Fabricated steel portal cover beam structure and construction method for construction across existing operating channel

Abstract

The application relates to the technical field of road and bridge construction, and discloses a fabricated steel portal cover beam structure for construction across an existing operating channel and a construction method thereof. The structure comprises a steel cover beam, a steel column arranged at one end of the steel cover beam, and a first supporting column and a second supporting column respectively arranged at the other end of the steel cover beam and below the steel column; the steel cover beam is fixedly connected with the steel column to form an L-shaped integral structure, one end of the steel cover beam is hingedly connected with the first supporting column, and the other end is fixedly connected with the second supporting column through the steel column; the second supporting column comprises a concrete platform body and a steel-concrete joint section above the concrete platform body, and the steel-concrete joint section comprises a steel column, outer wrapped reinforced concrete and internally filled concrete of the steel column. The application further provides a fabricated construction method, which realizes structure fixation by integral prefabrication and hoisting, combined with temporary connection and subsequent concrete construction. The scheme can reduce construction interference, shorten the construction period and reduce the engineering cost.

Description

Technical Field

[0001] This invention relates to the field of road and bridge construction technology, specifically to a prefabricated steel gantry girder structure and construction method for construction across existing operational passages. Background Technology

[0002] In the construction of highway and municipal bridges, it is common to encounter situations where the bridge superstructure needs to cross existing operating roads, ramps, or other traffic channels. This is especially true in highway interchange areas, where ramp traffic organization is complex and traffic volume is high, placing a strong emphasis on maintaining the normal operation of existing channels during construction. Therefore, how to complete the construction of the overpass structure without interrupting or minimizing the impact on existing traffic has become a crucial technical challenge in the field of bridge engineering.

[0003] In existing technologies, cap beam structures spanning existing operational roads typically employ cast-in-place prestressed concrete portal piers. This structure generally consists of two concrete piers and a monolithically cast concrete cap beam, rigidly connected to form a portal-shaped load-bearing system. While this type of structure offers good overall integrity and clearly defined stress distribution, construction often requires the erection of large-scale scaffolding or temporary support structures beneath the cap beam, sometimes even occupying existing road space, thus significantly disrupting traffic below. Furthermore, the construction cycle for concrete structures is lengthy, involving multiple stages such as formwork erection, concrete pouring, and curing, resulting in a prolonged impact on existing roads and often failing to meet traffic organization and safety management requirements in practical engineering.

[0004] In railway overpass engineering, due to the stricter requirements for the continuity of railway operation, closed construction is often difficult. Therefore, the portal frame cap beam structure, primarily based on steel structures, has gradually developed. This type of structure often adopts an all-steel portal frame system, with the cap beam and the steel columns on both sides forming an integrated load-bearing system through rigid connections. Compared to cast-in-place concrete structures, steel structures have advantages such as prefabrication of components and faster on-site installation, which can reduce interference with existing lines to some extent. However, this type of structure typically uses a double-sided fixed connection, with both the cap beam and columns participating in the load-bearing process as compression-bending members. To ensure structural stability, numerous stiffening structures are required, resulting in a large amount of steel consumption. Furthermore, due to the significant unbalanced internal forces generated by the structural system, the foundation bearing capacity requirements are high, often necessitating the use of pile foundations, leading to increased project costs.

[0005] In addition, some highway overpass construction projects have adopted steel-concrete composite portal girder structures. For example, steel sleeves are installed at the pier locations to combine the steel and concrete structures, balancing structural performance and construction convenience. However, this type of solution still has certain limitations in practical applications. For instance, the limited internal working space during on-site installation of the steel sleeve structure hinders welding, making it difficult to guarantee connection quality. Furthermore, the concrete inside the sleeve, as a crucial load-bearing component, is difficult to effectively inspect after construction, and any defects are difficult to repair promptly. Moreover, such structures often need to function as both formwork and load-bearing structures, resulting in relatively complex construction processes and high requirements for on-site construction conditions.

