Reinforced concrete box girder flange plate splicing reinforcement method

Abstract

The present application belongs to the technical field of existing bridge widening, and particularly relates to a reinforcing method for widening a reinforced concrete box girder flange plate, which comprises cantilever flange widening and web steel rib girder reinforcement. The cantilever flange widening comprises the following steps: installing steel book clamps along the edge of the flange plate to form a steel structure cantilever structure, the upper and lower steel plates of the steel book clamps being respectively attached to and parallel with the top surface and bottom surface of the flange plate, the upper and lower steel plates being fixed by bolts penetrating through the flange plate, the upper and lower steel plates being cantilevered out relative to the flange plate, the cantilevered ends of the upper and lower steel plates being closed and connected, and a plurality of steel book clamps being sequentially spliced along the length direction of the box girder; the top surface of the upper steel plate is paved with a bridge deck structure; the web steel rib girder reinforcement comprises the following steps: anchoring the steel rib girder by means of a post-installed anchor bolt at the root of the flange plate and the web concrete, so as to form an integral force with the box girder; the bridge widening part is a steel structure, and in the later maintenance stage, the disease part can be cut and welded for repair after deformation and damage, without the need for maintenance, so that the traffic can be opened, and the maintenance is relatively simple and fast.

Description

Technical Field

[0001] This invention belongs to the field of existing bridge widening technology, specifically relating to a method for widening and reinforcing the flange plates of a reinforced concrete box girder. Background Technology

[0002] With the rapid growth of my country's national economy and the increasing number of cars, many existing highway bridges can no longer meet traffic demands. Therefore, improving the transport capacity and load-bearing capacity of highway bridges has become particularly important under the current circumstances. The widening process for reinforced concrete box girder flanges typically involves using wet concrete joints on the outer side of the existing bridge to achieve this widening. This process not only has a long construction period but also high project costs. Summary of the Invention

[0003] This invention addresses the problems of long construction periods, high project costs, and the inability to remove and extend transverse prestressed steel strands in the flange plates when using concrete wet joint technology on the outside of old bridges to widen them.

[0004] This invention provides the following technical solution: a method for widening and reinforcing the flange of a reinforced concrete box girder, comprising widening the cantilever flange and reinforcing the web with steel rib beams;

[0005] Widening the cantilever flange: Remove the existing structure at the flange plate, install steel book clips along the edge of the flange plate to form a steel cantilever structure. The upper and lower steel plates of the steel book clips are attached to and parallel to the top and bottom surfaces of the flange plate, respectively. The upper and lower steel plates are fixed by bolts that pass through the flange plate. The upper and lower steel plates cantilever out of the flange plate, and the cantilever ends of the upper and lower steel plates are closed and connected. Several steel book clips are spliced ​​sequentially along the length of the box girder. The bridge deck structure is paved on the top surface of the upper steel plate.

[0006] Web plate steel rib beam reinforcement: The steel rib beam is anchored to the root of the flange plate and the web plate concrete by rebar anchor bolts, forming an integral load-bearing structure with the box girder.

[0007] Furthermore, before fabricating the steel book clips and steel rib beams, the prestressed tendons and steel strands inside the flange plate are scanned on-site; an ultrasonic low-frequency tomographic imager is used to detect the transverse prestressed steel strands and main reinforcements at the construction site of the flange plate, lines are drawn on the top surface of the flange plate, and the area of ​​the steel strand corrugated pipe is located. The prestressed tendon and steel strand areas are marked with a certain distance offset to the left and right of the center position of the steel strand.

[0008] Before drilling into the concrete structure, the positions of the steel book clips are laid out. The drilling positions of each steel book clip are arranged on the flange plate according to the designed bolt hole positions, and the drilling positions are adjusted to avoid the prestressing tendons and steel strand areas. Based on the layout positions, the line shape and bolt hole position data of each steel book clip are measured on site.

[0009] Based on the design of the steel rib beam positions and spacing, the installation axis is laid out on site, with no less than 3 points on each section; the positions are marked and marked on the web and flange plates of the box girder; the drilling positions are laid out avoiding the areas of prestressed tendons and steel strands.

[0010] Furthermore, the upper and lower surfaces of the flange plate are roughened to remove a 2-3 mm thick surface layer; the steel book clip model is used to collect data on the steel book clip's shape and the bolt hole positions on site. The steel book clip model includes an upper surface frame, a lower surface frame, and an outer side frame. The steel book clip model is manufactured at a 1:1 scale according to the design dimensions of the connection position between the steel book clip and the flange plate.

[0011] During measurement, the steel book clip model is clamped onto the flange plate, with the upper surface frame aligned with the top surface of the flange plate and the outer surface frame aligned with the side surface of the flange plate. The steel book clip model is aligned with the layout position of the steel book clip. Using the outer surface frame as a reference, the thickness of the flange plate side is measured. The distances from the bolt holes to the longitudinal and transverse side bars of the upper surface frame are measured on the top surface of the flange plate, which are the coordinates of the bolt holes in the upper steel plate. The distances from the bolt holes to the longitudinal and transverse side bars of the lower surface frame are measured on the bottom surface of the flange plate, which are the coordinates of the bolt holes in the lower steel plate. The distances from the four vertices of the lower surface frame to the bottom surface of the flange plate are the linear data of the lower steel plate.

