Steel box girder self-supporting hoisting device and construction method thereof

Abstract

The application discloses a steel box girder self-supporting hoisting device, which is used for sectional hoisting construction of a steel box girder in bridge engineering, and comprises a temporary support mechanism and an adjusting mechanism arranged on the top of the temporary support mechanism; the temporary support mechanism comprises a reinforced concrete foundation support unit, a steel pipe pile foundation support unit and a permanent pier support unit which can be selected according to the working condition of a construction site; the upper end of the adjusting mechanism is fixedly connected with the bottom of a steel box girder to be hoisted, and the lower end is fixedly connected with the top cross beam of the temporary support mechanism; the installation elevation of the adjusting mechanism is higher than the design elevation of the permanent pier of the steel box girder, and the adjusting mechanism has an elevation fine adjustment function. Through the arrangement of the three independently selectable temporary support units, one can be selected according to the working condition of the construction site, so that the poor adaptability of the existing temporary support system is fundamentally solved, and the existing structures and underground pipelines do not need to be damaged in the construction process, thereby greatly reducing the influence of the construction on the surrounding environment.

Description

Technical Field

[0001] This invention relates to the field of bridge engineering technology, specifically to a self-supporting hoisting device for steel box girders and its construction method. Background Technology

[0002] In modern bridge construction, steel box girders are widely used in urban overpasses, cross-track bridges, and other projects due to their advantages such as high structural strength, large span, and convenient construction. Steel box girder bridge projects typically employ a segmented pre-assembly construction method, requiring the installation of temporary supports and other auxiliary components during construction. Therefore, the erection of steel box girders has become a core construction phase in bridge engineering.

[0003] The construction of steel box girder erection is a complex and comprehensive project. During construction, strict control over the bridge alignment, component fit precision, and weld penetration depth is required. Simultaneously, it is necessary to address complex terrain and the frequent occurrence of defects at the connection between new and old bridges. The requirements for project quality and construction safety are extremely high. Existing steel box girder hoisting construction technologies suffer from poor adaptability of temporary support systems, making it difficult to simultaneously meet the demands of various complex working conditions such as complex underground pipelines, insufficient soil bearing capacity, and limited space. In some construction scenarios, the presence of elevated subway structures on top of existing bridges makes the traditional jacking process impractical. Furthermore, traditional construction methods require large site occupancy, have low mechanical construction efficiency, involve cumbersome installation and dismantling of temporary support systems, and incur high material and labor costs. In addition, insufficient precision in controlling the steel box girder alignment leads to frequent weld defects, which can easily affect the overall construction quality and service life of the bridge. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a self-supporting hoisting device for steel box girders and its construction method.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a self-supporting hoisting device for steel box girders, used for segmented hoisting construction of steel box girders in bridge engineering, including a temporary support mechanism and an adjustment mechanism set on the top of the temporary support mechanism; Temporary support structures include reinforced concrete foundation support units, steel pipe pile foundation support units, and permanent pier support units, which can be selected according to the construction site conditions. The upper end of the adjustment mechanism is fixedly connected to the bottom of the steel box girder to be hoisted, and the lower end is fixedly connected to the top crossbeam of the temporary support mechanism. The installation elevation of the adjustment mechanism is higher than the design elevation of the permanent support pier of the steel box girder, so that the self-weight of the steel box girder and the crane construction load during the hoisting process are all transferred to the temporary support mechanism through the adjustment mechanism, forming a self-supporting force system during the hoisting process; The adjustment mechanism has an elevation fine-tuning function, which is used to control the alignment accuracy during the hoisting process of the steel box girder. The adjustment mechanism can also be cut off after the entire steel box girder is welded and formed, so as to complete the conversion of the stress system from a temporary support structure to a permanent support.

[0006] Furthermore, the reinforced concrete foundation support unit includes a reinforced concrete foundation and a lattice-type temporary support pier; The reinforced concrete foundation is a double-layered, bidirectional reinforced concrete structure with embedded support connectors inside. The bottom of the lattice-type temporary support is fixedly connected to the reinforced concrete foundation through the support connector. The top of the lattice-type temporary support is welded with an I-beam support beam, and the lower end of the adjustment mechanism is fixedly connected to the upper flange of the support beam.

