Arrangement structure and design method of bridge slab connectors for a railway continuous steel-concrete composite beam

Abstract

An arrangement structure and design method of bridge slab connectors for a railway continuous steel-concrete composite beam provided by the present invention. The arrangement scheme includes: arranging first studs in the beam end area, arranging second studs in the mid-span area, arranging anti-pulling and non-shearing connectors in the negative moment area, and arranging flexible studs in the transition area between the mid-span area and the negative moment area. The flexible studs include third studs and flexible sleeves sleeved on the outer sides of their lower parts. The shear stiffness of the first studs is the same as that of the second studs, and the longitudinal spacing l 1 between two adjacent rows of first studs is less than the longitudinal spacing l 2 between two adjacent rows of second studs. The shear stiffness of the flexible studs is less than that of the second studs, and the shear stiffness of the flexible studs is adjusted by adjusting the height and / or thickness of the flexible sleeves. It can effectively reduce the shear force borne by the studs per unit area, reduce the possibility of fatigue failure or even shearing of the connectors, greatly reduce the number of studs per unit area, improve the economy and make the arrangement more convenient.

Description

Technical Field

[0001] The invention belongs to the technical field of steel-concrete composite beam bridges, and relates to an arrangement structure and design method of bridge deck connectors for a railway continuous steel-concrete composite beam bridge. Background Art

[0002] A steel-concrete composite beam bridge is composed of two materials, steel and concrete, which jointly bear the load, giving full play to the respective advantages of steel and concrete. After the two materials are combined, the overall working performance of the structure is significantly better than the simple superposition of the performances of the two materials, and it has high economic and technical advantages.

[0003] The steel of the steel-concrete composite beam bridge and the concrete bridge deck are usually connected by conventional stud connectors. The conventional stud connectors mainly play the following two major roles in the composite beam bridge: 1) Shear resistance: bear the longitudinal shear force at the interface between the steel beam and the concrete slab, limit the longitudinal free sliding at the interface between the two, so as to ensure the coordinated deformation and common work of the steel beam and the concrete slab, and improve the section stiffness and bearing capacity; 2) Uplift resistance: resist the vertical separation and lifting of the concrete slab caused by the overall longitudinal bending and local transverse bending.

[0004] Due to the large secondary dead load and live load of the railway continuous steel-concrete composite beam, anti-uplift but non-shear connectors are often used in the negative bending moment area of the continuous composite beam, so that the concrete bridge deck and the steel beam deck can "freely" slide. Outside a certain range of the negative bending moment area at the support, conventional stud connectors are set, and a transition zone needs to be set between the conventional stud connectors and the anti-uplift but non-shear connectors.

[0005] In the prior art, a relatively large number of conventional studs are usually arranged in the transition zone. However, because the number of studs required in the transition zone is very large, there are certain requirements for the cross-sectional form of the composite beam and the structural configuration of the transition zone. For example, for an I-shaped cross-section steel-concrete composite beam, it often brings problems that it is difficult to arrange the studs, which restricts the application of anti-uplift but non-shear connectors in the railway I-shaped cross-section steel-concrete continuous composite beam; moreover, the conventional stud connectors are used in the transition zone, and the shear stiffness is relatively large, while the anti-uplift but non-shear connectors are used in the negative bending moment area, and the shear stiffness is close to zero. There is a sudden change in stiffness at the junction of the two regions, which is relatively unfavorable for the structural stress and is prone to stress concentration; in addition, in the prior art, each row of connectors in the transition zone is regarded as evenly stressed, but the stress of the railway structure is different from that of buildings, highways, etc. The secondary dead load and live load of the railway bridge are large, and the action frequency is high. After the anti-uplift but non-shear connectors are used in the negative bending moment area of the steel-concrete composite beam, the stress of the first few rows of studs in the transition zone needs to be focused on. Once the first few rows of studs are damaged, a chain reaction may also occur. Summary of the Invention

[0006] The object of the present invention is to overcome the above deficiencies in the prior art that the layout of the connectors in the transition zone of the railway continuous steel-concrete composite beam is not reasonable enough, which easily leads to unreasonable force and limited layout, and to provide a layout structure and design method for the connectors of the bridge slab of the railway continuous steel-concrete composite beam.

