for prefabricated pavement panel systems with shared reinforcement. It includes prefabricated pavement panels, reinforcing bars, and rebar connectors. Multiple reinforcing bars are pre-embedded within the prefabricated pavement panels, and the reinforcing bars on adjacent prefabricated pavement panels are connected by rebar connectors. The rebar connectors include two T-shaped sleeves, a lower clamp, and an upper clamp. The two T-shaped sleeves are respectively fitted onto the ends of two adjacent reinforcing bars and clamped and fixed by the lower and upper clamps. Fasteners are installed on the upper and lower clamps. The fasteners apply a vertical clamping force, which is converted into a horizontal pre-tensioning force acting on the T-shaped sleeves through the curved surface contact between the lower and upper clamps and the T-shaped sleeves. This invention aims to solve the technical problems of low construction efficiency, insufficient error tolerance, and lack of bidirectional in-plane constraint in existing prefabricated pavement panel rebar connection technologies.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to a prefabricated road slab bidirectional pre-tightened steel bar connection structure and its rapid construction method. Background Technology

[0002] With the rapid development of industrialized construction, prefabricated concrete pavement has shown great application potential in road construction, reconstruction, expansion, and rapid repair projects due to its significant advantages such as fast construction speed, easy quality control, minimal impact on traffic and the environment, and green environmental protection. One of its core key technologies lies in the efficient and reliable connection of steel bars between prefabricated pavement slabs. The connection performance directly determines the integrity of the pavement structure, load transfer efficiency, durability, and driving smoothness.

[0003] In recent years, to further improve the construction efficiency and structural integrity of prefabricated pavement panels, researchers have proposed the concept of a precast pavement panel system with integrated lifting and rebar reinforcement. This system involves embedding reinforcing bars into the precast pavement panels, allowing them to function as lifting reinforcements during the hoisting and splicing phase, and then transferring loads between panels during service. This system combines the traditionally separate hoisting embedded parts with the inter-panel reinforcing bars, effectively reducing the number of embedded parts, simplifying the internal structure of the panels, and offering significant structural efficiency advantages. However, the integrated lifting and rebar reinforcement system places more stringent technical requirements on the inter-panel rebar connectors: the connectors must not only transfer the axial tensile and compressive forces of the reinforcing bars, but also adapt to the special stress state of the T-shaped sleeves as lifting points during hoisting, and provide multi-directional in-plane constraints between panels to ensure the integrity of the pavement structure.

[0004] Currently, the connection technologies for reinforcing bars between prefabricated pavement slabs can be mainly classified into the following categories: The first type is cast-in-place wet joint connection. Reinforcing bars are pre-installed on the side of the precast pavement slab. After installation, formwork is erected at the joint and concrete is poured. This method offers good overall connection integrity, but it suffers from drawbacks such as a long curing period, construction speed heavily influenced by weather, and numerous on-site wet operations, thus failing to fully leverage the advantages of prefabricated construction technology.

[0005] The second type is post-tensioned prestressed connection. Holes are pre-drilled in the precast slab, and prestressing tendons are inserted and tensioned after installation. This method provides good integrity and prestress, but it requires extremely high construction precision, has a complex tensioning process, cumbersome anchorage treatment, and warrants attention regarding long-term prestress loss and maintenance issues.

[0006] The third category is mechanical connection of pre-embedded reinforcing bars. Pre-embedded reinforcing bars on the side of the slab are joined using methods such as sleeve extrusion or threaded connections. This is currently the mainstream research and application direction. However, existing mechanical connectors still face many challenges: First, poor construction adaptability. Most connectors have extremely stringent requirements for the hoisting accuracy of precast slabs, with allowable installation errors typically only ±1 to 2 mm, which is difficult to guarantee in actual engineering, easily leading to connection failure or initial assembly stress. Second, limited functionality. Most connectors mainly achieve axial tensile and compressive force transmission of the reinforcing bars (perpendicular to the joint direction), with limited ability to restrict the relative displacement and opening of the pavement slab in the horizontal direction within the plane. This necessitates reliance on joint materials or other structures, affecting the lateral load distribution capability. Third, installation efficiency needs improvement. Some connectors require multi-step, multi-angle operations, or special tools and large operating spaces, making construction inconvenient in narrow road joint environments and hindering the goal of rapid construction.

[0007] Therefore, developing a prefabricated pavement connector that can simultaneously meet the requirements of efficient construction, strong fault tolerance, and reliable multi-directional constraints is of great practical significance for promoting the large-scale application of prefabricated concrete pavement technology. Summary of the Invention

[0008] This invention provides a bidirectional pre-tightened steel reinforcement connection structure for prefabricated road panels and its rapid construction method, which can solve the technical problems of low construction efficiency, insufficient error tolerance, and lack of in-plane bidirectional constraint in existing prefabricated road panel steel reinforcement connections. The technical solution is as follows: In a first aspect, embodiments of the present invention provide a prefabricated road panel bidirectional pre-tightened steel reinforcement connection structure, comprising: multiple prefabricated road panels, multiple force-transmitting steel bars, and multiple steel reinforcement connectors. Multiple force-transmitting steel bars are pre-embedded in each of the prefabricated road panels to form a lifting and shared reinforcement structure. In the scenario of the prefabricated road panel lifting and shared reinforcement structure, the force-transmitting steel bars on adjacent prefabricated road panels are connected by steel bar connectors. The rebar connector includes two T-shaped sleeves, a lower clamping plate, and an upper clamping plate. The two T-shaped sleeves are respectively fitted onto the ends of two adjacent force-transmitting rebars and clamped and fixed by the lower clamping plate and the upper clamping plate. Fasteners are provided on the upper clamping plate and the lower clamping plate. The lower clamping plate and the upper clamping plate are subjected to a vertical clamping force through fasteners. The vertical clamping force generates normal force and tangential force through the curved surface contact between the lower and upper clamping plates and the T-shaped sleeve based on the curvature mismatch. Through the synergistic effect of multiple inner grooves, it is transformed into a pre-tightening constraint force acting on the two T-shaped sleeves in two horizontal directions within the plate plane, thereby achieving bidirectional pre-tightening.

