Steel box girder installation construction method

Abstract

The invention discloses a steel box girder installation construction method, which belongs to the field of bridge construction, and comprises the following steps: S1, processing and manufacturing a steel box girder; s2, constructing a jig frame foundation, setting out the positions of the jig frame foundation and a steel pipe column connecting embedded part according to the jig frame positioning coordinates determined by dividing the steel main beam unit sections, pouring a C30 concrete foundation, and installing the embedded part; s3, after the concrete strength reaches 50%, jig frame steel pipe columns are installed, top distribution beams and inter-column web members are connected, and the perpendicularity of the steel pipe columns and the jig frame top elevation are controlled; s4, steel beam sections are hoisted, and a U-shaped steel box beam is installed through a high-tonnage truck crane; s5, bridge deck slab concrete construction; and S6, welding is ended, the concrete bridge deck is constructed through the steel-concrete composite beam, finish paint is sprayed, and the jig frame is dismantled. The process from manufacturing and machining of the steel box girder to the final disassembly of the steel box girder is finely planned. And the shrinkage amount of the panel after subsequent welding is reduced, the deformation amount of the panel after welding is reduced, and the workload of correcting the steel box girder in the later period is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of bridge construction, and in particular to a steel box girder installation construction method. Background Art

[0002] Steel box girder, also known as steel plate box girder, is a common structural form for long-span bridges. It is generally used in bridges with larger spans. Because it looks like a box, it is called a steel box girder. In large-span cable-supported bridges, the span of the steel box main beam is several hundred meters to thousands of meters. It is generally divided into several beam sections for manufacturing and installation. Its cross section has the characteristics of wide and flat appearance, and the aspect ratio is about 1:10.

[0003] Steel box girders are generally connected by a full welding method, including a top plate, a bottom plate, a web plate, a transverse diaphragm, a longitudinal diaphragm and stiffening ribs. The top plate is an orthogonal anisotropic bridge deck composed of a cover plate and longitudinal stiffening ribs. The length of the steel box girder panel welding is relatively long, so the shrinkage of the panel after welding is difficult to control, which results in a large deformation of the steel box girder panel after welding, resulting in a large workload for correction after welding. In addition, during the installation of steel box girders, due to the large span of the continuous steel box girder and the high steel columns, the forces at the node between the steel columns and the continuous steel box girder are complex and easily affected by temperature changes. The uneven changes in the thermal expansion and contraction of the steel structure will generate additional internal forces in the steel box girder, which will generate bending moments at the nodes between the steel columns and the continuous steel box girder when vehicles pass, thereby affecting the stability of the continuous steel box girder. The conventional erection method can no longer meet the current construction needs of the erection of continuous steel box girders. Summary of the invention

[0004] In order to solve the technical problem that the conventional steel box girder erection method in the above-mentioned prior art is easily affected by temperature changes, and the uneven changes in thermal expansion and contraction of the steel structure will generate additional internal forces in the steel box girder, the present invention provides a steel box girder installation construction method.

[0005] In order to realize the above technical solution, the present invention provides a steel box girder installation construction method, comprising the steps of:

[0006] S1: Processing and manufacturing steel box girders, producing parts and plate units in the workshop, and welding them into block units, participating in the multi-section continuous matching pre-assembly of the overall bridge position assembly site to carry out block hoisting and welding into a whole; the processing of steel box girders is completed

[0007] Finally, use transportation to transport the steel box girder to the construction site;

[0008] S2: Construction of the tire frame foundation, setting out the tire frame foundation according to the tire frame positioning coordinates determined by the steel main beam unit segment division

[0009] and the steel pipe column connection embedded parts position, pour C30 concrete foundation and install embedded parts;

[0010] S3: After the concrete strength reaches 50%, install the steel pipe column of the tire frame, the top distribution beam and the web connection between the columns, and control the steel

[0011] The verticality of the pipe string and the top elevation of the tire frame;

[0012] S4: Segmental lifting of steel beams, using high-tonnage truck cranes to install U-shaped steel box beams;

[0013] S5: Bridge deck concrete construction;

[0014] S6: Welding completion, construction of steel-concrete composite beam concrete bridge deck, topcoat spraying, and removal of tire frame.

[0015] Furthermore, the step S1 includes the sub-steps of:

[0016] S11: Quality control measures for steel box girder production, including the order of delivery, loading and unloading of parts, and stacking of steel box girders.

[0017] Requirements and welding requirements are planned;

[0018] S12: Pre-assembly of steel box beams. After the steel box beam block units are manufactured in the factory, they need to be assembled on the pre-assembly frame.