[0007] Furthermore, the steel pipe pile foundation support unit includes the steel pipe pile foundation and the lattice-type temporary support pier; The pile body of the steel pipe pile foundation enters the bearing layer, and the pile head of the steel pipe pile foundation is reinforced with a cross-shaped steel pipe welded inside. The bottom of the lattice-type temporary support is fixedly connected to the pile head of the steel pipe pile foundation, and the top support beam is fixedly connected to the lower end of the adjustment mechanism.

[0008] Furthermore, the permanent pier support unit includes the bridge permanent pier and the fish-belly type I-beam temporary crossbeam; the top of the bridge permanent pier is pre-embedded with a clamp structure, which is formed by rolling and welding steel plates and then pre-embedded in the concrete of the permanent pier. The two ends of the temporary crossbeam are hinged to the clamping structure, and the lower end of the adjusting mechanism is fixedly connected to the upper flange of the temporary crossbeam.

[0009] Furthermore, the adjustment mechanism includes a circular adjustment tube, with an annular widening connecting plate integrally provided at both the upper and lower ends of the adjustment tube; the upper annular widening connecting plate is welded and fixed to the bottom of the steel box girder to be hoisted, and the lower annular widening connecting plate passes through the upper flange of the top crossbeam of the temporary support mechanism through an elevation adjustment bolt and is locked and fixed by a nut; the elevation of the adjustment mechanism can be finely adjusted by turning the elevation adjustment bolt.

[0010] Furthermore, a diaphragm stiffening structure is provided on the top plate of the steel box girder at the position corresponding to the crane outrigger position. The diaphragm stiffening structure includes a stiffening plate welded to the diaphragm at the outrigger position, which is used to strengthen the structural strength of the steel box girder at the crane outrigger position and, together with the self-supporting force system, enables the crane to travel on the bridge and carry out lifting operations.

[0011] This invention also provides a self-supporting hoisting construction method for steel box girders, implemented using a self-supporting hoisting device for steel box girders, comprising the following steps: S1: Simulation and segmented design: The steel box girder is divided into segments, and the crane outrigger pressure, temporary support structure stress, steel box girder structural strength and stability are simulated and verified throughout the hoisting process to confirm the construction safety boundary. S2: Temporary support structure installation: Based on the construction site conditions, select reinforced concrete foundation support units, steel pipe pile foundation support units, or permanent pier support units for on-site installation, and install an adjustment mechanism on top of the temporary support structure to control the installation elevation of the adjustment mechanism to be higher than the design elevation of the permanent pier of the steel box girder. S3: Steel box girder hoisting operation: First, complete the ground hoisting and welding of the first span of steel box girder, then drive the crane to the already formed steel box girder bridge deck to carry out the on-bridge hoisting operation of the subsequent spans of steel box girder. During the hoisting process, the elevation of the steel box girder is finely adjusted by the adjustment mechanism to control the bridge alignment. S4: Steel box girder welding and forming: The steel box girder segments hoisted into place are welded laterally and longitudinally, and the welds are subjected to non-destructive testing after welding is completed; S5: Force system conversion and temporary support removal: The temporary support mechanism is unloaded in stages, the adjustment mechanism is cut off, the force system is converted from the temporary support mechanism to the permanent support, and then the temporary support mechanism is dismantled in sections.

[0012] Furthermore, when the underground pipelines are complex and the soil bearing capacity meets the requirements of the bearing layer, reinforced concrete foundation support units are selected; when the soil layer is poor, the bearing layer is deep, and the underground pipeline layout is simple, steel pipe pile foundation support units are selected; when the surrounding area is small and the distance between the bottom of the steel box girder and the ground is limited, permanent pier support units are selected.

[0013] Furthermore, after the steel box girder is hoisted into place, jacks are set on the already hoisted steel box girder segments, and inverted L-shaped steel plates are welded on the subsequently hoisted steel box girder segments. The L-shaped steel plates are pushed down by the jacks to level the steel box girder segments, and then the relative positions of the steel box girder segments are welded and fixed.

