Equal-strength steel truss reinforcing structure of structural damage PC box girder
By installing steel trusses on the web of the prestressed concrete box girder and fixing them with tie rods, the problems of large construction damage, complex processes and high maintenance costs of existing reinforcement methods are solved, achieving reinforcement effect of equal strength and low-cost construction scheme.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GANSU PROVINCE BAIYIN HIGHWAY DEV CENT JINGYUAN HIGHWAY SECTION
- Filing Date
- 2025-05-27
- Publication Date
- 2026-05-05
AI Technical Summary
Existing reinforcement methods for treating structural damage to prestressed concrete box girders suffer from problems such as significant construction damage, complex processes, high maintenance costs, and limited reinforcement effects, making it difficult to effectively address the safety hazards caused by structural damage.
An equal-strength steel truss reinforcement structure is adopted. By setting steel trusses on the web of the PC box girder and fixing them with tie rods, the concrete work in the damaged area is replaced, ensuring that the steel truss has the same strength as the original structure and achieving complete replacement of the load-bearing capacity.
It achieves efficient reinforcement of prestressed concrete box girders, with simple construction, low maintenance costs, and no secondary damage to the original structure. It has the same design values for bending and shear bearing capacity and can flexibly adapt to the reinforcement needs of damaged areas.
Smart Images
Figure CN224200306U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of building structure reinforcement technology, and relates to an equal-strength steel truss reinforcement structure for structurally damaged PC box girders. Background Technology
[0002] Structural damage to concrete structures refers to the appearance of through cracks (crack width > 0.3 mm), large-area spalling or delamination, significant corrosion and exposure of reinforcing steel, a cross-sectional loss rate exceeding 20%, and a reduction in load-bearing capacity to below 60% of the design value. This damage leads to a decline in structural performance and safety, resulting in significant economic losses and safety hazards. Therefore, addressing the structural damage problem in prestressed concrete box girders requires serious attention.
[0003] Generally, reinforced concrete box girders can be replaced as a whole span after structural damage. However, prestressed concrete continuous beams or continuous rigid frames are difficult to replace as a whole span due to the presence of longitudinal prestress, and can only be reinforced by comprehensive reinforcement.
[0004] There are four main existing methods for reinforcing the structural damage of prestressed concrete box girders: The first is the cross-section enlargement method, which increases the load-bearing capacity and stiffness of the beam by adding a new layer of concrete or prestressed concrete to the surface of the original beam; the second is the steel plate bonding method, which uses a high-strength adhesive to bond steel plates to the surface of the concrete beam, so that the steel plates and concrete share the load; the third is the external prestressing method, which applies external prestress to the beam by setting prestressing tendons on the outside of the beam, generating bending moments and shear forces opposite to the load to reduce the stress inside the beam; the fourth is the fiber composite material bonding method, which uses a special adhesive to bond fiber composite materials to the surface of the beam, with the fiber material bearing part of the load and working together with the original structure.
[0005] While these reinforcement methods can reduce structural damage to prestressed concrete box girders to some extent, they all have corresponding problems. The first method, increasing the cross-section, requires some demolition and treatment of the original structure during construction, causing significant damage and increasing the structure's self-weight, potentially adversely affecting the foundation. The second method, bonding steel plates, requires high-precision bonding techniques, making it difficult to guarantee bonding quality, and the steel plates are prone to corrosion, requiring appropriate rust prevention treatment. The third method, external prestressing, requires high-precision construction techniques and regular inspection and maintenance of the external prestressing tendons' corrosion protection and anchorage. The fourth method, bonding fiber composite materials, suffers from significant environmental influences on the bond performance between the fiber composite material and concrete, requiring further research on long-term performance, and has relatively high reinforcement costs. Furthermore, these methods share common drawbacks, such as the inability to account for the prestress in cracked concrete, limited local reinforcement effects, and difficulty in estimating later-stage defects.
[0006] Therefore, how to ensure that reinforcement causes less damage to the original structure, simplifies the construction process, guarantees the reinforcement effect, and reduces the later maintenance costs has become an urgent problem to be solved by those skilled in the art. Utility Model Content
[0007] In view of this, the purpose of this utility model is to provide a reinforced steel truss structure for structurally damaged PC box girders, while ensuring less damage to the original structure and a stronger reinforcement effect.
