Combined beam bridge deck and parameter design method thereof

Abstract

This invention discloses a composite beam bridge deck and its parameter design method, relating to the field of bridge engineering. On one hand, the parameter design method includes: determining the predetermined length of the prestressed steel bars based on the predetermined prestress loss caused by friction between the prestressed steel bars and the duct wall, and the tension control stress value under the prestressed steel bar anchor; determining the predetermined number of prestressed steel bars in each prestressed steel strand unit and the predetermined number of steel strand unit groups based on the predetermined tensile stress of the bridge deck and the effective prestress of the prestressed steel bars, combined with the transverse width of the bridge deck and the predetermined spacing between two adjacent prestressed steel bars in the transverse direction; and determining the predetermined distance between two adjacent prestressed steel bars based on the predetermined length and predetermined number of prestressed steel bars. On the other hand, the bridge deck is constructed using the above design method. By staggering the predetermined lengths of prestressed steel bars at predetermined spacing, the effective prestress can be increased, the amount of steel bars used can be reduced, and the ultimate span of the composite beam cable-stayed bridge can be increased.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, specifically to a method for designing the deck panels and parameters of a combined beam bridge. Background Technology

[0002] In the field of engineering construction, steel-concrete composite beams are lighter and more adaptable than concrete beams. Especially in bridge construction, compared to steel beams, they offer greater stiffness, better deck durability, lower operation and maintenance costs, and higher economic efficiency. Furthermore, concrete slabs can be cast on-site on already erected steel beams or prefabricated and then hoisted, making construction flexible and convenient. Therefore, composite beams are increasingly being used in engineering projects. Currently, the largest span of a composite beam completed in China is the 720m Chibi Yangtze River Bridge.

[0003] To counteract the tensile stress in the bridge deck caused by dead load, live load, and concrete shrinkage and creep, and to ensure that the entire concrete slab of the composite beam is under compression, prestressing tendons are generally tensioned within the concrete slab. Traditional steel-concrete composite beams typically employ long prestressing tendons arranged continuously on the concrete bridge deck in the tensile stress region of the mid-span. However, when the span of a cable-stayed composite beam exceeds a certain limit, the tensile stress value and area in the mid-span become quite large. Using traditional prestressing tendon arrangement methods, the effective prestress applied to the concrete bridge deck is very limited. This is mainly because a portion of the applied prestress is transferred to the steel beam through shear studs, and another portion is severely lost due to excessive friction loss caused by the excessive length of the tendons. To ensure the entire bridge deck is under compression, more prestress must be applied, but this results in even greater tensile stress caused by shrinkage and creep, creating a vicious cycle. Moreover, the width of the bridge deck is limited, as is the space for prestressing tendons. Summary of the Invention

[0004] In view of the deficiencies in the existing technology, the purpose of this invention is to provide a design method for the deck of a composite beam bridge and its parameters, so as to solve the problems of large prestress loss and large amount of prestressed steel strands in the deck of large-span composite beam bridges in the existing technology.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, this application provides a parametric design method for combined beam bridge decks, including the following steps:

[0007] The set length of the prestressed steel bar is determined based on the prestress loss caused by friction between the prestressed steel bar and the pipe wall, and the tension control stress value and effective prestress value under the prestressed steel bar anchor.

[0008] Based on the set tensile stress of the bridge deck and the effective prestress of the prestressed steel bars, and in combination with the width of the bridge deck in the transverse direction and the set spacing between two adjacent prestressed steel strands in the transverse direction, the set number of prestressed steel bars in each prestressed steel strand unit and the set number of steel strand unit groups in the transverse direction are determined.

[0009] Based on the set length and set number of prestressed steel bars, the set distance between two adjacent prestressed steel bars is determined.

[0010] In some alternative embodiments, determining the predetermined length of the prestressed steel bars includes:

[0011] According to σ l1 =σ con [1-e -(μθ+kx) Determine the set length x of the prestressed steel bars, where σ l1 σ is the prestress loss caused by friction between the prestressed steel bars and the pipe wall. con denoted as the tension control stress value under the prestressed steel bar anchor, μ is the friction coefficient between the prestressed steel bar and the pipe wall, θ is the sum of the angles from the tensioning end to the tangent of the pipe section of the calculated cross-section curve, and k is the influence coefficient of the local deviation per meter of the pipe on the membrane material.

