Local variable stiffness enhanced welding stud shear connector and steel-concrete combined track beam

Abstract

The utility model discloses a local variable stiffness enhanced welding stud shear connector and a steel-concrete combined track beam. The connector comprises a thickened bottom rod, a slender middle rod and a cylindrical head which are connected in sequence, the diameter of the thickened bottom rod is greater than that of the slender middle rod; the cylindrical head is larger in diameter than the elongated middle rod. The steel-concrete combined track beam comprises a UHPC cast-in-place bridge deck slab, a local variable stiffness enhanced welding stud shear connector and a track steel beam, and the local variable stiffness enhanced welding stud shear connecting piece is welded on the top surface of the track steel beam and is used for connecting the track steel beam with the UHPC cast-in-place bridge deck at the upper part. The connecting piece has the advantages of being suitable for the steel-concrete combined track beam and aiming at solving the problems that a traditional shearing force connecting piece is insufficient in shearing bearing capacity under the complex dynamic load environment, a concrete panel is prone to cracking and the like, and therefore the overall bearing capacity, durability and anti-cracking performance of the track beam are improved, and the quality and efficiency of the cast-in-place construction technology are optimized.

Description

TECHNICAL FIELD

[0001] The utility model belongs to rail transit bridge structure and steel - concrete composite structure technical field, mainly relates to a partial variable stiffness enhanced type welding bolt shear connector and steel concrete combined track beam. BACKGROUND

[0002] With the aggravation of traffic congestion in small and medium-sized cities in China, medium-capacity urban rail transit gradually becomes the preferred solution in second, third and fourth-tier cities. The medium-capacity rail system represented by the straddle-type monorail traffic has been widely used in countries along the "Belt and Road" due to its low construction cost, short construction period and strong environmental adaptability. However, the structure and connection technology of the existing track beam still have deficiencies in durability and construction efficiency, and need to be innovated and improved.

[0003] Currently, the track beam in the straddle-type monorail traffic system mainly adopts three forms of precast concrete beam, steel track beam or steel-concrete composite beam. Due to the influence of shrinkage and creep, the precast concrete beam has a large difficulty in linear control, and often needs to be ground and adjusted; although the steel track beam has good linear control performance, its running surface has poor weather resistance, and has large vibration and noise, and high maintenance cost. In comparison, the steel-concrete composite beam combines the linear control advantage of steel structure with the damping vibration reduction characteristics of concrete panel, which not only effectively reduces the beam weight and construction difficulty, but also improves the running stability of the rail system. Therefore, the steel-concrete composite track beam has high application prospect in medium and low-capacity rail transit projects.

[0004] However, in the actual application of the existing welding bolt shear connection technology in the steel-concrete composite beam, problems such as local cracking of concrete, deformation or loosening of welding bolt often occur, which makes it difficult to fully exert the cooperative stress performance between the bridge deck and the steel beam, and limits the advantage of UHPC in the track beam. In view of these problems, the utility model provides a local variable stiffness enhanced type welding bolt shear connector. Through the local thickening design of the bottom of the welding bolt, the connector can significantly improve the shear stiffness and uplift resistance, reduce the stress concentration effect of the welding area, and improve the shear deformation compatibility between the UHPC cast-in-place bridge deck and the track steel beam.

[0005] The innovative design of the local variable stiffness enhanced type welding bolt shear connector can be used with the UHPC cast-in-place bridge deck to improve the shear bearing capacity and connection reliability of the track beam, effectively reduce the risk of concrete cracking and welding bolt deformation. At the same time, the technical scheme also has the characteristics of simple construction, strong durability and low maintenance cost, which provides a new technical path for the long-life design of the track beam, and has wide engineering application value. UTILITY MODEL CONTENTS

[0006] The utility model discloses a main purpose is to provide a kind of partial variable stiffness enhanced shear bolt shear connector and steel concrete composite track beam, applicable to steel-concrete composite track beam, to solve the problem of traditional shear connector in complex dynamic load environment, such as insufficient shear capacity, concrete panel is easy to crack, to improve the overall bearing capacity of track beam, durability and anti-cracking performance, and optimize the quality and efficiency of cast-in-place construction process.

[0007] The utility model discloses a kind of partial variable stiffness enhanced shear bolt shear connector,

[0008] Including thickening bottom pole, slender middle pole and cylindrical head connected in sequence;The diameter of thickening bottom pole is greater than the diameter of slender middle pole;Cylindrical head diameter is greater than slender middle pole.