[0012] Furthermore, during the processing of the steel book clip, the upper steel plate is separated from other components, and the other components are made as a whole. The bolt holes on the upper and lower steel plates are drilled after the holes on the flange plate are drilled.

[0013] Furthermore, the steel book clip is bonded to the flange plate with structural adhesive; the structural adhesive is applied simultaneously to the prepared concrete surface and the bonding surface of the steel plate, with the adhesive layer being thicker in the middle and thinner at the edges; then the steel plate is attached to the predetermined position.

[0014] After the steel plate is pasted, it is fixed with through-bolts, shims are added, and nuts are tightened. The shims should correspond to the slope of the flange plate. Initial tightening is performed, and the tightening sequence is from the inside to the outside and from the middle to both sides. The through-bolts are tightened alternately to squeeze out the excess structural adhesive along the plate seam and bolt holes. The pressure for fixing is not less than 0.5MPa. At the same time, the steel plate is tapped to check the fullness of the structural adhesive under the steel plate. If there is insufficient structural adhesive under the steel plate and there are hollows, the bolts are loosened and the structural adhesive is filled into the gaps from the side of the steel plate to make the steel plate flat and tightly attached.

[0015] Maintain the temperature during the curing of the structural adhesive, and the curing time should not be less than 24 hours; after curing, tighten the bolts completely.

[0016] After all the through-bolts are tightened and the structural adhesive has cured, the upper steel plate is welded to the other parts of the steel book clip at the longitudinal disconnection point. The weld is made by bevel penetration welding and cross-seam transverse stiffening ribs are set to achieve the first-class weld.

[0017] Furthermore, the steel rib beam consists of a middle rib plate, a bottom edge plate, vertical stiffening ribs, and anchoring steel plates; the holes on the anchoring steel plates are drilled one by one according to the on-site layout results.

[0018] Grind and roughen the installation range of the anchoring steel plates on both sides of the installation axis of the steel rib beam; set an adhesive layer between the anchoring steel plates and the box beam.

[0019] Furthermore, the steel rib beams are installed using a truck-mounted crane and steel rib beam lifting equipment.

[0020] The steel rib beam lifting device includes a lifting frame consisting of an upper crossbeam, a lower crossbeam, and a counterweight vertical beam, and main anchor bolts for insertion into anchor bolt holes on the steel rib beam. The two ends of the counterweight vertical beam are connected to one end of the upper and lower crossbeams, respectively. The upper and lower crossbeams are located on the same side of the counterweight vertical beam and are both vertically fixed to it. The upper end of the upper crossbeam is equipped with a main lifting point and an adjusting lifting point. The adjusting lifting point is located at the end of the upper crossbeam furthest from the counterweight vertical beam and is a strip-shaped plate structure fixed to the upper end of the upper crossbeam. Several lifting holes are spaced apart on the strip-shaped plate structure. The main lifting point is located at the end of the upper crossbeam closest to the counterweight vertical beam. The lower crossbeam consists of two parallel beams with space between them to allow the steel rib beam to pass. The upper end of the lower crossbeam is equipped with an anchor bolt seat for receiving the main anchor bolt. The main anchor bolt is inserted into the anchor bolt seat and the corresponding anchor bolt hole on the steel rib beam and fixed with anti-loosening bolts to connect the steel rib beam to the lifting device.

[0021] The lower crossbeam is a telescopic beam, including a fixed beam and a sliding beam. The fixed beam is provided with a groove. Both the fixed beam and the sliding beam are provided with a number of bolt holes spaced apart along their length. The sliding beam slides along the groove of the fixed beam and is fixed by bolts inserted into the bolt holes. The anchor bolt seat is fixed to the sliding beam.

[0022] A secondary anchor bolt hole is provided at the end of the lower crossbeam away from the counterweight vertical beam. The secondary anchor bolt hole is connected to another anchor bolt hole on the steel rib beam through a secondary anchor bolt and fixed by an anti-loosening bolt. The secondary anchor bolt is located below the main anchor bolt on one side. The size of the main anchor bolt hole on the anchor bolt seat is larger than the diameter of the main anchor bolt to avoid the main anchor bolt from getting stuck.

[0023] Furthermore, after the flange plate widening and reinforcement structure is completed in one section, the construction of the crash barrier, the installation of the anti-throw net, the installation of the sound barrier, the construction of the bridge deck drainage, and the construction of the bridge deck paving will be carried out.