[0019] Pre-assembled;

[0020] S13: Factory inspection of steel box girders. The factory inspection of steel box girders includes: appearance inspection, dimension inspection,

[0021] Material inspection, weld flaw detection, structural performance inspection, manufacturing process inspection, parts and accessories inspection and qualified data inspection.

[0022] Furthermore, in step S2, the tire frame foundation adopts a C30 concrete 3.5m*2.5m independent foundation with a height of 50cm to 70cm. The tire frame foundation is embedded in the foundation 2cm to 3cm above the ground to enhance the stability of the tire frame and the bearing capacity of the foundation.

[0023] Furthermore, in step S3, the box-type support frame uses four Φ630*8 steel pipes as columns, the column base plates are welded to the foundation embedded parts, and the I-beams H200×200×8×12 are used as horizontal web supports for the steel pipe columns. The diagonal webs of the steel pipe columns use channel steel 16a or double angle steel double ∠80×6mm. The intersections of the diagonal webs are connected with node plates, and the intersection of the diagonal webs and the horizontal web axes is slightly 2cm to 3cm inward of the steel pipe axis.

[0024] Furthermore, the height of the tire frame is 7.5m, the top distribution beam of the tire frame adopts duplex 36b, the length is 6 meters, and each box-shaped supporting tire frame is processed with 4 beams.

[0025] Furthermore, in step S4, the steel beam section is lifted by four lifting points, and lifting ears are set at appropriate positions at both ends of the beam section corresponding to the web. The crane station and the beam transport trailer should be on the same side of the bridge axis for lifting operations to reduce the rotation of the crane and the extension of the boom; the steel beam segment is processed into a U-shaped steel box beam segment in the processing plant according to the segment planning and the requirements of the arch degree and longitudinal slope, and is shipped from the factory to the on-site installation in the installation sequence.

[0026] Furthermore, after all the steel beam segments are hoisted onto the bridge, the double-lane protective scaffolding is erected. The protective scaffolding adopts a steel pipe column processed steel frame structure, with a frame spacing of 3m and a steel pipe column of The I-beam is Ⅰ25a, and the frame is equipped with Ⅰ18 distribution beams with a spacing of 50cm. Then square wood, bamboo boards or thin iron sheets are laid upwards to close it, and supporting facilities such as safety nets are set up.

[0027] Furthermore, in step S5, the shear nails are installed according to the design after the prefabrication of the steel box girder in the factory is completed. During installation, the surface of the welded steel plate is firstly derusted and decontaminated, and then the positioning, layout and marking are performed according to the designed shear nail arrangement. Then, the shear nails are installed according to the marked shear nail positioning positions using a nail gun, and the shear nail installation position deviation is not greater than 1 mm.

[0028] Furthermore, when the reinforcement and concrete construction on the bridge is completed after the erection of the support formwork, a springboard is set up; the concrete is poured symmetrically and evenly; the concrete is vibrated using a vibrating scoop assisted by a flat vibrator; after the strength of the C55 concrete of the bridge deck reaches 100% of the design strength, the temporary support is removed, and then the bridge deck paving and auxiliary railings are constructed.

[0029] Furthermore, in step S6, the steel box girder segments are subjected to high-altitude butt joint flaw detection, concrete panel pouring, on-site primer repair, and topcoat spraying.

[0030] The beneficial effects of the present invention are:

[0031] 1. The present invention has carefully planned the entire process from the manufacturing and processing of the steel box girder to the final high-altitude docking flaw detection of the steel box girder segments, concrete panel pouring, on-site primer repair, and topcoat spraying, thereby solving the technical problems in the prior art that the conventional steel box girder erection method is easily affected by temperature changes, and the uneven changes in thermal expansion and contraction of the steel structure will generate additional internal forces in the steel box girder.

[0032] 2. The present invention adopts the U-shaped rib welding method, so that the panel will be restricted by the U-shaped rib when shrinking during the subsequent welding process, thereby reducing the shrinkage of the panel after subsequent welding, reducing the deformation of the panel after welding, and reducing the workload of correcting the steel box girder in the later stage;

[0033] 3. The present invention clamps and fixes the four sides of the panel on the tire frame by means of a clamp, and further reduces the shrinkage of the panel and the deformation of the panel by limiting the four sides of the panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0035] Figure 1 A flow chart of a steel box girder installation construction method provided by the present invention;

[0036] Figure 2 This is a flow chart of the pre-assembly process provided by the present invention. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] See also Figure 1 to Figure 2 As shown, the present invention provides a steel box girder installation construction method, comprising the steps of:

[0039] S1: Processing and manufacturing steel box girders, producing parts and plate units in the workshop, and welding them into block units, participating in the multi-section continuous matching pre-assembly of the overall bridge position assembly site to carry out block hoisting and welding into a whole; the processing of steel box girders is completed