[0006] In summary, existing cap beam construction technologies for crossing existing operational passageways still have shortcomings in terms of construction interference, construction period, structural economy, and the rationality of steel-concrete composite section construction. There is an urgent need to propose a new technical solution that can reduce the impact on existing traffic, simplify construction processes, and improve construction efficiency while meeting structural safety and load-bearing performance requirements. Summary of the Invention

[0007] The purpose of this invention is to address the problems existing in the prior art when constructing across existing operational passages, such as large construction interference, long construction period, large amount of structural steel, high foundation cost, and complex structure of steel-concrete composite sections, making it difficult to control construction quality. The invention provides a prefabricated steel gantry beam structure and its construction method for constructing across existing operational passages, so as to reduce the impact on the operation of existing passages and improve construction efficiency and structural economy while ensuring structural safety and load-bearing performance.

[0008] To achieve the above objectives, the present invention provides a prefabricated steel gantry cap beam structure for construction across existing operational channels, comprising a horizontally arranged steel cap beam and a vertically arranged steel column at one end of the steel cap beam, wherein the steel column is fixedly connected to the steel cap beam and together forms an L-shaped integral steel component. It also includes a first support column located below the other end of the steel cap beam and a second support column located below the steel column; The end of the steel cap beam near the first support column is hinged to the first support column via a support. The steel column is inserted into the upper part of the second support column and is fixedly connected to the second support column. The second support column includes a lower concrete platform and a steel-concrete composite section located above the concrete platform. The steel-concrete composite section includes the steel column, an outer reinforced concrete covering the outside of the steel column, and concrete filling the inside of the steel column. The outer reinforced concrete and the concrete platform are continuously connected by steel bars.

[0009] In some embodiments, the steel cap beam adopts a single-box single-cell box structure, including a top plate, two web plates and a bottom plate, wherein the top plate, two web plates and the bottom plate enclose a closed box cell; The steel cap beam is provided with transverse diaphragms and stiffening ribs inside. The transverse diaphragms are located at the support positions of the upper beams and slabs, and the top of the transverse diaphragms is provided with a local support and stiffening structure. The top plate is provided with longitudinal stiffening ribs, and the web plate is provided with longitudinal stiffening ribs and vertical stiffening ribs.

[0010] In some embodiments, the steel column adopts a single-box, single-cell box-shaped structure, which is formed by four side plates enclosing a box-shaped cross-section; Among them, the two steel column side plates that are coplanar with the web of the steel cap beam adopt a whole plate connection structure with the web of the steel cap beam, and the other two steel column side plates are connected to and fixed to the transverse diaphragm or connecting diaphragm in the steel cap beam.

[0011] In some embodiments, the outer surface of the steel column is provided with a plurality of shear-resistant connectors embedded in the outer reinforced concrete to enhance the cooperative stress distribution between the steel column and the outer reinforced concrete.

[0012] In some embodiments, the top of the concrete platform is provided with a pre-embedded connector, and the lower end of the steel column is fixedly connected to the pre-embedded connector to enhance the connection strength between the steel column and the concrete platform. The embedded connector is an embedded steel plate, and the bottom of the steel column is provided with a base plate, which is welded and / or bolted to the embedded steel plate.

[0013] In some embodiments, the top plate of the steel cap beam is provided with reinforced concrete pads at the corresponding positions of the upper beam support, and the top plate of the steel cap beam is also provided with limiting blocks arranged transversely along the bridge. The reinforced concrete pads and the limiting blocks are both connected to the top plate of the steel cap beam through shear-resistant connectors.

[0014] This invention also provides a construction method for prefabricated steel gantry girder spanning existing operational passageways, applicable to the aforementioned prefabricated steel gantry girder structure, comprising the following steps: S1. Prefabricated L-shaped integral steel component: Steel cap beams and steel columns are fabricated in the factory, and the steel columns are fixed to one end of the steel cap beams to form an L-shaped integral steel component; S2. Foundation and substructure construction: Construct the concrete platform at the bottom of the first support column and the second support column, and pre-embed connectors at the top of the concrete platform. S3. Overall hoisting: Hoist the L-shaped integral steel component to the designed position, so that the other end of the steel cap beam is placed at the top support of the first support column; S4. Temporary connection: The lower end of the steel column is fixedly connected to the pre-embedded connector to form a temporary connection. S5. Forming a steel-concrete composite section: pouring reinforced concrete on the outside of the steel column and continuously connecting the reinforced concrete with the concrete platform through steel bars; S6. Pour concrete into the interior of the steel column to form a steel-concrete composite section with an inner filling and an outer enclosure; S7. Construct support pads and / or limiting blocks on the top plate of the steel cap beam, and complete the installation of the upper beam plate.