[0008] To achieve the above objectives, this utility model provides the following technical solution:
[0009] A reinforced steel truss structure for structurally damaged PC box girders is provided on the web of the section of the PC box girder to be reinforced. It includes a steel truss of equal strength to the PC box girder, which is fixed to the web by tie rods. The steel truss is a cuboid spatial steel truss structure. A planar truss is provided on the opposite surface of the web to the steel truss, and the planar truss is connected to the steel truss by tie rods penetrating the web to achieve fixation of the steel truss.
[0010] Optionally, the steel truss is located inside the web of the PC box girder.
[0011] Optionally, the steel truss is located on the outside of the web of the PC box girder.
[0012] Optionally, the tie rod is further provided with anchor bolts and steel washers; the steel washers are located on the side of the steel truss or planar truss close to the web plate to strengthen and fix the steel truss or planar truss; the anchor bolts are located on the side of the steel truss or planar truss away from the web plate to anchor the tie rod.
[0013] Optionally, the tie rods are located at the connection points of the chords in the steel truss.
[0014] Optionally, the steel truss has a steel-concrete transition section at its end, and the transition section is fixed to the web by the tie rod.
[0015] Optionally, the number of tie rods on the transition connection section is n = T1 / T2, where T1 is the tensile force on the steel truss chord and T2 is the tensile force that a single tie rod can withstand.
[0016] Optionally, the steel truss is an eight-legged truss, a ten-legged truss, or a twelve-legged truss.
[0017] The beneficial effects of this utility model are as follows:
[0018] This utility model utilizes an equal-strength steel truss reinforcement method. In the web region of a prestressed concrete box girder that has suffered structural damage, the steel truss is connected to the web using tie rods, ensuring that the steel truss can replace the concrete in the damaged area. This method causes less damage to the original structure, simplifies the construction process, guarantees a strong reinforcement effect, and reduces subsequent maintenance costs.
[0019] This invention utilizes steel trusses to completely replace structurally damaged PC box girders, either partially or entirely. While this strengthens the overall PC box girder, in the replaced area, the steel truss not merely increases the load-bearing capacity of the PC box girder in a conventional way, but rather completely replaces it. Equal strength means that the steel truss and the PC box girder have the same design values for bending and shear bearing capacity. This equal-strength steel truss replacement reinforcement method allows for flexible reinforcement design based on the area of structural damage.
[0020] This reinforcement scheme will not cause further damage to the prestressed concrete box girder with existing structural damage; the replacement span of the steel truss with equal strength is within the damaged area, and equal strength is relatively easy to achieve; the design of the steel truss with equal strength is flexible according to the box girder in the damaged area, and the cross-section and prestress can be designed as needed; the overall structure can be prefabricated in the factory in advance, and the construction is modular, quick and easy; the structure is simple, processing and assembly are convenient, the strength and stiffness are large, and it can bear the load of the replaced cross-section, with a low overall cost.
[0021] Other advantages, objectives, and features of this invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination and study, or may be learned from practice of this invention. The objectives and other advantages of this invention can be realized and obtained through the following description. Attached Figure Description
[0022] To make the objectives, technical solutions, and advantages of this utility model clearer, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings, wherein:
[0023] Figure 1 This is an isometric drawing of the reinforced structure of this utility model;
[0024] Figure 2 This is a cross-sectional schematic diagram of the present invention (eight-limb girder);
[0025] Figure 3 This is an enlarged schematic diagram of the pull screw;
[0026] Figure 4 This is a cross-sectional schematic diagram of the present invention (ten-limb girder);
[0027] Figure 5This is a cross-sectional schematic diagram of the present invention (twelve-limb girder);
[0028] Figure 6 This is a cross-sectional schematic diagram of the present invention (the steel truss is located on the outside);
[0029] Figure 7 This is a schematic diagram of the steel-concrete transition section;
[0030] Figure 8 This is a schematic diagram of the equivalent cross-section.
[0031] Figure label:
[0032] 1. PC box girder, 11. Web plate, 2. Steel truss, 3. Tie rod, 4. Planar truss, 5. Anchor bolt, 6. Steel gasket, 7. Steel-concrete transition connection section. Detailed Implementation
[0033] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this utility model. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0034] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.