[0007] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0008] A layout structure of the connectors of the bridge slab of the railway continuous steel-concrete composite beam, in which the first stud bolts are arranged in the beam end area, the second stud bolts are arranged in the mid-span area, the anti-pull and non-shear connectors are arranged in the negative moment area, and the flexible studs are arranged in the transition zone between the mid-span area and the negative moment area. The flexible stud includes a third stud bolt and a flexible sleeve sleeved on the outer side of its lower part. The shear stiffness of the first stud bolt is the same as that of the second stud bolt, and the longitudinal spacing between two adjacent rows of the first stud bolts l 1 is less than the longitudinal spacing between two adjacent rows of the second stud bolts l 2. The shear stiffness of the flexible stud is less than that of the second stud bolt, and the shear stiffness of the flexible stud is adjusted by adjusting the height and / or thickness of the flexible sleeve.

[0009] Adopting the layout structure of the connectors of the bridge slab of the railway continuous steel-concrete composite beam described in the present invention, a transition zone is provided between the mid-span area and the negative moment area, and the flexible studs are used in the transition zone. The stiffness can be adjusted by changing the height and thickness of the flexible sleeve, which is convenient to adjust, has low cost, avoids the sudden change of stiffness at the junction of the negative moment area and the mid-span area, and prevents stress concentration. Due to the arrangement of the flexible sleeve, its shear bearing capacity remains unchanged, but the shear stiffness is small, which can allow a certain degree of slip between the concrete member and the steel member, effectively reducing the shear force borne by the stud bolt connector per unit area, reducing the possibility of fatigue failure or even direct shear-off of the connector, greatly reducing the number of stud bolt connectors per unit area, improving the economy and making the layout more convenient, providing strong support for the application of the anti-pull and non-shear connectors in the negative moment area of the continuous composite beam bridge in the railway field to optimize the stress of the bridge deck.

[0010] Preferably, the longitudinal spacing between two adjacent rows of the flexible studs l 3 satisfies l 1< l 3≤ l 2.

[0011] Preferably, the shear stiffness of the flexible stud gradually increases from the side close to the negative moment area to the side close to the mid-span area.

[0012] Adopting the layout structure described in the present invention can effectively adapt to the characteristic of uneven force on the connecting members in the transition zone. For the first few rows of areas with larger forces, connecting members with smaller stiffness are used, and for the remaining areas with smaller forces, connecting members with larger stiffness are used. This can make the forces on the connecting members in the transition zone more uniform, improve the utilization rate of stud bolts. At the same time, the stiffness change of the entire beam from the negative moment zone to the positive moment zone is more uniform, and the weakening of the structural stiffness is minimized.

[0013] Further preferably, the flexible studs include three to five shear stiffnesses, and the layout range of each shear stiffness is the same, and there is a linear change between each shear stiffness.

[0014] Adopting the above setting method is convenient for design calculation.

[0015] Preferably, the flexible sleeve is a rubber component or a sponge component

[0016] A design method for the layout structure of the bridge deck connecting members of a railway continuous steel-concrete composite beam bridge adopts the layout structure of the bridge deck connecting members of the railway continuous steel-concrete composite beam bridge as described in any of the above, and includes the following steps:

[0017] a. According to the structural layout requirements, determine the structural dimensions, including the beam height of the steel beam, the web spacing, the plate thickness, and the thickness of the concrete bridge deck. Then, arrange the conventional stud bolt scheme according to the specifications.

[0018] b. Conduct finite element analysis to obtain the internal force of the composite beam structure under the dead load condition, and then determine the range of the negative moment zone. Change the negative moment zone to arrange anti-pulling and non-shear connecting members, and the layout spacing of the anti-pulling and non-shear connecting members is determined according to the requirements of the standard structural spacing and the requirements of the stud bolt anti-pulling strength and fatigue check.

[0019] c. Determine the range of the transition zone, the number of shear stiffnesses in the transition zone, the value of each shear stiffness, the layout range of each shear stiffness, and the layout spacing between adjacent two rows of flexible studs. Change the transition zone to arrange flexible studs. Among them, the shear stiffness of the row of flexible studs closest to the negative moment zone is the smallest.

