Steel-concrete composite beam cable-stayed bridge midspan region stress control method and structure

Abstract

The application relates to a stress control method and structure for a steel-concrete combined beam cable-stayed bridge midspan region, which calculates the overall tensile stress value of the midspan region of a concrete panel of a finite element model; then based on the overall tensile stress value, a first stress specification value and the finite element model, the number of required joints in the midspan region of the concrete panel is determined to obtain a stress control scheme; according to the stress control scheme, joints and seamless expansion devices are arranged on the actual concrete panel; the above steps set proper numbers of joints in the midspan region of the concrete panel, release the stress, the main beam force is borne by the steel beam, the originally small stress in the midspan region of the concrete panel is reduced, the increased number of ordinary steel bars or prestressed steel bars is reduced, the remaining gap during pouring of the concrete panel is increased, the pouring is facilitated, the construction quality is improved; the seamless expansion device is installed at the joint, the two sides of the concrete are still supported on the continuous steel beam, the gap and the corner of the joint almost do not change, and the durability is good.

Description

Technical Field

[0001] This application relates to the field of bridge construction, and in particular to a method and structure for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge. Background Technology

[0002] Currently, steel-concrete composite beams combine the excellent tensile properties of steel with the excellent compressive properties of concrete. Compared with traditional reinforced concrete beams, composite beams reduce the structural self-weight and cross-sectional dimensions, increase the ductility of the beam, and shorten the construction period. Compared with steel beams, they reduce the amount of steel used, improve the stiffness of the bridge, increase the stability and integrity of the bridge, and at the same time improve the fire resistance and durability of the structure.

[0003] In related technologies, the concrete panels of steel-concrete composite cable-stayed bridges are prone to cracking or splitting, mainly due to the excellent compressive strength but poor tensile strength of concrete. When the concrete panel is subjected to tensile stress, cracks easily form. The tensile stress in the concrete panel is mainly caused by the following factors: ① Negative bending moment caused by structural self-weight and live load; ② Temperature change; ③ Shrinkage and creep; ④ Especially in the mid-span area of ​​the concrete panel, which is outside the arrangement range of the stay cables, the main beam has almost no axial pressure, but will generate a large tensile force due to the traction of the stay cables on both sides; at the same time, the mid-span area is the closure section, and the bridge panel of the closure section needs to be cast on site, and its shrinkage and creep effect is large. Therefore, the concrete bridge panel in the mid-span area often becomes a weak link in the design of cable-stayed bridges and is more prone to cracking.

[0004] To ensure that the concrete panel structure can withstand as much pressure as possible and prevent cracking, certain measures are generally required to increase the compressive stress reserve of the concrete panel. For example, one method is to use a top-drop beam method to increase the compressive stress of the concrete panel through construction measures; another is to use internal prestressing to increase the compressive stress of the concrete panel through prestressing. However, the following problems exist: In the mid-span region of a cable-stayed bridge, concrete typically bears significant tensile stress (generally exceeding +10 MPa), primarily caused by temperature and shrinkage / creep. Since jacking up the beam is not feasible in the mid-span region, prestressing tendons are usually placed in the middle of the concrete slab to control the tensile stress. This requires a large number of prestressing tendons with close spacing. Combined with the existing ordinary steel reinforcement, the remaining gaps are very small, making it difficult to pour wet-joint concrete and ensuring a dense, high-quality finish. Furthermore, the need for prestressing tendons within the concrete slab also results in a thicker concrete layer, increasing the weight of the slab and consequently the main beam, leading to material waste.

[0005] To address the above drawbacks, it is urgent to find new methods and structures for stress control in the mid-span region of steel-concrete composite cable-stayed bridges. Summary of the Invention

[0006] This application provides a method and structure for stress control in the mid-span region of a steel-concrete composite beam cable-stayed bridge, in order to solve the problem in the related art where the method of configuring multiple prestressed tendons in the mid-span region of a steel-concrete composite beam cable-stayed bridge to control the tensile stress of the concrete panel in the mid-span region affects the quality of wet joint concrete pouring.