[0024] Construction of crash barriers: The columns of the crash barriers are installed on the widened cantilever flange structure by butt welding, and the columns are perpendicular to the horizontal and vertical bridge planes;

[0025] Installation of anti-throw netting: The posts of the anti-throw netting are connected to the crossbeams of the crash barrier;

[0026] Sound barrier installation: The H-steel columns of the sound barrier are welded to the widened cantilever flange structure;

[0027] Bridge deck drainage construction: For the new bridge deck drainage, galvanized steel pipes will be installed every 5m along the axis of the lower side railing for river drainage, and PVC-U drainage pipes will be used for land drainage. The original bridge vertical drainage pipes will be sealed off. When installing the horizontal drainage pipes, the bridge deck elevation will be used as the control point, and the cross slope of the drainage pipe installation will be 10%.

[0028] Bridge deck paving construction: Inverted L-shaped steel bars are inserted into the original bridge deck; the steel mesh is tied and fixed to the shear nails and inverted L-shaped steel bars on the upper steel plate; and the concrete layer is paved.

[0029] Compared with the prior art, the advantages of the present invention are:

[0030] Construction safety: The entire operation takes place on the bridge, eliminating the need for cofferdams and temporary bridges, which greatly reduces construction risks.

[0031] Simple to operate and fast to complete; the steel structure is prefabricated in the factory and installed on site, requiring no curing, which greatly simplifies the on-site construction process and ensures the construction period.

[0032] The damage to the original bridge is minimal; the steel structure of the book-clamp plate is widened and connected to the original bridge using through high-strength bolts. Only holes need to be drilled in the flange plate of the reinforced concrete box girder, which minimizes the damage to the original bridge flange plate structure and does not affect the transverse prestressed steel strands of the beam.

[0033] Maintenance is convenient; the bridge's widened section is a steel structure, and in the later maintenance stage, if deformation or damage occurs, the damaged parts can be cut and welded for repair. No maintenance is required before traffic can be opened, making maintenance relatively simple and quick. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of widening and reinforcing the flange plates of the box girder;

[0035] Figure 2 This is a schematic diagram of the widened flange plate of the box girder;

[0036] Figure 3 This is a schematic diagram showing the layout of the steel book clip and bolt hole positions;

[0037] Figure 4 This is a structural schematic diagram of a steel book clip model;

[0038] Figure 5 This is a schematic diagram of a prefabricated steel book clip;

[0039] Figure 6 This is a three-dimensional schematic diagram of the overall structure of the steel rib beam lifting device;

[0040] Figure 7 This is a front view of the overall structure of the steel rib beam lifting device (when the lower crossbeam is telescopic);

[0041] Figure 8This is a side view of the overall structure of the steel rib beam lifting device;

[0042] Figure 9 This is a top view of the overall structure of the steel rib beam lifting device;

[0043] Figure 10 This is a three-dimensional schematic diagram of the connection structure between the steel rib beam lifting device and the steel rib beam.

[0044] Figure 11 This is a front view of the connection structure between the steel rib beam lifting device and the steel rib beam.

[0045] In the diagram: 1-Upper crossbeam; 2-Lower crossbeam; 2.1-Fixed beam; 2.11-Slide groove; 2.2-Sliding beam; 2.3-Secondary anchor bolt hole; 3-Counterweight vertical beam; 4.1-Main lifting point; 4.2-Adjusting lifting point; 5-Main anchor bolt; 6-Anchor bolt seat; 6.1-Main anchor bolt hole; 7-Bolt; 8-Secondary anchor bolt; 9-Reinforcing rib plate; 10-Steel rib beam; 11-Anchor bolt hole; 12-Anti-detachment bolt; 13-Reinforced concrete box girder; 14-Rebar anchor bolt; 15-Steel book clip; 15.1-Upper steel plate; 15.2-Lower steel plate; 15.3-Bottom beam; 15.4-Connecting column; 16-Through high-strength bolt; 17-Bridge deck pavement; 18-Shear stud; 19-Inverted L-shaped reinforcing bar; 20-Steel book clip model; 21-Anti-collision wall column. Detailed Implementation

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] A method for widening and reinforcing the flanges of a reinforced concrete box girder includes widening the cantilever flanges and reinforcing the web with steel rib beams.

[0048] Widening of the cantilever flange: Remove the existing structure at the flange plate, install steel book clips (15) on the edge of the flange plate to form a steel structure cantilever structure. The upper and lower steel plates of the steel book clips (10) are attached to and parallel to the top and bottom surfaces of the flange plate, respectively. The upper and lower steel plates are fixed by bolts that penetrate the flange plate. The upper and lower steel plates cantilever out of the flange plate. The cantilever ends of the upper and lower steel plates are closed and connected. Several steel book clips (10) are spliced ​​together in sequence along the length of the box girder. The bridge deck structure is paved on the top surface of the upper steel plate.

[0049] Web plate steel rib beam reinforcement: The steel rib beam (10) is anchored to the root of the flange plate and the web plate concrete by the anchor bolts (14), forming an integral force with the box girder.