[0020] d. Conduct a force check on the row of flexible studs closest to the negative moment zone. When the force requirements specified in the specifications are met, further determine the shear stiffness of the remaining rows of flexible studs in the transition zone.

[0021] e. Check the shear bearing capacity of the stud bolts, the stiffness of the beam structure, the strength of the steel beam, and the strength of the concrete bridge deck. If the requirements are met, complete the layout of the connecting members of the railway continuous steel-concrete composite beam bridge.

[0022] By adopting this method, flexible studs are arranged in the transition zone, which is conducive to quickly selecting a reasonable layout range and the stiffness value of the flexible studs, can effectively reduce the force and non-uniformity of the connectors in the transition zone, greatly optimize the arrangement quantity and method of the connectors, and provide good technical support for the application of the scheme of using anti-pulling and non-shear connectors in the negative moment area of continuous composite beam bridges to optimize the stress of the bridge deck in the railway field.

[0023] Preferably, if the force requirements specified in the code are not met for the row of flexible studs closest to the negative moment area, adjust the range of the transition zone and the shear stiffness values of each row of flexible studs, and then repeat d - e.

[0024] Preferably, if the checks of the shear bearing capacity of studs, the stiffness of the beam structure, the strength of the steel beam, and the strength of the concrete bridge deck do not meet the requirements, adjust the proposed structural dimensions, and then arrange the conventional stud scheme according to the code and repeat steps b - e.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. By adopting the layout structure of the bridge deck connectors of a railway continuous steel-concrete composite beam of the present invention, a transition zone is set between the mid-span area and the negative moment area, and flexible studs are used in the transition zone. The stiffness can be adjusted by changing the height and thickness of the flexible sleeve, which is convenient to adjust, has low cost, avoids sudden stiffness change at the junction between the negative moment area and the mid-span area, and prevents stress concentration. Due to the setting of the flexible sleeve, its shear bearing capacity remains unchanged, but the shear stiffness is small, which can allow a certain degree of slip between the concrete member and the steel member, effectively reducing the shear force borne by the stud connectors per unit area, reducing the possibility of fatigue failure or even direct shear of the connectors, greatly reducing the number of stud connectors per unit area, improving economy and making the layout more convenient, providing strong support for the application of using anti-pulling and non-shear connectors in the negative moment area of continuous composite beam bridges in the railway field to optimize the stress of the bridge deck.

[0027] 2. By adopting the design method of the layout structure of the bridge deck connectors of a railway continuous steel-concrete composite beam of the present invention, flexible studs are arranged in the transition zone, which is conducive to quickly selecting a reasonable layout range and the stiffness value of the flexible studs, can effectively reduce the force and non-uniformity of the connectors in the transition zone, greatly optimize the arrangement quantity and method of the connectors, and provide good technical support for the application of the scheme of using anti-pulling and non-shear connectors in the negative moment area of continuous composite beam bridges to optimize the stress of the bridge deck in the railway field. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the layout schematic diagram of the layout structure of the bridge deck connectors of a railway continuous steel-concrete composite beam of the present invention;

[0029] Figure 2It is a schematic structural diagram of the flexible nail described in the present invention;

[0030] Figure 3 It is the dead load bending moment diagram of the continuous steel-concrete composite beam of the railway in Embodiment 1;

[0031] Figure 4 It is the zoning diagram of the variable stiffness arrangement of the flexible nails;

[0032] Figure 5 It is the shear force diagram of the flexible nails under the main force condition in Embodiment 1.

[0033] Reference numerals: 1 - beam end area, 2 - mid-span area, 3 - negative bending moment area, 4 - transition area, 5 - flexible sleeve, 03 - third stud. Detailed implementation manners

[0034] The present invention will be further described in detail below in conjunction with the embodiments and specific implementation manners. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments. Any technology implemented based on the content of the present invention belongs to the scope of the present invention.