[0014] Furthermore, in step S5, during the staged unloading, multiple sets of jacks are set on the top of the temporary support structure directly below the longitudinal web of the steel box girder. After all the jacks are tightened simultaneously, the top support of the temporary support structure is cut in stages and lowered in stages until the load of the steel box girder is completely transferred to the permanent support. When the temporary support structure is dismantled, the lattice structure is cut into sections and then lowered smoothly to the ground for transport by lifting equipment.

[0015] The present invention has the following beneficial effects: The present invention provides a self-supporting hoisting device for steel box girders and its construction method: (1) The present invention provides three types of temporary support units that can be selected independently. The type can be flexibly selected according to the site geology, pipeline distribution and spatial conditions. The reinforced concrete foundation support unit can avoid complex underground pipelines and does not require large-scale excavation; the steel pipe pile foundation support unit can be adapted to scenarios with deep bearing layers such as soft soil and river channels; the permanent pier support unit can be adapted to scenarios with insufficient clearance under the bridge and small site. This fundamentally solves the problem of poor adaptability of the existing temporary support system. During the construction process, there is no need to damage existing structures and underground pipelines, which greatly reduces the impact of construction on the surrounding environment. (2) Through the elevation pre-control design of the adjustment mechanism, the self-weight and crane construction load during the hoisting process of the steel box girder are all transferred to the temporary support mechanism through the adjustment mechanism, forming a complete and clear self-supporting force system, avoiding the load from acting directly on the unformed beam and permanent support, and preventing permanent structural damage; at the same time, in conjunction with the graded unloading process, the force system is smoothly transferred from the temporary support to the permanent support, solving the problems of unclear load transfer and high risk of structural instability in existing construction. (3) This invention, through the reinforcement design of the steel box girder support leg position, combined with the self-supporting force system, enables the crane to travel and lift operations on the already formed steel box girder bridge deck without occupying the area under the bridge and the surrounding area. It is suitable for scenarios such as the connection between new and old bridges, the presence of restricted structures such as elevated subways above, and the small area in urban built-up areas where the jacking process cannot be used or ground lifting cannot be carried out, which greatly expands the scope of application of the steel box girder lifting method. (4) This invention, through the elevation fine-tuning function of the adjustment mechanism, combined with the segmental leveling mechanism of jack + inverted L-shaped steel plate, forms a two-level leveling system, which can accurately control the elevation and alignment of the steel box girder segments at the millimeter level, and completely solve the problem of segment misalignment; at the same time, combined with the full weld non-destructive testing process, it effectively ensures the weld penetration depth, prevents weld cracking, alignment deformation and other operational defects from the root, and significantly extends the service life of the bridge. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall model of the present invention; Figure 2 This is a schematic diagram of the reinforced concrete foundation support unit structure in this invention; Figure 3 This is a schematic diagram of the support pier connector structure in the reinforced concrete foundation support unit of the present invention; Figure 4 This is a schematic diagram of the steel pipe pile foundation support unit structure in this invention; Figure 5 This is a schematic diagram of the permanent support unit structure in this invention; Figure 6 This is a schematic diagram of the clamp structure of the permanent support unit in this invention; Figures 1 to 6 The reference numerals in the attached drawings are respectively: 101-reinforced concrete foundation, 102-lattice temporary support, 103-support connector, 104-I-beam support beam, 105-support beam, 201-steel pipe pile foundation, 301-permanent bridge support, 302-fish-belly type I-beam temporary beam, 303-clamp structure. Detailed Implementation

[0017] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0018] like Figures 1 to 6 As shown, a self-supporting hoisting device for steel box girders is used for segmented hoisting construction of steel box girders in bridge engineering. The device includes a temporary support structure comprising a reinforced concrete foundation support unit, a steel pipe pile foundation support unit, and a permanent pier support unit, selectable according to the construction site conditions. These three support units can be adapted to different construction scenarios, achieving full coverage of complex working conditions and effectively protecting surrounding pipelines and structures.