[0040] Finally, use transportation to transport the steel box girder to the construction site;

[0041] S2: Construction of the tire frame foundation, setting out the tire frame foundation according to the tire frame positioning coordinates determined by the steel main beam unit segment division

[0042] and the steel pipe column connection embedded parts position, pour C30 concrete foundation and install embedded parts;

[0043] S3: After the concrete strength reaches 50%, install the steel pipe column of the tire frame, the top distribution beam and the web connection between the columns, and control

[0044] The verticality of the steel pipe column and the top elevation of the tire frame;

[0045] S4: Segmental lifting of steel beams, using high-tonnage truck cranes to install U-shaped steel box beams;

[0046] S5: Bridge deck concrete construction;

[0047] S6: Welding completion, construction of steel-concrete composite beam concrete bridge deck, topcoat spraying, and removal of tire frame.

[0048] Overall construction concept: The steel main beam adopts the overall construction concept of "segmented processing in the processing plant, zoned construction on site, setting up two sets of supporting cradles on site, and hoisting and high-altitude welding in blocks (strips)."

[0049] In step S1, steel box girders are processed and manufactured in a professional workshop, and the connecting beams between the steel-concrete beams are shipped out of the factory in pieces after processing.

[0050] The structure of the steel box girder section is complex and the welds are dense, resulting in large welding deformation and residual stress. In order to control the welding deformation of the box structure, ensure the overall quality of the product and speed up the manufacturing progress, the steel box girder manufacturing adopts the "plate unit → plate unit → block unit → pre-assembly → painting → bridge assembly → bridge welding → painting" production method, that is, the workshop produces parts and plate units, and welds them into block units, which participate in multiple sections of continuous matching pre-assembly and the overall bridge assembly site to carry out block hoisting and welding into a whole.

[0051] During in-factory production, the steel plates that have passed the re-inspection are first rolled flat, and the parts are cut, corrected, and grooved according to the construction drawings. Then the components are assembled, welded, the welds are inspected, and trimmed to complete the production of unit components such as top plate plates, bottom plate plates, web plates, diaphragm units, and stiffening plate units. After production is completed, they are transported to the block assembly area for unit block assembly.

[0052] When assembling the unit blocks, the inverted assembly is adopted (the blocks without webs are assembled in the upright manner). First, the top plate is placed on the assembly platform (a certain amount of reverse deformation is given to the top plate unit in advance), the diaphragm units are assembled by marking, and the web plates are positioned in turn. After the penetration welds and other main welds at the web and the top plate are welded, the blocks are strengthened, and then the blocks are turned over as a whole, and the diaphragms, webs and bottom plates are welded. After the blocks are made, they are trimmed on the finishing platform. After passing the inspection, they are transported to the north span of the steel structure workshop to participate in the overall pre-assembly, and the line type is adjusted, the interface matching, the inlay section measurement, and the assembly and positioning matching parts are implemented. After the pre-assembly is completed, one segment is retained for the next matching pre-assembly, and the remaining beam segments are transported to the coating plant for rust removal and coating. After the coating is completed, they are transported to the bridge location storage site by car in the order of erection.

[0053] (1) Manufacturing process

[0054] 1) Cutting and processing of parts

[0055] The steel plates can only be put into production after passing the re-inspection at the factory.

[0056] Before cutting, the material and furnace batch number of the steel plate are transplanted (stamped). After the steel plate is rolled flat by the rolling machine, the cutting method is determined according to the specific shape and size of the parts. The cutting and processing methods are as follows:

[0057] ①Since the bridge plate units are all irregular in shape, the CNC cutting machine with CAM system is used for precision cutting.

[0058] ② For the angle steel used to strengthen the block, use a shearing machine or flame cutting to cut the material.

[0059] ③ For the butt joint groove of single-sided welding and double-sided forming, the groove is cut out at the same time during CNC cutting.

[0060] ④ For double-sided welding grooves (such as webs), use a planer to process the grooves.

[0061] ⑤ For welding edges that need to be processed or plates with high precision requirements (such as support plates, plates that need to be polished and tightened), use planers and milling machines for processing.

[0062] 2) Plate unit manufacturing process

[0063] The top plate, bottom plate, web plate and diaphragm plate units are the basic components that make up the steel box girder unit block. They are made using the following process:

[0064] ①. Roll the steel plate flat to eliminate residual prestress.

[0065] ② Place the rolled steel plate on the platform for rough material docking, welding, flaw detection, trimming, and then draw the vertical and horizontal reference lines.

[0066] ③. Lay the panel flat on the platform, assemble the U-shaped ribs along the line, and use a jack or jack for precise positioning when necessary.

[0067] ④. Weld the U-shaped ribs and plate rib welds on the plate anti-deformation frame according to the welding process, and perform flaw detection as required.

