Prestressed UHPC bridge and construction method thereof

Abstract

According to the prestressed UHPC bridge and the construction method thereof, the FRP ribs with the strength higher than that of the steel bars are used as the prestressed ribs, the stress reserve of components is improved, the main beam is prevented from cracking, the using amount of the steel bars can be reduced under the same bearing capacity requirement, and the FRP ribs are particularly suitable for being applied to bridge engineering in coastal areas due to the corrosion resistance of the FRP ribs; in addition, aramid fibers are added into the UHPC concrete, so that the UHPC concrete has higher pressure resistance and better durability, the advantages of high strength, durability, economical efficiency and the like are brought to the whole bridge, in addition, the construction method provided by the invention adopts a mode of combining prefabricated parts and on-site post-pouring, the construction efficiency is improved, and the project progress is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of bridge engineering, and further relates to a prestressed UHPC bridge and a construction method thereof. Background Art

[0002] Most existing bridges are made of reinforced concrete structures. In coastal areas and other places, due to the influence of high-corrosion environmental factors such as sea breeze, seawater, and salts in the atmosphere, the steel bars will get damp and rust. Rusting will reduce the bearing capacity of the steel bars, and thus affect the overall durability of the structure. For example, rusting causes the cross-sectional area of the steel bars to decrease and the bearing capacity to decline. Rusting will also generate expansion forces, causing the concrete to crack and further weakening the bearing capacity. Therefore, there is an urgent need to develop a bridge structure that not only has a strong bearing capacity but also has high durability to effectively cope with the high-corrosion environment in coastal areas and ensure the safety and long-term use of the bridge. Summary of the Invention

[0003] Aiming at the problems of insufficient durability and reduced bearing capacity caused by steel bar corrosion in the application of existing bridges in coastal areas, the purpose of the present invention is to provide a prestressed UHPC bridge and a construction method thereof. Use FRP bars with a strength higher than that of steel bars as prestressing tendons to increase the stress reserve of components, prevent the main girder from cracking, reduce the amount of steel bars used, and FRP bars are corrosion-resistant and suitable for bridge engineering in coastal areas. In addition, aramid fibers are added to the UHPC concrete to make it have higher compressive capacity and better durability. The construction method provided by the present invention adopts a combination of precast components and in-situ post-casting to improve the construction efficiency and project progress.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A prestressed UHPC bridge, comprising: a main girder, a bridge deck, an aramid fiber mesh, FRP bars, and aramid fiber concrete; the main girder includes a bottom plate and two oppositely arranged webs, the bottom plate is formed by casting the aramid fiber mesh with the aramid fiber concrete; the webs are supported and connected between the bottom plate and the bridge deck, and several of the FRP bars are arranged along the length direction in the webs; the bridge deck is arranged on the main girder and is formed by casting with the aramid fiber concrete; the aramid fiber concrete includes: aramid fibers and UHPC concrete.

[0006] In some embodiments, the fiber material of the FRP bars is any one of aramid fibers, glass fibers, and carbon fibers.

[0007] In some embodiments, the main girder is a U-shaped main girder.

[0008] In some embodiments, the U-shaped main girder further includes: columns, which are supported and arranged between the bottom plate and the bridge deck.

[0009] In some embodiments, a plurality of hollow structures are provided on the web.

[0010] In some embodiments, the prestressed UHPC bridge further includes: a detachable protection tube; the FRP bars have exposed portions exposed in the hollow structures, and the protection tube is sleeved on the exposed portions to protect the exposed portions.

[0011] The present invention also provides a construction method of the prestressed UHPC bridge as described above, including:

[0012] Precasting the main girder: arranging the aramid fiber mesh and the FRP bars, and after tensioning the aramid fiber mesh and the FRP bars, pouring the aramid fiber concrete to form the main girder;

[0013] Pouring the bridge deck: building a bridge deck pouring platform on the main girder, and pouring the aramid fiber concrete to form the bridge deck;

[0014] Secondary tensioning: tensioning the FRP bars again.

[0015] In some embodiments, the specific steps of arranging the aramid fiber mesh and the FRP bars include: arranging the aramid fiber mesh at the bottom of the main girder mold, respectively arranging a plurality of prestressed ducts at two side wall positions of the main girder mold, and the FRP bars pass through the prestressed ducts and are fixed.

[0016] In some embodiments, the specific steps of pouring the bridge deck include: installing brackets according to the size of the bridge deck, installing a plurality of templates on the brackets to form the bridge deck pouring platform, then pouring the aramid fiber concrete, and after the strength of the aramid fiber concrete reaches the preset strength, removing the templates and the brackets.