[0007] Firstly, a method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge is provided, which includes: Establish finite element models of steel beams, concrete panels, bridge towers, stay cables, and bridge piers; Calculate the overall tensile stress value in the mid-span region of the concrete panel in the finite element model; then, based on the overall tensile stress value, the first stress specification value, and the finite element model, determine the number of required fractures in the mid-span region of the concrete panel to obtain a stress control scheme. According to the stress control scheme, joints are set on the actual concrete panel; then seamless expansion joints are installed at the joints.

[0008] In some embodiments, after determining the required number of joints in the mid-span region of the concrete panel, and before actually installing the joints in the concrete panel, the following steps are included: The location of the concrete panel is determined by dividing the mid-span area into equal parts based on the number of fractures.

[0009] In some embodiments, based on the overall tensile stress value, the first stress specification value, and the finite element model, the required number of fracture joints in the mid-span region of the concrete panel is determined to obtain a stress control scheme, specifically including the following steps: Determine whether the overall tensile stress value is less than or equal to the first stress specification value; When the overall tensile stress value is less than or equal to the first stress specification value, the mid-span area of ​​the concrete panel meets the requirements, and the stress control scheme is to not set up a joint. When the overall tensile stress value is greater than the first stress specification value, the stress control scheme is verified and calculated in the finite element model by gradually adding fracture joints.

[0010] In some embodiments, the stress control scheme is verified and calculated in the finite element model by gradually adding fractures, specifically including the following steps: A fracture joint is pre-set in the mid-span region of the concrete panel in the finite element model as an initial stress control scheme. Calculate the stress value of each part of the mid-span region of the concrete panel after setting the fracture joint according to the initial stress control scheme; then determine whether the stress value of any part is less than or equal to the first stress specification value. If so, the initial stress control scheme will be used as the final stress control scheme. If not, add a fracture joint and update the initial stress control scheme; return to calculating the stress value of each part of the mid-span region of the concrete panel after setting the fracture joint according to the initial stress control scheme; then determine whether the stress value of any part is less than or equal to the first stress specification value.

[0011] In some embodiments, the joint extends laterally across the bridge and has a width of 10-20 mm.

[0012] In some embodiments, creating fracture joints on the actual concrete panel according to a stress control scheme includes the following steps: After the steel beams are joined together and the concrete panel in the mid-span area is poured, a corresponding number of joints are cut in the mid-span area of ​​the concrete panel according to the stress control scheme.

[0013] In some embodiments, creating fracture joints on the actual concrete panel according to a stress control scheme includes the following steps: After the steel beams are joined, when the concrete panel mid-span area is poured, the concrete panel mid-span area is divided into multiple segments according to the control plan. The concrete panel is poured in sections at the mid-span, so that a joint is formed between adjacent sections.

[0014] In some embodiments, the seamless telescopic device is a TST elastomeric seamless telescopic device.

[0015] Secondly, a stress control structure for the mid-span region of a steel-concrete composite beam cable-stayed bridge is provided, which includes a concrete panel, which is constructed according to the stress control method for the mid-span region of a steel-concrete composite beam cable-stayed bridge.

[0016] In some embodiments, the concrete panel is connected to the steel beam by shear studs.

[0017] The beneficial effects of the technical solution provided in this application include: This application provides a method and structure for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge. First, the overall tensile stress value of the concrete panel in the mid-span region is calculated using a finite element model. Then, based on the overall tensile stress value, the first stress specification value, and the finite element model, the required number of joints in the mid-span region of the concrete panel is determined to obtain a stress control scheme. Joints are then set on the actual concrete panel according to the stress control scheme. Finally, seamless expansion joints are installed at the joints. Through these steps, a suitable number of joints are set in the mid-span region of the concrete panel to release its stress. At this point, the main beam in the mid-span region is primarily supported by the steel beams, while the concrete panel in the mid-span region originally experiences less stress, eliminating the need for prestressing tendons. Simultaneously, the amount of ordinary steel reinforcement is reduced, increasing the remaining gaps during concrete panel pouring, facilitating dense pouring, and improving the construction quality of wet-joint concrete. The installation of seamless expansion joints ensures that the concrete on both sides remains supported on the continuous steel beams, and the gap and angle of the joints remain almost unchanged, resulting in excellent durability. Attached Figure Description

[0018] 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.