[0009] Further, the height and diameter ratio of thickening bottom pole is optimized design, thickening bottom pole diameter is 1.5 to 2 times of slender middle pole diameter, and thickening bottom pole height is 1 / 6 to 1 / 3 of total height of weld bolt. To significantly improve the shear stiffness and pullout resistance of weld bolt.

[0010] The utility model also has another technical scheme: a steel-concrete composite track beam with partial variable stiffness enhanced shear bolt shear connector, characterized by: comprising UHPC cast-in-place bridge deck, partial variable stiffness enhanced shear bolt shear connector and track steel beam;Partial variable stiffness enhanced shear bolt shear connector is welded on the top surface of track steel beam, connecting track steel beam and upper UHPC cast-in-place bridge deck.

[0011] Further, thickening bottom pole is located at the bottom of weld bolt, and is fixedly connected with the top surface of track steel beam by welding mode;Improve the shear stiffness and pullout resistance of shear connection, while reducing stress concentration effect of welding site;

[0012] Slender middle pole is located in flexible transition area of weld bolt;Its length and diameter are optimized design according to shear demand possibly generated in track beam use process, can effectively alleviate the problem of shear deformation incoordination between UHPC cast-in-place bridge deck and track steel beam, prevent cracking or fatigue failure caused by local stress concentration;

[0013] Cylindrical head is provided at the top end of weld bolt, and the surface is smooth cylindrical, and is wrapped by UHPC material in UHPC cast-in-place bridge deck pouring process. Provide mechanical bite force and anti-slippage performance, further improve the carrying capacity of shear connector.

[0014] Further, UHPC cast-in-place bridge deck adopts ultra-high performance concrete material, and the compressive strength is not less than 120 MPa.

[0015] Track steel beam adopts single-box single-chamber section structure, as the main load-bearing component of track bridge;

[0016] The UHPC cast-in-place bridge deck is integrally poured above the track steel beam, and the UHPC cast-in-place bridge deck and the track steel beam are integrally connected through the locally variable rigidity enhanced welded stud shear connector to form an integrated connection structure. The high-efficiency shear resistance and uplift resistance are provided, and the fatigue durability of the whole structure is improved; before the UHPC cast-in-place bridge deck is poured, a steel mesh is arranged around the welded stud group to optimize the stress performance of the bridge deck, improve the overall bonding effect and crack resistance of the UHPC cast-in-place bridge deck and the welded stud, thereby effectively improving the shear bearing capacity and durability of the structure, and ensuring that the UHPC cast-in-place bridge deck has high strength, crack resistance and long service life performance when bearing heavy load railway vehicle load.

[0017] Further, the flat link cross beam is arranged between the double-line track steel beams and welded to the side surface of the track steel beam to enhance the lateral rigidity of the track beam and improve the anti-tilting ability of the whole bridge structure.

[0018] Further, the number and arrangement spacing of the flat link cross beam are optimized according to the bridge span and lateral rigidity requirement, and the flat link cross beam is fixed to the track steel beam through welding or bolt connection to improve the lateral stability and torsion resistance of the whole bridge.

[0019] Further, the locally variable rigidity enhanced welded stud shear connector is installed through arc stud welding or automatic welding equipment to ensure the connection strength and construction precision of the welded part and reduce the stress concentration phenomenon in the construction process.

[0020] Compared with the traditional shear connection scheme, the locally variable rigidity enhanced welded stud shear connector of the utility model in combination with the cast-in-place UHPC bridge deck construction process has the following advantages:

[0021] 1. The shear capacity is significantly improved: the welded stud structure with locally variable rigidity design can effectively enhance the shear bearing capacity and uplift resistance of the shear connector, thereby improving the overall bearing capacity of the track beam and meeting the use requirements in the complex dynamic load environment.

[0022] 2. Improve the overall structure and durability: the cast-in-place UHPC bridge deck is used to seamlessly combine the welded stud shear connector and the concrete, significantly improve the overall structural rigidity of the track beam, reduce the stress concentration phenomenon at the joint, delay the cracking and damage of the bridge deck, and effectively improve the service life and durability of the track beam.

