Construction method of variable cross-section cast-in-situ beam parallel to existing bridge

Abstract

The application provides a construction method of a variable cross-section cast-in-situ beam parallel to an existing bridge, and relates to the technical field of existing bridge crossing construction. Three-dimensional modeling analysis is performed on the existing bridge to determine the stress load of the existing bridge; a leveling layer is cast on the top surface of the pier of the existing bridge; main I-beams are installed on the top of the leveling layer along the transverse direction of the existing bridge; the main I-beams are sequentially installed with Bailey pieces and disc buckle supports; and the variable cross-section cast-in-situ box beam is constructed on the disc buckle supports. The support load is uniformly transmitted to the solid section of the support point of the existing bridge through the leveling layer, and then sequentially transmitted to the bent cap, the pier column and the pile foundation, so that the lower part and the foundation structure of the existing bridge are fully utilized as the cast-in-situ support foundation, the foundation is stable, the stress is uniform and reasonable, the safety of the support and the existing bridge structure is favorable, the support foundation treatment cost is saved, the construction process is reduced, the construction period is shortened, and the safety of the support erection and disassembly is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of construction technology for overpass construction of existing bridges, and more specifically, to a construction method for parallel overpass construction of existing bridges using cast-in-place beams with variable cross-sections. Background Technology

[0002] In existing technologies, when a variable cross-section cast-in-place beam is constructed to span an existing simply supported beam bridge, the cast-in-place support is directly installed on the bridge deck. The entire load of the cast-in-place support is applied to the bridge deck, resulting in high stress on the bridge deck. This may lead to damage to the bridge deck due to excessive stress and strain. In particular, some ultra-wide simply supported beam bridges have relatively low load-bearing capacity. The cast-in-place support cannot span the existing bridge in one span, and the precast beams of the existing bridge cannot directly bear the load of the full-span support, which increases the construction difficulty. The excessive load on the bridge deck can easily cause safety hazards to the existing bridge.

[0003] In view of the shortcomings of the existing technology, it is necessary to provide a construction method for parallel overpass of existing bridges with variable cross-section cast-in-place beams that can solve the problems mentioned in the background technology. Summary of the Invention

[0004] The purpose of this invention is to provide a construction method for a variable cross-section cast-in-place beam to cross an existing bridge in parallel. This method addresses the shortcomings of existing technologies by providing a solution, making full use of the existing bridge substructure and foundation as the foundation for the cast-in-place support. The foundation is stable, the stress is uniform and reasonable, and this is beneficial to the safety of the support and the existing bridge structure.

[0005] An embodiment of the present invention provides a construction method for a variable cross-section cast-in-place beam to cross an existing bridge in parallel, comprising the following steps:

[0006] Three-dimensional modeling and analysis of the existing bridge were performed to determine the stress load on the existing bridge.

[0007] Based on the stress load of the existing bridge, a leveling layer is poured on the top surface of the piers of the existing bridge.

[0008] Based on the load-bearing capacity of the existing bridge, the main I-beams are installed on the top of the leveling layer along the transverse direction of the existing bridge.

[0009] Based on the load-bearing capacity of the existing bridge, Bailey bridge panels and disc-lock brackets are installed sequentially on the main I-beams.

[0010] Variable cross-section cast-in-place box girders are constructed on the aforementioned disc-locked bracket.

[0011] In some embodiments of the present invention, the step of performing three-dimensional modeling and analysis on an existing bridge to determine the stress load on the existing bridge includes:

[0012] Measurement points were taken from the existing bridge using surveying instruments;

[0013] The measured data is imported into the software, and the software is used to create a three-dimensional model of the existing bridge.

[0014] Stress analysis was performed on the 3D model to determine the stress load on the existing bridge.

[0015] In some embodiments of the present invention, the step of pouring a leveling layer on the top surface of the piers of the existing bridge according to the load of the existing bridge includes:

[0016] The size of the leveling layer is determined based on the stress load of the existing bridge.

[0017] The leveling layer is poured onto the top surface of the piers of the existing bridge according to its size.

[0018] In some embodiments of the present invention, the step of installing the main I-beams on the top of the leveling layer along the transverse direction of the existing bridge according to the load-bearing capacity of the existing bridge includes:

[0019] Based on the stress load of the existing bridge, determine the type and number of main I-beams to be installed;

[0020] The main I-beams are installed on the top of the leveling layer along the transverse direction of the existing bridge, according to their model and number.