[0009] Optionally, each of the lower clamping plates has two symmetrically formed lower inner grooves at its top, and each of the upper clamping plates has two symmetrically formed upper inner grooves at its bottom. Both the lower and upper inner grooves are arc-shaped curved surfaces used to form line or surface contact with the outer wall of the T-shaped sleeve. The fastener includes a screw vertically disposed at the top of the lower clamping plate, a circular hole in the upper clamping plate for the screw to pass through, a nut fitted onto the screw, and a washer placed on the upper clamping plate for adjusting the clamping force of the upper and lower clamping plates.

[0010] Optionally, the radius of curvature of the lower inner groove and the upper inner groove is greater than the outer wall radius of the T-shaped sleeve to accommodate construction errors and achieve multi-point contact.

[0011] Optionally, the lower inner groove includes a first arc-shaped segment and a second arc-shaped segment extending along a direction perpendicular to the axis of the force-transmitting steel bar, and a third arc-shaped segment extending along the axis of the force-transmitting steel bar, with a smooth transition between the first, second, and third arc-shaped segments. The upper inner groove has the same structure as the lower inner groove and is symmetrically arranged.

[0012] Optionally, each of the T-shaped sleeves includes an upper T-shaped cylinder and a lower T-shaped cylinder, which are connected vertically and smoothly. The end of the force-transmitting steel bar is inserted into the lower T-shaped cylinder and transitions into the inner wall of the lower T-shaped cylinder.

[0013] Optionally, the first and second arc-shaped segments are closely attached to the bottom of the upper T-shaped cylinder, used to restrict the degree of freedom of movement and rotation of the lower T-shaped cylinder along its axial direction. The third arc-shaped segment is closely attached to the bottom of the lower T-shaped cylinder, used to restrict the degree of freedom of movement and rotation of the upper T-shaped cylinder along its axial direction. The upper inner groove is closely attached to the top of the T-shaped sleeve, and the lower inner groove and the upper inner groove are used to restrict the degree of freedom of movement and rotation of the T-shaped sleeve in the vertical direction.

[0014] Optionally, the radius of curvature R of the lower inner groove and the upper inner groove is equal to the outer wall radius of the T-shaped sleeve. The relationship between them is: in The target construction error tolerance is K, which is the safety factor, ranging from 0.3 to 1.0 mm. The angle between the radius direction and the vertical direction at the contact point between the curved surfaces of the lower and upper inner grooves and the outer wall of the T-shaped sleeve is... , where the value of θ ranges from 0° to 90°; The arc angle between the lower inner groove and the upper inner groove is α, and α satisfies: Where δmax=δ+k is the maximum radial offset, and β is the contact allowance, with a value range of 10°~20°, to ensure that the T-shaped sleeve still maintains effective contact with the inner groove when it is at the extreme offset position.

[0015] Optionally, each of the precast road panels is pre-embedded with four force-transfer reinforcing bars, which are arranged in a grid pattern.

[0016] Optionally, a semi-circular groove is provided on each side of the plurality of precast road panels and at the end of the corresponding reinforcing bar to reserve space for the installation of the reinforcing bar connector.

[0017] Secondly, embodiments of the present invention also provide a rapid construction method for prefabricated road panels, employing the aforementioned bidirectional pre-tightened steel reinforcement connection structure for prefabricated road panels, comprising the following steps: S1. According to the design drawings, install the steel formwork for the precast road panel in the concrete precast plant and tie the reinforcing bars to form a grid-shaped reinforcing bar skeleton. The distance between each reinforcing bar and the side of the formwork is consistent, and each reinforcing bar is tied in an alternating manner. Stirrup supports are placed below the binding of the reinforcing bars, and concrete is poured to form the precast road panel.

[0018] S2. After the precast pavement slab is demolded, the lower T-shaped cylindrical part of the T-shaped sleeve is inserted into the exposed end of the reinforcing bar, ensuring the bottom surface of the T-shaped sleeve is completely flush with the exposed end of the reinforcing bar and that the axis is horizontal. The bottom surface of the T-shaped sleeve is then fully welded to the perimeter of the reinforcing bar end to form a solid, integrated structure. This step converts the tensile and compressive forces of the reinforcing bar into shear and tensile forces on the T-shaped sleeve.

[0019] S3. After the precast pavement slabs reach the specified strength, the lifting ropes are slipped onto the lower cylinder of the T-shaped sleeve for hoisting, preventing the ropes from slipping off the reinforcing bars. The precast pavement slabs are then hoisted to the designed position, ensuring that the corresponding reinforcing bars of adjacent slabs and their T-shaped sleeves are basically aligned.

[0020] S4. This is the core on-site operation. First, insert the lower and upper clamping plates into the welded T-shaped sleeve from top to bottom, ensuring the outer wall of the T-shaped sleeve is embedded in the corresponding inner grooves of the upper and lower clamping plates; ensure the screw of the lower clamping plate passes smoothly through the central hole of the upper clamping plate. Then, insert the washer into the screw, and then screw in the nut. Finally, the construction worker uses a pneumatic wrench to tighten the nut from top to bottom. As the nut is tightened, the upper and lower clamping plates are pulled closer, and the curved surface of their inner grooves begins to press against the outer wall of the T-shaped sleeve.