[0023] 3. Reduce long-term maintenance cost: the UHPC bridge deck is significantly better than the ordinary concrete bridge deck in terms of wear resistance and corrosion resistance, reduces the cracking, spalling and steel corrosion problems in the use process, thereby greatly reducing the maintenance and maintenance cost of the track beam in the long-term operation process.

[0024] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, and can be implemented according to the content of the specification, the following is the preferred embodiment of the present application and the detailed description of the drawings as follows. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The present application is a structural diagram.

[0026] Figure 2 The present application is a side view of the steel-concrete composite track beam with the locally variable rigidity enhanced type of welded nail shear connector.

[0027] Figure 3 The present application is a top view of the steel-concrete composite track beam with the locally variable rigidity enhanced type of welded nail shear connector.

[0028] Figure 4 The present application is a top view of the steel-concrete composite track beam with the locally variable rigidity enhanced type of welded nail shear connector.

[0029] Figure 5 The present application is a schematic diagram of the flat link cross beam.

[0030] 1 is a UHPC cast-in-place bridge deck, 2 is a locally variable rigidity enhanced type of welded nail shear connector, 3 is a track steel beam, and 4 is a flat link cross beam. DETAILED DESCRIPTION

[0031] The technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0032] As Figures 1-5As shown, the utility model discloses a kind of partial variable stiffness enhanced type weld bolt shear connectors suitable for steel-ultra high performance concrete (UHPC) combined track beam, especially for the efficient connection demand between track beam concrete panel and steel beam. The shear connector adopts a partial variable stiffness enhanced type weld bolt structure with thickened bottom local area, which is composed of thickened columnar rod, slender rod and round head, and the weld bolt bottom end is fixed on the steel beam flange plate by welding process, and is densely arranged with certain spacing to form weld bolt group. During bridge deck construction, first, weld bolt group is arranged on steel beam flange plate according to design requirements, and after binding steel mesh, UHPC bridge deck is integrally poured, and concrete wraps weld bolt group to form integral connection structure. UHPC material has excellent durability, crack resistance and compressive strength, which can effectively cope with the dynamic load of straddle-type monorail traffic vehicles and complex environmental conditions. The reasonable arrangement form of partial variable stiffness enhanced type weld bolt shear connector, combined with the high performance characteristics of UHPC material, not only improves the shear bearing capacity and connection reliability of track beam, reduces the risk of concrete cracking and weld bolt deformation, but also significantly improves construction efficiency and quality, prolongs the service life of track beam, and has high application prospect and popularization value.

[0033] The utility model provides a kind of novel track beam bridge shear connection structure system, mainly by UHPC cast-in-place bridge deck, partial variable stiffness enhanced type weld bolt shear connector, track steel beam and flat link cross beam are constituted. The shear connector of UHPC cast-in-place bridge deck and track steel beam is connected by the reserved uniform distribution type weld bolt, to improve the shear capacity and durability of overall structure.

[0034] As the preferred embodiment of the above, the partial variable stiffness enhanced type weld bolt shear connector is composed of weld bolt welded to the flange of track steel beam. The weld bolt is evenly arranged on the flange of track steel beam and distributed at certain intervals to improve the stability of connection. The core feature of the connector is to optimize the arrangement density and local variable stiffness design of weld bolt, so that the weld bolt has higher shear capacity in the connection area, thereby effectively reducing the stress concentration problem of the connection area. Compared with traditional shear connectors, the partial variable stiffness enhanced type weld bolt shear connector used in the utility model has higher fatigue resistance and connection reliability, and is particularly suitable for application scenarios of high-load and long-life structures such as track beam bridges.

[0035] As the preferred embodiment of the above, the track steel beam 3 is the main structural component for bearing track and vehicle load. To further enhance the overall stiffness of track beam bridge and balance load distribution, flat link cross beams are arranged between track steel beams, as shown in Figure 5 The flat link cross beam 4 not only helps to improve the stability of the overall structure, but also effectively disperses the impact load generated during vehicle travel.

[0036] As a preferred embodiment of the above, in the actual construction process, first, the partially variable stiffness enhanced welded shear connector is arranged and welded on the flange plate of the track steel beam. After welding, the track steel beam is hoisted and erected to the predetermined position. Then, the cast-in-place UHPC bridge deck is directly poured at one time to ensure that the group of welded studs is completely embedded in the connection area, thereby forming a stable shear connection.

