Prefabricated pre-tensioned UHPC I-beam

Abstract

This utility model discloses a prefabricated prestressed high-pressure concrete (UHPC) I-beam. The prefabricated UHPC upper slab has multiple upper mounting slots, each containing upper stirrups. The prefabricated UHPC lower slab has multiple lower mounting slots, each containing lower stirrups. Multiple node components are provided on both the upper and lower sides of the prefabricated UHPC web. These node components on the lower side of the web correspond one-to-one with the lower mounting slots on the lower slab, and then a cast-in-place UHPC block is poured. Similarly, the multiple node components on the upper side of the web correspond one-to-one with the upper mounting slots on the upper slab, and then a cast-in-place UHPC block is poured. This utility model employs a combined prefabrication and cast-in-place design, solving several problems in traditional bridge construction. Factory prefabrication shortens the construction cycle, reduces on-site construction uncertainties, and precise assembly improves assembly efficiency, reduces construction errors, ensures the mechanical properties and durability of the structure, and solves problems such as weak joint connections and long construction cycles.

Description

Technical Field

[0001] This utility model belongs to the field of bridge technology, and in particular relates to a prefabricated prestressed UHPC I-beam. Background Technology

[0002] With the progress of society and economy and the continuous development of technology, traditional ordinary concrete, due to its lower mechanical strength and poorer durability, has gradually failed to meet the higher requirements of civil engineering, especially bridge engineering, for structural reliability and durability. Therefore, ultra-high performance concrete (UHPC), as a new type of high-performance material, has received widespread attention for improving the strength, durability, and corrosion resistance of bridge structures. By optimizing particle size distribution and incorporating steel fibers and reactive powders, UHPC not only possesses superior compressive and tensile strength but also exhibits higher durability and corrosion resistance.

[0003] However, existing precast UHPC I-beams still have some obvious shortcomings in practical applications, which to some extent limit their promotion and application in large-scale bridge construction.

[0004] The size and weight of prefabricated UHPC components are severely restricted by the transport clearances and weight limits of highways and bridges. This forces compromises to be made on the size and weight of components during hoisting and installation, thus affecting construction efficiency and component design optimization.

[0005] In prefabricated bridges, the connections between components are often difficult to match those in cast-in-place structures. Existing connection methods cannot effectively guarantee the strength, stiffness, ductility, and durability of the connection points, especially when the stress at the joints is complex, which can easily lead to connection failures and affect the safety and reliability of the overall bridge structure.

[0006] The production of UHPC requires large quantities of cement, silica fume, special fine aggregates (such as silica sand), as well as high-efficiency water-reducing agents and steel fibers. The use of these special raw materials makes UHPC significantly more expensive than ordinary concrete. In addition, the steel fibers often need to be copper-plated, which further increases its production cost and limits the widespread application of UHPC.

[0007] Although UHPC theoretically possesses extremely high durability and reliability, its application as a major load-bearing component in bridge engineering, especially in I-beams, is still in its early stages, lacking sufficiently long-term monitoring data on actual engineering performance. This has led to some lingering doubts within the engineering community regarding the long-term performance of UHPC in practical use.

[0008] These technological bottlenecks have spurred an urgent need for new construction methods and techniques, particularly in improving the manufacturing efficiency of precast UHPC I-beams, reducing costs, strengthening component connections, and enhancing structural durability. Utility Model Content

[0009] This invention provides a pre-tensioned prestressed UHPC I-beam to solve existing technical problems.