[0012] In some optional embodiments, determining the predetermined number of prestressed steel bars in each of the aforementioned prestressed steel strand units and the predetermined number of groups of the aforementioned steel strand units includes:

[0013] Based on the set tensile stress of the bridge deck and the effective prestress of the prestressed steel bars, the initial set number of the prestressed steel strand unit group is determined according to the initial preset number of prestressed steel bars in the prestressed steel strand unit.

[0014] Based on the transverse width of the bridge deck and the set spacing between two adjacent prestressed steel strands in the transverse direction, the initial preset number of prestressed steel bars in the prestressed steel strand unit is checked and adjusted until the final preset number of bars and the set number of groups meet the design requirements.

[0015] In some optional embodiments, determining the initial set number of the above-mentioned steel strand unit groups includes, according to Determine the initial set number N of the above-mentioned steel strand unit groups, where σ t The set tensile stress for the bridge deck, σ pe The effective prestress of the aforementioned prestressed steel bars.

[0016] In some optional embodiments, the preset range of the initial preset number n of prestressed steel bars in the prestressed steel strand unit is 10≤n≤14.

[0017] In some optional embodiments, the initial preset number n of prestressed steel bars in the prestressed steel strand unit is checked, including, according to The preset number n of prestressed steel bars in the above prestressed steel strand unit is checked, where B is the width of the bridge deck in the transverse direction and s' is the preset spacing between two adjacent prestressed steel strands in the transverse direction.

[0018] In some alternative embodiments, the effective prestress σ of the prestressed steel bars is... pe According to σ pe =σ con -σ l1 Sure.

[0019] In some alternative embodiments, the effective prestress σ of the prestressed steel bars is... pe ≤1209Mpa.

[0020] In some alternative embodiments, determining the predetermined distance at which two adjacent prestressed steel bars are staggered includes, according to Determine the aforementioned distance S.

[0021] On the other hand, this application also provides a composite beam bridge deck, constructed using the above-mentioned parameter design method, wherein the composite beam bridge deck includes:

[0022] A predetermined number of longitudinal steel strand unit groups are arranged at intervals along the transverse direction of the bridge. Each group of the longitudinal steel strand unit groups includes multiple prestressed steel strand units arranged sequentially along the longitudinal direction of the bridge. Each prestressed steel strand unit includes multiple prestressed steel bars of predetermined length arranged at intervals along the transverse direction of the bridge. The ends of two adjacent prestressed steel bars in each prestressed steel strand unit are staggered by a predetermined distance along the longitudinal direction of the bridge. The ends of the corresponding prestressed steel bars in two adjacent prestressed steel strand units along the longitudinal direction are spaced apart by the predetermined distance along the longitudinal direction of the bridge.

[0023] Compared with the prior art, the advantages of the present invention are as follows: By arranging multiple prestressed steel strand units at intervals along the longitudinal and transverse directions of the bridge, each prestressed steel strand unit includes multiple prestressed steel bars of a set length arranged at intervals along the transverse direction of the bridge, thereby reducing the length of each prestressed steel bar, thereby reducing the friction between the prestressed steel bar and the pipe wall, reducing prestress loss, improving the prestress effect, and reducing the amount of prestressed steel strands used; and by staggering the ends of two adjacent prestressed steel bars in each group by a set distance, and arranging two adjacent prestressed steel strand units at intervals along the longitudinal direction of the bridge, the prestressed steel bars are arranged in an alternating manner and compensate for each other, extending continuously along the longitudinal direction of the bridge without attenuating the prestress effect, thereby increasing the ultimate span of the combined beam. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a flowchart of a parameter design method for a combined beam bridge deck according to the present invention;

[0026] Figure 2 This is a schematic diagram of a transverse cross-section of a combined beam bridge deck according to the present invention;

[0027] Figure 3 for Figure 2 Schematic diagram of the structure of the prestressed steel strand unit;

[0028] Figure 4 for Figure 3 A schematic diagram of the arrangement of prestressed steel strand units on the bridge deck;

[0029] Figure 5 for Figure 2 A top view of the middle bridge deck.

[0030] In the diagram: 1. Steel strand unit group; 10. Prestressed steel strand unit; 110. Prestressed steel reinforcement; 2. Bridge deck. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] As described in the background section, such as Figure 2 As shown, with the increase of bridge span, the prestressed steel strands will inevitably become longer and longer, and the prestress loss is closely related to the length of the prestressed steel strands.