[0021] S5. During the tightening process, because the grooves are arc surfaces with mismatched curvature, their compression of the outer wall of the T-shaped sleeve is not purely radial clamping. According to the principle of curved surface contact mechanics, this curved surface contact will generate a normal force (pointing towards the center) and a tangential force (horizontal direction). The synergistic effect of multiple inner grooves ultimately transforms the vertical preload of the nut into a constraint force on the T-shaped sleeve (i.e., the force-transmitting reinforcing bar) in two horizontal directions within the plate plane, thus achieving bidirectional preload. At the same time, the outer wall of the T-shaped sleeve is firmly locked in the inner grooves, ensuring the effective transmission of axial force.

[0022] Repeat steps S4 to S5 until all the reinforcing bars between adjacent precast pavement slabs are connected by reinforcing bar connectors.

[0023] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: By combining precast pavement panels, multiple reinforcing bars, and various rebar connectors, this system is better suited for assembling precast pavement panels with interconnected reinforcing bars in specific scenarios. It enables rapid, dry assembly without the need for on-site concrete pouring or curing, and construction is unaffected by weather conditions. A single person can complete all installation operations using a single wrench, with operations uniformly directed from top to bottom. This makes construction extremely convenient in narrow road joints, significantly improving efficiency. Furthermore, its unique curved contact design between the upper and lower clamps and the T-shaped sleeve accommodates some construction errors, effectively reducing the stringent requirements for precast and hoisting precision, significantly increasing the installation success rate, and converting vertical clamping force into horizontal pre-tensioning force.

[0024] By creating a lower inner groove on the lower clamping piece and an upper inner groove on the upper clamping piece, both of which are arc-shaped curved surfaces, the curved surface compression mechanism of the upper clamping piece, lower clamping piece, and T-shaped sleeve actively provides bidirectional pre-tightening constraint within the plate plane while achieving reliable axial force transmission. Compared to traditional connectors that only provide unidirectional axial force transmission, this invention can simultaneously restrict the relative displacement of the pavement panel in both directions parallel and perpendicular to the joint, effectively enhancing the pavement's integrity and lateral load distribution capability.

[0025] This invention achieves a clear force transmission path: rebar under stress → welding interface → T-shaped sleeve flange → clamp groove contact surface → clamp body → screw under tension and shear → nut. Mechanical compression is the primary stress mode, resulting in stable stress distribution. The force-transmitting rebar is transmitted through the T-shaped sleeve, avoiding weakening of the rebar cross-section, ensuring uniform stress distribution, and exhibiting good fatigue performance. Each component has a simple structure and can be precision-machined in a machining plant or use standard parts, maximizing the control of construction errors within the factory and demonstrating excellent engineering economics.

[0026] Abandoning empirical fixed-size design, based on a precise geometric model of the T-shaped sleeve outer wall and the inner groove of the clamping piece, the contact angle θ is clearly defined as an independent design parameter. A quantitative relationship of horizontal constraint force in curved surface contact mechanics is established, and active design of error tolerance is realized. This allows the connector to be parametrically customized according to different engineering requirements (high precision, standard type, optimal preload, large tolerance), thereby elevating the design of the connector from "empirical selection" to "precise calculation".

[0027] The semi-circular grooves on the side of the precast pavement slab provide installation space for the steel reinforcement connectors, improving the ease and efficiency of installation. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0029] Figure 1 This is a schematic diagram of the prefabricated road panel structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the connector assembly provided in an embodiment of the present invention; Figure 3 This is an isometric view of the T-shaped sleeve provided in an embodiment of the present invention; Figure 4 This is a side view of the T-shaped sleeve provided in an embodiment of the present invention; Figure 5 This is a top view of the T-shaped sleeve provided in an embodiment of the present invention; Figure 6 This is an isometric view of the lower clamping piece provided in an embodiment of the present invention; Figure 7 This is an isometric view of the upper clamping piece provided in an embodiment of the present invention; Figure 8 This is an isometric drawing of the gasket provided in an embodiment of the present invention; Figure 9 This is an isometric view of the nut provided in an embodiment of the present invention; Figure 10 This is a flowchart of the rapid construction method provided in the embodiments of the present invention; Figure 11 This is a schematic diagram of the rapid construction method provided in an embodiment of the present invention.

[0030] Figure 12 This is a schematic diagram of the geometric model of the parametric design method based on surface contact mechanics provided in Embodiment 3 of the present invention.

[0031] In the diagram: 1-Precast road panel; 2-Reinforcing steel bar; 3-T-shaped sleeve; 4-Lower clamp; 5-Upper clamp; 6-Washer; 7-Nut; 1-1-Semi-circular groove; 3-1-Upper T-shaped cylinder; 3-2-Lower T-shaped cylinder; 3-3-Bottom of cylinder; 3-4-Inner diameter of cylinder; 3-5-Outer diameter of cylinder; 4-1-Screw; 4-2-Lower inner groove; 5-1-Round hole; 5-2-Upper inner groove; 4-2-1-First arc segment; 4-2-2-Second arc segment; 4-2-3-Third arc segment; 5-2-1-Fourth arc segment; 5-2-2-Fifth arc segment; 5-2-3-Sixth arc segment. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] Example 1 like Figures 1 to 9 As shown, this embodiment of the invention provides a bidirectional pre-tightened steel bar connection structure for prefabricated road panels, aiming to solve the technical problems of low construction efficiency, insufficient error tolerance, and lack of in-plane bidirectional constraint in the existing prefabricated road panel steel bar connection. It includes: a prefabricated road panel 1, a force-transmitting steel bar 2, a T-shaped sleeve 3, a lower clamping plate 4, an upper clamping plate 5, a washer 6, and a nut 7.

