A method for connecting steel bars for replacing old crash barrier wall with new one

Abstract

This invention discloses a method for connecting reinforcing bars during the replacement of old and new precast crash barriers, belonging to the field of bridge engineering technology. The method includes the following steps: removing the concrete of the old crash barrier to expose the original reinforcing bars connected to the box girder structure; based on the installation elevation requirements of the new precast crash barrier and the elevation of the bridge deck pavement, if the anchorage depth of the original reinforcing bars is sufficient, vertically bending the exposed original reinforcing bars to form bent reinforcing bars; hoisting the new precast crash barrier into place, and extending the precast crash barrier's reserved reinforcing bars into the wet joint, aligning and fixing them with the bent reinforcing bars; setting up a formwork at the junction of the old and new precast crash barriers to form a wet joint pouring space, and pouring concrete into the wet joint pouring space; after the concrete reaches the design strength, removing the formwork and proceeding with the bridge deck pavement restoration work. This invention solves the problem of mismatch between reinforcing bar length and installation elevation by bending the original reinforcing bars into bent reinforcing bars instead of cutting them off.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering technology, and specifically relates to a method for connecting steel bars for replacing old and new crash barriers. Background Technology

[0002] As transportation infrastructure ages, many old bridges require replacement of their crash barriers due to aging and damage. During replacement work, the newly cast or precast crash barriers need to be reliably connected to the existing bridge structure.

[0003] However, existing construction methods face the following technical bottlenecks when connecting old and new structures: Poor elevation adaptability: After the old bridge crash barrier is demolished, the length of the exposed rebar is limited by the original structure and often does not match the installation elevation of the new crash barrier. Conventional cutting methods result in wasted rebar. Limited working conditions: It cannot effectively address the failure of the original rebar caused by the misalignment of prestressed anchors. Frequent rebar conflicts: When the installation position of the precast crash barrier is moved outward, some old rebars will deviate from the wet joint range, resulting in insufficient rebar density in the joint and reduced connection strength. Prestressing interference: The existence of transverse prestressing of the box girder and the influence area of ​​prestressed anchors makes rebar installation difficult, and conventional rebar installation is prone to conflict with prestressed tendons.

[0004] Therefore, a method for connecting steel bars for replacing old and new crash barriers needs to be proposed to solve the above problems. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for connecting steel bars when replacing old and new crash barriers. This method flexibly adopts bending or rebar reinforcement schemes according to the actual situation of the old bridge structure, ensuring the reliability of the connection between the old and new structures and effectively avoiding interference from prestressed anchorages.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention discloses a method for connecting steel bars in the replacement of old and new crash barriers, comprising the following steps: S1. Remove the old concrete of the crash barrier that needs to be replaced to expose the original steel bars connected to the box girder structure; S2. According to the installation elevation requirements of the new precast crash barrier and the elevation of the bridge deck pavement, if the anchorage depth of the original steel bars is sufficient, the exposed original steel bars are vertically bent at 90° to form a ring-shaped bent steel bar. S3. Hoist the new precast crash barrier into place and form a wet joint between the new precast crash barrier and the old crash barrier for pouring concrete, and insert the precast steel bars of the crash barrier into the wet joint and align and fix them with the bent steel bars; S4. Set up formwork at the junction of the old crash barrier and the new precast crash barrier to form a wet joint pouring space, and pour concrete into the wet joint pouring space. S5. After the concrete reaches the design strength, remove the formwork and carry out the bridge deck pavement restoration work.

[0007] Furthermore, in step S2, if the anchorage depth of the original reinforcing bar is insufficient, the following steps must be followed: S21. Drill and clean holes between the two rows of reinforcing bars pre-installed in the old crash barrier, inject adhesive into the holes, and then insert replacement reinforcing bars. S22. Cut off the original steel bars exposed on the side near the bridge deck, and weld new steel bars on the side of the original steel bars near the wet joint on the side near the bridge deck. Bend the new steel bars into the wet joint to form bent and welded steel bars. S23. Insert longitudinal main bars longitudinally, and weld the longitudinal main bars with bent bars, replanted bars and bent welded bars to form an integral steel reinforcement skeleton.

[0008] Furthermore, in step S21, the location of the rebar to be installed is outside the influence area of ​​the prestressed anchorage and must avoid the location of the transverse prestressing action of the box girder.

[0009] Furthermore, the height of the wet joint is higher than the height of the exposed bent reinforcing bars.

[0010] Furthermore, the concrete is UHPC concrete.

[0011] The beneficial effects of this invention are as follows: 1. Good elevation adaptability: By bending the original steel bars into bent steel bars instead of cutting them off, the utilization rate of the original steel bars is preserved, and the height requirements of the new crash barrier can be flexibly adapted to, solving the problem of mismatch between steel bar length and installation elevation; 2. Effectively address anchorage misalignment: To address the problem of rebar failure caused by prestressed anchorage misalignment, a dual approach of replanting rebar and bending and welding the original rebar on the bridge deck side into bent and welded rebar is adopted to ensure the rebar density and connection strength within the wet joint. 3. Avoid prestressing interference: The re-installation of steel bars should strictly avoid the influence area of ​​the prestressed anchorage and the area of ​​transverse prestressing of the box girder to ensure that the original structural stress system is not damaged; 4. Avoid steel bar conflict: The design of equally spaced steel bars in the same row effectively avoids steel bar conflict during the installation of prefabricated crash barriers; 5. Excellent connection performance: Combining the strong bonding force of UHPC with the synergistic force of the overall steel skeleton, the integrity and shear resistance of the new and old structures are significantly improved; 6. Shorten the construction cycle: The early strength characteristics of UHPC can significantly shorten the maintenance time and reduce traffic disruption. Attached Figure Description

[0012] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a schematic diagram of the original exposed state of the reinforcing steel bars just after removal in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the original state of the steel bar after bending in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the connection treatment of the new and old anti-collision wall steel bars in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the connection treatment of the new and old anti-collision wall steel bars in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of the reinforcement density compensation in the wet joint of Embodiment 2 of the present invention.