[0021] In some embodiments of the present invention, the step of sequentially installing Bailey bridge panels and disc-lock brackets on the main I-beam according to the load-bearing capacity of the existing bridge includes:

[0022] Based on the stress load of the existing bridge, determine the type of Bailey bridge section;

[0023] Bailey panels are installed on the main I-beam according to the model of the Bailey panel;

[0024] Install a disc buckle bracket on the top of the Bailey panel.

[0025] In some embodiments of the present invention, the step of installing Bailey panels on the main I-beam according to the model of the Bailey panel includes:

[0026] A support frame is installed on the side of the existing bridge;

[0027] According to the model of the Bailey bridge section, Bailey bridge sections are installed on the main I-beam, wherein the bottom end of the Bailey bridge section is supported on the support frame.

[0028] In some embodiments of the present invention, the disc buckle bracket includes an upright, a horizontal bar, a vertical diagonal bar, and multiple steel pipe supports. The upright, the horizontal bar, and the vertical diagonal bar are connected to each other to form a grid frame. The multiple steel pipe supports are inclinedly arranged on opposite sides of the top of the disc buckle bracket to form inclined opposite sides. The top of the upright is provided with a top support, and the bottom of the upright is provided with a bottom support. The height of the upright decreases from one side to the other.

[0029] In some embodiments of the present invention, the step of constructing the variable cross-section cast-in-place box girder on the disc-lock bracket includes:

[0030] A bottom template and side template are installed at the bottom of the disc buckle bracket;

[0031] The bottom template and the side template are pre-compressed using water bags;

[0032] After prestressing is completed, the box girder reinforcement is tied and the inner and top formwork is installed;

[0033] The box girder was then grouted.

[0034] In some embodiments of the present invention, the step of constructing the variable cross-section cast-in-place box girder on the disc-lock bracket further includes:

[0035] After the casting is completed, the box girder is cured, prestressed, and grouted.

[0036] In some embodiments of the present invention, the step of constructing the variable cross-section cast-in-place box girder on the disc-lock bracket further includes:

[0037] During the water bag pre-pressurization and grouting process, intelligent detection equipment is used to continuously detect the stress and strain of the uprights and issue warnings when the stress and strain exceed the stress and strain threshold range.

[0038] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

[0039] This invention utilizes 3D modeling and analysis of existing bridges to determine their load-bearing capacity. Based on this load, a leveling layer is poured on top of the bridge piers. Main H-beams are then installed along the transverse direction of the existing bridge on top of the leveling layer. Bailey bridge sections and disc-locked supports are then sequentially installed on the main H-beams. A variable cross-section cast-in-place box girder is constructed on the disc-locked supports. This invention replaces ordinary steel pipe Bailey bridge supports with a Bailey bridge section and disc-locked supports structure, transforming the load-bearing capacity from point loads on steel pipes to line loads on Bailey bridge sections. The load is evenly transferred through the leveling layer to the solid sections of the existing bridge supports, and then sequentially to the cap beams, piers, and pile foundations. This fully utilizes the existing bridge substructure and foundation as the foundation for the cast-in-place supports, resulting in a stable foundation with uniform and reasonable stress distribution. This is beneficial to the safety of both the supports and the existing bridge structure, saving on foundation treatment costs, reducing construction steps, accelerating the construction period, and significantly improving the safety of support erection and dismantling. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a construction structure for a variable cross-section cast-in-place beam that crosses an existing bridge in parallel, according to an embodiment of the present invention.

[0042] Figure 2 This is a flowchart illustrating the construction steps of a variable cross-section cast-in-place beam parallel overpass construction method for an existing bridge, as described in an embodiment of the present invention.

[0043] Attached reference numerals: 1. Existing bridge; 2. Leveling layer; 3. Main I-beam; 4. Bailey bridge panel; 5. Disc-lock scaffold; 51. Upright pole; 52. Horizontal bar; 53. Vertical diagonal bar; 54. Steel pipe support; 55. Top support; 56. Bottom support; 6. Box girder; 61. Bottom formwork; 62. Side formwork; 7. Support frame. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] In the description of the embodiments of the present invention, it should be noted that if terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and are not intended to 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 the present invention.

[0048] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0049] Example

[0050] Reference Figures 1-2 , Figure 1 This is a schematic diagram of a construction structure for a variable cross-section cast-in-place beam that crosses an existing bridge in parallel, according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the steps of a construction method for a variable cross-section cast-in-place beam that crosses an existing bridge in parallel, according to an embodiment of the present invention.