[0019] Figure 1 A schematic diagram showing the location of the fracture in the steel-concrete composite beam, provided for an embodiment of this application; Figure 2 A schematic diagram illustrating the positional relationship between the joint, steel beam, mid-span area of ​​the concrete panel, and non-mid-span area of ​​the concrete panel, provided for embodiments of this application. Figure 3 A schematic diagram illustrating the general flow of the stress control method for the mid-span region of a steel-concrete composite cable-stayed bridge provided in this application embodiment; Figure 4 This is a structural diagram of the seamless expansion joint and mid-span expansion joint of the steel-concrete composite beam cable-stayed bridge provided in the embodiments of this application.

[0020] In the diagram: 1. Steel beam; 2. Mid-span area of ​​concrete panel; 3. Joint; 4. Non-mid-span area of ​​concrete panel; 5. Seamless expansion joint; 6. Vertical support components of steel beam. Detailed Implementation

[0021] 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.

[0022] To facilitate understanding, the following explanations are provided for key terms in this application: Ordinary reinforcing steel: Typically made of hot-rolled steel (such as HRB335, HRB400), it has lower strength and is mainly used to passively enhance the tensile strength of concrete. It bears tensile stress after concrete cracks, belonging to the category of "passive stress bearing," and is mainly used to limit crack propagation and maintain the structural integrity. It is usually arranged in a straight line along the direction of stress, such as at the bottom of the tension zone or as stirrups required for shear resistance. It enhances tensile and shear resistance and controls crack width.

[0023] Prestressed tendons: Made of high-strength materials (such as steel strands and carbon steel wires), their tensile strength can reach 3 to 5 times that of ordinary steel bars. Stress is actively applied through tensioning. This is done before (pre-tensioning) or after (post-tensioning) concrete hardening, applying pre-stress to the concrete to preemptively offset the tensile stress caused by external loads; this is considered "active reinforcement." They may be arranged in curved or zigzag patterns to optimize stress distribution (e.g., parabolic shapes adapt to changes in bending moment). This improves crack resistance, stiffness, and load-bearing capacity, while reducing deformation.

[0024] Joint 3: Refers to the gap in the mid-span region 2 of the concrete panel, within which a seamless expansion joint 5 is installed. Joint 3 is generally located within the range of the secondary junction cable-stayed structure in the mid-span, such as... Figure 1 As shown.

[0025] Concrete panel mid-span region 2: This refers to the area between two non-mid-span concrete panel regions, located outside the arrangement range of the stay cables, such as... Figure 2 As indicated by the markings, the non-mid-span area of ​​the concrete panel is marked as 4.

[0026] In the mid-span region of a cable-stayed bridge, concrete typically bears significant tensile stress (generally exceeding +10 MPa), primarily caused by temperature and shrinkage / creep. Since jacking up the beam is not feasible in the mid-span region, prestressing tendons are usually placed in the middle of the concrete slab to control the tensile stress. This requires a large number of prestressing tendons with close spacing. Combined with the existing ordinary steel reinforcement, the remaining gaps are very small, making it difficult to pour wet-joint concrete and ensuring a dense, high-quality finish. Furthermore, the need for prestressing tendons within the concrete slab also results in a thicker concrete layer, increasing the weight of the slab and consequently the main beam, leading to material waste.

[0027] To address the above drawbacks, it is urgent to find new methods and structures for stress control in the mid-span region of steel-concrete composite cable-stayed bridges.