[0068] ⑤. Use cold correction and flame correction methods to correct the plate welding warping deformation, focusing on correcting the wave deformation of the edge.

[0069] ⑥. Correct the horizontal baseline based on the vertical baseline.

[0070] ⑦. Using the corrected vertical and horizontal baselines as the reference, mark the cutting lines around the plate, pay attention to the reserved process volume, and use a semi-automatic trolley to finely cut the perimeter and groove. (For the top and bottom plates, leave one end uncut in the length direction, and mark and cut uniformly when assembling into block units and pre-assembling the entire beam section)

[0071] ⑧. Trim the slabs, with a focus on the surrounding slope areas, to ensure they meet the flatness requirements for bridge docking.

[0072] ⑨. Spray the plate number with white paint at the specified location.

[0073] 3) Fabrication of diaphragms

[0074] ①Production process

[0075] The diaphragm is the inner tube of the steel box girder assembly, and its accuracy directly affects the cross-sectional accuracy of the steel box girder. According to the unit block division scheme, each diaphragm of the main line bridge is made of seven pieces, and each diaphragm of the ramp bridge is made of three pieces. The butt joint avoids the longitudinal butt welds of the top and bottom plates and the position of the stiffening ribs. According to its structural characteristics, the following manufacturing process is proposed:

[0076] a. All parts are cut by CNC precision cutting, and the manhole and the butt-joint slope are cut out at the same time.

[0077] b. Mark and weld the stiffeners and manhole reinforcement rings, etc., and fix them rigidly on the platform. Use CO2 gas shielded welding. During the welding process, strictly follow the prescribed welding sequence and welding process to reduce welding deformation. At the same time, use a press and flame method for correction.

[0078] c. Draw vertical and horizontal reference lines and butt edge cutting lines on the platform.

[0079] d. Using the reference line as a reference, plane the butt edge along the line.

[0080] ②Welding process

[0081] Since the partition is thin and irregular in shape, it is easy to deform during welding. In order to reduce welding deformation, the partition stiffening ribs are welded by CO2 gas shielded semi-automatic welding, and the welding material is ER50-6φ1.2mm welding wire.

[0082] Before welding, place the partition on a rigid fixed platform, set a fixed point at a distance of about 1.5 meters around the partition to fix the platform, and then adopt a symmetrical, dispersed, and same-direction welding method. First weld the horizontal corner welds of the stiffening ribs, and then weld the vertical corner welds between the stiffening ribs.

[0083] ③Process assurance measures

[0084] a. Before and after cutting, the steel plate needs to be mechanically rolled flat using a rolling machine to eliminate rolling and flame shear stresses, thereby reducing welding deformation of subsequent components.

[0085] b. Accurately mark and assemble the horizontal and vertical stiffening ribs on a special marking platform. After welding and correction, return to the platform for marking and machine the periphery to ensure the external dimensions of the diaphragm.

[0086] c. Under the rigid constraint of the platform, CO2 gas shielded semi-automatic welding with low line energy is used to reduce welding deformation.

[0087] 4) Block unit overall assembly and welding

[0088] ① Assembly of block elements with webs

[0089] The inverted assembly method is adopted. When assembling the blocks, the top plate is first placed on the assembly platform with pre-camber pads, and then the web plate is assembled according to the line, and the partition unit and top plate are assembled in sequence, and then the penetration welds and main fillet welds of the web and top plates are welded. After the flaw detection is completed, the longitudinal partition of the process truss is installed, and then the unit block is turned over as a whole with an L-shaped hanger. The remaining welds are welded on a special welding platform, and the flange partition and the top plate are spot welded after passing the inspection.

[0090] ② Assembly of block elements without webs

[0091] When assembling the blocks, the front-mounted method is used. When assembling by the front-mounted method, the bottom plate is first placed on the qualified assembly platform for positioning, and then the partition unit and the top plate unit are assembled in sequence according to the line. After the welding is qualified, the truss-type longitudinal partition is welded and connected.

[0092] As a preferred embodiment, the step S1 includes sub-steps: S11, quality control measures for steel box girder manufacturing; S12, pre-assembly of steel box girder; S13, factory inspection of steel box girder.