[0034] For example, the effective prestress of the prestressed steel bars decreases as the tensioning and anchoring process and time progresses. Furthermore, the prestressed steel bars are embedded in the prestressed ducts of the bridge deck. As the length of the prestressed steel bars increases, the friction loss between the prestressed steel bars and the duct wall also gradually increases. As a result, the compressive stress generated by the effective prestress on the bridge deck is insufficient to offset the tensile stress of the bridge deck, causing the bridge deck to crack.

[0035] Therefore, it is necessary to rationally arrange and anchor the long prestressed tendons, and appropriately convert the long prestressed tendons into short tendons, so as to improve the permanent prestress in the ultra-long prestressed steel tendon beam, reduce prestress loss, and at the same time improve prestressing efficiency and reduce the amount of prestressed steel bars used.

[0036] On the one hand, this application provides a parametric design method for combined beam bridge decks, such as... Figure 1 As shown, it includes the following steps:

[0037] S1: Determine the set length of the prestressed steel bar 110 based on the set prestress loss caused by friction between the prestressed steel bar 110 and the pipe wall and the tension control stress value under the anchor of the prestressed steel bar 110.

[0038] Specifically, according to σ l1 =σ con [1-e -(μθ+kx) Determine the set length x of the prestressed steel bar 110, where σ l1 σ is the prestress loss caused by friction between the prestressed steel bar 110 and the pipe wall. con denoted as the tension control stress value under the prestressed steel bar anchor, μ is the friction coefficient between the prestressed steel bar 110 and the pipe wall, θ is the sum of the angles from the tensioning end to the tangent of the pipe section of the calculated cross-section curve, and k is the influence coefficient of the local deviation per meter of the pipe on the membrane material.

[0039] In some alternative embodiments, μ = 0.25 for the metal corrugated pipe embedded in the bridge deck 2. θ H For the vertical bend angle, θ V The angle of the bend can be obtained by those skilled in the art based on the construction design parameters.

[0040] In this example, the prestress loss is set to be controlled within 86 MPa.

[0041] S2: Based on the set tensile stress of the bridge deck 2 and the effective prestress of the prestressed steel bars 110, and in combination with the transverse width of the bridge deck 2 and the set spacing between two adjacent prestressed steel bars 110 in the transverse direction, determine the set number of prestressed steel bars 110 spaced apart in the transverse direction in each prestressed steel strand unit 10 and the set number of steel strand unit groups 1 spaced apart in the transverse direction.

[0042] Specifically, step S2 above includes:

[0043] S21: Based on the set tensile stress of the bridge deck 2 and the effective prestress of the prestressed steel bar 110, the initial set number of the steel strand unit group 1 is determined according to the initial preset number of prestressed steel bars 110 in the prestressed steel strand unit 10.

[0044] In some alternative embodiments, according to Determine the initial set number N of the prestressed steel strand unit group 1, where σ t The set tensile stress for bridge deck 2, σ pe The effective prestress of the aforementioned prestressed steel bar 110.

[0045] It is understandable that σ pe =σ con -σ l1 =σ con -σ con [1-e -(μθ+kx) ].

[0046] In this example, the initial preset number n of prestressed steel bars 110 in each prestressed steel strand unit 10 ranges from 10 ≤ n ≤ 14, and the effective prestress σ of the prestressed steel bars 110 is... pe ≤1209Mpa.

[0047] S22: Based on the width of the bridge deck 2 in the transverse direction and the set spacing between two adjacent prestressed steel bars 110 in the transverse direction, the initial preset number n of prestressed steel bars 110 in the prestressed steel strand unit 10 is checked and the initial preset number is adjusted until the final preset number and set number of groups meet the design requirements.

[0048] In some alternative embodiments, according to The preset number n of prestressed steel bars 110 in the prestressed steel strand unit 10 is checked, where B is the width of the bridge deck 2 in the transverse direction and s' is the preset spacing between two adjacent prestressed steel bars 110 in the transverse direction.

[0049] It should be noted that during the initial preset number n of prestressed steel bars 110 in the preset prestressed steel strand unit 10 and the verification process, the value of n·N should be made as close as possible to... That is, all reviews meet the following conditions. Take the largest value from the given values.