[0051] Specifically, the steps include the following:

[0052] S110. Perform three-dimensional modeling and analysis on existing bridge 1 to determine the stress load on existing bridge 1.

[0053] S120. Based on the load of the existing bridge 1, pour the leveling layer 2 on the top surface of the pier of the existing bridge 1.

[0054] S130. Based on the load of the existing bridge 1, install the main I-beam 3 on the top of the leveling layer 2 along the transverse direction of the existing bridge 1.

[0055] S140. Based on the load of the existing bridge 1, install Bailey bridge panels 4 and disc-lock brackets 5 sequentially on the main I-beam 3.

[0056] S150, Construct the variable cross-section cast-in-place box girder 6 on the disc-lock scaffold 5.

[0057] This invention determines the load on an existing bridge 1 by performing three-dimensional modeling and analysis; based on the load on the existing bridge 1, a leveling layer 2 is poured on the top surface of the piers of the existing bridge 1; based on the load on the existing bridge 1, a main I-beam 3 is installed on the top of the leveling layer 2 along the transverse direction of the existing bridge 1; based on the load on the existing bridge 1, Bailey bridge panels 4 and disc-locked brackets 5 are installed sequentially on the main I-beam 3; and a variable cross-section cast-in-place box girder 6 is constructed on the disc-locked brackets 5. The Bailey bridge structure with 4 sections and 5 disc-lock scaffolds replaces the ordinary steel pipe Bailey bridge scaffold. This transforms the point load on the scaffold from the usual steel pipe to the line load on the Bailey bridge section 4. The load of the scaffold is evenly transferred to the solid section of the existing bridge 1 support through the leveling layer 2, and then sequentially transferred to the cap beam → pier → pile foundation. The existing bridge 1 substructure and foundation structure are fully utilized as the foundation for the cast-in-place scaffold. The foundation is stable and the stress is even and reasonable, which is conducive to the safety of the scaffold and the existing bridge structure. This not only saves the cost of foundation treatment for the scaffold, reduces construction procedures, and speeds up the construction period, but also greatly improves the safety of scaffold erection and dismantling.

[0058] The following will further explain the construction method of a variable cross-section cast-in-place beam parallel overpass of an existing bridge 1 in this exemplary embodiment.

[0059] It should be noted that, in the embodiments of this application, a construction method for changing the load-bearing structure is used as an example of a cast-in-place beam with a variable cross-section crossing an existing ultra-wide simply supported beam bridge. This method is applicable to situations where the cast-in-place support cannot cross the existing ultra-wide simply supported beam bridge in one span and the existing bridge's precast beam slabs cannot directly bear the load of the full-span support. It is applicable to situations where the cast-in-place support crosses an existing, already opened ultra-wide (box girder width 6 over 25 meters) simply supported beam bridge, the single span of the existing simply supported beam bridge is within 20 meters, and the existing bridge's precast beam slabs cannot directly bear the load of the full-span support. However, it is not limited to existing ultra-wide simply supported beam bridges, and other similar existing overpass bridges can also be constructed by referring to this method.

[0060] In this embodiment of the application, as described in step S110, a three-dimensional modeling analysis is performed on the existing bridge 1 to determine the stress load on the existing bridge 1.

[0061] Specifically, measuring instruments are used to measure and collect data points on the existing bridge 1; the measured data is imported into software, and the software is used to create a three-dimensional model of the existing bridge 1; stress analysis is performed on the three-dimensional model to determine the stress load on the existing bridge 1, so as to determine the structural type and load to be subsequently installed on the existing bridge 1, and to ensure the stress balance of the existing bridge 1.

[0062] In this embodiment of the application, as described in step S120, a leveling layer 2 is poured on the top surface of the pier of the existing bridge 1 according to the load of the existing bridge 1.

[0063] Specifically, based on the load on the existing bridge 1, the size of the leveling layer 2 is determined. Specifically, during the stress analysis, the load that the existing bridge 1 needs to bear is evenly distributed to each structural component, and the load that each structural component can apply to the existing bridge 1 is determined in turn, thereby determining the size, model, number, etc. of the corresponding structural components. In this embodiment, the load that the leveling layer 2 will apply to the existing bridge 1 and the load that the leveling layer 2 receives are determined to calculate and determine the optimal size of the leveling layer 2. Based on the size of the leveling layer 2, the leveling layer 2 is poured on the top surface of the pier of the existing bridge 1. It should be noted that the leveling layer 2 mainly plays the role of bearing and transmitting the load, and evenly distributing the load to the existing bridge 1 at the bottom.