[0093] In step S11, the specific operation mode of the steel box girder manufacturing quality control measures is as follows:

[0094] (1) The delivery sequence of each batch of components must be planned, and the trucks must be loaded and unloaded in order, and the site must meet the stacking requirements;

[0095] (2) Considering the material cutting seam and the requirements for the arching of the composite beam, a certain margin should be placed on the materials of the top plate, bottom plate and web plate of each section of the composite beam when purchasing. Considering the shrinkage caused by on-site docking, a shrinkage margin should be placed on each section to ensure the accurate positioning of the composite beam at the middle pier and side pier;

[0096] (3) For composite beams with different designed pre-arches and slopes in the width direction of the top plate, the factory pre-assembles the segmented composite beams. The segmented positions are equipped with bolted clamps to facilitate the on-site lifting of the segmented steel beams. The installation bolts must make the steel plate layers fit tightly. The number of rivets at each connection point must not be less than 15% of the total number of holes, and the number of bolts must not be less than 25% of the total number of holes to improve the on-site assembly accuracy.

[0097] (4) Welding requirements

[0098] 1) Welders must pass the examination organized by the relevant functional departments and obtain a qualification certificate, and can only engage in work within the scope of the qualification certificate.

[0099] 2) The welding process must be prepared according to the welding process assessment report, and the welding process should be strictly followed during welding.

[0100] 3) The welding material should match the parent material Q345qD, and the corresponding welding material should be selected according to the welding process qualification report. This project intends to conduct welding process qualification for the following four types of welding joints.

[0101] Table 1 Steel box girder welding requirements

[0102]

[0103] 4) Welding operations should be carried out indoors, and the humidity of the welding environment should not be greater than 80%; the ambient temperature for welding low-alloy steel should not be lower than 5°C, and the ambient temperature for welding carbon structural steel should not be lower than 0°C; the main rods should be welded within 24 hours after assembly. If outdoor welding operations are necessary, wind and rain protection measures should be taken, and the main rods should be welded within 12 hours after assembly. If the welding time is exceeded or the welding area is exposed to rain, the welding area can be cleaned or dehumidified according to different situations before welding.

[0104] 5) Before welding, the workshop primer and other harmful substances in the area to be welded must be thoroughly removed. It is strictly forbidden to strike an arc at the non-welding part of the parent material during welding. After welding, the slag on the weld surface and the spatter on both sides should be cleaned. It is strictly forbidden to apply wax to remove slag.

[0105] 6) The preheating temperature before welding should be determined through welding performance tests and welding process assessments.

[0106] 7) In order to reduce welding deformation, the CO2 gas shielded welding method with low heat input and high working efficiency should be adopted on site.

[0107] 8) Parts must not be impacted or vibrated during welding or weld cooling.

[0108] 9) The negative bending moment in the middle of the composite beam is the largest, the shear force in the middle pier area of ​​the web joint of the beam is the largest, and there should be no weld joints; the upper flange is subjected to the largest tension, and there should be no butt joints;

[0109] 10) The positive bending moment of the mid-span beam is the largest, and the tension on the lower flange is the largest, so butt joints are not recommended;

[0110] 11) To reduce welding residual stress, it is advisable to: weld the butt weld first and then the T-type weld, symmetrically and synchronously un-weld the same weld, and weld the butt welds of the top plate, bottom plate and web at the same time to prevent the weld welded first from shrinking first.

[0111] In step S12, the specific operation method of pre-assembling the steel beam is as follows:

[0112] (1) Pre-assembly

[0113] In order to reduce the difficulty of adjusting the unit blocks during bridge installation, accurately achieve the erection line shape and matching accuracy, speed up the installation, and ensure the smooth erection of the steel box girder, the steel box girder block units need to be pre-assembled on the pre-assembly frame after being manufactured in the factory according to the girder erection sequence.

[0114] (2) Main problems solved by pre-assembly

[0115] 1) Steel box girder camber control;

[0116] 2) Horizontal curve control of steel box girder;

[0117] 3) Control of steel box girder length;

[0118] 4) Control of interface matching accuracy (adjustment of weld gap and misalignment of adjacent interfaces)

[0119] 5) Determination of the length of the U-shaped rib and the lath rib patching section;

[0120] 6) Assemble temporary connectors for erecting steel box girders (positioning matching parts, marking installation positioning inspection lines);

[0121] 7) Arrangement of reference lines for bridge installation and erection.

[0122] Pre-assembly process flow chart Figure 2 As shown, the preparations before pre-assembly include:

[0123] 1) Prepare detailed segment pre-assembly process and pre-assembly sequence; layout, simulated elevation calculation, measurement and inspection methods for each installation stage, etc.

[0124] 2) The unit blocks submitted for pre-assembly shall be inspected and accepted. Unqualified products cannot be pre-assembled.

[0125] 3) Review the horizontal reference line of the tire frame and make corrections if the deviation exceeds the limit. Use jacks, rollers and other beam shifting tools to fine-tune the beam section and shift the alignment.

[0126] 4) Design of positioning matching parts

[0127] 5) Design of block lifting lugs

[0128] (4) Basic pre-assembly process

[0129] 1) Arrange the middle block unit according to the longitudinal reference line set on the tire frame, and then arrange the adjacent block units in sequence according to the transverse reference line.