[0034] like Figure 1 As shown, multiple precast pavement panels 1 each have several pre-embedded reinforcing bars 2, forming a shared reinforcement structure. The reinforcing bars 2 on adjacent precast pavement panels 1 are connected by reinforcing bar connectors. The precast pavement panels 1 adopt a shared reinforcement precast pavement panel system, meaning the reinforcing bars 2 within the panels serve both as lifting bars during hoisting and as reinforcement for load transfer between panels. Each precast pavement panel 1 has four pre-embedded reinforcing bars 2 arranged in a grid pattern, with two extending longitudinally and two extending transversely. At the end of each reinforcing bar 2 on the side of the precast pavement panel 1, a semi-circular groove 1-1 is reserved to provide space for connecting the reinforcing bars 2 of subsequent panels. A total of eight semi-circular grooves are reserved in each precast pavement panel 1. The lengths of the longitudinal and transverse reinforcing bars 2 are slightly less than the length or width of the precast pavement panel 1, while the length of the reinforcing bars 2 is greater than the difference between the length or width of the precast pavement panel 1 and twice the radius of the semi-circular groove 1-1, facilitating the installation of subsequent connectors.

[0035] like Figure 2As shown, the reinforcing bars 2 on adjacent precast pavement slabs 1 are connected by reinforcing bar connectors. The reinforcing bar connectors include two T-shaped sleeves 3, a lower clamp 4, and an upper clamp 5. The two T-shaped sleeves 3 are respectively fitted onto the ends of two adjacent reinforcing bars 2, and the cylindrical bottom surface 3-3 of the T-shaped sleeves is fully welded to the periphery of the end of the reinforcing bar using arc welding or other reliable welding processes to form a solid whole, and is clamped and fixed by the lower clamp 4 and the upper clamp 5.

[0036] like Figures 3 to 5 As shown, the T-shaped sleeve 3 includes an upper T-shaped cylinder 3-1 and a lower T-shaped cylinder 3-2, which are connected vertically and smoothly. The bottom surface 3-3 of the lower T-shaped cylinder 3-2 is an annular plane. The inner diameter 3-4 of the lower T-shaped cylinder 3-2 transitions with the outer wall of the force-transmitting steel bar 2, and the outer diameter 3-5 is slightly larger than the diameter of the force-transmitting steel bar 2. The specific dimensions can be designed according to the size of the connector or the magnitude of the force. The end of the force-transmitting steel bar 2 is inserted into the lower T-shaped cylinder 3-2 and transitions with the inner wall of the lower T-shaped cylinder 3-2. The outer wall of the T-shaped sleeve 3 can provide a force-bearing surface for the subsequent compression of the lower clamping plate 4 and the upper clamping plate 5. During implementation, after the T-shaped sleeve 3 is inserted into the exposed end of the force transmission steel bar 2, the cylindrical bottom surface 3-3 of the T-shaped sleeve 3 is fully welded and sealed to the periphery of the end of the force transmission steel bar 2 using arc welding or other reliable welding processes to form a solid whole, thereby converting the tensile and compressive forces of the force transmission steel bar 2 into shear and tensile forces on the T-shaped sleeve 3.

[0037] like Figure 6 As shown, the lower clamping piece 4 is one of the core clamping and adjusting elements. A vertically upward screw 4-1 is located at the center of the lower clamping piece 4, and two symmetrical lower inner grooves 4-2 are formed at the top of the lower clamping piece 4. Each lower inner groove 4-2 includes a first arc-shaped segment 4-2-1 and a second arc-shaped segment 4-2-2 extending perpendicular to the axis of the force-transmitting steel bar 2, and a third arc-shaped segment 4-2-3 extending along the axis of the force-transmitting steel bar 2. The first arc-shaped segment 4-2-1, the second arc-shaped segment 4-2-2, and the third arc-shaped segment 4-2-3 transition smoothly. The cross-section of the lower inner groove 4-2 is not a simple semi-circle, but an arc-shaped surface with a radius of curvature slightly larger than the radius of the outer wall of the T-shaped sleeve 3. For example, when the outer wall diameter of the T-shaped sleeve used with A28 steel bar is 30mm, the groove diameter can be designed to be 34mm. The larger diameter of the inner groove provides a radial construction error tolerance space of ±2mm, and the arc-shaped surface ensures line or surface contact with the outer wall of the T-shaped sleeve 3. The first arc segment 4-2-1 and the second arc segment 4-2-2 are closely attached to the bottom of the upper T-shaped cylinder 3-1, and are used to restrict the degree of freedom of movement and rotation of the lower T-shaped cylinder 3-2 along its axial direction. The third arc segment 4-2-3 is closely attached to the bottom of the lower T-shaped cylinder 3-2, and is used to restrict the degree of freedom of movement and rotation of the upper T-shaped cylinder 3-1 along its axial direction.

[0038] like Figure 7 As shown, the upper clamping plate 5 is an irregularly shaped steel plate component used in conjunction with the lower clamping plate 4. The upper clamping plate 5 has a circular hole 5-1 at its center for the screw 4-1 to pass through, and two symmetrical upper inner grooves 5-2 are formed at the bottom of the upper clamping plate 5. The upper inner grooves 5-2 and the lower inner grooves 4-2 have the same structure and are symmetrically arranged, including a fourth arc-shaped segment 5-2-1, a fifth arc-shaped segment 5-2-2, and a sixth arc-shaped segment 5-2-3. The upper inner grooves 5-2 are in close contact with the top of the T-shaped sleeve 3. The lower inner groove 4-2 and the upper inner grooves 5-2 are used to restrict the vertical and rotational degrees of freedom of the T-shaped sleeve 3.