[0015] In some implementations, the shear connectors on the outer surface of the steel column are installed in the factory.

[0016] In some implementations, the first support column is constructed first, and the second support column is constructed first to the top elevation of the concrete platform, so as to allow the L-shaped integral steel component to be hoisted and positioned. In step S4, the lower end of the steel column is fixed to the pre-embedded connector by welding and / or bolting to form a stable support before the outer reinforced concrete is poured.

[0017] In some embodiments, in step S5, the thickness of the outer reinforced concrete is 20-40 cm; In step S6, the concrete poured inside the steel column is non-shrink concrete.

[0018] Compared with existing technologies, the prefabricated steel gantry girder structure and its construction method for construction across existing operational corridors provided by this invention have the following beneficial effects: Significantly reduces construction disruption to existing traffic flow: This invention employs an L-shaped integrated structure formed by the steel cap beam and steel columns, and utilizes an asymmetrical connection method with one end hinged and the other fixed, eliminating the need for large-scale supports or temporary structures under the crossing area during construction. Combined with the overall hoisting construction method, the crossing structure can be installed in a shorter time, thus avoiding prolonged occupation of existing traffic space, significantly reducing the degree of disruption to operational traffic, and improving construction safety.

[0019] Shortening the construction cycle and improving construction efficiency: This invention prefabricates and assembles the steel cap beams and columns in the factory, requiring only overall hoisting and partial concrete construction on site. This reduces the complex procedures of formwork erection, segmented pouring, and curing found in traditional cast-in-place concrete structures. Furthermore, by first forming temporary connections and then completing the steel-concrete composite section, the structure possesses a stable load-bearing system during the construction phase, significantly shortening the on-site construction cycle and minimizing disruption to existing access routes, thus improving construction efficiency.

[0020] Reduced steel consumption and foundation construction costs: This invention employs an L-shaped structural system with steel columns on one side. Compared to the traditional portal-shaped double-column fixed structure, this reduces the number of steel columns and related stiffening structures on one side, effectively lowering the overall steel consumption. Simultaneously, the use of a load-bearing system with one hinged end and one fixed end reduces the unbalanced bending moment generated by the structure, lowering the requirements for foundation bearing capacity. This allows the foundation form to be optimized from a complex pile foundation to a simpler one, significantly reducing the amount of foundation work and project costs.

[0021] Improving construction convenience and quality controllability: This invention employs a steel column inserted into the concrete structure on the fixed side, with an outer reinforced concrete casing on the outside of the steel column and an inner concrete filling, forming a composite structure of inner filling and outer casing. This structure avoids the welding difficulties caused by limited internal space in traditional steel sleeve solutions. Furthermore, the outer concrete casing has a moderate thickness, providing ample space for construction operations and simplifying the construction process. On the other hand, both the outer concrete casing and the inner filling concrete can be quality controlled and tested using conventional methods, improving the controllability and reliability of construction quality.

[0022] Enhancing structural stability and safety during construction: By installing pre-embedded connectors at the top of the concrete platform and fixing the lower ends of the steel columns to these connectors, a stable temporary load-bearing system can be established before the outer concrete is poured. This ensures good stability of the overall structure after hoisting. Subsequent construction of the outer and inner concrete layers gradually transforms the structure into the final overall load-bearing system, effectively improving structural safety during the construction phase.

[0023] Furthermore, this invention, through the coordinated use of structural design and construction methods, enables the steel structure to undertake the main installation and rapid crossing functions, while the concrete structure bears the long-term stress and stability requirements. During construction, the temporary connections are gradually transformed into a monolithic, fixed structure. This technical solution not only meets the stress performance requirements of bridge structures but also achieves an effective balance between prefabricated construction and structural performance, demonstrating good engineering applicability and promotional value.

[0024] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the prefabricated steel gantry beam structure after construction according to the present invention; Figure 2 This is a schematic diagram of the L-shaped steel cap beam in this invention; Figure 3 This is a diagram showing the connection nodes on one side of the steel cap beam with steel columns; Figures 4-8 This is a simplified diagram of the construction process.