[0019] An adjustment mechanism is installed at the top of the temporary support structure. The upper end of the adjustment mechanism is fixedly connected to the bottom of the steel box girder to be hoisted, and the lower end is fixedly connected to the top crossbeam of the temporary support structure. The installation elevation of the adjustment mechanism is higher than the design elevation of the permanent support pier of the steel box girder, so that the self-weight of the steel box girder and the crane construction load during the hoisting process are all transferred to the temporary support structure through the adjustment mechanism, forming a self-supporting force system during the hoisting process, avoiding the load from acting directly on the permanent support pier, and ensuring the structural integrity of the permanent support pier.

[0020] The adjustment mechanism has a fine-tuning function for elevation, which can adjust the elevation in real time during the hoisting of the steel box girder, so as to achieve the accuracy control of the alignment during the hoisting process. Moreover, the adjustment mechanism can be cut off after the entire steel box girder is welded and formed, so as to complete the conversion of the stress system from a temporary support structure to a permanent pier, ensuring the structural stability of the bridge in subsequent use.

[0021] In this invention, the reinforced concrete foundation support unit includes a reinforced concrete foundation 101 and a lattice-type temporary support 102, which is suitable for construction scenarios where the underground pipelines are complex and the soil bearing capacity meets the requirements of the bearing layer.

[0022] The reinforced concrete foundation 101 bears all vertical and horizontal loads from the superstructure temporary support 102, the steel box girder, and the crane construction load, evenly distributing the concentrated load to the lower bearing layer of the foundation to ensure that the bearing capacity of the foundation meets the construction requirements and to prevent uneven settlement and overall instability of the system. The reinforced concrete foundation 101 is a double-layer, bidirectional reinforced concrete structure. The double-layer, bidirectional reinforced concrete structure has excellent overall stiffness, crack resistance and resistance to eccentric loads. It can resist the bending and shear stresses generated by the dynamic loads and eccentric loads brought by the upper hoisting operations, prevent foundation cracking and deformation, and ensure the elevation stability of the upper support system throughout the process. The reinforced concrete foundation 101 has a pre-embedded support connector 103. This component is a rigid force transmission intermediate between the reinforced concrete foundation 101 and the lattice temporary support 102 to achieve a reliable anchoring connection between the upper and lower structures. At the same time, it evenly distributes the concentrated load of the column transmitted by the lattice support to a larger section of the reinforced concrete foundation 101, so as to avoid damage to the concrete foundation due to local bearing pressure. The bottom of the lattice-type temporary support 102 is fixedly connected to the reinforced concrete foundation 101 through the support connector 103. The top of the lattice-type temporary support 102 is welded with an I-beam support beam 104. The lower end of the adjustment mechanism is fixedly connected to the upper flange of the support beam 105. The lattice-type temporary support 102 vertically transfers the self-weight of the steel box girder and the crane construction load transmitted by the upper I-beam support beam 104 to the lower reinforced concrete foundation 101. At the same time, through its own height design, it adapts to the clearance requirements under the bridge between the design elevation of the steel box girder and the ground, raising the support point from the ground to the design elevation of the bottom of the beam. The lattice-type temporary support 102 adopts a lattice structure of steel pipe columns and angle steel / channel steel welded together. Compared with a single column, it has extremely strong longitudinal bending resistance, lateral shear resistance and overturning resistance. It can effectively resist dynamic loads, eccentric loads and horizontal wind loads during hoisting, avoid structural instability and deformation, and ensure the safety of hoisting operations.