[0039] like Figure 8 and Figure 9 As shown, washer 6 is a standard steel ring washer with an inner diameter slightly larger than that of screw 4-1. It is fitted around the outer circumference of screw 4-1 and is located on top of upper clamping plate 5 to increase the bearing surface of nut 7. Nut 7 is a standard part that matches the thread on screw 4-1 and is used for final tightening.

[0040] In this embodiment, a vertical clamping force is applied between the lower clamping plate 4 and the upper clamping plate 5 via a screw 4-1 and a nut 7. This vertical clamping force is converted into a horizontal preload acting on the two T-shaped sleeves 3 through the curved surface contact between the lower inner groove 4-2 of the lower clamping plate 4 and the upper inner groove 5-2 of the upper clamping plate 5 and the T-shaped sleeve 3. Specifically, since the radius of curvature of the groove is greater than the radius of curvature of the outer wall of the T-shaped sleeve 3, i.e., the curvatures of the two are mismatched, the compression of the outer wall of the T-shaped sleeve 3 is not a purely radial clamping. According to the Hertzian surface contact mechanics principle, let the radius of curvature of the outer wall of the T-shaped sleeve be R0, the radius of curvature of the inner groove of the clamping plate be R (R>R0), and the angle between the sleeve radius direction and the vertical direction at the contact point be θ, then the vertical preload F v At the contact surface, it decomposes into a normal force F. n =F v / cosθ and tangential friction force F f =F v ·tanθ, normal force F n Further generating a horizontal component force F h =F v • sin2θ / 2. The synergistic effect of multiple inner grooves ultimately transforms the vertical preload into a constraint force on the T-shaped sleeve 3 in two horizontal directions (parallel to the joint direction and perpendicular to the joint direction) within the plate plane, thus achieving bidirectional preload. Simultaneously, the outer wall of the T-shaped sleeve 3 is firmly locked within the inner grooves, ensuring the effective transmission of axial force. This curved surface contact mechanics mechanism is the core principle of this invention for achieving the conversion of vertical force into horizontal bidirectional preload.

[0041] In this embodiment, both the precast pavement slab 1 and the reinforcing steel bars 2 can be precisely constructed in a precast concrete component factory. The T-shaped sleeve 3, lower clamp 4, and upper clamp 5 have simple structures and can all be precision-machined in a machining plant. The gasket 6 and nut 7 are standard mechanical design parts. The above solution largely controls construction errors within the factory, while the uncontrollable factor of hoisting errors on the construction site is accommodated by the radial allowance provided by the difference in the radius of curvature ΔR in the curved surface contact design.

[0042] Example 2 like Figures 10 to 11 As shown, this embodiment provides a rapid construction method for the prefabricated road slab bidirectional pre-tightened steel bar connection structure of Embodiment 1, specifically including the following steps: S1. Precast Stage: According to the design drawings, the steel formwork for the precast pavement slab 1 is installed in the concrete precast plant, and the reinforcing bars 2 are tied to form a grid-shaped reinforcing steel skeleton (a hoisted and connected common reinforcement system). The distance between each reinforcing bar 2 and the side of the formwork must be consistent, and each reinforcing bar 2 is tied alternately to ensure the accuracy of the reinforcing bar position. A stirrup support is placed below the reinforcing bar tying to prevent the reinforcing bars from sagging. Finally, concrete is poured to form the precast pavement slab 1. This stage is completed in the factory, ensuring high construction precision and effectively controlling the error in the pre-embedded position of the reinforcing bars 2.

[0043] S2. Welding Stage: After the precast pavement panel 1 is demolded, the T-shaped sleeve 3 is fitted onto the exposed end of the reinforcing bar 2, ensuring that the bottom surface 3-3 of the lower T-shaped cylinder 3-2 of the T-shaped sleeve 3 is completely flush with the exposed end surface of the reinforcing bar 2, and that the axis is kept horizontal. Using arc welding or other reliable welding techniques, the bottom surface 3-3 of the T-shaped sleeve 3 is fully welded to the periphery of the end of the reinforcing bar 2 to form a solid whole. The mechanical significance of this step is to convert the tensile and compressive forces of the reinforcing bar 2 into shear and tensile forces on the T-shaped sleeve 3, providing a reliable load-bearing foundation for subsequent connection via clamps.

[0044] S3. On-site hoisting stage: After the precast pavement slab 1 reaches the specified strength, hoisting and splicing work can begin. In the hoisting and connection system with shared reinforcement, the T-shaped sleeves 3 on the force-transferring steel bars 2 directly serve as hoisting attachment points, eliminating the need for additional hoisting embedded parts. During hoisting, the hoisting rope is slipped onto the lower T-shaped cylinder 3-2 of the T-shaped sleeve 3. The flange of the upper T-shaped cylinder 3-1 effectively prevents the hoisting rope from slipping, improving hoisting safety. The precast pavement slab 1 is hoisted to the designed position, ensuring that the corresponding embedded force-transferring steel bars 2 and their T-shaped sleeves 3 on adjacent slabs are basically aligned. Due to the curved contact design of the connectors, which has a radial error tolerance of ±2mm, the requirements for hoisting accuracy are greatly reduced, improving on-site construction efficiency.

[0045] S4. Rapid Assembly Stage: This is the core on-site operation step. The specific operation is as follows: First, insert the lower clamping piece 4 and the upper clamping piece 5 into the welded T-shaped sleeve 3 from top to bottom, so that the outer wall of the T-shaped sleeve 3 is embedded in the lower inner groove 4-2 of the lower clamping piece 4 and the upper inner groove 5-2 of the upper clamping piece 5, respectively; ensure that the screw 4-1 of the lower clamping piece 4 passes smoothly through the central hole 5-1 of the upper clamping piece 5. Then, insert the washer 6 into the screw 4-1, and then screw in the nut 7. Finally, the construction worker uses a pneumatic wrench to tighten the nut 7 from top to bottom. The upper and lower clamping pieces are pulled closer, and their inner groove curved surfaces begin to press against the outer wall of the T-shaped sleeve. The entire operation process does not require side operation and can be completed in one direction, making it particularly suitable for narrow road joint environments.