[0010] To solve the above-mentioned technical problems, the technical solution proposed by this utility model is as follows:

[0011] A precast prestressed high-pressure precast concrete (UHPC) I-beam includes a precast UHPC upper slab, a precast UHPC web, and a precast UHPC lower slab. The precast UHPC upper slab has multiple upper mounting slots, each containing upper stirrups that extend into the precast UHPC upper slab and are precast integrally with it. The precast UHPC lower slab has multiple prestressed tendons and multiple lower mounting slots, each containing lower stirrups that extend into the precast UHPC lower slab and are precast integrally with it. The UHPC lower plate is prefabricated as a single unit. The prefabricated UHPC web is provided with stirrups. Multiple node members are provided on the upper and lower sides of the prefabricated UHPC web. Each node member is fixedly connected to the stirrups and the prefabricated UHPC web is prefabricated as a single unit. Multiple node members on the lower side of the prefabricated UHPC web are engaged with multiple lower mounting slots on the prefabricated UHPC lower plate one by one, and a cast-in-place UHPC block is then cast. Multiple node members on the upper side of the prefabricated UHPC web are engaged with multiple upper mounting slots on the prefabricated UHPC upper plate one by one, and a cast-in-place UHPC block is then cast.

[0012] As a further improvement to the above technical solution:

[0013] The precast UHPC web has multiple oblique stirrups embedded in it, and each of the oblique stirrups extends along the direction of principal tensile stress.

[0014] The precast UHPC web is provided with multiple through holes, each of which is located between two adjacent diagonal stirrups.

[0015] The height of each through hole is half the height of the prefabricated UHPC web.

[0016] Each of the through holes is an elliptical hole with a major axis to minor axis ratio of 3:1, and each of the through holes extends along the direction of principal tensile stress.

[0017] Each of the prestressed tendons has an anchor head at both ends, and the anchor head is located on the outer side of the end of the precast UHPC lower slab.

[0018] Each of the above-mentioned upper stirrups includes connected long longitudinal bars and long transverse bars, each of the above-mentioned lower stirrups includes connected long longitudinal bars, long transverse bars, short transverse bars and short longitudinal bars, each of the above-mentioned node members includes connected node transverse bars, node longitudinal bars and node vertical bars, the node transverse bars, node longitudinal bars and node vertical bars are inserted on the node member and exposed on the outside of the node member, and the node vertical bars are connected to the web stirrups.

[0019] The precast UHPC lower slab is provided with an upper layer of steel reinforcement structure and a lower layer of steel reinforcement structure. The upper layer of steel reinforcement structure is formed by binding long longitudinal bars and long transverse bars together. The lower layer of steel reinforcement structure is formed by binding prestressed tendons, long transverse bars, short transverse bars and short longitudinal bars together.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0021] Precast prestressed high-pressure concrete (UHPC) I-beams, through an integrated design combining prefabrication and cast-in-place construction, solve several problems inherent in traditional bridge construction. Firstly, the precast UHPC upper slab, web, and lower slab utilize factory prefabrication, significantly shortening on-site construction time and reducing uncertainties and quality control difficulties. Secondly, the upper and lower mounting slots on the precast UHPC upper and lower slabs effectively integrate the upper and lower stirrups with the UHPC structure within the slab, improving the strength and stability of the joint connections. Furthermore, the prefabrication design of the web stirrups and joint components on the web ensures the strength and structural integrity of the web, and the interlocking of the joint components between the web and the lower and upper slabs with the mounting slots makes the splicing of each component more precise and reliable. This precise assembly technology greatly improves assembly efficiency, reduces quality problems that may be caused by on-site construction errors, and ensures the overall mechanical performance and durability of the structure. It also solves problems such as weak node connections, long construction period and difficulty in quality control in the background technology. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a three-dimensional structural diagram of a pre-tensioned prestressed UHPC I-beam.

[0024] Figure 2 This is a longitudinal section diagram of a precast prestressed UHPC I-beam.

[0025] Figure 3 This is a top-view sectional view of a precast prestressed UHPC I-beam.

[0026] Figure 4 This is a schematic diagram of the mid-span section of a precast prestressed UHPC I-beam.

[0027] Figure 5 This is a three-dimensional structural diagram of the prefabricated UHPC top plate;

[0028] Figure 6 This is a top view of the prefabricated UHPC top plate;

[0029] Figure 7 This is a three-dimensional structural diagram of the prefabricated UHPC web.

[0030] Figure 8 This is a front view schematic diagram of the prefabricated UHPC web;

[0031] Figure 9 This is a three-dimensional structural diagram of the prefabricated UHPC lower plate;

[0032] Figure 10 This is a top view of the prefabricated UHPC lower plate.