[0017] In some embodiments, between the precasting of the main girder and the pouring of the bridge deck, it further includes: curing the main girder: after the aramid fiber concrete is poured, performing spray curing to ensure that the aramid fiber concrete reaches the design strength; after the aramid fiber concrete reaches the design strength, removing the main girder mold, storing it for a period of time and then performing subsequent installation construction; and / or, after the secondary tensioning, it further includes: constructing the bridge deck paving and ancillary works.

[0018] Compared with the prior art, the prestressed UHPC bridge and its construction method provided by the present invention have the following beneficial effects:

[0019] 1. In the UHPC concrete of the present invention, aramid fibers are added and mixed to form aramid fiber concrete materials. The addition of aramid fibers improves the toughness of the concrete materials, enabling them to have better resistance when subjected to impact or dynamic loads, enhancing the overall strength and durability, and can also reduce the thickness size of components, thereby reducing the self-weight.

[0020] 2. The present invention uses aramid FRP bars with a strength six times that of steel bars as prestressing tendons to improve the load-bearing capacity of the entire structure. Under the same load-bearing capacity requirements, the use of FRP bars can reduce the material consumption, thereby reducing costs, and is also beneficial to improving the transportation, installation, and construction efficiency of the structure. In addition, FRP bars are corrosion-resistant, and their performance will not decline even in harsh environments, such as acidic or alkaline environments, improving the durability of the bridge structure and being suitable for coastal areas.

[0021] 3. The present invention provides a hollow structure on the web, which reduces the material consumption, reduces the self-weight of the main beam, and reduces the construction cost. Moreover, the hollow structure also facilitates maintenance personnel to conveniently inspect the inside of the main beam for repair and maintenance during the bridge operation period.

[0022] 4. The construction method provided by the present invention adopts a combination of factory prefabrication and on-site post-casting. The precast main beams are mass-produced in the factory, unaffected by weather and environmental factors, improving the construction efficiency and project progress. On the one hand, the precast components can reduce the self-weight of component transportation, and on the other hand, only simple assembly and post-casting construction need to be carried out on-site. The U-shaped main beam is used as a support for the in-situ casting of the bridge deck, reducing the on-site construction time and labor requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following will further illustrate the above characteristics, technical features, advantages and their implementation manners of the present invention in a clear and understandable manner in combination with the drawings of the preferred embodiments.

[0024] Figure 1 It is a schematic structural diagram of the prestressed UHPC bridge provided by the present invention;

[0025] Figure 2 It is a front view of the main beam provided by the present invention;

[0026] Figure 3 It is a schematic structural diagram of the bridge deck casting platform provided by the present invention;

[0027] Figure 4 It is a schematic structural diagram of the web provided by the present invention.

[0028] Explanation of the reference numerals in the drawings:

[0029] 1 - Main girder; 101 - Bottom plate; 102 - Web; 103 - Column; 2 - Bridge deck; 3 - Aramid FRP bars; 4 - Bridge deck casting platform; 401 - Support; 402 - Formwork. Detailed implementation mode

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation modes of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, and other implementation modes can also be obtained.

[0031] To make the drawings concise, only the parts related to the invention are schematically shown in each drawing, and they do not represent the actual structure of the product. In addition, to make the drawings concise and easy to understand, in some drawings, components with the same structure or function are only schematically shown as one of them, or only one of them is marked. In this article, "one" not only means "only this one", but also means "more than one" situation.

[0032] It should also be further understood that the term "and / or" used in the description of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0033] In this article, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] In addition, in the description of the present invention, the terms "first", "second", etc. are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

[0035] Embodiment 1

[0036] As Figures 1 to 4 shown, this embodiment provides a prestressed UHPC bridge including: main girder 1, bridge deck 2, aramid fiber mesh, FRP bars and aramid fiber concrete. Specifically:

[0037] Fiber Reinforced Polymer Plastic, abbreviated as FRP, is a high-performance material formed by mixing fiber materials and matrix material resin in a certain proportion. It has the characteristics of being light and hard, non-conductive, high mechanical strength, less recyclable, and corrosion-resistant. The above-mentioned fiber materials can be selected from aramid fiber, glass fiber, carbon fiber, etc., that is, aramid fiber reinforced composite plastic KFRP, fiberglass fiber reinforced composite plastic GFRP, carbon fiber reinforced composite plastic CFRP. Therefore, the fiber material used for the FRP bars provided by the present invention can be any one of aramid fiber, glass fiber, and carbon fiber.

[0038] Taking the aramid FRP bar 3 made of aramid fiber as the fiber material provided by the present invention as an example, it is formed by bundling about 200,000 aramid fibers and then infiltrating with epoxy resin. Its strength is 6 times that of steel bars. Compared with the weight of steel bars, the weight of the aramid FRP bar 3 is very light, which is more convenient during construction and installation. Moreover, the aramid FRP bar 3 does not corrode and is suitable for harsh environments or projects sensitive to corrosion.