[0046] S5. Mechanical Action Formation Stage: As nut 7 is tightened, upper clamping plate 5 and lower clamping plate 4 are pulled closer, and the arc surfaces of lower inner groove 4-2 and upper inner groove 5-2 begin to compress the outer wall of T-shaped sleeve 3. Since the grooves are arc surfaces with mismatched curvature, their compression of the outer wall of T-shaped sleeve 3 is not purely radial clamping. According to the principle of surface contact mechanics, this surface contact will generate a normal force (pointing towards the center) and a tangential force (horizontal direction). The synergistic effect of multiple inner grooves ultimately transforms the vertical preload of nut 7 into a constraint force on T-shaped sleeve 3 (i.e., force-transmitting steel bar 2) in two horizontal directions within the plate plane, namely, a bidirectional preload force parallel to the joint direction and perpendicular to the joint direction. At the same time, the outer wall of T-shaped sleeve 3 is firmly locked in the inner grooves, ensuring the effective transmission of axial force and forming a complete force transmission path.

[0047] Repeat steps S4 and S5 above, connecting the reinforcing bars 2 at each joint one by one, until all the reinforcing bars 2 between adjacent precast pavement slabs 1 are connected by reinforcing bar connectors. Each rapid assembly process is a repetition of the above steps, realizing a standardized and modular construction process.

[0048] The construction method in this embodiment achieves a completely dry operation, eliminating the need for pouring concrete at joints and waiting for curing time, thus significantly shortening the construction cycle. Construction workers only need a pneumatic screwdriver to complete the operation, making it simple to operate, with low learning costs, and enabling rapid single-person construction. The curved contact design of the connectors ensures reliable installation and provides effective bidirectional preload even with certain lifting deviations, guaranteeing the integrity and durability of the prefabricated pavement structure.

[0049] Example 3 like Figure 12 As shown, this embodiment of the invention provides a bidirectional pre-tightened steel bar connection structure for prefabricated road panels, and also includes a parametric design method for T-shaped extrusion connectors based on curved surface contact mechanics, including: design principles, design formulas for geometric parameters, typical parameter combinations and their design process.

[0050] 1. Design Principles The design principle of this embodiment is as follows: by utilizing the coupling relationship between the normal force and the horizontal component force in Hertzian surface contact mechanics, the vertical preload of the nut is transformed into a horizontal constraint force on the T-shaped sleeve (i.e., bidirectional preload). By precisely controlling the radius of curvature of the groove inside the clamping plate, active control of the bidirectional preload can be achieved while ensuring the tolerance capacity for construction errors.

[0051] (1) Precise geometric model of surface contact Let the outer radius of the T-sleeve be R0, and the radius of curvature of the groove inside the clamp be R, where R > R0. Define the difference in radii of curvature: When two circles are internally tangent, the distance between their centers is equal to the difference in their radii. Where O1 is the center of the T-shaped sleeve and O2 is the center of the curvature of the groove inside the clamping piece. The tangent point P is located on the line connecting the two centers and is outside the center of the larger circle O2 (i.e., the sequence is P-O1-O2).

[0052] The angle θ between the line connecting the centers O1O2 and the vertical direction is a free parameter, representing the position of the contact point P on the circumference of the sleeve (rotated by an angle θ from the vertical direction). When θ=0, the contact point is located directly above (below) the sleeve; when θ=90°, the contact point is located on the rightmost (outer) side of the sleeve. For a given ΔR, contact can occur at any position θ, depending on the positioning design of the groove inside the clamping piece.

[0053] (2) Contact surface direction and force decomposition At the point of tangency P, the radius of the sleeve points from P to O1, and this direction makes an angle θ with the vertical direction. The common tangent is perpendicular to the radius, so the angle between the common tangent and the horizontal direction is also θ.

[0054] Vertical preload F v Acting on the connection system, it decomposes at the contact point into a normal force F perpendicular to the contact surface. n And the tangential force (friction) parallel to the contact surface F f From the equilibrium condition: Normal force F n Further decompose the force into a horizontal component F. h : The horizontal component F h The force acts directly on the T-shaped sleeve, creating lateral compression within the plate plane, thus achieving a "bidirectional pre-tightening" effect. The horizontal component F... hIt is closely related to θ, but not directly related to ΔR (unless indirectly related through θ). When θ = 45°, F h To obtain the maximum value F v / 2; When θ = 0° or 90°, F h =0.

[0055] (3) Error tolerance When ΔR>0, the outer wall of the T-sleeve has radial movement space within the inner groove. Maximum radial offset δ max The tolerance for construction errors (i.e., the tolerance capacity) is determined by the geometry of the inner groove: Where θ max The angle of the inner groove of the clamping piece is determined by the arc angle α of the inner groove and the radius R0 of the sleeve. In simplified design, it can be approximated that δmax≈ΔR, that is, the larger ΔR is, the greater the allowable deviation of the center of the reinforcing bar.

[0056] (4) Design trade-offs The above analysis reveals the following key trade-offs in this design: The contact angle θ is preset by controlling the geometry of the groove inside the clamping piece (arc angle α and positioning method), so that F h To achieve the optimal value; at the same time, select an appropriate ΔR to meet the requirements for construction error tolerance.

[0057] 2. Design formulas for geometric parameters Given the radius R0 of the T-sleeve and the target error tolerance δ (i.e., the maximum allowable center deviation of the reinforcing bar), the radius of curvature R of the groove is determined by the following formula: Where K is the safety factor, with a value ranging from 0.3 to 1.0 mm, used to compensate for machining and assembly errors.