[0028] This application provides a method and structure for stress control in the mid-span region of a steel-concrete composite beam cable-stayed bridge, in order to solve the problem in the related art where the method of configuring multiple prestressed tendons in the mid-span region of a steel-concrete composite beam cable-stayed bridge to control the tensile stress of the concrete panel in the mid-span region affects the quality of wet joint concrete pouring.

[0029] Please see Figures 1-3 A method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge includes the following steps: Step 100: Establish finite element models of steel beam 1, concrete panel, bridge tower, stay cables, and piers; This step of establishing finite element models is a standard skill for those skilled in the art, so the specific modeling steps will not be described. Step 200: Calculate the overall tensile stress value of the mid-span region 2 of the concrete panel in the finite element model; then, based on the overall tensile stress value, the first stress specification value and the finite element model, determine the number of required fractures 3 on the mid-span region 2 of the concrete panel to obtain the stress control scheme. Step 300: Set a joint 3 on the actual concrete panel according to the stress control scheme; then set a seamless expansion joint 5 at the joint 3.

[0030] Through the above steps By setting an appropriate number of joints 3 in the mid-span region 2 of the concrete panel, stress is released. At this time, the main force of the main beam in the mid-span region is mainly borne by the steel beam 1, while the stress in the mid-span region 2 of the concrete panel is originally small, so there is no need to configure prestressing tendons. At the same time, the amount of ordinary steel bars is reduced, which increases the remaining gaps when pouring the concrete panel, making it easier to pour densely and improving the construction quality of wet joint concrete. On the other hand, after setting joints, only ordinary steel bars are used, without prestressing tendons. Compared with the original tensioning method, the amount of ordinary steel bars is reduced, the thickness of the concrete slab is reduced, and thus the weight of the concrete panel is reduced. It can also be understood that without prestressing tendons, the thickness of the concrete slab can be reduced, further reducing the self-weight of the structure, saving materials, eliminating the prestressing tensioning process, and shortening the construction period by 15%-20%.

[0031] Furthermore, a seamless expansion joint 5 is installed at the fracture joint 3. The concrete on both sides of the fracture joint 3 is still supported on the continuous steel beam 1. The gap and angle of the fracture joint 3 hardly change, so the expansion joint hardly shifts and has excellent durability.

[0032] The detailed principle above is as follows: In a combined cable-stayed bridge, the main girder (steel beam 1 + concrete slab) generally experiences relatively low stress in the mid-span region. The tensile stress in the concrete slab is primarily caused by the temperature difference between the steel and concrete, as well as the shrinkage and creep of the concrete itself, while the stress in steel beam 1 is very small. Since only the concrete slab experiences significant tensile stress and crack control is difficult, the concrete slab is simply broken open to release its stress. At this point, the main stress in the mid-span region is primarily borne by steel beam 1, which already experiences relatively low stress, resulting in very limited material addition to steel beam 1. Simultaneously, a fracture joint 3 is created in the concrete slab, with a seamless expansion joint 5 installed at this joint. The concrete on both sides of the fracture joint 3 remains supported by the continuous steel beam 1, and the gap and angle of the fracture joint 3 remain almost unchanged. Therefore, the expansion joint experiences almost no displacement, resulting in excellent durability.

[0033] The above describes a change from the active method of controlling tensile stress in the concrete slab using prestressed tendons to a passive method that allows cracking and then incorporates fracture joint 3. This scheme eliminates the need for a large number of prestressed tendons, which are generally expensive, thus reducing material costs. The construction of prestressed tendons (prestressing bars) is also relatively complex, reducing construction costs. Furthermore, eliminating the need for prestressed tendons allows for further reduction in the thickness of the concrete slab, decreasing the structure's self-weight and saving materials.

[0034] Reference Appendix Figure 4 As shown, the seamless expansion joint 5 is a TST elastomeric seamless expansion joint, which ensures that the bridge deck is seamless, longitudinally continuous, adaptable to deformation, waterproof, and durable.