[0033] Legend:

[0034] 1. Precast UHPC top slab; 11. Upper mounting groove; 12. Upper stirrups; 121. Long longitudinal bars; 122. Long transverse bars; 2. Precast UHPC web; 21. Web stirrups; 22. Nodes; 221. Node transverse bars; 222. Node longitudinal bars; 223. Node vertical bars; 23. Diagonal stirrups; 24. Through holes; 3. Precast UHPC bottom slab; 31. Prestressed tendons; 311. Anchor heads; 32. Lower mounting groove; 33. Lower stirrups; 331. Short transverse bars; 332. Short longitudinal bars; 4. Cast-in-place UHPC blocks. Detailed Implementation

[0035] To facilitate understanding of this utility model, the following description will be provided in more comprehensive and detailed manner with reference to the accompanying drawings and preferred embodiments. However, the scope of protection of this utility model is not limited to the following specific embodiments.

[0036] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of protection of this invention.

[0037] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0038] Example: Figures 1-10 As shown, the precast prestressed UHPC I-beam of this embodiment includes a precast UHPC upper plate 1, a precast UHPC web 2, and a precast UHPC lower plate 3. The precast UHPC upper plate 1 has multiple upper mounting grooves 11, each containing upper stirrups 12 that extend into the precast UHPC upper plate 1 and are precast integrally with it. The precast UHPC lower plate 3 has multiple prestressed tendons 31 and multiple lower mounting grooves 32, each containing lower stirrups 33 that extend into the precast UHPC lower plate 3 and are precast integrally with it. The precast UHPC lower slab 3 is precast as a single unit. The precast UHPC web 2 contains stirrups 21. Multiple node members 22 are provided on both the upper and lower sides of the precast UHPC web 2. Each node member 22 is fixedly connected to the stirrups 21 and precast as a single unit. Multiple node members 22 on the lower side of the precast UHPC web 2 are correspondingly engaged with multiple lower mounting slots 32 on the precast UHPC lower slab 3, and then cast-in-place UHPC blocks 4 are poured. Multiple node members 22 on the upper side of the precast UHPC web 2 are correspondingly engaged with multiple upper mounting slots 11 on the precast UHPC upper slab 1, and then cast-in-place UHPC blocks 4 are poured. The precast prestressed UHPC I-beam, through its integrated precast and cast-in-place design, solves several problems existing in traditional bridge construction. First, the precast UHPC upper slab 1, precast UHPC web 2, and precast UHPC lower slab 3 are manufactured using a factory prefabrication method, which not only significantly shortens on-site construction time but also reduces uncertainties and quality control difficulties during on-site construction. Factory production ensures that all components are manufactured strictly according to design requirements and quality standards, guaranteeing high consistency and reliability. Second, the upper mounting groove 11 and lower mounting groove 32 on the precast UHPC upper slab 1 and precast UHPC lower slab 3 effectively integrate the upper stirrups 12 and lower stirrups 33 with the UHPC structure within the slab, improving the strength and stability of the joint connections. This integrated design results in more uniform stress distribution at the joint connections, significantly enhancing the overall structure's load-bearing capacity and seismic performance.

[0039] Furthermore, the prefabrication design of the stirrups 21 and node components 22 on the prefabricated UHPC web 2 ensures the strength and structural integrity of the prefabricated UHPC web 2. The interlocking of the node components 22 with the mounting grooves 11 and 32 between the prefabricated UHPC web 2, the prefabricated UHPC lower slab 3, and the prefabricated UHPC upper slab 1 makes the splicing between components more precise and reliable. This precise assembly technology not only reduces errors during on-site assembly but also speeds up installation, thereby effectively reducing the construction period. Due to the precise splicing method, the components fit together more tightly, effectively avoiding problems such as loose joints and insufficient node strength found in traditional cast-in-place structures, thus improving the overall structural safety.