[0023] In this invention, the steel pipe pile foundation support unit includes a steel pipe pile foundation 201 and a lattice-type temporary support 102. It is suitable for construction scenarios with poor soil conditions, deep bearing strata, and simple underground pipeline layout, such as construction across rivers or in soft soil areas. The structure of the lattice-type temporary support 102 is completely identical to that of the lattice-type temporary support 102 in the reinforced concrete foundation support unit. The pile body of the steel pipe pile foundation 201 enters the bearing layer. The pile head of the steel pipe pile foundation 201 is welded with a cross-shaped steel pipe reinforcement structure. The bottom of the lattice-type temporary support pier 102 is fixedly connected to the pile head of the steel pipe pile foundation 201, and the top support beam 105 is fixedly connected to the lower end of the adjustment mechanism. The steel pipe pile foundation 201 adopts a steel pipe pile structure. During construction, the steel pipe piles are driven into the soil layer using a vibratory pile driving process, ensuring the bearing capacity of the foundation. The pile heads are reinforced with cross-shaped steel pipes welded inside, effectively resisting load changes during the installation and hoisting of the temporary supports, preventing pile head deformation, and improving the stability of the foundation structure. The bottom of the lattice-type temporary support 102 is welded and fixed to the pile head of the steel pipe pile foundation 201, and the top supporting beam 105 is fixedly connected to the lower end of the adjustment mechanism.

[0024] In this invention, the permanent pier support unit includes a permanent bridge pier 301 and a fish-belly-shaped I-beam temporary crossbeam 302, which is suitable for construction scenarios where the surrounding area is small, the distance between the bottom of the steel box girder and the ground is limited, and the clearance under the bridge is insufficient.

[0025] The top of the permanent bridge pier 301 is pre-embedded with a clamp structure 303. The clamp structure 303 is made of steel plate rolled and welded and then pre-embedded in the concrete of the permanent pier. The two ends of the temporary crossbeam are hinged and fixed to the clamp structure 303, and the lower end of the adjustment mechanism is fixedly connected to the upper flange of the temporary crossbeam. The permanent pier 301 is a permanent structure designed for the bridge. During the concrete pouring process of the permanent pier, a clamp structure 303 is pre-embedded at its top. The clamp structure 303 is made of rolled and welded steel plate and is pre-embedded in the top concrete of the permanent pier, forming an integral structure with the permanent pier, which has extremely strong pull-out resistance and load-bearing capacity. The two ends of the fish-belly-shaped I-beam temporary crossbeam 302 are hinged to the clamp structures 303 on both sides of the permanent pier through a hinged structure. The hinged connection can adapt to minor deformations during construction and avoid additional stress on the structure. The lower end of the adjustment mechanism is fixedly connected to the upper flange of the temporary crossbeam, eliminating the need for a foundation on the ground, which is perfectly suited to scenarios with insufficient clearance and limited space under the bridge.

[0026] In this invention, the adjustment mechanism includes a circular adjustment tube body, which is made of steel pipe, resulting in uniform stress distribution and strong load-bearing capacity; both the upper and lower ends of the adjustment tube body are integrally provided with annular widening connecting plates, which are welded perpendicularly to the adjustment tube body, greatly increasing the connection contact area and improving connection stability. The upper annular widening connecting plate is welded and fixed to the bottom of the steel box girder to be hoisted. The lower annular widening connecting plate passes through the upper wing plate of the top crossbeam of the temporary support mechanism through the elevation adjustment bolt and is locked and fixed with nuts. During construction, the overall height of the adjustment mechanism can be adjusted by turning the nuts of the elevation adjustment bolts, so as to achieve fine adjustment of the elevation of the adjustment mechanism and millimeter-level fine adjustment of the elevation of the steel box girder. It is convenient to operate, has high leveling accuracy, and accurately controls the bridge alignment.

[0027] In this invention, a stiffening structure is provided on the top plate of the steel box girder at the position corresponding to the crane outrigger position. The stiffening structure includes a stiffening plate welded to the stiffening plate at the outrigger position, which is used to strengthen the structural strength of the steel box girder at the crane outrigger position and, together with the self-supporting force system, enables the crane to travel on the bridge and carry out lifting operations. The stiffening plates welded to the corresponding diaphragms of the outrigger positions can significantly improve the out-of-plane stiffness, shear capacity and bending performance of the diaphragms, and quickly and evenly distribute the concentrated load of the outriggers to the web and longitudinal main structure of the steel box girder, avoiding local stress concentration and eliminating local structural damage to the steel box girder during construction from the root, thus ensuring the safety of the beam structure. When the crane moves to a new location, the outrigger load is a moving dynamic load. The diaphragm stiffening structure can ensure that the steel box girders at all preset positions along the outrigger movement path have sufficient bearing capacity, avoiding plastic deformation and fatigue micro-cracks in the beam during the movement process, and eliminating potential operational defects after the bridge is completed from the root.