[0050] By measuring the flange plate shape on-site and scanning the old bridge steel strands, steel book clip prefabricated parts are processed in the factory based on the measurement data. The steel book clip cantilever structure is installed on-site, and the upper and lower steel plates are connected and fixed by M16 high-strength friction bolts to achieve the purpose of widening the flange plate.

[0051] Widening of the cantilever flange includes the following.

[0052] 1.1 Demolition of structures on the old bridge

[0053] The existing structures on the old bridge were demolished using tools and equipment such as wire saws, in the following order from top to bottom: sound barrier, municipal steel railing, sidewalk, railing longitudinal beam foundation, until a certain height was reached from the top of the beam. The remaining concrete was ground smooth with a water grinder and removed, and the steel bars were cut with a grinding wheel, ensuring that the beam structure was not damaged.

[0054] 1.2 Scanning flange steel strands

[0055] Ultrasonic low-frequency tomography was used to detect the transverse prestressed steel strands and main reinforcements at the construction site of the flange plate. In order to more accurately avoid the prestressed steel strands and main reinforcements, the area was marked with chalk lines and the original steel strand corrugated pipe area was located. The prestressed tendon area was marked with red paint 5cm to the left and right of the original steel strand center. Drilling in this area is strictly prohibited.

[0056] like Figure 3 As shown: Before drilling holes in the concrete structure, the positions of steel book clips are laid out at longitudinal intervals of 1.2m. The drilling positions of each steel book clip are first arranged according to the designed bolt hole positions to ensure the number of 12 high-strength bolt holes. The hole positions are adjusted appropriately according to the scanning results of the steel strand to avoid damaging the original structural steel bars and steel strands.

[0057] 1.3 Drilling holes in the flange plate

[0058] To ensure the smooth passage of the through bolts, the diameter of the through bolt holes is 24mm. The bolt holes are drilled using a diamond core drill, strictly following the scanning and layout positions. This ensures that there are 12 bolt holes on each steel book clip (1.2m longitudinal distance of the bridge). The holes are drilled perpendicular to the upper surface of the flange plate and penetrate the entire flange plate, with a theoretical drilling depth of 18.8-23.8cm.

[0059] 1.4 Sampling of book clip line shape and hole position

[0060] To address the discrepancy between the actual flange profile and bolt hole positions and the ideal design, each steel book clip was measured based on the on-site layout. For example... Figure 4The data shown is collected using a steel book clip model and a steel tape measure to obtain the line shape of the steel book clip and the location of bolt holes on site. The steel book clip model is made of aluminum alloy square tubes and mainly consists of an upper surface frame, a lower surface frame, and an outer side frame. The steel book clip model is manufactured at a 1:1 scale according to the design dimensions of the connection position between the steel book clip and the flange plate. The upper and lower frame dimensions are 120cm × 130cm, and the side frame dimensions are 20cm × 120cm. During measurement, the steel book clip model is clamped onto the flange plate, with the upper surface frame aligned with the top surface of the flange plate and the outer surface frame aligned with the side surface of the flange plate. The steel book clip model is aligned with the layout position of the steel book clip. Using the outer surface frame as a reference, the thickness of the flange plate side is measured. The distances from the bolt holes to the longitudinal and transverse side bars of the upper surface frame are measured on the top surface of the flange plate, which are the coordinates of the bolt holes in the upper steel plate. The distances from the bolt holes to the longitudinal and transverse side bars of the lower surface frame are measured on the bottom surface of the flange plate, which are the coordinates of the bolt holes in the lower steel plate. The distances from the four vertices of the lower surface frame to the bottom surface of the flange plate are measured, which are the linear data of the lower steel plate. The data for each hole position is recorded and delivered to the processing plant for cutting, processing, and hole making.

[0061] 1.5 Factory-processed steel book clips

[0062] The steel book clip is made of Q345B steel, and the shear nails used for the splicing structure reinforcement are made of ML15 steel with a diameter of 13mm and a length of 50mm after welding.

[0063] like Figure 5 As shown: When processing the steel book clip, the upper steel plate is separated from other components. Other components besides the upper steel plate are made as a whole. The bolt holes on the upper and lower steel plates are drilled after the holes on the flange plate are drilled.

[0064] The steel book clip 15 includes an upper steel plate 15.1, a lower steel plate 15.2, a bottom beam 15.3, and a connecting column 15.4. The bottom beam 15.3 is welded to the bottom surface of the lower steel plate 15.2, and the connecting column 15.4 is welded to the top surface of the lower steel plate 15.2. The anti-collision wall column is connected to the connecting column 15.4. The lower steel plate 15.2, the bottom beam 15.3, and the connecting column 15.4 constitute an integral load-bearing structure, dispersing the impact force borne by the connecting column 15.4 to the box girder.

[0065] 1.6 Steel book clip installation

[0066] Use a truck crane to lift the upper and lower steel plates of the steel book clip to the layout position, ensuring that the bolt holes on the steel plate and the holes on the flange plate are aligned.