[0040] This invention utilizes an ultra-high performance concrete (UHPC) material system, achieving a generational breakthrough in its superior compressive strength, tensile strength, and fracture energy. The high bond strength between the steel fibers and the matrix effectively inhibits the propagation of microcracks. The excellent interlocking between the reinforcing steel bars at the joints and the UHPC, as well as the mechanical interlocking between the web joint ends and the cast-in-place UHPC, effectively controls interface slippage. The strain coordination between the prestressed tendons and the UHPC significantly enhances the structure's ultimate bearing capacity. Through the multi-scale synergistic effect between the UHPC matrix and the steel components, both ultimate bearing capacity and structural ductility are simultaneously improved, further enhancing the overall load-bearing capacity and durability of the bridge structure.

[0041] This advanced assembly technology significantly improves assembly efficiency, reduces quality issues that may arise from on-site construction errors, and further enhances the overall mechanical performance and durability of the structure through high-performance joint technology. Standardized connection nodes and factory-prefabricated components enable faster and more stable installation of all parts, avoiding the instability and safety hazards inherent in traditional bridge construction. Simultaneously, precise manufacturing processes ensure the overall durability of the bridge during use, reducing maintenance needs and long-term operating costs. This addresses issues such as weak node connections, long construction cycles, and difficulties in quality control found in previous technologies, providing a more efficient, safe, and economical solution for bridge construction.

[0042] This embodiment achieves fully industrialized production through factory prefabrication of UHPC components and utilizes high-performance joint technology for modular assembly, significantly improving assembly efficiency. Based on the ultra-high strength properties of UHPC material and the perforation technology, lightweight structural components are achieved, and standardized connection nodes greatly reduce overall construction costs. This technology system not only enhances the performance and efficiency of bridge construction but also achieves a breakthrough in low-cost construction technology, providing solid technical support for the large-scale application of prestressed UHPC bridges.

[0043] In this embodiment, multiple diagonal stirrups 23 are pre-embedded within the precast UHPC web 2, each extending along the direction of principal tensile stress. The mechanical interlocking between the diagonal stirrups 23, the node members 22, and the cast-in-place UHPC blocks 4 forms a multiple shear resistance mechanism. The diagonal stirrups 23 effectively enhance the shear resistance of the precast UHPC web 2, further improving the mechanical properties of the web node ends at the node members 22. The combination of these diagonal stirrups 23 and the cast-in-place UHPC blocks 4 enhances the shear strength of the node ends and the overall stability of the structure, thereby greatly improving the durability and reliability of the entire bridge structure.

[0044] In this embodiment, the precast UHPC web 2 is provided with multiple through holes 24, each through hole 24 being located between two adjacent diagonal stirrups 23. This effectively reduces the self-weight of the precast UHPC web 2 while ensuring its mechanical properties and stability. The arrangement of the through holes not only optimizes material usage and reduces unnecessary structural weight, but also further enhances the shear and bending resistance of the structure through synergy with the diagonal stirrups 23, thereby improving the overall reliability and durability of the structure.

[0045] In this embodiment, the height of each through hole 24 is half the height of the prefabricated UHPC web 2. This effectively reduces the self-weight of the prefabricated UHPC web 2 while maintaining the structural stiffness required during stress. By reasonably controlling the height of the through holes 24, material usage can be minimized without significantly affecting mechanical properties, further optimizing the structural design and achieving a balance between lightweight and high efficiency.

[0046] In this embodiment, each through hole 24 is an elliptical hole with a major axis to minor axis ratio of 3:1, and each through hole 24 extends along the direction of principal tensile stress. This elliptical hole design, in conjunction with the principal tensile stress direction, effectively reduces stress concentration and improves the crack resistance of the precast UHPC web 2 under load. The 3:1 ratio of the major axis to minor axis of the elliptical hole optimizes material usage while avoiding excessive weakening of the load-bearing capacity of the precast UHPC web 2. Furthermore, the arrangement of the holes along the principal tensile stress direction helps to better disperse stress and reduce the adverse effects of the openings on the structural mechanical properties.