[0026] Explanation of reference numerals in the attached figures 1-Steel cap beam; 2-Steel column; 3-First support column; 4-Second support column, 4a-Concrete platform, 4b-Steel-concrete composite section; 5-Support; 6-Shear connector; 7-Limit stop; 8-Reinforcing steel. Detailed Implementation

[0027] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0028] In this invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the orientation in the assembled and used state. "Inner" and "outer" refer to the inner and outer sides relative to the outline of each component itself.

[0029] I. Prefabricated steel gantry cap beam structure (see attached document) Figure 1 ) This invention provides a prefabricated steel gantry girder structure for construction across existing operational passages. The structure is an asymmetrical gantry system, used to achieve cross-support of the bridge superstructure without affecting or minimizing the impact on the normal operation of the existing passage.

[0030] The prefabricated steel gantry cap beam structure includes a steel cap beam, a steel column at one end of the steel cap beam, a first support column at the other end of the steel cap beam, and a second support column at the bottom of the steel column.

[0031] The steel cap beam is arranged transversely along the bridge to bear the load transferred from the superstructure. The steel columns are arranged vertically and fixed to one end of the steel cap beam. The two are welded together in the factory to form an integrated structure, thus constituting an L-shaped integral steel component. By pre-assembling the steel cap beam and steel columns into an integral structure, it can be installed on-site in a single hoisting operation, reducing on-site assembly work.

[0032] In terms of support structure, the end of the steel cap beam furthest from the steel column is connected to the first supporting column via a support, forming a hinged connection that allows rotational constraints to be released at that end. The lower end of the steel column is inserted into the upper part of the second supporting column and forms a fixed connection with it, thus creating an asymmetric force-bearing system with one end hinged and the other fixed. This connection method allows the structure to meet load-bearing capacity requirements while reducing structural constraints and optimizing the stress state.

[0033] The first supporting column is preferably a concrete pier structure with a support mounting area at its top for supporting the end of the steel cap beam. The second supporting column includes a lower concrete platform and a steel-concrete composite section structure located thereon. The steel-concrete composite section is composed of a steel column body, an outer reinforced concrete covering the outside of the steel column, and concrete filling the inside of the steel column. The outer reinforced concrete and the lower concrete platform are continuously connected by reinforcing bars, thereby forming an integral load-bearing system between the steel column and the concrete structure.

[0034] The lower end of the steel column is connected to the top of the concrete platform through a pre-set embedded connector. During the structural installation stage, the lower end of the steel column and the embedded connector form a fixed connection to provide stable support during the construction stage. After the subsequent construction of the outer concrete and the inner filling concrete is completed, the connection works together with the steel-concrete joint section to form the final fixed connection state.

[0035] Through the above overall structural arrangement, the present invention can complete the installation and stress transfer of the cap beam structure in the area crossing the existing passage without setting up a temporary support system. At the same time, through the combination of L-shaped integral steel components and asymmetrical connection methods, the structure has good stability and stress performance in both the construction and use stages, providing a foundation for subsequent prefabricated construction.

[0036] II. Steel cap beam structure (see attached document) Figure 2 ) The steel cap beam is the main load-bearing component in the prefabricated steel portal cap beam structure of this invention. It is arranged transversely along the bridge and is used to bear the load transmitted by the upper beam and slab structure, and to transmit the load to the first support column on the hinged side and the steel column on the fixed side respectively.

[0037] In this embodiment, the steel cap beam preferably adopts a single-box, single-cell closed box girder structure, which is formed by a top plate, a bottom plate, and web plates on both sides to enclose the box. This closed section form has high overall stiffness, especially in terms of torsional performance, and can effectively resist the torsional effect caused by the eccentric loading or asymmetrical arrangement of the superstructure, thereby ensuring the stability of the structure during the construction and operation phases.

[0038] To improve the local stability of the steel cap beam under compression and bending conditions, longitudinal stiffeners are installed along the longitudinal direction on its top plate and web; simultaneously, vertical stiffeners are installed along the vertical direction on the web to enhance its buckling resistance. This combined arrangement of longitudinal and vertical stiffening structures allows the steel cap beam to meet strength and stability requirements even with a relatively small plate thickness, thus optimizing steel consumption while ensuring structural performance.