[0067] After test-installing the high-strength bolts and screws to ensure that all bolts can smoothly pass through the upper steel plate, flange plate, and lower steel plate, the steel book clips will be officially installed.

[0068] Before installing the spliced ​​structure, the mating surfaces of the upper and lower steel plates and flange plates should be treated. For rusty steel plate bonding surfaces, grind and remove rust to ensure that the bonding surfaces are clean.

[0069] The steel book clip is bonded to the flange plate with structural adhesive; the structural adhesive is applied to both the prepared concrete surface and the steel plate bonding surface at the same time, with the adhesive layer being thicker in the middle and thinner at the edges; then the steel plate is attached to the predetermined position.

[0070] Each bolt is designed with a preload of 20 kN. The bolts are 8.8S grade M16 high-strength bolts. According to the formula for final tightening torque: TC = K × D × PC, after testing, K = 0.136, the nominal diameter of the bolt is 16 mm, and PC is 20 kN. Therefore, the final tightening torque TC = 43.6 N·m is obtained. The initial tightening torque is 50% of the final tightening torque, which is 21.8 N·m.

[0071] After the steel plates are pasted, they are fixed with through-bolts, shims are added, and nuts are tightened. The shims should correspond to the slope of the flange plate. Initial tightening is performed, with a torque of 21.8 N·m applied. The tightening sequence is from the inside out and from the middle to both sides. Each through-bolt is tightened alternately, squeezing out excess structural adhesive along the plate seams and bolt holes. The pressure for fixing should not be less than 0.5 MPa. At the same time, the steel plate is tapped to check the fullness of the structural adhesive under the steel plate. If there is insufficient structural adhesive under the steel plate and there are hollow areas, the bolts are loosened, and structural adhesive is filled into the gaps from the side of the steel plate to make the steel plate flat and tightly attached.

[0072] Maintain the temperature during the curing of the structural adhesive, and the curing time shall not be less than 24 hours; after curing, tighten the bolts for the final tightening; apply a torque of 43.6 N·m.

[0073] After all the through-bolts are tightened and the structural adhesive has cured, the upper steel plate is welded to the other parts of the steel book clip at the longitudinal disconnection point. The weld is made by bevel penetration welding and cross-seam transverse stiffening ribs are set to achieve the first-class weld.

[0074] The reinforcement of the web steel ribs includes the following.

[0075] Before fabricating the steel rib beam, the prestressing tendons and steel strands inside the flange plate are scanned on-site. An ultrasonic low-frequency tomographic imaging instrument is used to detect the transverse prestressing steel strands and main reinforcements at the construction site of the flange plate. Lines are drawn on the top surface of the flange plate, and the area of ​​the steel strand corrugated pipe is located. The prestressing tendon and steel strand area is marked with a certain distance offset to the left and right of the center position of the steel strand.

[0076] Based on the design of the steel rib beam positions and spacing, the installation axis is laid out on site, with no less than 3 points on each section; the positions are marked and marked on the web and flange plates of the box girder; the drilling positions are laid out avoiding the areas of prestressed tendons and steel strands.

[0077] The steel rib beam consists of a middle rib plate, a bottom edge plate, vertical stiffening ribs, and anchor steel plates. The holes on the anchor steel plates are drilled one by one according to the on-site layout results. The steel rib beam is ground and roughened within 15cm to the left and right of the installation axis. An adhesive layer is set between the anchor steel plate and the box girder.

[0078] The steel rib beams were installed using a truck-mounted crane and steel rib beam lifting equipment; for example Figures 6 to 11 As shown, the steel rib beam lifting device consists of a lifting frame composed of an upper crossbeam 1, a lower crossbeam 2, and a counterweight vertical beam 3, and a main anchor bolt 5 for insertion into the anchor bolt holes 11 on the steel rib beam 10. The two ends of the counterweight vertical beam 3 are connected to one end of the upper crossbeam 1 and the lower crossbeam 2, respectively. The upper crossbeam 1 and the lower crossbeam 2 are located on the same side of the counterweight vertical beam 3 and are both vertically fixed to the counterweight vertical beam 3. The upper end of the upper crossbeam 1 is provided with a main lifting point 4.1 and an adjusting lifting point 4.2. The lower crossbeam 2 consists of two parallel lower crossbeams with space between them to avoid the steel rib beam. The upper end of the lower crossbeam 2 is provided with an anchor bolt seat 6 for receiving the main anchor bolt 5. The main anchor bolt 5 is inserted into the anchor bolt seat 6 and the corresponding anchor bolt hole 11 on the steel rib beam 10 and fixed by the anti-loosening bolt 12 to achieve the connection between the steel rib beam 10 and the lifting device.

[0079] To accommodate the requirements of steel rib beams 10 of different specifications, the lower crossbeam 2 can be configured as a telescopic beam, such as... Figure 2 As shown, it includes a fixed beam 2.1 and a sliding beam 2.2. The fixed beam is provided with a groove 2.11. Both the fixed beam 2.1 and the sliding beam 2.2 are provided with a number of bolt holes at intervals along their length. The sliding beam 2.2 slides along the groove 2.11 of the fixed beam 2.1 and is fixed by bolts 7 inserted into the bolt holes. The anchor seat 6 is fixedly connected to the sliding beam 2.2.