[0064] In this embodiment of the application, as described in step S130, the main I-beam 3 is installed on the top of the leveling layer 2 along the transverse direction of the existing bridge 1 according to the load of the existing bridge 1.

[0065] Specifically, based on the load on the existing bridge 1, the model and number of main I-beams 3 are determined. Based on the load on the existing bridge 1, the load of the main I-beams 3 on the leveling layer 2 below and the load transmitted to the existing bridge 1 through the leveling layer 2 are determined, thereby determining the model and number of main I-beams 3. In this application, I14 I-beams are used. Based on the model and number of main I-beams 3, the main I-beams 3 are installed on the top of the leveling layer 2 along the transverse direction of the existing bridge 1.

[0066] In this embodiment of the application, as described in step S140, Bailey bridge panels 4 and disc-lock brackets 5 are sequentially installed on the main I-beam 3 according to the load of the existing bridge 1.

[0067] Specifically, based on the load on the existing bridge 1, the model of Bailey section 4 is determined. Based on the load on Bailey section 4 and the load transferred to the existing bridge 1 below through stress analysis, the model of Bailey section 4 is determined to make the stress more stable and balanced. This application adopts Bailey section 4 421. Bailey section 4 is installed on the main I-beam 3 according to the model of Bailey section 4. Disc buckle bracket 5 is installed on the top of Bailey section 4.

[0068] It should be noted that the six supports of the upper span box girder are usually supported by 321 steel pipe Bailey supports. The supports are subjected to point loads on the steel pipes. Uneven point loads can easily lead to stress concentration, causing stress and strain at certain points on the bridge, resulting in damage and safety hazards.

[0069] In this embodiment, the optimization is a Bailey bridge + disc-lock scaffold 5. The disc-lock scaffold 5 includes uprights 51, horizontal bars 52, vertical diagonal bars 53, and multiple steel pipe supports 54. The uprights 51, horizontal bars 52, and vertical diagonal bars 53 are interconnected to form a grid frame. The multiple steel pipe supports 54 are inclinedly arranged on opposite sides of the top of the disc-lock scaffold 5 to form inclined opposite sides for supporting the side formwork 62 of the upper span box girder 6. The top of the uprights 51 is provided with a top support 55, and the bottom of the uprights 51 is provided with a bottom support 56. The height of the uprights 51 is determined by one side. Lowering the beam to the other side creates a variable cross-section for the upper box girder 6. Under the action of the vertical diagonal braces 53 of the disc-lock scaffold 5, the inclined steel pipe supports 54, and the top and bottom supports 55 and 56, the scaffold is transformed from being subjected to point loads on the steel pipes to line loads on the Bailey panels 4. The scaffold load is evenly transferred through the leveling layer 2 to the solid section of the existing bridge 1 support, and then sequentially transferred to the cap beam → pier → pile foundation. This fully utilizes the existing bridge substructure and foundation as the foundation for the cast-in-place scaffold, ensuring foundation stability and uniform and reasonable stress distribution, which is beneficial to the safety of both the scaffold and the existing bridge structure. Utilizing the existing piers as the main support not only saves on foundation treatment costs and reduces construction procedures, but also accelerates the construction cycle and greatly improves the safety of scaffold erection and dismantling.

[0070] As an example, the steps of installing Bailey bridge section 4 on the main I-beam 3 according to the model of Bailey bridge section 4 are as follows: setting up a support frame 7 on the side of the existing bridge 1; installing Bailey bridge section 4 on the main I-beam 3 according to the model of Bailey bridge section 4, wherein the bottom end of Bailey bridge section 4 is supported on the support frame 7, and a separate support frame 7 is set at the end of Bailey bridge section 4 to bear the load of Bailey bridge section 4 exposed outside the existing bridge 1.

[0071] In this embodiment of the application, as described in step S150, a variable cross-section cast-in-place box girder 6 is constructed on the disc-lock bracket 5.

[0072] Specifically, a bottom formwork 61 and a side formwork 62 are installed at the bottom of the disc-lock bracket 5; water bags are used to pre-press the bottom formwork 61 and the side formwork 62; after pre-pressing, the steel bars of the box girder 6 are tied and the inner formwork and the top formwork are installed; the box girder 6 is grouted; during the water bag pre-pressing and grouting process, intelligent detection equipment is used to continuously detect the stress and strain of the upright 51, and an early warning is issued when the stress and strain exceed the stress and strain threshold range. Water bags were formed by making full use of surrounding water resources and pre-pressurized for about seven days. Intelligent detection equipment for the support was used to collect and warn of the stress and strain of the uprights 51 during pre-pressurization and pouring. The main reinforcement of the crossbeams of box girder 6 was welded using MIG welding. MIG welding (carbon dioxide gas shielded welding) is suitable for welding various large steel structure projects of low carbon steel and low alloy high strength steel. It has high welding productivity, good crack resistance, small welding deformation, and a wide range of adaptable deformation. It can be used for welding thin and medium-thick plates. Prestressed snap-fit ​​corrugated pipe joints were used to improve the sealing performance of the corrugated pipes and avoid grout leakage during concrete pouring, which greatly improved the construction efficiency of the overpass and the solid quality of box girder 6.