[0039] Inside the steel cap beam, a transverse diaphragm structure is installed according to the stress requirements. The diaphragms are preferably located at the support positions of the upper beams, creating localized areas of high stiffness to withstand concentrated loads transmitted from the upper beams through supports or pads. The diaphragms can connect with the top plate, web, and bottom plate, thereby effectively distributing the concentrated loads throughout the entire box girder structure.

[0040] At the top of the diaphragm, a local support stiffening structure can be further installed to enhance the load-bearing capacity of the top plate in the support area and prevent local deformation or buckling under concentrated loads.

[0041] The connection between the steel cap beam and the steel column is located at one end of the steel cap beam. As a key part of the structure, the cross-sectional structure and internal partition arrangement of this connection area can be appropriately strengthened according to the stress conditions to ensure the smooth transmission of force between the steel cap beam and the steel column and avoid significant stress concentration.

[0042] Through the above structural design, the steel cap beam can not only meet the basic function of load transfer of the bridge superstructure, but also has good overall stiffness, torsional performance and local stability, providing a reliable guarantee for the stress safety of the entire L-shaped gantry structure.

[0043] III. Steel columns and their connection structure with steel cap beams The steel column is set at one end of the steel cap beam to transfer the load transmitted by the steel cap beam downward to the second support column, and to bear the main vertical load and bending moment transmission in the overall structure.

[0044] In this embodiment, the steel column preferably adopts a single-box, single-cell box-shaped cross-section structure, which is formed by multiple side plates enclosing a closed section. This box-shaped structure has high overall stiffness and stability, which can effectively improve the resistance to instability under compression and bending stress, and at the same time provide a good structural foundation for the subsequent steel-concrete composite section construction.

[0045] The steel columns and steel cap beams are fabricated as a single unit in the factory and then welded together to form an L-shaped integral steel component. This integrated connection method avoids the construction complexities of on-site splicing while ensuring the integrity and structural continuity of the connection area.

[0046] In terms of specific connection construction, the steel columns and steel cap beams adopt a zoned connection method: The two steel column side plates that are on the same plane as the web of the steel cap beam adopt a whole plate connection structure with the web of the steel cap beam. That is, the steel column side plates are integrally formed with the web of the steel cap beam or are spliced ​​together to form a continuous component, so that the force flow is continuously transmitted in this direction, reducing the stress concentration at the connection. The other two steel column side plates, which are not coplanar with the web of the steel cap beam, are connected to the transverse diaphragms or connecting diaphragms inside the steel cap beam and are rigidly connected by welding, thereby forming a stable force path in the direction perpendicular to the web.

[0047] The combination of the above-mentioned integral plate connection and the top-to-top connection of the partition plate forms a spatial force-coordination system between the steel column and the steel cap beam. This ensures the continuity in the main force direction and realizes the force transmission in the lateral and torsional directions through the internal partition structure, thereby significantly improving the overall stiffness and stress reliability of the node area.

[0048] Inside the steel column, longitudinal and transverse stiffening structures can be set according to the stress requirements to improve its local stability and prevent local buckling under compression and bending conditions; in the connection area between the steel column and the steel cap beam, the stiffening structure can be appropriately densified to further enhance the load-bearing capacity of the joint area.

[0049] Through the above structural design, the steel column can not only serve as a vertical load-bearing component to stably transfer the load, but also the overall connection structure formed between it and the steel cap beam can effectively ensure the stress continuity of the L-shaped gantry system, providing a reliable foundation for the formation of the subsequent steel-concrete composite section and the stress of the overall structure.

[0050] IV. Steel-concrete composite section structure on the fixed side (see attached document) Figure 3 ) The lower end of the steel column is fixedly connected to the second support column through a steel-concrete composite section. This composite section is used to reliably transfer the bending moment and axial force borne by the steel column to the lower concrete structure and form a stable fixed end constraint in the overall structure.

[0051] The second supporting column includes a lower concrete platform and a steel-concrete composite section structure located on top of it. The steel-concrete composite section uses a steel column as its core, combined with an outer reinforced concrete casing and an inner infill concrete structure to form a composite load-bearing system.