[0035] Among them, the appendix Figure 4The diagram illustrates the connection between the vertical support component 6 of the steel beam 1 and the mid-span area 2, joint 3, and non-mid-span area 4 of the concrete panel. The vertical support component 6 of the steel beam below joint 3 is sealed with rubber strip A. Shear nails C are installed in the cast-in-place joint B between the mid-span area 2 and the non-mid-span area 4 of the concrete panel before pouring. Rubber strip A is also installed between the bottom of the cast-in-place joint B and the vertical support component 6 of the steel beam. A paving layer D is laid on top of both the non-mid-span area 4 and the mid-span area 2 of the concrete panel.

[0036] The construction process of the TST elastomeric seamless expansion joint is as follows: After the asphalt concrete pavement layer of the bridge deck is completed, the bridge deck around the expansion joint is cleaned, the groove width is laid out according to the design requirements, the joint is cut, the removed pavement material is removed, and the groove is cleaned.

[0037] Drive an expansion bolt every 250mm in the transverse direction, 50mm from the edge of the groove, to a height of 1 / 2 groove depth. Weld a 12mm steel bar through the bolt head along the seam, or first drill a 12mm hole 60mm deep. Drive in a 12×100mm steel bar, and then weld a 12mm steel bar through the seam on the inner side of the top.

[0038] Clean the groove opening with a high-pressure water gun, then heat and dry the surface of the groove opening with a flame torch. Fill the gaps between adjacent beam ends with sponge strips, filling them as completely as possible without leaving any gaps.

[0039] Apply TST-specific adhesive evenly to the exposed surface of the groove, wait 15 minutes, then pour in melted TST and spread it evenly on the bottom and sides of the groove with a scraper, to a thickness of 1-2 mm. Then place the cross-joint steel plate and fix it with positioning nails, paying attention to centering.

[0040] Starting from one end of the trough, place preheated (130-150℃) large stones into the trough and spread them evenly in the first section, with a length of 2-3 meters and a thickness sufficient to expose the underlying TST. Then pour in TST to submerge the stones.

[0041] Lay the second layer of gravel, thick enough to expose the underlying TST layer, and then pour TST again to submerge the gravel. Due to the depth of the trench in this project, a total of three layers of gravel and three pours were required.

[0042] Lay down heated small stones, 10mm higher than the bridge surface, compact them with a plate vibrator, and then smooth them with a scraper. Generally, to prevent sinking, leave them 1-2mm higher than the bridge surface. At this point, you can adjust them as needed and then flatten them with a shovel.

[0043] Pour enough TST to submerge the pebbles. To prevent the TST from flowing onto the bridge deck, you can use wooden planks to block the sides of the channel to keep the edges neat.

[0044] Continue with the above method for the next section until the entire or half section is completed. Starting from one end, use a special paver to spread the surface (the amount of TST should be adjusted according to the seepage situation), and use a heated shovel to smooth it out. Pour the TST while scraping backward to refine the surface. The entire process requires heat preservation with a flame torch. The surface TST should not be more than 2 mm higher than the stone.

[0045] Trim the edges, remove the side panels, let it cool for 1-2 hours, and then open it to traffic.

[0046] In some preferred embodiments, step 200 includes the following steps: Based on the overall tensile stress value, the first stress specification value, and the finite element model, the number of required fracture joints 3 on the mid-span region 2 of the concrete panel is determined to obtain a stress control scheme, which specifically includes the following steps: Step 200-1: Determine whether the overall tensile stress value is less than or equal to the first stress specification value; Step 200-1: When the overall tensile stress value is less than or equal to the first stress specification value, the mid-span area 2 of the concrete panel meets the requirements, and the stress control scheme is to not set up a joint 3. Step 200-2: When the overall tensile stress value is greater than the first stress specification value, add steps step by step according to the fracture 3, and verify and calculate the stress control scheme in the finite element model.