[0130] 2) Fine-tune each block from the middle to both sides in turn so that it is accurately positioned according to the baseline. Use a total station and a steel ruler to check so that the baseline is within the allowable deviation range, adjust the misalignment between the partitions, and ensure that each block is aligned without any excess.

[0131] 3) After all the blocks of a beam section are in place, adjust the position, length, arch, curvature and transverse working weld gap based on the top, bottom and web plates.

[0132] 4) After all points have been inspected and qualified, the beam sections are marked and cut, leaving a second cutting end, and the grooves are cut at the same time (except for the closed section).

[0133] 5) Assemble and weld the segment positioning matching parts, and mark the bridge installation positioning inspection line.

[0134] 6) Measure and match the length of the U-shaped rib and the slat rib patching section. The U-shaped rib and the slat rib patching section shall be numbered and marked as shown in the construction drawing.

[0135] 7) Disassemble the blocks that make up the beam section and transport them to the painting workshop by flatbed truck for rust removal and painting. After the paint is completely dry, pack the U-shaped ribs and slat rib patching sections according to the numbers and ship them to the bridge site.

[0136] In step S13, the specific operation of the factory inspection of the steel box girder is as follows:

[0137] (1) Appearance inspection:

[0138] Check whether the surface of the steel box girder is flat and smooth, and whether there are defects such as cracks, pores, slag inclusions, rust spots, etc.

[0139] The appearance quality of the weld should meet the requirements, the weld size should be uniform and full, and there should be no obvious welding defects.

[0140] Check the coating quality; the coating should be uniform without peeling, blistering, etc.

[0141] (2) Dimension inspection:

[0142] Accurately measure the main dimensions of the steel box girder, such as length, width, and height, to ensure that they meet the design requirements.

[0143] Check whether the position and size of each component are accurate, such as the arrangement of stiffening ribs, partitions, etc.

[0144] (3) Material inspection:

[0145] Check the material certification of the steel to ensure that the steel used meets the design standards.

[0146] Inspect welding materials, etc. to ensure their quality.

[0147] (4) Weld flaw detection:

[0148] Use non-destructive testing methods (such as ultrasonic testing, radiographic testing, etc.) to inspect key welds to ensure that the internal quality of the welds is qualified.

[0149] (5) Structural performance inspection:

[0150] Check whether the overall stiffness and strength of the steel box girder meet the requirements.

[0151] Simple testing can be performed through simulated loading and other methods.

[0152] (6) Manufacturing process inspection:

[0153] Check the process documents in the manufacturing process, including welding process, painting process, etc., to ensure that the process execution meets the specifications.

[0154] (7) Inspection of accessories and attachments:

[0155] Check whether various connecting accessories, bolts, etc. are complete and intact.

[0156] (8) Document review:

[0157] Check whether relevant materials such as product certificates, inspection reports, construction records, etc. are complete.

[0158] Only after strict factory acceptance and ensuring that the steel box girder is of qualified quality can it be transported and installed to ensure the quality and safety of the entire project.

[0159] After the steel-concrete beams are processed, they are transported to the site by car.

[0160] Steel box girder hoisting plan: After the traffic diversion is completed, the steel box girder hoisting operation is carried out in the closed traffic section. The main beam of the steel box girder adopts three sections of steel main beams in the length direction and is placed on the tire frame for installation. A QAY220-ton truck crane is stationed on one side of the tire frame, and the steel-concrete composite beam on this side is hoisted in sections and the connecting beam is installed, and then high-altitude welding is carried out.

[0161] As a preferred embodiment, in step S2, the specific operation method of the tire frame foundation construction is as follows:

[0162] According to the positioning coordinates of the cradle determined by the segment division of the steel main beam unit, the cradle foundation and the positions of the embedded parts of the steel pipe column connections are accurately laid out, the C30 concrete foundation is poured and the embedded parts are installed.

[0163] The tire frame foundation adopts C30 concrete 3.5m*2.5m independent foundation, 50~70cm high (determined on site according to actual conditions). If the site conditions permit, the tire frame foundation should be embedded in the foundation 2~3cm above the ground to enhance the stability of the tire frame and the bearing capacity of the foundation.

[0164] As a preferred embodiment, in step S3, after the concrete strength reaches more than 50%, the steel pipe columns of the frame, the top distribution beam and the web connection between the columns are installed. The verticality of the steel pipe columns and the control elevation of the top of the frame after considering the pre-arch of the steel main beam should be well controlled.