[0050] S3: Based on the set length of the prestressed steel bar 110 and the set number of the prestressed steel bars 110, determine the set distance at which two adjacent prestressed steel bars 110 are staggered in the transverse direction.

[0051] In some alternative embodiments, determining the predetermined distance at which two adjacent prestressed steel bars 110 are staggered includes, according to Determine the aforementioned distance S.

[0052] It should be noted that multiple steel strand unit groups 1 are arranged at intervals along the transverse direction of the bridge, and multiple prestressed steel strand units 10 in each steel strand unit group 1 are arranged at intervals along the longitudinal direction of the bridge, and multiple prestressed steel bars 110 in the prestressed steel strand unit 10 are arranged at intervals along the transverse direction of the bridge.

[0053] On the other hand, this application also provides a composite beam bridge deck, which is constructed using the above-mentioned parameter design method. Specifically, the composite beam bridge deck includes a predetermined number of longitudinal steel strand unit groups 1 arranged at intervals along the transverse direction of the bridge. Each of the longitudinal steel strand unit groups 1 includes a plurality of prestressed steel strand units 10 arranged sequentially along the longitudinal direction of the bridge. Each of the prestressed steel strand units 10 includes a plurality of prestressed steel bars 110 with predetermined lengths arranged at intervals along the transverse direction of the bridge. The ends of two adjacent prestressed steel bars 110 in each of the prestressed steel strand units 10 are staggered by a predetermined distance along the longitudinal direction of the bridge. The ends of the prestressed steel bars 110 corresponding to two adjacent prestressed steel strand units 10 in the longitudinal direction are spaced apart by the predetermined distance along the longitudinal direction of the bridge.

[0054] Understandable, such as Figure 3 and Figure 4 As shown, multiple prestressed steel bars 110 are arranged at predetermined distances in both the transverse and longitudinal directions of the bridge, and the interval between two adjacent prestressed steel bars 110 in the longitudinal direction is also a predetermined distance. This arrangement can shorten the length of the prestressed steel bars 110 and reduce the amount of prestressed steel bars 110 used, while compensating for the gaps between two adjacent prestressed steel bars with other prestressed steel bars. This ensures that the prestressing efficiency meets the design requirements while increasing the effective prestress of the bridge deck.

[0055] Taking a 900m span combined road and rail cable-stayed bridge as an example, the effective prestress of a conventional 360m long steel strand arrangement is only 357 MPa. The effective prestress of the combined beam bridge deck after the arrangement using this parameter design method is 982 MPa, which is 2.75 times that of the conventional prestressed steel strand arrangement.

[0056] However, it should be noted that the set length, set spacing, and number of prestressed steel bars 110 in this application need to be determined based on the prestress requirements of the bridge and the design requirements of the bridge deck, combined with the prestress loss of the prestressed steel strands, etc.

[0057] In some alternative embodiments, such as Figure 5As shown, multiple sets of the aforementioned prestressed steel strand units 10 are arranged in the tensile stress region of the bridge deck 2. The number of prestressed steel strand units 10 is specifically set according to the range of the tensile stress region of the bridge deck. Optionally, in the tensile stress region, the ends of all the aforementioned prestressed steel bars 110 at both ends of the longitudinal direction of the bridge are aligned.

[0058] It is understandable that prestressed steel bars 110 are laid throughout the tensile stress area of ​​the entire bridge deck 2, so that the overall prestress of the bridge deck meets the requirements and the prestress is evenly distributed.

[0059] This invention discloses a composite beam bridge deck and its parameter design method. By arranging multiple prestressed steel strand units at intervals along the longitudinal and transverse directions of the bridge, each prestressed steel strand unit includes multiple prestressed steel bars of a predetermined length arranged at intervals along the transverse direction. This reduces the length of each prestressed steel bar, thereby reducing friction between the prestressed steel bars and the duct wall, reducing prestress loss, and reducing the amount of prestressed steel strands used. Furthermore, by staggering the ends of adjacent prestressed steel bars in each group by a predetermined distance, and arranging adjacent prestressed steel strand units at predetermined intervals along the longitudinal direction of the bridge, the prestressed steel bars are staggered and mutually compensated, improving the effective prestress of the bridge deck. Using the parameter design method of the composite beam bridge deck of this application, the applicable span of the composite beam bridge can be greatly increased, meeting construction requirements.