[0047] In this embodiment, considering the stress characteristics of a simply supported beam, the normal stress is relatively small and the shear stress is relatively large near the neutral axis, and the direction of the principal tensile stress is approximately 45°. Therefore, an elliptical through-hole 24 forming a 45° angle with the direction of the principal tensile stress was selected. The major-minor axis ratio of the through-hole 24 is 3, and the through-holes 24 are positioned at the bending-shear section, the pure bending section, and the junction of the two in the simply supported beam. The spacing of the through-holes 24 can accommodate three reinforcing diagonal stirrups 23, ensuring a reasonable distribution of the hole positions. This design effectively reduces the beam's self-weight, reduces the beam's cracking load and bending capacity, and enhances the beam's mechanical properties.

[0048] Specifically, the parallel alignment of the long axis of the diagonal stirrups 23 with the long axis of the through-hole 24, and the parallel alignment with the direction of the principal tensile stress, effectively inhibits the development of bending cracks in the beam, further enhancing its overall stability. Meanwhile, the prestressed tendons 31 placed within the precast UHPC web 2 compensate for the decrease in bending capacity caused by the through-hole 24, strengthening the beam's load-bearing capacity. The coordinated stress distribution between the reinforcing steel bars in the precast UHPC web 2 and the prestressed tendons 31 provides sufficient mechanical performance assurance, ensuring the overall load-bearing capacity and durability of the structure. This innovative design of the through-hole 24 and reinforcement method effectively improves the load-bearing performance of the UHPC I-beam, providing reliable technical support for bridge construction and use.

[0049] In this embodiment, each prestressing tendon 31 is provided with anchor heads 311 at both ends, and the anchor heads 311 are located on the outer side of the end of the precast UHPC lower slab 3. This effectively enhances the anchorage performance of the prestressing tendons 31, ensures effective tensile force transmission of the prestressing tendons 31, and improves the overall stability and load-bearing capacity of the structure. Through the design of the anchor heads 311, not only can the tension of the prestressing tendons 31 be better controlled, but stress concentration in the anchorage area is also avoided, thereby improving the durability and service life of the structure.

[0050] In this embodiment, each upper stirrup 12 includes a connected long longitudinal bar 121 and a long transverse bar 122, and each lower stirrup 33 includes a connected long longitudinal bar 121, a long transverse bar 122, a short transverse bar 331, and a short longitudinal bar 332. Each node member 22 includes a connected node transverse bar 221, node longitudinal bar 222, and node vertical bar 223. The node transverse bar 221, node longitudinal bar 222, and node vertical bar 223 are inserted into the node member 22 and exposed on the outside of the node member 22. The node vertical bar 223 is connected to the web stirrup 21. The reinforcement and stability of the node are fully considered. Through the reasonable configuration of the node transverse bar 221, node longitudinal bar 222, and node vertical bar 223, the shear and bending resistance of the node is enhanced, effectively improving the overall integrity and reliability of the structure. In particular, the connection design between the node 22 and the precast UHPC web 2 ensures good mechanical transfer between the node and the precast UHPC web 2. The exposed node horizontal reinforcement 221, node longitudinal reinforcement 222 and node vertical reinforcement 223 make the node more uniformly stressed, reduce stress concentration, and thus improve the seismic resistance and durability of the structure.

[0051] In this embodiment, the precast UHPC lower slab 3 is provided with an upper and lower reinforcing steel structure. The upper reinforcing steel structure is formed by binding long longitudinal bars 121 and long transverse bars 122 together, and the lower reinforcing steel structure is formed by binding prestressed tendons 31, long transverse bars 122, short transverse bars 331, and short longitudinal bars 332 together. The optimized arrangement of the reinforcing steel allows the upper and lower reinforcing steel structures to function in different positions. The upper reinforcing steel structure enhances the bending resistance of the beam, ensuring better stability when subjected to bending moments. The lower reinforcing steel structure, through the addition of prestressed tendons 31, enhances the tensile strength of the structure, further improving the crack resistance and load-bearing capacity of the beam. This design rationally distributes the reinforcing steel, meeting the strength requirements of the structure while fully utilizing the high-performance characteristics of the materials, thus improving the overall mechanical properties and fatigue resistance of the structure.