[0037] Specifically, a partially variable stiffness enhanced welded shear connector, comprising a thickened bottom rod (2-1), an elongated middle rod (2-2) and a cylindrical head (2-3) connected in turn; the diameter of the bottom rod (2-1) is greater than the diameter of the elongated middle rod (2-2); the diameter of the cylindrical head (2-3) is greater than the elongated middle rod (2-2); the height to diameter ratio of the thickened bottom rod (2-1) is optimized, the diameter of the thickened bottom rod (2-1) is 1.5 to 2 times the diameter of the elongated middle rod (2-2), and the height of the thickened bottom rod (2-1) is 1 / 6 to 1 / 3 of the total height of the welded stud. Thus, the shear stiffness and pullout resistance of the welded stud are significantly improved. The height of the thickened bottom area of the partially variable stiffness enhanced welded shear connector is about 1 / 6 to 1 / 3 of the total height of the welded stud, which optimizes the welding process while improving the shear capacity of the welded stud, thereby reducing the difficulty of welding operation during construction.

[0038] Specifically, a steel-concrete composite track beam with a partially variable stiffness enhanced welded shear connector, comprising a UHPC cast-in-place bridge deck (1), a partially variable stiffness enhanced welded shear connector (2) and a track steel beam (3); the partially variable stiffness enhanced welded shear connector (2) is welded to the top surface of the track steel beam (3) to connect the track steel beam (3) with the upper UHPC cast-in-place bridge deck (1).

[0039] Specifically, a steel-concrete composite track beam with a partially variable stiffness enhanced welded shear connector, the thickened bottom rod (2-1) is located at the bottom of the welded stud and is fixedly connected to the top surface of the track steel beam (3) by welding; the shear stiffness and pullout resistance of the shear connection are improved, and the stress concentration effect at the welded part is reduced;

[0040] The elongated middle rod (2-2) is located in the flexible transition area of the welded stud; its length and diameter are optimized according to the shear demand that may occur during the use of the track beam, which can effectively alleviate the problem of shear deformation incoordination between the UHPC cast-in-place bridge deck (1) and the track steel beam (3), and prevent cracking or fatigue failure caused by local stress concentration;

[0041] The cylindrical head (2-3) is provided at the top end of the welded stud, and the surface is a smooth cylinder, which is wrapped by UHPC material during the pouring of the UHPC cast-in-place bridge deck (1). It provides mechanical interlocking force and anti-slippage performance, further improving the load-carrying capacity of the shear connector.

[0042] Specifically, a steel-concrete composite track beam with a locally variable stiffness enhanced stud shear connector, the UHPC cast-in-place deck slab (1) is made of ultra-high performance concrete material, with a compressive strength not less than 120 MPa;

[0043] The track steel beam (3) adopts a single-box single-chamber section structure as the main load-bearing component of the track bridge;

[0044] The UHPC cast-in-place deck slab (1) is integrally poured above the track steel beam (3), and the concrete wraps the stud group during pouring. The UHPC cast-in-place deck slab (1) and the track steel beam (3) form an integrated connection structure through the locally variable stiffness enhanced stud shear connector (2). It provides efficient shear and uplift resistance and improves the overall fatigue durability of the structure. Before pouring the UHPC cast-in-place deck slab, a steel mesh is arranged around the stud group to optimize the stress performance of the deck slab and improve the overall bonding effect and crack resistance of the UHPC cast-in-place deck slab and the stud, thereby effectively improving the shear capacity and durability of the structure, ensuring that the UHPC cast-in-place deck slab has high strength, crack resistance and long service life when subjected to heavy load railway vehicle loads.

[0045] Specifically, a steel-concrete composite track beam with a locally variable stiffness enhanced stud shear connector, further comprises a flat link beam (4) arranged between the double-track steel beams (3) and welded to the side surface of the track steel beam (3). To enhance the lateral stiffness of the track beam and improve the lateral stability of the overall bridge structure.

[0046] Specifically, a steel-concrete composite track beam with a locally variable stiffness enhanced stud shear connector, the number and arrangement spacing of the flat link beams (4) are optimized according to the bridge span and lateral stiffness requirements, and the flat link beams are fixed to the track steel beams (3) by welding or bolting. To improve the lateral stability and torsional performance of the overall bridge.