[0060] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0061] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0062] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A parametric design method for a bridge deck combined with a beam, characterized in that, Includes the following steps: The set length of the prestressed steel bar (110) is determined based on the prestress loss caused by friction between the prestressed steel bar (110) and the pipe wall, and the tension control stress value and effective prestress value under the anchor of the prestressed steel bar (110). Based on the set tensile stress of the bridge deck (2) and the effective prestress of the prestressed steel bars (110), and combined with the width of the bridge deck (2) in the transverse direction and the set spacing between two adjacent prestressed steel bars (110) in the transverse direction, determine the set number of prestressed steel bars (110) in each prestressed steel strand unit (10) and the set number of steel strand unit groups (1) in the transverse direction. Based on the set length and the set number of prestressed steel bars (110), the set distance between two adjacent prestressed steel bars (110) is determined.

2. The parameter design method as described in claim 1, characterized in that, Determining the set length of the prestressed steel bar (110) includes: according to Determine the set length x of the prestressed steel bar (110), where, The prestress loss is defined as the prestress loss caused by friction between the prestressed steel bars (110) and the pipe wall. This refers to the tension control stress value under the prestressed steel reinforcement anchor. The coefficient of friction between the prestressed steel bar (110) and the pipe wall is given. The sum of the angles from the tensioning end to the tangent of the duct section of the calculated cross-section curve is given by , and k is the influence coefficient of local deviation per meter of duct on the membrane material.

3. The parameter design method as described in claim 2, characterized in that, Determining the set number of prestressed steel bars (110) in each prestressed steel strand unit (10) and the set number of steel strand unit groups (1), including: Based on the set tensile stress of the bridge deck (2) and the effective prestress of the prestressed steel bars (110), the initial set number of steel strand unit groups (1) spaced along the transverse direction is determined according to the initial preset number of prestressed steel bars (110) in the prestressed steel strand unit (10). Based on the width of the bridge deck (2) in the transverse direction and the set spacing of two adjacent prestressed steel bars (110) in the transverse direction, the initial preset number of prestressed steel bars (110) in the prestressed steel strand unit (10) is checked and the initial preset number of bars is adjusted until the final preset number of bars and the set number of groups meet the design requirements.

4. The parameter design method as described in claim 3, characterized in that, Determining the initial set number of the steel strand unit group (1) includes, according to Determine the initial set number N of the steel strand unit group (1), where, To set the tensile stress for the bridge deck (2), The effective prestress of the prestressed steel bar (110) is given.

5. The parameter design method as described in claim 3, characterized in that, The preset range of the initial preset number n of prestressed steel bars (110) in the prestressed steel strand unit (10) is as follows: .

6. The parameter design method as described in claim 3, characterized in that, The initial preset number n of prestressed steel bars (110) in the prestressed steel strand unit (10) is reviewed, including, according to The preset number n of prestressed steel bars (110) in the prestressed steel strand unit (10) is checked, where B is the width of the bridge deck in the transverse direction. The set spacing between two adjacent prestressed steel bars (110) in the transverse direction of the bridge.

7. The parameter design method as described in claim 4, characterized in that, The effective prestress of the prestressed steel bar (110) according to Sure.

8. The parameter design method as described in claim 4, characterized in that, The effective prestress of the prestressed steel bar (110) .

9. The parameter design method as described in claim 4, characterized in that, Determining the set distance between two adjacent prestressed steel bars (110) includes, according to Determine the set distance S.

10. A composite beam bridge deck, characterized in that, The composite beam bridge deck, constructed using the parametric design method as described in any one of claims 1-9, comprises: A predetermined number of longitudinal steel strand unit groups (1) are arranged at intervals along the transverse direction of the bridge. Each longitudinal steel strand unit group (1) includes a plurality of prestressed steel strand units (10) arranged sequentially along the longitudinal direction of the bridge. Each prestressed steel strand unit (10) includes a plurality of prestressed steel bars (110) with predetermined lengths arranged at intervals along the transverse direction of the bridge. The ends of two adjacent prestressed steel bars (110) in each prestressed steel strand unit (10) are staggered by a predetermined distance along the longitudinal direction of the bridge. The ends of the prestressed steel bars (110) corresponding to two adjacent prestressed steel strand units (10) in the longitudinal direction are spaced apart by the predetermined distance along the longitudinal direction of the bridge.

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