[0052] Specifically, the lower end of the steel column is inserted into the upper part of the second support column, so that the steel column is partially embedded in the subsequently formed concrete structure, forming an insert-type connection structure. Multiple shear connectors are provided on the outer surface of the steel column along the circumferential and height directions to enhance the bonding performance and shear capacity between the steel column and the outer concrete, thereby ensuring that the two can work together during the stress process.

[0053] An outer layer of reinforced concrete is poured on the outside of the steel column to form a covering structure around the steel column. This outer concrete is continuously connected to the lower concrete platform through pre-placed steel bars, making the outer concrete and the concrete platform an integral whole, thereby further transferring the internal forces transmitted by the steel column to the foundation structure.

[0054] After the outer concrete reaches a certain strength, concrete is poured into the interior of the steel column, forming a filling structure inside. Through the combined action of the outer and inner concrete, a composite structural system of inner filling and outer cladding is formed, transforming the steel column from a single steel component into a steel-concrete composite component, thereby improving its overall stability and enhancing its compressive and bending resistance.

[0055] In addition, pre-embedded connectors are installed at the top of the concrete platform, and the lower end of the steel column is fixedly connected to the pre-embedded connectors after hoisting into place. This connection serves as temporary support before the outer concrete is poured, giving the steel column stability during the construction phase; after the outer concrete and internal filling concrete are completed, this connection works together with the steel-concrete composite section to form the final fixed connection system.

[0056] Through the above construction, the steel column is embedded into the concrete structure in an insert manner, and together with the outer concrete and the inner filling concrete, a composite force-bearing system is formed. This not only avoids the problem of limited construction space in the closed steel sleeve structure, but also improves the operability of the construction process and the controllability of the structural quality. Furthermore, through the synergistic force-bearing of steel and concrete, the fixed side has good rigidity and load-bearing capacity, thereby meeting the force requirements of the entire portal frame structure.

[0057] V. Hinged Side Connection Structure In this embodiment, the end of the steel cap beam away from the steel column is connected to the first support column through a hinged connection structure to form a hinged end in the structural system, thereby forming an asymmetric force system with one end hinged and the other end fixed together with the fixed side.

[0058] Specifically, the first support column is preferably a reinforced concrete pier structure, with a support portion at its top for installing the bearing. This support portion can be leveled and its elevation controlled by setting bearing pads to ensure the stress state and geometric accuracy of the steel cap beam after installation.

[0059] A hinged support is installed on the support pad, and the end of the steel cap beam is supported on the hinged support, thereby realizing a hinged connection between the steel cap beam and the first support column. This hinged connection allows the steel cap beam to rotate within a certain range at this end while bearing vertical loads, thereby releasing bending moment constraints and reducing the overall internal force level of the structure.

[0060] In this hinged-side connection structure, the steel cap beam end only transmits vertical loads and necessary horizontal forces to the first support column through supports, without forming a rigid consolidation relationship, thus avoiding large constraint stresses in the structure. At the same time, this connection method can accommodate minor deformations that may occur during the construction and operation phases, improving the structure's adaptability.

[0061] By setting up the above-mentioned hinged connection structure, the steel cap beam forms a rotatable support at one end, which cooperates with the fixed connection at the other end. This ensures the stability of the structure while optimizing the overall stress state and provides conditions for reducing the internal forces of the foundation and improving the economy of the structure.

[0062] VI. Top Plate Support and Limiting Structure In this embodiment, the top plate of the steel cap beam is used to bear the load of the upper beam structure. In order to ensure that the load can be reliably transferred to the main structure of the steel cap beam and to control the displacement of the upper structure during use, a top plate support structure and a limiting structure are provided on the top plate of the steel cap beam.

[0063] Specifically, reinforced concrete blocks are installed at the support positions of the upper beam slab corresponding to the top plate of the steel cap beam. The reinforced concrete blocks are used to bear the vertical loads transmitted by the upper beam slab through the supports and distribute the loads to the top plate of the steel cap beam, thereby avoiding concentrated loads acting directly on the steel plate and causing local stress concentration or local deformation.

[0064] The reinforced concrete pads are connected to the top plate of the steel cap beam through shear connectors, so that the pads and the steel structure form an integral whole, thus enabling them to work together during the stress process and ensuring the continuity and reliability of the load transfer path.