[0035] Embodiment 1

[0036] An arrangement structure of a connector for a continuous steel-concrete composite beam bridge of a railway, as Figure 1 shown, the first studs are arranged in the beam end area 1, the second studs are arranged in the mid-span area 2, the anti-pulling and non-shear connectors are arranged in the negative bending moment area 3, and flexible nails are arranged in the transition area 4 between the mid-span area 2 and the negative bending moment area 3. The flexible nails include the third studs 03 and the flexible sleeves 5 sleeved on the outer sides of their lower parts. As Figure 2 shown, the flexible sleeve 5 is a rubber member or a sponge member. The shear stiffness of the first studs is the same as that of the second studs, and the longitudinal spacing l 1 between two adjacent rows of the first studs is less than the longitudinal spacing l 2 between two adjacent rows of the second studs. The shear stiffness of the flexible nails is less than that of the second studs, and the shear stiffness of the flexible nails is adjusted by adjusting the height and / or thickness of the flexible sleeve 5.

[0037] Preferably, the longitudinal spacing l 3 between two adjacent rows of the flexible nails satisfies l 1 < l 3 ≤ l2. Increase the stud layout spacing in the transition zone 2, which is beneficial to reducing the requirements for the structure. The shear stiffness of the flexible studs gradually increases from the side close to the negative moment zone 3 to the side close to the mid-span zone 2, effectively adapting to the characteristic of uneven force on the connectors in the transition zone. For the area with larger force, connectors with smaller stiffness are used, and for the area with smaller force, connectors with larger stiffness are used, which can make the force on the connectors in the transition zone more uniform and improve the utilization rate of studs. At the same time, the stiffness change of the whole beam from the negative moment zone to the positive moment zone is more uniform. For the convenience of design calculation, the flexible studs do not need to be set with variable stiffness in each row. For example, if there are three to five kinds of shear stiffness, each kind of shear stiffness includes several rows of flexible studs, the layout range of each kind of shear stiffness is the same, and there is a linear change between each kind of shear stiffness. The layout spacing of the flexible studs in the whole transition zone 2 is the same.

[0038] Adopt the design method of the layout structure of the connectors of the above-mentioned railway continuous steel-concrete composite beam bridge, including the following steps:

[0039] a. According to the structural layout requirements, draw up the structural dimensions, which include the beam height of the steel beam, the web spacing, the plate thickness and the plate thickness of the concrete bridge deck, and then carry out the conventional stud layout according to the specifications.

[0040] b. Conduct finite element analysis to obtain the internal force of the composite beam structure under the dead load condition, and then determine the range of the negative moment zone 3. Change the negative moment zone 3 to arrange anti-pulling and non-shear connectors, and the layout spacing of the anti-pulling and non-shear connectors is determined according to the requirements of the specification construction spacing and the requirements of the stud anti-pulling strength and fatigue check.

[0041] c. Draw up the range of the transition zone 4, the number of shear stiffnesses in the transition zone 4, the value of each shear stiffness, the layout range of each shear stiffness and the layout spacing between adjacent two rows of flexible studs, and change the transition zone 4 to arrange flexible studs. Among them, the shear stiffness of the row of flexible studs closest to the negative moment zone 3 is the smallest.

[0042] d. Conduct a force check on the row of flexible studs closest to the negative moment zone 3. When the force requirements specified in the specifications are met, then determine the shear stiffness of the remaining rows of flexible studs in the transition zone 4.

[0043] e. Check the shear bearing capacity of the studs, the stiffness of the beam structure, the strength of the steel beam and the strength of the concrete bridge deck. If the requirements are met, complete the layout of the connectors of the railway continuous steel-concrete composite beam bridge.

[0044] According to the structural layout, such as the span and width of the beam, analyze and determine the structural dimensions. Taking a 4×40m continuous composite beam as an example, according to the analysis, the height of the steel beam is determined to be 2.7m, the thickness of the concrete slab is 0.3m, the web spacing is 2.4m + 2.6m + 2.4m, the web thickness is 16mm, the thicknesses of the upper and lower flanges at the mid-span are both 24mm, and the thicknesses of the upper and lower flanges at the supports are 28mm and 32mm respectively. Then, the ordinary studding scheme is adopted for the layout of the entire beam. The ordinary studding scheme means arranging according to the range of the negative moment zone 3 given by the specification and the minimum studding spacing between the negative moment zone 3 and other zones.