[0080] The lower crossbeam 2 is provided with a secondary anchor bolt hole 2.3 at the end away from the counterweight vertical beam 3. The secondary anchor bolt hole 2.3 is connected to another anchor bolt hole on the steel rib beam 10 through a secondary anchor bolt 8 and fixed by an anti-loosening bolt 12. The secondary anchor bolt 8 is located below the main anchor bolt 5 on one side. The size of the main anchor bolt hole 6.1 on the anchor bolt seat 6 is larger than the diameter of the main anchor bolt 5 to avoid the main anchor bolt 5 from getting stuck. The setting of the secondary anchor bolt 8 can increase the stability of the hoisting.

[0081] The adjusting lifting point 4.2 is located at the end of the upper crossbeam 1 away from the counterweight vertical beam 3. The adjusting lifting point 4.2 is a strip-shaped plate structure fixed to the upper end of the upper crossbeam 1. Several lifting holes are provided at intervals on the strip-shaped plate structure. The main lifting point 4.1 is located at the end of the upper crossbeam 1 close to the counterweight vertical beam 3. By changing the position of the lifting rope on the adjusting lifting point 4.2, it can be matched with steel rib beams 10 of different specifications.

[0082] The upper crossbeam 1 and lower crossbeam 2 are connected to the counterweight vertical beam 3 with reinforcing ribs 9 to ensure the stability of the overall structure. The weight of the counterweight vertical beam 3 matches the specifications of the steel ribs 10. The length of the lower crossbeam 2 is greater than the length of the upper crossbeam 1.

[0083] Detailed operation steps:

[0084] First, connect the secondary anchor bolt 8 to the anchor bolt hole 11 of the steel rib beam 10 using anti-loosening bolts 12. Then, insert the main anchor bolt 5 into the anchor bolt seat 6 and the anchor bolt hole 11 at another position of the steel rib beam 10, and connect it using anti-loosening bolts 12. Connect the lifting ropes of the lifting device to the main lifting point 4.1 and the adjusting lifting point 4.2 of the upper crossbeam 1, and lift the steel rib beam 10 to the lower end of the box girder installation position. During installation, the construction personnel assist in adjusting the position of the steel rib beam 10 and anchoring the steel rib beam 10 to the box girder. After installation, remove the anti-loosening bolts 12, separate the lifting tools from the installed steel rib beam 10, and return to the placement point of the steel rib beam 10 under the drive of the lifting device for the next lifting operation.

[0085] After the flange plate widening and reinforcement structure is completed, the construction of the crash barrier, the installation of the anti-throw net, the sound barrier, the bridge deck drainage, and the bridge deck paving will be carried out.

[0086] Construction of the crash barrier: The columns of the crash barrier are installed on the widened cantilever flange structure by butt welding, and the columns are perpendicular to the horizontal and vertical bridge planes; the crash barrier is vertically set with three horizontal beams, which are made of 140mm square tubes and the ends are closed with square tubes. The horizontal beams are connected by M10 bolts.

[0087] Installation of anti-throw netting: The posts of the anti-throw netting are connected to the crossbeams of the crash barrier; the anti-fall netting is fixed by horizontal and vertical frames and installed in sections on the posts using bolts; during installation, the metal mesh should be stretched and tightened, and the entire structure should not be twisted.

[0088] Sound barrier installation: The H-steel columns of the sound barrier are welded to the widened cantilever flange structure.

[0089] Bridge deck drainage construction: For the new bridge deck drainage, galvanized steel pipes will be installed every 5m along the axis of the lower side railing for river drainage, and PVC-U drainage pipes will be used for land drainage. The original bridge vertical drainage pipes will be sealed off. When installing the horizontal drainage pipes, the bridge deck elevation will be used as the control point, and the cross slope of the drainage pipe installation will be 10%.

[0090] Bridge deck paving construction: Inverted L-shaped steel bars are inserted into the original bridge deck; the steel mesh is tied and fixed to the shear nails and inverted L-shaped steel bars on the upper steel plate; and the concrete layer is paved.

[0091] Application Examples

[0092] This construction method was applied to the Xiamen Haixiang Avenue Improvement Project undertaken by China Railway 12th Bureau Group. This project involved upgrading and renovating the existing road. The total length of the route is 2.1686km, including the existing bridge, which is 397.7m long and consists of three sections: (4×30.0+5×30.0+4×30.0)m of uniform cross-section prestressed concrete continuous box girder. The bridge renovation included widening the cantilever flanges on the outer side and the inner side of the median strip, as well as reinforcing the steel ribs.