[0058] (2) Contact Angle Design Formula The contact angle θ is determined by the arc angle α of the inner groove of the clamping piece and the positioning method of the sleeve within the inner groove. For symmetrically designed inner grooves, the contact point is usually located at the center of symmetry of the inner groove, in which case θ is determined by the angle between the centerline of the inner groove and the vertical direction. In this embodiment, θ can be used as an independent design parameter and directly selected according to the horizontal constraint requirements, with a recommended range of 15°~45°.

[0059] (3) Formula for designing arc angle To ensure that at the maximum radial offset δ max When δ+k occurs, the T-sleeve and the inner groove still maintain effective contact, and the arc angle α of the inner groove must satisfy: Where β is the contact allowance, ranging from 10° to 20°. This formula ensures that the outer wall of the sleeve does not detach from the inner groove when it is at its limit offset position and at the designed contact angle θ.

[0060] (4) Formula for estimating horizontal constraint force For a given vertical preload F v The actual horizontal constraint force F generated h for: Where θ is the contact angle, which is determined by the geometric design of the clamp groove.

[0061] 3. Typical parameter combinations Given that the T-sleeve flange radius R0 = 15mm and the groove curvature radius R = 16mm, then ΔR = 1mm. Based on different engineering requirements, this embodiment provides the following four typical design parameters: Type 1: High-precision type (small contact angle, low preload conversion rate) Type 2: Standard type (medium contact angle, balanced design) Type 3: Optimal preload type (θ=45°) Type 4: High tolerance type (increases ΔR, sacrifices pre-tightening optimization space) Design Parameter Summary Table (Taking R0=15mm as an example) 4. Design Process Based on the parametric design method described above, this embodiment provides the following design flow: S1: Determine the target error tolerance δ and target horizontal constraint requirements based on engineering needs.

[0062] S2: Select the radius of curvature R of the inner groove so that ΔR=R-R0≥δ+k (k is 0.3~1.0mm) to ensure that the error tolerance meets the requirements.

[0063] S3: Select the design contact angle θ based on the horizontal constraint force requirements. If the maximum horizontal constraint force is required, take θ = 45°; if a moderate force is required, take θ = approximately 30°.

[0064] S4: Calculate α using the arc angle formula. min The result is rounded down to a value that is easy to process (usually with an additional 5°~10° margin).

[0065] S5: Based on the determined R and α, process the inner groove of the clamping piece, ensuring that the angle between the center line of the inner groove and the vertical direction is the design contact angle θ.

[0066] S6: Machining a T-shaped sleeve according to the corresponding R.

[0067] This embodiment abandons empirical fixed-dimensional design and, based on a precise geometric model of the tangency between the outer wall of the T-shaped sleeve and the inner groove of the clamping piece, clarifies the status of the contact angle θ as an independent design parameter and establishes the horizontal constraint force F in the surface contact mechanics. h =F v The quantitative relationship of sin2θ / 2 enables the active design of error tolerance δmax≈ΔR, allowing connectors to be parametrically customized according to different engineering requirements (high precision, standard type, optimal preload, large tolerance), thereby elevating connector design from "experience-based selection" to "precise calculation".

[0068] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0069] The above description is merely an optional 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 principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A prefabricated road slab bidirectional pre-tightened steel bar connection structure, characterized in that, include: Multiple precast pavement panels (1), multiple reinforcing bars (2), and multiple reinforcing bar connectors, Multiple force-transmitting steel bars (2) are pre-embedded in each of the prefabricated road panels (1) to form a hanging and connected reinforcement structure. In the scenario of the prefabricated road panel hanging and connected reinforcement structure, the force-transmitting steel bars (2) on adjacent prefabricated road panels (1) are connected by steel bar connectors. The steel bar connector includes two T-shaped sleeves (3), a lower clamp (4) and an upper clamp (5). The two T-shaped sleeves (3) are respectively sleeved on the ends of two adjacent force-transmitting steel bars (2) and clamped and fixed by the lower clamp (4) and the upper clamp (5). Fasteners are provided on the upper clamp (5) and the lower clamp (4). The lower clamping piece (4) and the upper clamping piece (5) are subjected to a vertical clamping force by fasteners. The vertical clamping force generates normal force and tangential force through the curved surface contact between the lower clamping piece (4) and the upper clamping piece (5) and the T-shaped sleeve (3) based on the curvature mismatch. Through the synergistic effect of multiple inner grooves, it is transformed into a pre-tightening constraint force acting on the two T-shaped sleeves (3) in two horizontal directions in the plate plane, thereby realizing bidirectional pre-tightening.

2. The prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 1, characterized in that, Two lower inner grooves (4-2) are symmetrically opened on the top of each of the multiple lower clamping pieces (4), and two upper inner grooves (5-2) are symmetrically opened on the bottom of each of the multiple upper clamping pieces (5). The lower inner grooves (4-2) and the upper inner grooves (5-2) are both arc-shaped curved surfaces, which are used to form line contact or surface contact with the outer wall of the T-shaped sleeve (3). The fastener includes a screw (4-1) vertically disposed on the top of the lower clamping plate (4), a round hole (5-1) opened on the upper clamping plate (5) for the screw (4-1) to pass through, a nut (7) fitted on the screw (4-1), and a washer (6) placed on the upper clamping plate (5) for adjusting the clamping force of the upper clamping plate (5) and the lower clamping plate (4).

3. The prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 2, characterized in that, The radius of curvature of the lower inner groove (4-2) and the upper inner groove (5-2) is greater than the outer wall radius of the T-shaped sleeve (3) to accommodate construction errors and achieve multi-point contact.