[0165] The box-type support tire frame adopts four Steel pipes are used as columns, and the column base plates are welded to the embedded foundation parts. I-beams H200×200×8×12 are used to support the horizontal webs of steel pipe columns. The diagonal webs of steel pipe columns are made of channel steel 16a or double angle steel double ∠80×6mm. The intersection of the diagonal webs should be connected with node plates. The intersection of the diagonal webs and the horizontal web axes should be slightly inward of the steel pipe axis by 2 to 3 cm.

[0166] The height of the tire frame is determined by the actual terrain, with an average of about 7.5 meters. The distribution beam on the top of the tire frame adopts duplex 36b, with a length of 6 meters, and 4 beams are processed for each box-shaped supporting tire frame.

[0167] As a preferred embodiment, in step S4, the specific operation of lifting the steel beam segment is as follows:

[0168] A 220-ton truck crane is used to install the U-shaped steel box girder. The steel beam section is hoisted at four lifting points, and lifting ears are set at appropriate positions at both ends of the beam section corresponding to the web. The crane station and the beam transport trailer should be on the same side of the bridge axis for hoisting operations to reduce the rotation of the crane and the extension of the boom.

[0169] The steel beam segments are processed into U-shaped steel box beam segments in the processing plant according to the segment planning, arch rise and longitudinal slope requirements, and transported to the on-site installation according to the installation sequence. The connecting beams between the steel main beams are shipped from the factory in loose parts and spliced ​​and installed on-site.

[0170] After all the steel beam segments in the closed lane were hoisted onto the bridge, the double lane protection scaffolding was erected. The protection scaffolding adopts a steel pipe column + I-beam frame structure with a frame spacing of 3m. The I-beam is Ⅰ25a. The Ⅰ18 distribution beam with a spacing of 50cm is set on the rack. Then square wood, bamboo board or thin iron sheet is laid on top to close it, and safety protection nets and other supporting facilities are set up. The next step of lane change construction can be carried out only after the protective scaffolding is completed.

[0171] As a preferred embodiment, in step S5, the specific operations of the bridge deck concrete construction are as follows:

[0172] The construction of the concrete composite bridge deck is carried out after the hoisting and splicing of each single segment unit of the steel main beam box is completed. The support formwork and bridge deck reinforcement binding and concrete pouring construction are carried out on the already erected protective scaffolding. The support formwork is designed with reference to the support formwork schematic diagram provided by the design.

[0173] After the prefabrication of the steel box girder in the factory is completed, the shear nails are installed according to the design. During installation, the surface of the welded steel plate is first derusted and cleaned, and then the shear nails are positioned and marked according to the designed shear nail layout. The shear nails are then installed according to the marked shear nail positioning positions using a nail gun. The deviation of the shear nail installation position is not greater than 1mm, and the shear nail construction quality standards should be strictly carried out in accordance with the relevant steel structure construction quality specifications.

[0174] When constructing steel bars and concrete on the bridge after the erection of the scaffolding formwork is completed, a springboard should be set up according to construction needs. It is strictly forbidden for construction machinery to walk on the formwork, and personnel should also use the springboard to walk as much as possible. Jumping on the formwork is strictly prohibited.

[0175] The concrete pouring should be carried out symmetrically and evenly, and the pouring order is: longitudinally, first the middle part and then the two ends, and transversely, first the top of the box and then the box space and then the two sides. Concrete vibration is carried out with a vibrating scoop supplemented by a flat plate vibrator.

[0176] After the C55 concrete strength of the bridge deck reaches 100% of the design strength, the temporary support will be removed, and then the bridge deck paving and auxiliary railings will be constructed.

[0177] As a preferred embodiment, in step S6, the specific operation steps of welding finishing, steel-concrete composite beam construction of concrete bridge deck, topcoat spraying, and tire frame removal are as follows:

[0178] After all the steel box girder segment units are hoisted, the longitudinal and transverse slopes, pre-camber, bridge axis and other design indicators should be fully checked, verified and adjusted to ensure the construction accuracy requirements. After the review and adjustment, a comprehensive inspection and reinforcement can be carried out before the painting, repair, welding and spraying of the inner and outer surfaces of the steel beam box body can be carried out. Because the painting, repair, welding and spraying of the inner and outer surfaces of the steel beam box body slightly conflict with the subsequent bridge deck concrete construction, a comprehensive inspection and painting construction should be carried out after the concrete bridge deck construction is completed.

[0179] Finally, the steel box girder segments were subjected to high-altitude butt joint flaw detection, concrete panel pouring, on-site primer repair and topcoat spraying as required.