[0039] During the mixing process of ultra-high performance concrete (UHPC), aramid fiber is added, and the above-mentioned aramid fiber concrete is finally obtained. This aramid fiber concrete has the characteristics of high strength and high durability. This aramid fiber concrete material is used during the pouring process of the main beam 1 and the bridge deck 2 to improve its overall performance.

[0040] As Figure 2 shown, the above-mentioned main beam 1 includes a bottom plate 101 and two oppositely arranged webs 102. The bottom plate 101 is formed by pouring aramid fiber concrete on an aramid fiber mesh, that is, an aramid fiber mesh is arranged at the bottom of the main beam mold, and then the above-mentioned aramid fiber concrete is cured to form the bottom plate 103.

[0041] The above-mentioned web 102 is supported and connected between the bottom plate 101 and the bridge deck 2. A number of the above-mentioned aramid FRP bars 3 are arranged along the length direction inside the web 102, and the length of the aramid FRP bar 3 is determined according to the length of the web 103.

[0042] The bridge deck 2 is arranged on the main beam 1 and is also formed by pouring aramid fiber concrete.

[0043] In some embodiments, as Figure 2 shown, the main beam 1 is preferably a U-shaped main beam.

[0044] Further, the above U-shaped main girder further includes: a column 102, which is supported between the bottom plate 101 and the bridge deck 2. The U-shaped main girder and the middle column 102 can be cast integrally or separately. For example, first cast the U-shaped main girder, and then cast the column 102 after the main girder reaches a certain strength. The U-shaped main girder itself is prone to torsion and lateral displacement under the action of lateral force. By adding a column 103 in the middle, the overall stability of the structure can be significantly improved, lateral deformation can be reduced, and stress can be effectively dispersed and transmitted, reducing the stress concentration of the main girder 1 and improving the load-bearing capacity and service life of the structure.

[0045] It should be noted that the length of the above main girder 1 matches the total length of the bridge and can range from dozens of meters to hundreds of meters. During design, it can be comprehensively considered according to specific engineering requirements and the above factors. Similarly, the span of the main girder 1 is also determined according to the specific situation of the design requirements.

[0046] In some embodiments, a number of hollow structures are provided on the above web 103, such as Figure 4 As shown, the shape of the above hollow structure can be diamond-shaped, rectangular, circular or irregular. The setting of the hollow structure can reduce the self-weight of the structure. The hollow structure is also convenient for maintenance personnel to check the internal defects of the main girder during the bridge operation period. In addition, it can be used to build a bridge deck casting platform during the casting process of the bridge deck 2. For details, see the construction method described in Embodiment 2.

[0047] Further, the prestressed UHPC bridge further includes: a detachable protective tube. The aramid FRP bar 3 has an exposed part exposed in the hollow structure, and the protective tube is sleeved on the exposed part to protect the exposed part. In addition, the protective tube can be opened during the bridge maintenance process to check the damage of the aramid FRP bar 3.

[0048] The material of the protective tube is preferably rubber.

[0049] Embodiment 2

[0050] On the basis of Embodiment 1, the present invention further provides a construction method of the above prestressed UHPC bridge, including:

[0051] S1. Prefabricate the main girder: Lay out the aramid fiber mesh and the aramid FRP bar 3. After tensioning the aramid fiber mesh and the aramid FRP bar 3 by the pretensioning method, form the main girder 1 by casting aramid fiber concrete.

[0052] Further, the specific steps of laying out the aramid fiber mesh and the aramid FRP bar 3 include:

[0053] Install the main beam mold according to the design drawings and construction requirements. The main beam mold usually includes a bottom mold and side molds, which are used to shape the bottom plate and web of the main beam respectively. Lay an aramid fiber mesh at the bottom of the main beam mold, and set a number of prestressed ducts at the positions of the two side walls of the main beam mold. The aramid FRP bars 3 pass through the prestressed ducts and are fixed. Subsequently, conduct the initial prestress tensioning on the aramid fiber mesh and the aramid FRP bars 3 to form a preliminary prestress state.

[0054] Furthermore, after tensioning the aramid fiber mesh and the aramid FRP bars 3, the steps also include: anchoring the aramid FRP bars 3 after the first tensioning to maintain their prestress state. The anchored aramid FRP bars 3 will transfer prestress to the aramid fiber concrete, enhancing the bearing capacity of the structure. Subsequently, pour the aramid fiber concrete to fill the voids around the prestressed ducts to form the above-mentioned web 102.

[0055] It should be noted that during the pouring process of the main beam 1 and the bridge deck 2, the concrete pouring needs to ensure compaction. A vibrator can be used to avoid voids or cracks.

[0056] S2. Maintenance of the main beam: After the aramid fiber concrete is poured, conduct spray maintenance to prevent early cracks and strength loss of the concrete, and ensure that the aramid fiber concrete reaches the design strength.