[0065] In addition, limiting blocks are installed on the top plate of the steel cap beam along the transverse direction of the bridge to limit the lateral movement of the upper beam structure. These limiting blocks are also connected to the top plate of the steel cap beam via shear connectors, ensuring that they can effectively transfer lateral forces to the main structure of the steel cap beam when subjected to them.

[0066] The aforementioned limiting structure can constrain the upper beams in the transverse direction of the bridge, preventing excessive lateral displacement due to load, temperature changes, or other factors during operation, thereby improving the overall stability and safety of the structure.

[0067] By setting reinforced concrete pads and lateral limiting blocks on the top plate of the steel cap beam, the load of the superstructure can be transferred to the steel cap beam through a clear path, while the displacement of the superstructure can be effectively controlled, thereby achieving the unity of load-bearing and limiting functions.

[0068] VII. Prefabricated Construction Methods (See Appendix) Figure 4-8 ) The present invention also provides a prefabricated construction method applicable to the above-mentioned prefabricated steel gantry beam structure, which achieves efficient construction under existing operational conditions by combining factory prefabrication with rapid on-site installation.

[0069] The construction method generally includes stages such as component prefabrication, foundation construction, overall hoisting, temporary connection, formation of steel-concrete composite section and installation of superstructure. Each stage is interconnected, so that the structure gradually transforms from the temporary stress state of the construction stage into the final overall stress system.

[0070] During the component prefabrication stage, the steel cap beams and steel columns are fabricated in the steel structure processing plant, and the steel columns are fixed to one end of the steel cap beams, forming an L-shaped integral steel component. During this process, the shear-resistant connectors on the outer surface of the steel columns can be installed simultaneously, thereby reducing on-site work and improving the degree of prefabrication.

[0071] During the foundation and substructure construction phase, the first support column was constructed on-site, and the second support column was constructed in stages. Specifically, the lower concrete platform of the second support column was constructed first, and connectors were pre-embedded at its top to provide a connection foundation for the subsequent installation of the steel column.

[0072] During the overall hoisting phase, the prefabricated L-shaped steel components are transported to the construction site and hoisted to the designed position using hoisting equipment. During hoisting, the end of the steel cap beam furthest from the steel column is accurately positioned at the support top of the first support column, thus forming a hinged end support.

[0073] During the temporary connection phase, the lower end of the steel column is fixedly connected to the pre-embedded connectors on the top of the concrete platform. The connection method can be welding and / or bolting, so that the steel column can obtain stable support before the steel-concrete joint section is formed, thereby ensuring the safety of the structure during the construction phase.

[0074] In the steel-concrete composite section formation stage, firstly, formwork is erected on the outside of the steel column and reinforced concrete is poured to form an integral connection with the lower concrete platform through steel reinforcement; after the outer concrete reaches the design strength, concrete is poured into the inside of the steel column to form a filling structure inside the steel column, thereby constructing a composite load-bearing system with inner filling and outer wrapping, so that a reliable fixed connection is formed between the steel column and the concrete structure.

[0075] During the installation of the superstructure, reinforced concrete pads and limiting blocks are constructed at the corresponding positions on the top plate of the steel cap beam, and the installation of the superstructure beam and slab structure is completed on them, so that the superstructure load is transferred to the steel cap beam through the pads.

[0076] The above construction method allows the steel structure to form a preliminary stable system immediately after hoisting, and the connection stiffness is gradually increased through subsequent concrete construction, realizing the transformation from a temporary connection to a final fixed connection. This construction method avoids the need to erect a large-scale support system in the crossing area, thereby reducing the time occupied by existing passageways, improving construction efficiency, and minimizing the impact of construction on existing traffic.

[0077] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0078] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0079] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A prefabricated steel gantry girder structure for construction across existing operational passageways, characterized in that, It includes a horizontally arranged steel cap beam and a vertically arranged steel column at one end of the steel cap beam. The steel column is fixedly connected to the steel cap beam and together they form an L-shaped integral steel component. It also includes a first support column located below the other end of the steel cap beam and a second support column located below the steel column; The end of the steel cap beam near the first support column is hinged to the first support column via a support. The steel column is inserted into the upper part of the second support column and is fixedly connected to the second support column. The second support column includes a lower concrete platform and a steel-concrete composite section located above the concrete platform. The steel-concrete composite section includes the steel column, an outer reinforced concrete covering the outside of the steel column, and concrete filling the inside of the steel column. The outer reinforced concrete and the concrete platform are continuously connected by steel bars.