[0035] In the accompanying drawings of this utility model, the same or similar reference numerals correspond to the same or similar components. In the description of this utility model, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting this utility model. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0036] Please see Figures 1 to 8This is a reinforcement structure of a structurally damaged PC box girder 1 with an equal-strength steel truss 2, which is installed on the web 11 of the section of the PC box girder 1 to be reinforced. It includes a steel truss 2 with the same strength as the PC box girder 1, and the steel truss 2 is fixed to the web 11 by tie rods 3. The steel truss 2 is a cuboid spatial steel truss structure. A planar truss 4 is provided on the opposite surface of the web 11 to the steel truss 2. The planar truss 4 is connected to the steel truss 2 by tie rods 3 that pass through the web 11 to fix the steel truss 2.
[0037] The equal-strength reinforcement principle in this embodiment is based on two equivalence principles. The first equivalence principle is cross-sectional equivalence, i.e., EI = E1I1, where E is the elastic modulus of the original structure, I is the moment of inertia of the original structure, EI is the bending stiffness of the original structure, E1 is the elastic modulus of the equal-strength steel truss 2, I1 is the moment of inertia of the equal-strength steel truss 2, and E1I1 is the bending stiffness of the equal-strength steel truss 2. It is assumed that the prestressed concrete box girder 1 in the structurally damaged section is completely decommissioned, and its bearing capacity is completely replaced by the equal-strength steel truss 2. The second equivalence principle is shear equivalence. The equal-strength steel truss 2 is connected to the original structure through tie rods, and the shear resistance of the original concrete web 11 is replaced by the shear resistance of the vertical members of the steel truss 2, i.e., V = τ, where V is the shear bearing capacity of the original concrete web 11, and τ is the shear bearing capacity of the vertical members of the equivalent truss. The steel truss 2 is designed based on the strength design value of the PC box girder 1, and the strength design value of the steel truss 2 is required to be consistent with that of the undamaged PC box girder 1.
[0038] The tie rod 3 is also equipped with anchor bolts 5 and steel washers 6; the steel washers 6 are located on the side of the steel truss 2 or the planar truss 4 closest to the web plate 11, to strengthen and fix the steel truss 2 or the planar truss 4 and ensure better connectivity; the anchor bolts 5 are located on the side of the steel truss 2 or the planar truss 4 furthest from the web plate 11, to anchor the tie rod 3. The tie rods 3 are located at the connection points of the chord members in the steel truss 2.
[0039] The steel truss 2 has a steel-concrete transition section 7 at its end, which is fixed to the web plate 11 by tie rods 3.
[0040] The number of tie rods 3 on the transition connection section 7 is n = T1 / T2, where T1 is the tension force on the chord of the steel truss 2, and T2 is the tension force that a single tie rod 3 can withstand.
[0041] Example 1
[0042] Based on the above-mentioned equal-strength steel truss 2 reinforcement structure, in this embodiment, the steel truss 2 is located inside the web 11 of the PC box girder 1, while the planar truss 4 is located outside the web 11 of the PC box girder 1. The planar truss 4 and the steel truss 2 are fixed to both sides of the web 11 by tie rods 3 to achieve the reinforcement effect of the PC box girder 1.
[0043] Example 2
[0044] Based on the aforementioned reinforced structure of equal-strength steel truss 2, in this embodiment, steel truss 2 is located on the outer side of the web 11 of PC box girder 1, while planar truss 4 is located on the inner side of the web 11 of PC box girder 1. Planar truss 4 and steel truss 2 are fixed to both sides of the web 11 by tie rods 3, thereby achieving the reinforcement effect of PC box girder 1. This embodiment is suitable for situations where the internal space of PC box girder 1 is relatively small.
[0045] Example 3
[0046] like Figure 2 , 4 As shown in Figure 5, based on the above-described Embodiment 1 or Embodiment 2, this embodiment limits the number of legs of the equal-strength steel truss 2. The number of legs of the equal-strength steel truss 2 is determined according to the magnitude of the stress on the structurally damaged section, and the steel truss 2 can be an eight-legged truss, a ten-legged truss, or a twelve-legged truss.