[0057] After the concrete reaches the design strength, remove the main beam mold and store it for a period of time before continuing with the subsequent installation construction.

[0058] S3. Transport the main beam 1 to the construction site and hoist the main beam 1 to the bridge position.

[0059] S4. Pour the bridge deck: Build a bridge deck pouring platform on the main beam 1 and pour the aramid fiber concrete to form the bridge deck 2.

[0060] Further, the specific steps include: as Figure 3 shown, install the brackets 401 according to the size of the bridge deck 2, install a number of templates 402 on the brackets 401. The templates 402 are arranged in sequence along the length direction of the main beam 1. After forming a flat bridge deck pouring platform, pour the aramid fiber concrete. After the strength of the aramid fiber concrete reaches the preset strength, remove the templates 402 and the brackets 401.

[0061] The above-mentioned templates are usually made of wood, metal, plastic or other synthetic materials, and their material and structural design must be able to withstand the pressure of the concrete and the vibration during the construction process.

[0062] S5. Secondary tensioning: Tension the aramid FRP bars 3 again. The aramid FRP bars 3 have been tensioned for the first time in step S1 to support the initial structure. However, certain prestress losses may occur after the first tensioning, which may be caused by factors such as concrete shrinkage, creep, and anchor slip. Therefore, after the bridge deck 3 is formed, the aramid FRP bars 3 are tensioned for the second time to compensate for this part of the prestress loss and ensure that the structure has sufficient prestress.

[0063] It should be noted that the operation of performing two tensionings needs to be carried out strictly in accordance with the design and construction specifications to ensure the correct force and sequence for each tensioning to avoid adverse effects on the structure.

[0064] S6. Construction of bridge deck paving and ancillary works: Install the second-phase guardrails, install bridge deck drainage facilities and lighting facilities, etc.

[0065] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A prestressed UHPC bridge, characterized in that: include: Main beam, bridge deck, aramid fiber mesh, FRP bars and aramid fiber concrete; The main beam comprises a bottom plate and two oppositely arranged webs, wherein the bottom plate is formed by pouring the aramid fiber concrete onto the aramid fiber mesh; The web support is connected between the bottom plate and the bridge deck, and a plurality of FRP ribs are arranged in the web along the length direction; The bridge deck is arranged on the main beam and is formed by pouring the aramid fiber concrete; The aramid fiber concrete comprises: aramid fiber and UHPC concrete.

2. The prestressed UHPC bridge according to claim 1, characterized in that: The fiber material of the FRP bar is any one of aramid fiber, glass fiber and carbon fiber.

3. The prestressed UHPC bridge according to claim 1, characterized in that: The main beam is a U-shaped main beam.

4. The prestressed UHPC bridge according to claim 3, characterized in that: The U-shaped main beam further includes: a column, wherein the column support is arranged between the bottom plate and the bridge deck.

5. The prestressed UHPC bridge according to claim 1, characterized in that: A plurality of hollow structures are arranged on the web.

6. The prestressed UHPC bridge according to claim 5, characterized in that: Also included: a removable protective tube; The FRP bar has an exposed portion exposed in the hollow structure, and the protection tube is sleeved on the exposed portion to protect the exposed portion.

7. A construction method for a prestressed UHPC bridge according to any one of claims 1 to 6, characterized in that: include: Prefabricating the main beam: laying the aramid fiber mesh and the FRP bars, tensioning the aramid fiber mesh and the FRP bars, and then pouring the aramid fiber concrete to form the main beam; Casting the bridge deck: building a bridge deck casting platform on the main beam, and using the aramid fiber concrete to cast the bridge deck; Secondary tensioning: the FRP tendons are tensioned again.

8. The construction method according to claim 7, characterized in that: The specific steps of laying out the aramid fiber mesh and the FRP ribs include: The aramid fiber mesh is arranged at the bottom of the main beam mold, and a plurality of prestressed pipes are respectively arranged at the two side walls of the main beam mold, and the FRP tendons pass through the prestressed pipes and are fixed.

9. The construction method according to claim 7, characterized in that: The specific steps of casting the bridge deck include: installing a bracket according to the size of the bridge deck, installing a number of templates on the bracket, forming the bridge deck casting platform and then casting the aramid fiber concrete, and after the strength of the aramid fiber concrete reaches a preset strength, removing the template and the bracket.

10. The construction method according to claim 7, characterized in that: Also included between the prefabricated main beam and the cast bridge deck: Main beam maintenance: After the aramid fiber concrete is poured, spray maintenance is carried out to ensure that the aramid fiber concrete reaches the designed strength; After the aramid fiber concrete reaches the designed strength, the main beam mold is removed and stored for a period of time before subsequent installation and construction; and / or, After the secondary tensioning, the following steps are also included: bridge deck paving and ancillary project construction.

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