Claims

1. A prefabricated prestressed UHPC I-beam, characterized in that, The precast UHPC includes a precast UHPC upper plate (1), a precast UHPC web plate (2), and a precast UHPC lower plate (3). The precast UHPC upper plate (1) is provided with multiple upper mounting grooves (11), and upper stirrups (12) are provided in the upper mounting grooves (11). The upper stirrups (12) extend into the precast UHPC upper plate (1) and are precast together with the precast UHPC upper plate (1). The precast UHPC lower plate (3) is provided with multiple prestressed tendons (31) using the pre-tensioning method. The precast UHPC lower plate (3) is provided with multiple lower mounting grooves (32), and lower stirrups (33) are provided in the lower mounting grooves (32). The lower stirrups (33) extend into the precast UHPC lower plate (3) and are precast together with the precast UHPC lower plate (3). The prefabricated UHPC web (2) is prefabricated as a whole. The prefabricated UHPC web (2) is provided with stirrups (21). The upper and lower sides of the prefabricated UHPC web (2) are provided with multiple node pieces (22). Each node piece (22) is fixedly connected with the stirrups (21) and the prefabricated UHPC web (2) is prefabricated as a whole. The multiple node pieces (22) on the lower side of the prefabricated UHPC web (2) are connected to the multiple lower mounting grooves (32) on the prefabricated UHPC lower plate (3) one by one, and the cast-in-place UHPC block (4) is poured. The multiple node pieces (22) on the upper side of the prefabricated UHPC web (2) are connected to the multiple upper mounting grooves (11) on the prefabricated UHPC upper plate (1) one by one, and the cast-in-place UHPC block (4) is poured.

2. The prefabricated prestressed UHPC I-beam according to claim 1, characterized in that, The precast UHPC web (2) has multiple pre-embedded diagonal stirrups (23), each of which extends along the direction of principal tensile stress.

3. The prefabricated prestressed UHPC I-beam according to claim 2, characterized in that, The precast UHPC web (2) is provided with multiple through holes (24), and each through hole (24) is located between two adjacent diagonal stirrups (23).

4. The prefabricated prestressed UHPC I-beam according to claim 3, characterized in that, The height of each of the through holes (24) is half the height of the prefabricated UHPC web (2).

5. The prefabricated prestressed UHPC I-beam according to claim 3, characterized in that, Each of the through holes (24) is an elliptical hole with a major axis to minor axis ratio of 3:1, and each of the through holes (24) extends along the direction of principal tensile stress.

6. The prefabricated prestressed UHPC I-beam according to claim 1, characterized in that, Each of the prestressed tendons (31) is provided with an anchor head (311) at both ends, and the anchor head (311) is located on the outer side of the end of the precast UHPC lower plate (3).

7. The prefabricated prestressed UHPC I-beam according to any one of claims 1-6, characterized in that, Each of the upper stirrups (12) includes a connected long longitudinal bar (121) and a long transverse bar (122). Each of the lower stirrups (33) includes a connected long longitudinal bar (121), a long transverse bar (122), a short transverse bar (331), and a short longitudinal bar (332). Each of the node members (22) includes a connected node transverse bar (221), a node longitudinal bar (222), and a node vertical bar (223). The node transverse bar (221), node longitudinal bar (222), and node vertical bar (223) are inserted on the node member (22) and exposed on the outside of the node member (22). The node vertical bar (223) is connected to the web stirrup (21).

8. The prefabricated prestressed UHPC I-beam according to claim 7, characterized in that, The precast UHPC lower slab (3) is provided with an upper layer steel reinforcement structure and a lower layer steel reinforcement structure. The upper layer steel reinforcement structure is formed by binding long longitudinal bars (121) and long transverse bars (122). The upper layer steel reinforcement structure is formed by binding prestressed tendons (31), long transverse bars (122), short transverse bars (331) and short longitudinal bars (332).

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