[0073] As an example, as described in the following steps, after the casting is completed, the box girder 6 is cured, prestressed, and grouted. After these steps are completed, the support can be removed. The construction of the upper span box girder 6 is then completed.

[0074] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A construction method for a variable cross-section cast-in-place beam parallel to an existing bridge, characterized in that, The steps include the following: Three-dimensional modeling and analysis of the existing bridge were performed to determine the stress load on the existing bridge. The process of casting a leveling layer on the top surface of the piers of the existing bridge according to the load of the existing bridge includes: determining the size of the leveling layer according to the load of the existing bridge; and casting the leveling layer on the top surface of the piers of the existing bridge according to the size of the leveling layer. Installing main I-beams on the top of the leveling layer along the transverse direction of the existing bridge, based on the load-bearing capacity of the existing bridge, includes: determining the model and number of main I-beams based on the load-bearing capacity of the existing bridge; and installing the main I-beams on the top of the leveling layer along the transverse direction of the existing bridge based on the model and number of main I-beams. Based on the load-bearing capacity of the existing bridge, Bailey bridge sections and disc-locked brackets are installed sequentially on the main I-beam, including: determining the model of the Bailey bridge section based on the load-bearing capacity of the existing bridge; installing the Bailey bridge section on the main I-beam according to the model of the Bailey bridge section; and installing disc-locked brackets on the top of the Bailey bridge section. A variable cross-section cast-in-place box girder is constructed on the aforementioned disc-lock bracket; The disc buckle bracket includes uprights, horizontal bars, vertical diagonal bars, and multiple steel pipe supports. The uprights, horizontal bars, and vertical diagonal bars are connected to each other to form a grid frame. The multiple steel pipe supports are inclined on opposite sides of the top of the disc buckle bracket to form inclined opposite sides. The top of the upright is provided with a top support, and the bottom of the upright is provided with a bottom support. The height of the upright decreases from one side to the other.

2. The construction method for a variable cross-section cast-in-place beam parallel to an existing bridge as described in claim 1, characterized in that, The steps of performing three-dimensional modeling and analysis on existing bridges to determine the loads on the existing bridges include: Measurement points were taken from the existing bridge using surveying instruments; The measured data is imported into the software, and the software is used to create a three-dimensional model of the existing bridge. Stress analysis was performed on the 3D model to determine the stress load on the existing bridge.

3. The construction method for a variable cross-section cast-in-place beam parallel to an existing bridge as described in claim 1, characterized in that, The step of installing Bailey panels on the main I-beam according to the model of the Bailey panel includes: A support frame is installed on the side of the existing bridge; According to the model of the Bailey bridge section, Bailey bridge sections are installed on the main I-beam, wherein the bottom end of the Bailey bridge section is supported on the support frame.

4. The construction method for a variable cross-section cast-in-place beam parallel to an existing bridge as described in claim 1, characterized in that, The steps for constructing the variable cross-section cast-in-place box girder on the disc-lock bracket include: A bottom template and side template are installed at the bottom of the disc buckle bracket; The bottom template and the side template are pre-compressed using water bags; After prestressing is completed, the box girder reinforcement is tied and the inner and top formwork is installed; The box girder was then grouted.

5. The construction method for a variable cross-section cast-in-place beam parallel overpass of an existing bridge according to claim 4, characterized in that, The step of constructing the variable cross-section cast-in-place box girder on the disc-lock bracket further includes: After the casting is completed, the box girder is cured, prestressed, and grouted.

6. The construction method for a variable cross-section cast-in-place beam parallel to an existing bridge as described in claim 4, characterized in that, The step of constructing the variable cross-section cast-in-place box girder on the disc-lock bracket further includes: During the water bag pre-pressurization and grouting process, intelligent detection equipment is used to continuously detect the stress and strain of the uprights and issue warnings when the stress and strain exceed the stress and strain threshold range.

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