[0093] The old bridge flange plates are connected to the upper and lower steel plates (steel book clips) by through-type M16 high-strength friction bolts to achieve the purpose of widening the outer cantilever by 30cm and the inner cantilever by 49cm. One steel book clip is arranged every 1.2m along the longitudinal direction of the bridge, with a total of 1345m (1121 steel book clips) for the entire bridge.

[0094] This construction method, through safe, rapid, and efficient construction, successfully widened the bridge flange plates and increased the number of lanes, greatly alleviating traffic pressure on the surrounding road network and reducing traffic accidents. It has received unanimous praise from the owner, supervisor, and peers, and is worthy of reference and use in similar projects, showing promising application prospects.

[0095] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for widening and reinforcing the flange plates of a reinforced concrete box girder, characterized in that: This includes widening the cantilever flanges and reinforcing the web with steel ribs; Widening of the cantilever flange: Remove the existing structure at the flange plate, install steel book clips (15) on the edge of the flange plate to form a steel structure cantilever structure. The upper and lower steel plates of the steel book clips (15) are attached to and parallel to the top and bottom surfaces of the flange plate, respectively. The upper and lower steel plates are fixed by bolts that penetrate the flange plate. The upper and lower steel plates cantilever out of the flange plate. The cantilever ends of the upper and lower steel plates are closed and connected. Several steel book clips (15) are spliced ​​in sequence along the length of the box girder. The bridge deck structure is paved on the top surface of the upper steel plate. Web plate steel rib beam reinforcement: The steel rib beam (10) is anchored to the root of the flange plate and the web plate concrete by the anchor bolts (14), forming an integral force with the box girder; Before making the steel book clip (15) and steel rib beam (10), the prestressed tendons and steel strands inside the flange plate were scanned on site; the construction part of the flange plate was detected by an ultrasonic low-frequency tomographic imager, the transverse prestressed steel strands and main reinforcements were detected, the top surface of the flange plate was marked, the range of the steel strand corrugated pipe was located, and the prestressed tendon and steel strand area was marked by offsetting the center position of the steel strand by a certain distance to the left and right; Before drilling the concrete structure, the positions of the steel book clips (15) are laid out. The drilling positions of each steel book clip (15) are arranged on the flange plate according to the designed bolt hole positions, and the drilling positions are adjusted to avoid the prestressing tendons and steel strand areas. The line shape and bolt hole position data of each steel book clip (15) are measured on site according to the layout position. According to the design of the steel rib beam (10) position and spacing, the installation axis is laid out on site, with no less than 3 points on each section; the position is marked and marked on the web and flange of the box girder; the drilling position is arranged in the area of ​​prestressed tendons and steel strands. The upper and lower surfaces of the flange plate are roughened to remove a 2-3 mm thick surface layer; the steel book clip model (20) is used to collect the steel book clip line shape and on-site bolt hole data. The steel book clip model (20) includes an upper surface square, a lower surface square and an outer side square. The steel book clip model (20) is manufactured according to the design dimensions of the connection position between the steel book clip (15) and the flange plate at a 1:1 scale. During measurement, the steel book clip model (20) is clamped onto the flange plate, with the upper surface frame fitting against the top surface of the flange plate and the outer surface frame fitting against the side surface of the flange plate. The steel book clip model (20) is aligned with the steel book clip layout position. The thickness of the side surface of the flange plate is measured with the outer surface frame as a reference. The distance from the bolt hole position to the longitudinal and transverse side bars of the upper surface frame is measured on the top surface of the flange plate, which is the coordinate of the bolt hole position in the upper steel plate. The distance from the bolt hole position to the longitudinal and transverse side bars of the lower surface frame is measured on the bottom surface of the flange plate, which is the coordinate of the bolt hole position in the lower steel plate. The distance from the four vertices of the lower surface frame to the bottom surface of the flange plate is measured, which is the linear data of the lower steel plate.

2. The method for widening and reinforcing the flange of a reinforced concrete box girder according to claim 1, characterized in that: When processing the steel book clip (15), the upper steel plate is separated from other components. Other components besides the upper steel plate are made as a whole. The bolt holes on the upper and lower steel plates are drilled after the holes on the flange plate are drilled.

3. The method for widening and reinforcing the flange of a reinforced concrete box girder according to claim 2, characterized in that: The steel book clip (15) is bonded to the flange plate with structural adhesive; the structural adhesive is applied to the prepared concrete surface and the steel plate bonding surface at the same time, with the adhesive layer being thicker in the middle and thinner at the edges; then the steel plate is attached to the predetermined position. After the steel plate is pasted, it is fixed with through high-strength bolts (16), with shims and nuts. The shims correspond to the slope of the flange plate, and initial tightening is performed. The tightening sequence is from the inside to the outside and from the middle to both sides. Tighten each through high-strength bolt (16) alternately, and squeeze out the excess structural adhesive along the plate seam and bolt holes. The pressure for fixing is not less than 0.5MPa. At the same time, tap the steel plate to check the fullness of the structural adhesive under the steel plate. If there is insufficient structural adhesive under the steel plate and there are hollows, loosen the bolts and fill the gaps with structural adhesive from the side of the steel plate to make the steel plate flat and tightly attached. Maintain the temperature during the curing of the structural adhesive, and the curing time should not be less than 24 hours; after curing, tighten the bolts completely. After all the through-through high-strength bolts (16) are tightened and the structural adhesive is cured, the upper steel plate and the other parts of the steel book clip (15) are welded at the longitudinal disconnection position. The groove penetration weld is adopted, and the transverse stiffening ribs across the seam are set. The weld reaches the first-class weld.