[0028] This invention also provides a self-supporting hoisting construction method for steel box girders, implemented using a self-supporting hoisting device for steel box girders, comprising the following steps: S1: Simulation and segmented design: Based on the overall design requirements of the bridge project, the steel box girder is divided into segments. At the same time, the crane outrigger pressure, temporary support structure stress, steel box girder structural strength and stability are simulated and verified throughout the hoisting process to confirm the construction safety boundary. S2: Temporary support structure installation: Based on the construction site conditions, select reinforced concrete foundation support units, steel pipe pile foundation support units, or permanent pier support units for on-site installation, and install an adjustment mechanism on top of the temporary support structure to control the installation elevation of the adjustment mechanism to be higher than the design elevation of the permanent pier of the steel box girder. When the underground pipelines are complex and the soil bearing capacity meets the requirements of the bearing layer, reinforced concrete foundation support unit is selected; when the soil layer is poor, the bearing layer is deep, and the underground pipeline layout is simple, steel pipe pile foundation support unit is selected; when the surrounding area is small and the distance between the bottom of the steel box girder and the ground is limited, permanent pier support unit is selected. Among them, when installing the reinforced concrete foundation support unit, the foundation trench is first constructed by open excavation, and then the reinforced concrete foundation 101 is formed by the process of erecting formwork, tying steel bars, pouring concrete, and removing formwork for curing. Before pouring concrete, the support pier connector 103 is pre-embedded. When installing the steel pipe pile foundation support unit, the steel pipe pile foundation 201 is constructed by the process of surveying and setting out, lifting steel pipe piles, vibratory pile driving, and cutting pile heads. The cross-shaped steel pipe reinforcement structure is welded at the pile head. When installing the permanent support pier support unit, the clamp structure 303 is pre-embedded at the top of the permanent support pier, and then the fish-belly type I-beam temporary crossbeam 302 is hinged and fixed to the clamp structure 303.

[0029] S3: Steel box girder hoisting operation: First, complete the ground hoisting and welding of the first span of steel box girder, then drive the crane to the already formed steel box girder bridge deck to carry out the on-bridge hoisting operation of the subsequent spans of steel box girder. During the hoisting process, the elevation of the steel box girder is finely adjusted by the adjustment mechanism to control the bridge alignment. After the steel box girder is hoisted into place, jacks are set on the already hoisted steel box girder segments, and inverted L-shaped steel plates are welded on the subsequently hoisted steel box girder segments. The L-shaped steel plates are pushed down by the jacks to level the steel box girder segments. After leveling, the relative positions of the steel box girder segments are welded and fixed. Specifically, a crane is first used to hoist the first span of the steel box girder into sections on the ground. After the steel box girder sections are hoisted to the designated positions and initially fixed, the entire first span of the steel box girder is then welded together. After the first span of the steel box girder is formed, the crane is driven onto the bridge deck of the formed steel box girder to carry out the on-bridge hoisting operation for the subsequent spans of the steel box girder. Roadbed boxes are set at the positions of the crane outriggers to ensure that the outriggers are evenly stressed. After the steel box girder sections are hoisted into place, jacks are set on the already hoisted steel box girder sections, and inverted L-shaped steel plates are welded onto the subsequently hoisted steel box girder sections. The L-shaped steel plates are pushed down by the jacks to precisely level the steel box girder sections. After leveling, the relative positions of the steel box girder sections are welded and fixed. During the hoisting process, the elevation of the steel box girder is finely adjusted by turning the elevation adjustment bolts of the adjustment mechanism to achieve high-precision control of the bridge alignment.