[0045] Then, perform finite element analysis, read the internal forces of the composite beam structure under the dead load condition, as Figure 3 shown. The length of the negative moment zone 3 is obtained as 6m. The negative moment zone 3 is changed to be arranged with tensile-resistant and shear-non-resistant connectors. According to the specification, the layout spacing of the tensile-resistant and shear-non-resistant connectors should not be greater than 400mm. Considering the requirements of the studding tensile strength and fatigue check, the longitudinal and transverse spacings of the tensile-resistant and shear-non-resistant connectors are both taken as 300mm.

[0046] According to the position of the negative moment zone 3, determine the range of the transition zone 4, the number of shear stiffness values in the transition zone 4, each shear stiffness value, the layout range of each shear stiffness, and the layout spacing between adjacent rows of flexible studs. The transition zone 4 is changed to be arranged with flexible studs. For example, the range of the transition zone 4 can start from 0.05L, where L is the span of the beam. The number of shear stiffness values can be taken as 3 - 5 kinds, that is, how many rows of flexible studs are there before changing the stiffness, or each row of shear stiffness can also be different. The shear stiffness of the row of flexible studs closest to the negative moment zone 3 is the smallest, and the rest of the rows can be determined corresponding to the shear stiffness of the first row. The change of the shear stiffness can be determined linearly or non-linearly. In this embodiment, the length of the transition zone 4 is 2m, and four shear stiffness values are set. Then, the layout range of each shear stiffness is 0.5m, and the shear stiffness increases from the side of the negative moment zone 3 to the side of the mid-span zone 2. According to the specification and relevant test data, the shear stiffness of the conventional studding connectors, that is, the first stud and the second stud, is taken as 350kN / mm, and the tensile stiffness is 530kN / mm; the shear stiffness of the tensile-resistant and shear-non-resistant connectors is taken as 0.1kN / mm (equivalent to zero stiffness), and the tensile stiffness is 530kN / mm; the initial shear stiffness values of the flexible studs from the negative moment zone 3 to the mid-span zone 2 are K1, 2K1, 3K1, and 4K1 in sequence, as Figure 4 shown. K1 = 0.25K = 87.5kN / mm, that is, 87.5kN / mm, 175kN / mm, 262.5kN / mm, and 350kN / mm are taken respectively, and the tensile stiffness is taken as 530kN / mm. The layout structures of the beam end zone 1 and the mid-span zone 2 remain unchanged.

[0047] Then, a force check calculation is carried out on the row of flexible studs closest to the negative moment area 3. When the force requirements specified in the code are met, the shear stiffness of the remaining rows of flexible studs in the transition area 4 is determined. In this embodiment, for example, the slip values of the first row of stud bolts under the main load condition are 0.571 mm respectively, and the corresponding shear force is 49.9 kN, which does not meet the code requirements. Then, it can be divided into sections every 0.5 m, and the range of the transition area 4 is gradually increased. Divided into sections according to 0.5K = 17.5 kN / mm, the shear stiffness of the flexible studs is gradually reduced. After trial calculation, when the length range of the transition area 4 is increased to 2.5 m, and the stiffness of the flexible studs from the first row is successively 70 kN / mm, 140 kN / mm, 210 kN / mm, and 280 kN / mm, the force on the stud bolts in the transition area 4 under the main load condition is as Figure 5 shown. Among them, the shear force of the first row of stud bolts is 41.1 kN, which meets the code requirements.

[0048] Then, the shear bearing capacity of the stud bolts, the stiffness of the beam structure, the strength of the steel beam, and the strength of the concrete bridge deck are checked and calculated, as shown in Tables 1 - 4 below:

[0049] Table 1 Check calculation of shear bearing capacity of stud bolts

[0050]

[0051] Table 2 Check calculation of beam stiffness

[0052]

[0053] Table 3 Check calculation of steel beam strength

[0054]

[0055] Table 4 Check calculation of concrete bridge deck strength

[0056]

[0057] According to the above analysis results, all meet the requirements, and the layout of the connectors of the railway continuous steel-concrete composite beam bridge is completed.