4. The method for widening and reinforcing the flange of a reinforced concrete box girder according to claim 1, characterized in that: The steel rib beam (10) consists of a middle rib plate, a bottom edge plate, vertical stiffening ribs and an anchoring steel plate; the holes on the anchoring steel plate are made one by one according to the on-site layout results; Grind and roughen the anchoring steel plates within the installation range on both sides of the steel rib beam installation axis; install an adhesive layer between the anchoring steel plates and the box beam.

5. The method for widening and reinforcing the flange of a reinforced concrete box girder according to claim 4, characterized in that: The steel rib beam (10) was installed using a truck-mounted crane and steel rib beam lifting equipment. The steel rib beam lifting device includes a lifting frame consisting of an upper crossbeam (1), a lower crossbeam (2), and a counterweight vertical beam (3), and a main anchor bolt (5) for insertion into the anchor bolt holes on the steel rib beam. The two ends of the counterweight vertical beam (3) are connected to one end of the upper crossbeam (1) and the lower crossbeam (2), respectively. The upper crossbeam (1) and the lower crossbeam (2) are located on the same side of the counterweight vertical beam (3) and are both vertically fixed to it. The upper end of the upper crossbeam (1) is provided with a main lifting point (4.1) and an adjusting lifting point (4.2). The adjusting lifting point (4.2) is located at the end of the upper crossbeam (1) furthest from the counterweight vertical beam (3). The lifting point (4.2) is a strip-shaped plate structure fixed to the upper end of the upper crossbeam (1). Several lifting holes are provided at intervals on the strip-shaped plate structure. The main lifting point (4.1) is located at one end of the upper crossbeam (1) near the counterweight vertical beam (3). The lower crossbeam (2) consists of two parallel beams. There is space between the two lower crossbeams (2) to avoid the steel rib beam. The upper end of the lower crossbeam (2) is provided with an anchor seat (6) for inserting the main anchor bolt (5). The main anchor bolt (5) is inserted into the anchor seat (6) and the corresponding anchor bolt hole on the steel rib beam and fixed by the anti-loosening bolt (11) to realize the connection between the steel rib beam and the lifting tool. The lower crossbeam (2) is a telescopic beam, including a fixed beam (2.1) and a sliding beam (2.2). The fixed beam is provided with a groove (2.11). Both the fixed beam (2.1) and the sliding beam (2.2) are provided with a number of bolt holes at intervals along their length. The sliding beam (2.2) slides along the groove (2.11) of the fixed beam (2.1) and is fixed by bolts (7) inserted into the bolt holes. The anchor seat (6) is fixed to the sliding beam (2.2). The lower crossbeam (2) is provided with a secondary anchor bolt hole (2.3) at one end away from the counterweight vertical beam (3). The secondary anchor bolt hole (2.3) is connected to another anchor bolt hole on the steel rib beam by a secondary anchor bolt (8) and fixed by an anti-loosening bolt (11). The secondary anchor bolt (8) is located below one side of the main anchor bolt (5). The size of the main anchor bolt hole (6.1) on the anchor bolt seat (6) is larger than the diameter of the main anchor bolt (5) to avoid the main anchor bolt (5) from getting stuck.

6. The method for widening and reinforcing the flange of a reinforced concrete box girder according to claim 3, characterized in that: After the flange plate widening and reinforcement structure is completed, the construction of the crash barrier, the installation of the anti-throw net, the installation of the sound barrier, the construction of the bridge deck drainage, and the construction of the bridge deck paving will be carried out. Construction of crash barriers: The columns of the crash barriers are installed on the widened cantilever flange structure by butt welding, and the columns are perpendicular to the horizontal and vertical bridge planes; Installation of anti-throw netting: The posts of the anti-throw netting are connected to the crossbeams of the crash barrier; Sound barrier installation: The H-steel columns of the sound barrier are welded to the widened cantilever flange structure; Bridge deck drainage construction: For the new bridge deck drainage, galvanized steel pipes will be installed every 5m along the lower side railing axis for river drainage, and PVC-U drainage pipes will be used for land drainage. The original bridge vertical drainage pipes will be sealed off. When installing the transverse drainage pipes, the bridge deck elevation will be used as the control point, and the cross slope of the drainage pipes will be 10%. Bridge deck paving construction: Inverted L-shaped steel bars are inserted into the original bridge deck; the steel mesh is tied and fixed to the shear nails and inverted L-shaped steel bars on the upper steel plate; and the concrete layer is paved.

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