[0030] S4: Steel box girder welding and forming: The steel box girder segments hoisted into place are welded laterally and longitudinally, and the welds are subjected to non-destructive testing after welding is completed; Specifically, after the steel box girder segments are leveled and fixed, the transverse welding of the steel box girder is carried out first. After the transverse welding is completed to form a span, the longitudinal welding of the steel box girder is carried out. Solid core welding wire carbon dioxide gas shielded welding is used during the welding process to improve the welding quality. After all welding operations are completed, the welds are subjected to comprehensive non-destructive testing to promptly identify welding defects, prevent weld diseases, and ensure the structural strength and service life of the steel box girder. S5: Load-bearing system conversion and temporary support removal: The temporary support structure is unloaded in stages, the adjustment mechanism is cut off, and the load-bearing system is converted from the temporary support structure to the permanent support. Then, the temporary support structure is dismantled in sections. During the staged unloading, multiple sets of jacks are set on the top of the temporary support structure directly below the longitudinal web of the steel box girder. After all the jacks are tightened simultaneously, the top support of the temporary support structure is cut in stages and lowered in stages until the load of the steel box girder is completely transferred to the permanent support. During the dismantling of the temporary support structure, the lattice components are cut into sections and then lowered smoothly to the ground for off-site transportation using lifting equipment.

[0031] Additionally, it should be noted that components not described in detail in this article are existing technologies.

[0032] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A self-supporting hoisting device for steel box girders, characterized in that, Used for the segmented hoisting construction of steel box girders in bridge engineering, including a temporary support mechanism and an adjustment mechanism set on top of the temporary support mechanism; The temporary support structure includes a reinforced concrete foundation support unit, a steel pipe pile foundation support unit, and a permanent support pier support unit, which can be selected according to the construction site conditions. The upper end of the adjustment mechanism is fixedly connected to the bottom of the steel box girder to be hoisted, and the lower end is fixedly connected to the top crossbeam of the temporary support mechanism. The installation elevation of the adjustment mechanism is higher than the design elevation of the permanent support pier of the steel box girder, so that the self-weight of the steel box girder and the crane construction load during the hoisting process are all transferred to the temporary support mechanism through the adjustment mechanism, forming a self-supporting force system during the hoisting process. The adjustment mechanism has an elevation fine-tuning function, which is used to control the alignment accuracy during the hoisting process of the steel box girder. The adjustment mechanism can also be cut off after the entire steel box girder is welded and formed, so as to complete the conversion of the stress system from a temporary support structure to a permanent support.

2. The self-supporting hoisting device for steel box girders according to claim 1, characterized in that, The reinforced concrete foundation support unit includes a reinforced concrete foundation (101) and a lattice-type temporary support (102). The reinforced concrete foundation (101) is a double-layer, bidirectional reinforced reinforced concrete structure with a support connector (103) pre-embedded inside. The bottom of the lattice-type temporary support (102) is fixedly connected to the reinforced concrete foundation (101) through the support connector (103). The top of the lattice-type temporary support (102) is welded with an I-beam support beam (104). The lower end of the adjustment mechanism is fixedly connected to the upper flange of the support beam (105).

3. The self-supporting hoisting device for steel box girders according to claim 2, characterized in that, The steel pipe pile foundation support unit includes a steel pipe pile foundation (201) and a lattice-type temporary support (102). The pile body of the steel pipe pile foundation (201) enters the bearing layer, and the pile head of the steel pipe pile foundation (201) is welded with a cross-shaped steel pipe reinforcement structure. The bottom of the lattice-type temporary support (102) is fixedly connected to the pile head of the steel pipe pile foundation (201), and the top of the support beam (105) is fixedly connected to the lower end of the adjustment mechanism.

4. The self-supporting hoisting device for steel box girders according to claim 1, characterized in that, The permanent pier support unit includes a permanent bridge pier (301) and a fish-belly type I-beam temporary crossbeam (302); the top of the permanent bridge pier (301) is pre-embedded with a clamp structure (303), which is formed by rolling and welding steel plates and then pre-embedded in the concrete of the permanent pier. The two ends of the temporary crossbeam are hinged and fixed to the clamp structure (303), and the lower end of the adjustment mechanism is fixedly connected to the upper flange of the temporary crossbeam.