4. The prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 2, characterized in that, The lower inner groove (4-2) includes a first arc-shaped segment (4-2-1) and a second arc-shaped segment (4-2-2) extending along the direction perpendicular to the axis of the force-transmitting steel bar (2), and a third arc-shaped segment (4-2-3) extending along the axis of the force-transmitting steel bar (2). The first arc-shaped segment (4-2-1), the second arc-shaped segment (4-2-2), and the third arc-shaped segment (4-2-3) are smoothly transitioned together. The upper inner groove (5-2) has the same structure as the lower inner groove (4-2) and is symmetrically arranged.

5. The prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 4, characterized in that, Each of the T-shaped sleeves (3) includes an upper T-shaped cylinder (3-1) and a lower T-shaped cylinder (3-2), which are connected vertically and smoothly. The end of the force-transmitting steel bar (2) is inserted into the lower T-shaped cylinder (3-2) and transitions with the inner wall of the lower T-shaped cylinder (3-2).

6. The prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 5, characterized in that, The first arc segment (4-2-1) and the second arc segment (4-2-2) are closely attached to the bottom of the upper T-shaped cylinder (3-1) to restrict the degree of freedom of movement and rotation of the lower T-shaped cylinder (3-2) along its axial direction; The third arc segment (4-2-3) is closely attached to the bottom of the lower T-shaped cylinder (3-2) and is used to restrict the degree of freedom of movement and rotation of the upper T-shaped cylinder (3-1) in the axial direction. The upper inner groove (5-2) is close to the top of the T-shaped sleeve (3), and the lower inner groove (4-2) and the upper inner groove (5-2) are used to restrict the vertical and rotational degrees of freedom of the T-shaped sleeve (3).

7. The prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 6, characterized in that, The radius of curvature R of the lower inner groove (4-2) and the upper inner groove (5-2) is the same as the outer wall radius of the T-shaped sleeve (3). The relationship between them is: in The target construction error tolerance is K, which is the safety factor, ranging from 0.3 to 1.0 mm. The angle between the radius direction and the vertical direction at the contact point between the curved surfaces of the lower inner groove (4-2) and the upper inner groove (5-2) and the outer wall of the T-shaped sleeve (3) is... , where the value of θ ranges from 0° to 90°; The arc angle between the lower inner groove (4-2) and the upper inner groove (5-2) is α, and α satisfies: Where δmax=δ+k is the maximum radial offset and β is the contact allowance, with a value range of 10°~20°, to ensure that the T-shaped sleeve (3) still maintains effective contact with the inner groove when it is at the extreme offset position.

8. The prefabricated road panel bidirectional pre-tightened steel reinforcement connection structure according to claim 1, characterized in that, Each of the precast road panels (1) is pre-embedded with four force-transmitting steel bars (2), which are arranged in a grid pattern.

9. A prefabricated road panel bidirectional pre-tightened steel bar connection structure according to claim 8, characterized in that, A semi-circular groove (1-1) is provided on each side of the multiple precast road panels (1) and at the end of the corresponding force-transmitting steel bar (2) to reserve space for the installation of the steel bar connector.

10. A rapid construction method for prefabricated road slabs, employing the steel reinforcement connectors as described in any one of claims 1 to 9, characterized in that, S1. According to the design drawings, install the steel formwork of the precast road panel (1) in the concrete precast plant and tie the reinforcing bars (2) to form a grid-shaped reinforcing bar skeleton. The distance between each reinforcing bar (2) and the side of the formwork is consistent, and each reinforcing bar (2) is tied in an alternating manner. Place stirrup supports under the binding of the reinforcing bars (2) and pour concrete to form the precast road panel (1). S2. After the precast road panel (1) is demolded, the lower T-shaped cylinder (3-2) of the T-shaped sleeve (3) is inserted into the exposed end of the force transmission steel bar (2), so that the bottom surface of the T-shaped sleeve (3) is completely close to the exposed end surface of the force transmission steel bar (2) and the axial direction is kept horizontal. The bottom surface of the T-shaped sleeve (3) is fully welded to the periphery of the end of the force transmission steel bar (2) to form a solid whole. S3. After the precast road panel (1) reaches the specified strength, the hoisting rope is put into the lower cylinder (3-2) of the T-shaped sleeve (3) for hoisting. The precast road panel (1) is hoisted to the design position so that the force transmission steel bars (2) corresponding to the adjacent precast road panels (1) and the T-shaped sleeve (3) on them are basically aligned. S4. Insert the lower clamp (4) and the upper clamp (5) into the welded T-shaped sleeve (3) from the top and bottom directions, so that the outer wall of the T-shaped sleeve (3) is embedded in the lower inner groove (4-2) of the lower clamp (4) and the upper inner groove (5-2) of the upper clamp (5) respectively. Let the screw (4-1) of the lower clamp (4) pass through the round hole (5-1) of the upper clamp (5). Put the washer (6) into the screw (4-1), and then screw in the nut (7). Use a pneumatic wrench to tighten the nut (7) from top to bottom. S5. As the nut (7) is tightened, the upper clamp (5) and the lower clamp (4) are pulled closer. The arc surfaces of the lower inner groove (4-2) and the upper inner groove (5-2) press against the outer wall of the T-shaped sleeve (3). According to the principle of surface contact mechanics, the surface contact generates normal force and tangential force. The synergistic effect of multiple inner grooves transforms the vertical preload of the nut (7) into a constraint force on the T-shaped sleeve (3) in two horizontal directions within the plate plane, thus achieving bidirectional preload. Repeat steps S4 to S5 until the connection of the reinforcing bars (2) between all adjacent precast pavement panels (1) is completed.

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