[0047] The design and construction method of the equal-strength steel truss 2 reinforcement structure of this utility model includes the following steps:
[0048] S1. Determine the frame structure dimensions, fixing bolts, and assembly bolt types and quantities based on the stress on the specific structurally damaged section. During the design process, ensure that all components have sufficient strength, stiffness, and stability.
[0049] S2, all components of the equal-strength steel truss 2 are prefabricated in the steel structure factory. Standardized design and fabrication can be adopted for bridges with box girders 1 of the same or similar cross-sections.
[0050] S3, using connecting tie rods 3, anchor bolts 5 and steel shims 6 to fix each segment of the steel truss 2 to the web section 11 of the PC box girder 1 that needs to be reinforced.
[0051] S4, the steel truss 2 is assembled and connected or welded using assembly bolts.
[0052] S5, installation complete.
[0053] This invention utilizes a steel truss 2 of equal strength to reinforce the web 11 area of a prestressed concrete box girder 1 that has suffered structural damage. The steel truss 2 and web 11 are connected by tie rods 3, ensuring that the steel truss 2 can replace the concrete in the damaged area. This method causes less damage to the original structure, simplifies the construction process, guarantees a strong reinforcement effect, and reduces subsequent maintenance costs.
[0054] This invention utilizes a steel truss 2 to completely replace the structurally damaged PC box girder 1, either partially or entirely. While this strengthens the PC box girder 1 as a whole, in the replaced area, the steel truss 2 does not merely increase the load-bearing capacity of the PC box girder 1 in a conventional way; rather, it completely replaces the load-bearing capacity of the PC box girder 1. Equal strength means that the steel truss 2 and the PC box girder 1 have the same design values for bending and shear bearing capacity. This equal-strength steel truss 2 replacement reinforcement method allows for flexible reinforcement design based on the area of structural damage.
[0055] This reinforcement scheme will not cause further damage to the prestressed concrete box girder 1, which already has structural damage. The replacement span of the steel truss 2 with the same strength is within the damaged area, and the same strength is relatively easy to achieve. The design of the steel truss 2 with the same strength is flexible according to the damaged box girder 1, and the cross-section and prestress can be designed as needed. The overall structure can be prefabricated in the factory in advance, and the construction is modular, quick and easy. The structure is simple, easy to process and assemble, has high strength and stiffness, can bear the load of the replaced cross-section, and has a low overall cost.
[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of this technical solution, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.
Claims
1. A reinforced steel truss structure for structurally damaged PC box girders, characterized in that: A steel truss (2) of equal strength to the PC box girder (1) is provided on the web plate (11) of the section to be reinforced. The steel truss (2) is fixed to the web plate (11) by tie rods (3). The steel truss (2) is a cuboid spatial steel truss (2) structure. A planar truss (4) is provided on the web plate (11) opposite to the steel truss (2). The planar truss (4) is connected to the steel truss (2) by tie rods (3) that penetrate the web plate (11) to fix the steel truss (2).
2. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 1, characterized in that: The steel truss (2) is located inside the web (11) of the PC box girder (1).
3. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 1, characterized in that: The steel truss (2) is located on the outside of the web (11) of the PC box girder (1).
4. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 1, characterized in that: The tie rod (3) is also provided with anchor bolts (5) and steel washers (6); the steel washers (6) are located on the side of the steel truss (2) or the planar truss (4) close to the web plate (11) to strengthen and fix the steel truss (2) or the planar truss (4); the anchor bolts (5) are located on the side of the steel truss (2) or the planar truss (4) away from the web plate (11) to anchor the tie rod (3).
5. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 1, characterized in that: The tie rod (3) is located at the connection of each chord in the steel truss (2).
6. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 1, characterized in that: The steel truss (2) is provided with a steel-concrete transition section (7) at its end, and the transition section (7) is fixed to the web plate (11) by the tie rod (3).
7. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 6, characterized in that: The number of tie rods (3) on the transition connection section (7) is n = T1 / T2, where T1 is the tension on the chord of the steel truss (2) and T2 is the tension that a single tie rod (3) can withstand.
8. The equal-strength steel truss reinforcement structure for structurally damaged PC box girders according to claim 1, characterized in that: The steel truss (2) is an eight-limb truss, a ten-limb truss, or a twelve-limb truss.