[0047] Following the step-by-step addition of fracture 3, the stress control scheme was verified and calculated in the finite element model, specifically including the following steps: A fracture joint 3 is pre-set in the mid-span region 2 of the concrete panel in the finite element model as an initial stress control scheme. Calculate the stress value of each part of the mid-span region 2 of the concrete panel after setting the fracture 3 according to the initial stress control scheme; then determine whether the stress value of any part is less than or equal to the first stress specification value; If so, the initial stress control scheme will be used as the final stress control scheme. If not, add a fracture joint 3 and update the initial stress control scheme; return to the step of calculating the stress value of each part of the concrete panel mid-span region 2 after setting fracture joint 3 according to the initial stress control scheme; and then determine whether the stress value of any part is less than or equal to the first stress specification value.

[0048] The above explanation details the determination of the specific number of fracture joints (3), thus establishing a concrete construction plan. In this case, ordinary steel reinforcement can control cracks in the concrete slab without the need for prestressed tendons.

[0049] In some preferred embodiments, the number of seams 3 has been described and limited in detail in the above steps, but the location of seams 3 also has an impact, so the following settings are made: The location of the concrete panel mid-span region 2 is determined by dividing the concrete panel mid-span region 2 equally according to the number of fracture joints 3.

[0050] By setting this step, after determining the quantity, the joint is divided equally. For example, when the quantity is 1, the joint 3 is divided into two equal parts, and the position of the joint 3 is at the middle position of the length direction of the mid-span area 2 of the concrete panel; when the quantity is 2, the joint 3 is divided into three equal parts, and the position of the joint 3 is at the two equal division points of the length direction of the mid-span area 2 of the concrete panel.

[0051] The above steps can determine the specific location for constructing joint 3, providing guidance for blindly setting up joint 3 and facilitating construction.

[0052] In some preferred embodiments, the joint 3 extends laterally along the bridge, and the width of the joint 3 is 10-20 mm. The construction of the joint 3 can take the following two forms: The first method involves setting joint 3 on the actual concrete panel according to the stress control scheme, including the following steps: After the steel beam 1 is closed and the concrete panel mid-span area 2 is poured, a corresponding number of fractures 3 are cut in the concrete panel mid-span area 2 according to the stress control scheme.

[0053] The second method involves setting joint 3 on the actual concrete panel according to the stress control scheme, including the following steps: After the steel beam 1 is closed, when the concrete panel mid-span area 2 is poured, the concrete panel mid-span area 2 is divided into multiple segments according to the control plan. The concrete panel in the mid-span area 2 is poured in two sections simultaneously to create a joint 3 between adjacent sections.

[0054] The two methods above are just different approaches, but other settings are not excluded.

[0055] This application also proposes a stress control structure for the mid-span region of a steel-concrete composite beam cable-stayed bridge, which includes a concrete panel, the concrete panel being constructed according to the above-mentioned stress control method for the mid-span region of a steel-concrete composite beam cable-stayed bridge.

[0056] The main components of a stress control structure in the mid-span region of a steel-concrete composite cable-stayed bridge include: steel beam 1, concrete deck, bridge tower, stay cables, and piers. At least one concrete joint 3 is transversely installed in the mid-span region. The number of joints 3 is determined based on the span and stress analysis; for example, one joint is installed for shorter spans, and two or more for longer spans. Seamless expansion joints such as TST elastomeric materials are used at the joints 3 to ensure longitudinal continuity, waterproofing, and durability of the bridge deck.

[0057] The concrete panel is connected to the steel beam 1 by shear studs. The concrete panel and the steel beam 1 are connected by shear studs such as studs to keep the steel beam 1 continuous at the joint 3.

[0058] The tensile stress in the concrete panel is released through fracture joint 3, and the load in the mid-span area is borne by steel beam 1. Since the main beam in the mid-span experiences relatively small stress, the increase in material volume of steel beam 1 is limited, and the concrete panel does not require prestressing tendons, only ordinary steel bars are needed to control cracks.