5. The self-supporting hoisting device for steel box girders according to claim 1, characterized in that, The adjustment mechanism includes a circular adjustment tube, with an annular widening connecting plate integrally provided at both the upper and lower ends of the adjustment tube. The upper annular widening connecting plate is welded and fixed to the bottom of the steel box girder to be hoisted, and the lower annular widening connecting plate passes through the upper flange of the top crossbeam of the temporary support mechanism through an elevation adjustment bolt and is locked and fixed with a nut. The elevation of the adjustment mechanism can be finely adjusted by turning the elevation adjustment bolt.

6. The self-supporting hoisting device for steel box girders according to claim 5, characterized in that, The top plate of the steel box girder is equipped with a diaphragm stiffening structure corresponding to the position of the crane outriggers. The diaphragm stiffening structure includes a stiffening plate welded to the diaphragm at the outrigger position, which is used to strengthen the structural strength of the steel box girder at the crane outrigger position and, together with the self-supporting force system, enables the crane to travel on the bridge and carry out lifting operations.

7. A method for self-supporting hoisting construction of steel box girders, characterized in that, The self-supporting hoisting device for steel box girders as described in any one of claims 1 to 6 is used for the following steps: S1: Simulation and segmented design: The steel box girder is divided into segments, and the crane outrigger pressure, temporary support structure stress, steel box girder structural strength and stability are simulated and verified throughout the hoisting process to confirm the construction safety boundary. S2: Temporary support structure installation: Based on the construction site conditions, select reinforced concrete foundation support units, steel pipe pile foundation support units, or permanent pier support units for on-site installation, and install an adjustment mechanism on top of the temporary support structure to control the installation elevation of the adjustment mechanism to be higher than the design elevation of the permanent pier of the steel box girder. S3: Steel box girder hoisting operation: First, complete the ground hoisting and welding of the first span of steel box girder, then drive the crane to the already formed steel box girder bridge deck to carry out the on-bridge hoisting operation of the subsequent spans of steel box girder. During the hoisting process, the elevation of the steel box girder is finely adjusted by the adjustment mechanism to control the bridge alignment. S4: Steel box girder welding and forming: The steel box girder segments hoisted into place are welded laterally and longitudinally, and the welds are subjected to non-destructive testing after welding is completed; S5: Force system conversion and temporary support removal: The temporary support mechanism is unloaded in stages, the adjustment mechanism is cut off, the force system is converted from the temporary support mechanism to the permanent support, and then the temporary support mechanism is dismantled in sections.

8. The self-supporting hoisting construction method for steel box girders according to claim 7, characterized in that, In step S2, when the underground pipelines are complex and the soil bearing capacity meets the requirements of the bearing layer, a reinforced concrete foundation support unit is selected; when the soil layer is poor, the bearing layer is deep, and the underground pipeline layout is simple, a steel pipe pile foundation support unit is selected; when the surrounding area is small and the distance between the bottom of the steel box girder and the ground is limited, a permanent pier support unit is selected.

9. The self-supporting hoisting construction method for steel box girders according to claim 7, characterized in that, In step S3, after the steel box girder is hoisted into place, jacks are set on the hoisted steel box girder segments, and inverted L-shaped steel plates are welded on the subsequently hoisted steel box girder segments. The inverted L-shaped steel plates are pushed by the jacks to level the steel box girder segments, and the relative positions of the steel box girder segments are welded and fixed after leveling.

10. The self-supporting hoisting construction method for steel box girders according to claim 7, characterized in that, In step S5, during the staged unloading, multiple sets of jacks are set on the top of the temporary support mechanism directly below the longitudinal web of the steel box girder. After all the jacks are tightened simultaneously, the top support of the temporary support mechanism is cut in stages, and the steel box girder is lowered in stages until the load is completely transferred to the permanent support. When the temporary support structure is dismantled, the lattice components are cut into sections and then lowered smoothly to the ground for transport using lifting equipment.

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