[0180] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A steel box girder installation construction method, characterized in that: Includes steps: S1: Processing and manufacturing steel box girders, producing parts and plate units in the workshop, and welding them into block units, participating in the multi-section continuous matching pre-assembly of the overall bridge position assembly site to carry out block hoisting and welding into a whole; after the steel box girder is processed, it is transported to the construction site by means of transportation; S2: Construction of the tire frame foundation. According to the tire frame positioning coordinates determined by the steel main beam unit segment division, the positions of the tire frame foundation and the steel pipe column connection embedded parts are laid out, the C30 concrete foundation is poured, and the embedded parts are installed; S3: After the concrete strength reaches 50%, install the steel pipe column of the tire frame, the top distribution beam and the web connection between the columns, and control the verticality of the steel pipe column and the top elevation of the tire frame; S4: Segmental lifting of steel beams, using high-tonnage truck cranes to install U-shaped steel box beams; S5: Bridge deck concrete construction; S6: Welding completion, construction of steel-concrete composite beam concrete bridge deck, topcoat spraying, and removal of tire frame.

2. The steel box girder installation construction method according to claim 1, characterized in that: The step S1 comprises the following sub-steps: S11: Quality control measures for steel box girder production, planning of the delivery sequence, parts loading and unloading sequence, stacking requirements and welding requirements of steel box girders; S12: Pre-assembly of steel box beams. After the steel box beam block units are manufactured in the factory, they need to be pre-assembled on the pre-assembly frame; S13: Factory inspection of steel box girders. The factory inspection of steel box girders includes: appearance inspection, dimension inspection, Material inspection, weld flaw detection, structural performance inspection, manufacturing process inspection, parts and accessories inspection and qualified data inspection.

3. The steel box girder installation construction method according to claim 1, characterized in that: In step S2, the tire frame foundation adopts a C30 concrete 3.5m*2.5m independent foundation with a height of 50-70cm. The tire frame foundation is embedded in the foundation 2-3cm above the ground to enhance the stability of the tire frame and the bearing capacity of the foundation.

4. The steel box girder installation construction method according to claim 3 is characterized in that: In step S3, the box-type support tire frame adopts four Steel pipes are used as columns, and the column base plates are welded to the embedded foundation parts. I-beams H200×200×8×12 are used to support the horizontal webs of steel pipe columns. The diagonal webs of steel pipe columns are made of channel steel 16a or double angle steel double ∠80×6mm. The intersection of the diagonal webs is connected with node plates, and the intersection of the diagonal webs and the horizontal web axes is slightly 2cm to 3cm inward of the steel pipe axis.

5. The steel box girder installation construction method according to claim 4, characterized in that: The height of the tire frame is 7.5m. The distribution beam on the top of the tire frame adopts duplex 36b with a length of 6 meters. Each box-shaped supporting tire frame is processed with 4 beams.

6. The steel box girder installation construction method according to claim 3, characterized in that: In step S4, the steel beam section is lifted by four lifting points, and lifting ears are set at appropriate positions at both ends of the beam section corresponding to the web. The crane station and the beam transport trailer should be on the same side of the bridge axis for lifting operations to reduce the rotation of the crane and the extension of the boom; the steel beam segment is processed into a U-shaped steel box beam segment in the processing plant according to the segment planning and the requirements of the arch and longitudinal slope, and is shipped from the factory to the on-site installation in the installation sequence.

7. The steel box girder installation construction method according to claim 6, characterized in that: After all the steel beam segments are hoisted onto the bridge, the double-lane protective scaffolding is erected. The protective scaffolding adopts a rack structure of steel pipe columns processed with steel, with a rack spacing of 3m and steel pipe columns. The I-beam is Ⅰ25a, and the frame is equipped with Ⅰ18 distribution beams with a spacing of 50cm. Then square wood, bamboo boards or thin iron sheets are laid upwards to close it, and supporting facilities such as safety nets are set up.

8. The steel box girder installation construction method according to claim 3, characterized in that: In step S5, the shear nails are installed according to the design after the prefabrication of the steel box girder in the factory. During installation, the surface of the welded steel plate is firstly derusted and decontaminated, and then the shear nails are positioned, marked and marked according to the designed shear nail arrangement. Then, the shear nails are installed according to the marked shear nail positioning positions using a nailing gun, and the shear nail installation position deviation is not greater than 1 mm.

9. The steel box girder installation construction method according to claim 8, characterized in that: During the construction of reinforcement and concrete on the bridge after the erection of the support formwork is completed, a springboard is set up; the concrete is poured symmetrically and evenly; the concrete is vibrated using a vibrating scoop assisted by a flat vibrator; after the strength of the C55 concrete on the bridge deck reaches 100% of the design strength, the temporary support is removed, and then the bridge deck paving and auxiliary railings are constructed.

10. The steel box girder installation construction method according to claim 3, characterized in that: In step S6, the steel box girder segments are subjected to high-altitude butt joint flaw detection, concrete panel pouring, on-site primer repair, and topcoat spraying.

Images