[0059] 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.

[0060] 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.

[0061] 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 method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge, characterized in that, It includes: Establish finite element models of steel beams (1), concrete panels, bridge towers, stay cables, and piers; Calculate the overall tensile stress value of the mid-span region (2) of the concrete panel in the finite element model; then, based on the overall tensile stress value, the first stress specification value and the finite element model, determine the number of required fracture joints (3) on the mid-span region (2) of the concrete panel to obtain the stress control scheme. According to the stress control scheme, a joint (3) is set on the actual concrete panel; then a seamless expansion joint (5) is set at the joint (3).

2. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 1, characterized in that, After determining the number of required joints (3) in the mid-span area (2) of the concrete panel, the following steps are included before the actual concrete panel is fitted with joints (3): The concrete panel mid-span region (2) is divided equally according to the number of the fracture joints (3) to determine the location of the fracture joints (3).

3. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 1, characterized in that, Based on the overall tensile stress value, the first stress specification value, and the finite element model, the number of required fracture joints (3) on the mid-span region (2) of the concrete panel is determined to obtain a stress control scheme, which specifically includes the following steps: Determine whether the overall tensile stress value is less than or equal to the first stress specification value; When the overall tensile stress value is less than or equal to the first stress specification value, the mid-span area (2) of the concrete panel meets the requirements, and the stress control scheme is to not set up a joint (3). When the overall tensile stress value is greater than the first stress specification value, the stress control scheme is obtained by gradually adding steps according to the fracture (3) and verifying the calculation in the finite element model.

4. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 3, characterized in that, Following the steps of gradually adding the fracture joint (3), the stress control scheme is verified and calculated in the finite element model, specifically including the following steps: A fracture joint (3) is pre-set in the mid-span region (2) of the concrete panel in the finite element model as an initial stress control scheme; Calculate the stress value of each part of the mid-span region (2) of the concrete panel after setting the fracture joint (3) according to the initial stress control scheme; then determine whether the stress value of any part is less than or equal to the first stress specification value; If so, the initial stress control scheme will be used as the final stress control scheme. If not, add a break (3) and update the initial stress control scheme; return to the step of calculating the stress value of each part of the mid-span region (2) of the concrete panel after setting the break (3) according to the initial stress control scheme; and then determine whether the stress value of any part is less than or equal to the first stress specification value.

5. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 1, characterized in that: The joint (3) extends laterally on the bridge and has a width of 10-20 mm.

6. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 1, characterized in that, According to the stress control scheme, joints are set on the actual concrete panel (3), including the following steps: After the steel beam (1) is closed and the concrete panel mid-span area (2) is poured, cut out the corresponding number of joints (3) in the concrete panel mid-span area (2) according to the stress control scheme.

7. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 1, characterized in that, According to the stress control scheme, the fracture joints (3) are set on the actual concrete panel, including the following steps: After the steel beam (1) is closed, when the concrete panel mid-span area (2) is poured, the concrete panel mid-span area (2) is divided into multiple segments according to the control scheme. The concrete panel in the mid-span area (2) is poured in sections simultaneously to form a joint (3) between adjacent sections.

8. The method for stress control in the mid-span region of a steel-concrete composite cable-stayed bridge as described in claim 1, characterized in that: The seamless telescopic device (5) is a TST elastomeric seamless telescopic device.

9. A stress control structure in the mid-span region of a steel-concrete composite beam cable-stayed bridge, characterized in that, It includes: concrete The concrete panel is constructed in accordance with the stress control method for the mid-span region of a steel-concrete composite beam cable-stayed bridge as described in any one of claims 1-8.

10. The stress control structure in the mid-span region of the steel-concrete composite beam cable-stayed bridge as described in claim 9, characterized in that: The concrete panel is connected to the steel beam (1) by shear studs.

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