[0047] The locally variable stiffness enhanced stud shear connector includes the following three parts:

[0048] 1. Thickened bottom rod: the diameter of the stud bottom area is increased and welded to the surface of the steel beam flange plate to enhance the connection strength of the stud and the steel beam, while effectively reducing the stress concentration risk of the welding area.

[0049] 2. Slender middle rod: as a transition area of the stud, its length and diameter are optimized according to the shear demand to alleviate the shear deformation incoordination between the deck slab and the steel beam, and reduce the deformation and cracking risk of the stud.

[0050] 3. Cylindrical head: the top end of the stud is a smooth cylindrical head with a diameter larger than the middle rod to improve the anchoring performance of the stud and ensure the effective connection of the concrete slab and the steel beam.

[0051] Further, the cast-in-situ UHPC bridge deck is constructed, the groups of welding studs on the flange plates of the steel beam are arranged according to design requirements, and then the UHPC material is cast in one time, so that the groups of welding studs are completely wrapped in the concrete, and reliable connection effect is achieved. The UHPC material has excellent crack resistance and durability, and can effectively cope with dynamic load brought by the straddle-type monorail vehicle and complex environmental influence.

[0052] The basic principle, main features and advantages of the utility model are shown and described above. The skilled in the art should understand that the utility model is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principle of the utility model, and various changes and improvements of the utility model can be made without departing from the spirit and scope of the utility model, and these changes and improvements all fall within the scope of the utility model claimed. The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A locally variable stiffness reinforced welded stud shear connector, characterized in that: It includes a thickened bottom rod (2-1), a slender middle rod (2-2), and a cylindrical head (2-3) connected in sequence; the diameter of the thickened bottom rod (2-1) is larger than the diameter of the slender middle rod (2-2); the diameter of the cylindrical head (2-3) is larger than that of the slender middle rod (2-2).

2. The locally variable stiffness reinforced welded stud shear connector according to claim 1, characterized in that: The height and diameter ratio of the thickened bottom rod (2-1) are optimized. The diameter of the thickened bottom rod (2-1) is 1.5 to 2 times the diameter of the slender middle rod (2-2), and the height of the thickened bottom rod (2-1) is 1 / 6 to 1 / 3 of the total height of the weld stud.

3. A steel-concrete composite track beam with locally variable stiffness reinforced welded stud shear connectors according to claim 2, characterized in that: It includes a UHPC cast-in-place bridge deck (1), a locally variable stiffness reinforced welded stud shear connector (2), and a track steel beam (3); the locally variable stiffness reinforced welded stud shear connector (2) is welded to the top surface of the track steel beam (3) to connect the track steel beam (3) with the upper UHPC cast-in-place bridge deck (1).

4. A steel-concrete composite track beam with locally variable stiffness reinforced welded stud shear connectors according to claim 3, characterized in that: The thickened bottom rod (2-1) is located at the bottom of the welding stud and is fixedly connected to the top surface of the rail steel beam (3) by welding. The slender central rod (2-2) is located in the flexible transition area of ​​the weld stud; The cylindrical head (2-3) is located at the top of the weld stud and has a smooth cylindrical surface. It is wrapped with UHPC material during the casting of the UHPC cast-in-place bridge deck (1).

5. A steel-concrete composite track beam with locally variable stiffness reinforced welded stud shear connector as described in claim 4, characterized in that: UHPC cast-in-place bridge deck (1) is made of ultra-high performance concrete material with a compressive strength of not less than 120 MPa; The track steel beam (3) adopts a single-box single-cell cross-section structure and serves as the main load-bearing component of the track bridge; The UHPC cast-in-place bridge deck (1) is cast on top of the track steel beam (3). During the casting process, the concrete wraps around the welded stud group. The UHPC cast-in-place bridge deck (1) and the track steel beam (3) form an integrated connection structure through the locally variable stiffness reinforced welded stud shear connector (2).

6. A steel-concrete composite track beam with locally variable stiffness reinforced welded stud shear connectors according to claim 5, characterized in that: It also includes a horizontal crossbeam (4), which is set between the double-track steel beams (3) and welded to the side of the track steel beams (3).

7. A steel-concrete composite track beam with locally variable stiffness reinforced welded stud shear connectors according to claim 6, characterized in that: The number and spacing of the horizontal crossbeams (4) are optimized according to the bridge span and lateral stiffness requirements. The horizontal crossbeams are fixed to the track steel beams (3) by welding or bolting.

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