[0058] If any of the above does not meet the requirements, then adjust at least one of the structural dimensions to be determined, such as the height of the steel beam, the web spacing, the plate thickness, and the thickness of the concrete bridge deck, and then carry out the layout of the conventional stud bolt scheme according to the code and repeat steps b - e.

[0059] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An arrangement structure of bridge slab connectors for a railway continuous steel-concrete composite beam bridge, characterized in that Arrange the first stud in the beam end area (1), arrange the second stud in the mid-span area (2), arrange the anti-pulling and non-shearing connectors in the negative moment area (3), and arrange flexible studs in the transition area (4) between the mid-span area (2) and the negative moment area (3). The flexible stud includes a third stud (03) and a flexible sleeve (5) sleeved on the outer side of its lower part. The shear stiffness of the first stud is the same as that of the second stud. The longitudinal spacing between two adjacent rows of the first studs l 1 is less than the longitudinal spacing between two adjacent rows of the second studs l 2, and the longitudinal spacing between two adjacent rows of flexible studs l 3 satisfies l 1 < l 3 ≤ l 2. The shear stiffness of the flexible stud is less than that of the second stud. The shear stiffness of the flexible stud is adjusted by adjusting the height and / or thickness of the flexible sleeve (5). The shear stiffness of the flexible stud gradually increases from the side close to the negative moment area (3) to the side close to the mid-span area (2). The flexible stud includes three to five shear stiffnesses, and the arrangement ranges of each shear stiffness are the same, and a linear change occurs between each shear stiffness.

2. The layout structure of the bridge deck connector of the railway continuous steel-concrete composite beam as described in claim 1, wherein, The flexible sleeve (5) is a rubber component or a sponge component.

3. A design method for the layout structure of the bridge deck connector of a railway continuous steel-concrete composite beam, characterized in that Adopting the layout structure of the bridge slab connector of the railway continuous steel-concrete composite beam as described in any one of claims 1-2, it includes the following steps: a. According to the structural layout requirements, determine the structural dimensions, including the height of the steel beam, the web spacing, the plate thickness, and the thickness of the concrete bridge deck. Then, conduct the conventional stud structure layout according to the specifications. b. Conduct finite element analysis to obtain the internal force of the composite beam structure under the dead load condition, and then determine the range of the negative moment zone (3). Change the negative moment zone (3) to arrange the tensile-resistant but shear-non-resistant connectors, and the layout spacing of the tensile-resistant but shear-non-resistant connectors is determined according to the requirements of the specification construction spacing and the requirements of the stud tensile strength and fatigue check. c. Determine the range of the transition zone (4), the quantity of the shear stiffness of the transition zone (4), each shear stiffness value, the layout range of each shear stiffness, and the layout spacing of adjacent two rows of flexible studs. Change the transition zone (4) to arrange flexible studs. Among them, the shear stiffness of the row of flexible studs closest to the negative moment zone (3) is the smallest. d. Conduct a force check on the row of flexible studs closest to the negative moment zone (3). When the force requirements specified in the specifications are met, then determine the shear stiffness of the remaining rows of flexible studs in the transition zone (4). e. Check the shear bearing capacity of the studs, the stiffness of the beam structure, the strength of the steel beam, and the strength of the concrete bridge deck. If the requirements are met, complete the layout of the connectors of the railway continuous steel-concrete composite beam bridge.

4. The design method of the layout structure of the bridge slab connectors of the railway continuous steel-concrete composite beam, as described in claim 3, is characterized in that, If the row of flexible studs closest to the negative moment zone (3) does not meet the force requirements specified in the specifications, then adjust the range of the transition zone (4) and the shear stiffness values of each row of flexible studs, and then repeat steps d-e.

5. The design method of the layout structure of the bridge deck connectors of the railway continuous steel-concrete composite beam, characterized in that, If the checks of the shear bearing capacity of the studs, the stiffness of the beam structure, the strength of the steel beam, and the strength of the concrete bridge deck do not meet the requirements, then adjust the determined structural dimensions, and then conduct the conventional stud structure layout according to the specifications and repeat steps b-e.

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