2. The prefabricated steel gantry cap beam structure according to claim 1, characterized in that, The steel cap beam adopts a single-box single-cell box structure, including a top plate, two web plates and a bottom plate, which together form a closed box. The steel cap beam is provided with transverse diaphragms and stiffening ribs inside. The transverse diaphragms are located at the support positions of the upper beams and slabs, and the top of the transverse diaphragms is provided with a local support and stiffening structure. The top plate is provided with longitudinal stiffening ribs, and the web plate is provided with longitudinal stiffening ribs and vertical stiffening ribs.

3. The prefabricated steel gantry cap beam structure according to claim 1, characterized in that, The steel column adopts a single-box, single-cell box-shaped structure, which is formed by four side plates enclosing a box-shaped cross section. Among them, the two steel column side plates that are coplanar with the web of the steel cap beam adopt a whole plate connection structure with the web of the steel cap beam, and the other two steel column side plates are connected to and fixed to the transverse diaphragm or connecting diaphragm in the steel cap beam.

4. The prefabricated steel gantry cap beam structure according to claim 1, characterized in that, The outer surface of the steel column is provided with multiple shear connectors, which are embedded in the outer reinforced concrete to enhance the cooperative stress between the steel column and the outer reinforced concrete.

5. The prefabricated steel gantry cap beam structure according to claim 1, characterized in that, The top of the concrete platform is provided with a pre-embedded connector, and the lower end of the steel column is fixedly connected to the pre-embedded connector to enhance the connection strength between the steel column and the concrete platform. The embedded connector is an embedded steel plate, and the bottom of the steel column is provided with a base plate, which is welded and / or bolted to the embedded steel plate.

6. The prefabricated steel gantry cap beam structure according to claim 1, characterized in that, The top plate of the steel cap beam is provided with reinforced concrete pads at the corresponding positions of the upper beam support. The top plate of the steel cap beam is also provided with limiting blocks arranged in the transverse direction of the bridge. The reinforced concrete pads and the limiting blocks are connected to the top plate of the steel cap beam through shear connectors.

7. A construction method for prefabricated steel gantry girder spanning existing operational passageways, applicable to the prefabricated steel gantry girder structure described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Prefabricated L-shaped integral steel component: Steel cap beams and steel columns are fabricated in the factory, and the steel columns are fixed to one end of the steel cap beams to form an L-shaped integral steel component; S2. Foundation and substructure construction: Construct the concrete platform at the bottom of the first support column and the second support column, and pre-embed connectors at the top of the concrete platform. S3. Overall hoisting: Hoist the L-shaped integral steel component to the designed position, so that the other end of the steel cap beam is placed at the top support of the first support column; S4. Temporary connection: The lower end of the steel column is fixedly connected to the pre-embedded connector to form a temporary connection. S5. Forming a steel-concrete composite section: pouring reinforced concrete on the outside of the steel column and continuously connecting the reinforced concrete with the concrete platform through steel bars; S6. Pour concrete into the interior of the steel column to form a steel-concrete composite section with an inner filling and an outer enclosure; S7. Construct support pads and / or limiting blocks on the top plate of the steel cap beam, and complete the installation of the upper beam plate.

8. The construction method according to claim 7, characterized in that, In step S1, the shear connectors on the outer surface of the steel column are installed in the factory.

9. The construction method according to claim 7, characterized in that, In step S2, the first support column is constructed first, and the second support column is constructed first to the top elevation of the concrete platform so that the L-shaped integral steel component can be hoisted and positioned. In step S4, the lower end of the steel column is fixed to the pre-embedded connector by welding and / or bolting to form a stable support before the outer reinforced concrete is poured.

10. The construction method according to claim 7, characterized in that, In step S5, the thickness of the outer reinforced concrete is 20-40 cm; In step S6, the concrete poured inside the steel column is non-shrink concrete.

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