[0013] The following are marked in the attached diagram: 1. Bridge deck pavement layer; 2. Box girder structure; 3. Original reinforcing bars; 4. Bent reinforcing bars; 5. Reserved reinforcing bars for precast crash barriers; 6. Wet joint; 7. Area affected by prestressed anchorages; 8. Longitudinal main reinforcement; 9. Bent and welded reinforcing bars; 10. Original reinforcing bars on the side near the bridge deck; 11. Transverse prestressing of the box girder; 12. Reinforcement bars added. Detailed Implementation

[0014] Example 1: This example is applicable to situations where the structure of the old bridge basically matches the drawings, requiring only routine elevation adjustments. Combined with... Figure 1 , Figure 2 , Figure 3 As shown, the specific steps are as follows: S1. Demolition of the old crash barrier: The concrete of the old crash barrier to be replaced is chiseled away, exposing the original reinforcing steel bars 3 connected to the box girder structure 2. At this point, the original reinforcing steel bars 3 are in their pre-bending state, such as... Figure 1 As shown in the figure, the bridge deck pavement layer 1, the box girder structure 2, and the original steel reinforcement 3 are visible. S2. Elevation Measurement and Bending Treatment: Based on the installation elevation requirements of the new precast crash barrier and the elevation of the bridge deck pavement layer 1, the exposed original steel bars 3 are retained to a sufficient length according to the specifications, and then vertically bent to form the bent steel bars 4. Figure 2 As shown in the figure, the bridge deck pavement layer 1, the box girder structure 2, and the bent steel bars 4 are visible. The bending angle is determined according to the actual elevation to ensure that the bent steel bars 4 can accurately extend into the subsequent wet joint 6 after bending. S3. New crash barrier hoisting: Hoist the prefabricated crash barrier into place and extend the pre-reserved steel bar 5 of the prefabricated crash barrier into the wet joint area 6; S4. Reinforcing bar connection: Align and connect the bent reinforcing bar 4 with the pre-reserved reinforcing bar 5 in the precast crash barrier (welding or mechanical connection can be used). Figure 3As shown in the figure, the bridge deck pavement layer 1, box girder structure 2, bent steel bars 4, precast crash barrier reserved steel bars 5, and the wet joint 6 between the two can be seen. S5. Formwork erection and concrete pouring: Formwork is erected at the junction of the new and old crash barriers to form a wet joint 6 pouring space, and UHPC concrete is poured. S6. Subsequent construction: After the UHPC concrete reaches the design strength, the formwork will be removed and subsequent work such as restoring the bridge deck pavement layer 1 will be carried out.

[0015] Example 2: This example applies to situations where misalignment of prestressed anchorages occurs in old bridge structures, leading to the failure of the original reinforcing steel, or where the installation position of the precast crash barrier needs to be moved outward. Combined with... Figure 4 , Figure 5 As shown, the specific steps are as follows: S1. Demolition and Assessment of the Old Crash Barrier: The old crash barrier concrete was removed to expose the original reinforcing bars 3 on the box girder structure 2. The location of the prestressed anchorage influence area 7 was determined by observing the positions of the bridge deck pavement layer 1, the box girder structure 2, the original reinforcing bars 3, and the original reinforcing bars 10 on the bridge deck side. Figure 4 As shown, during the cleaning process, it was found that some of the original steel bars 3 were pulled out and failed due to insufficient anchoring depth caused by misalignment of the anchorage, or the installation position of the prefabricated crash barrier needs to be moved outward according to the design requirements. S2. Rebar Installation Reinforcement: According to the design drawings, rebar installation work should be carried out outside the prestressed anchorage influence area 7, avoiding the transverse prestressing 11 of the box girder (e.g., Figure 5 (As shown). The specific location is chosen in the middle of the two rows of pre-reserved steel bars in the old crash barrier. After drilling, cleaning, and injecting adhesive, 12 additional steel bars are inserted. Figure 5 As shown in the figure, the bridge deck pavement layer 1, the original steel reinforcement 3, the original steel reinforcement 10 on the side near the bridge deck, the transverse prestressing of the box girder 11, and the replanted steel reinforcement 12 can be seen. S3. Treatment of Reinforcing Steel on the Bridge Deck Side: Due to the outward relocation of the prefabricated crash barrier installation position, the original reinforcing steel 10 on the bridge deck side will later deviate from the range of the wet joint 6. The exposed portion of the original reinforcing steel 10 on the bridge deck side will be cut off, and new reinforcing steel will be welded to its side (the side closest to the wet joint 6). The new reinforcing steel will be bent into the wet joint 6 to form a bent and welded reinforcing steel 9, as shown below. Figure 4 As shown; S5. Longitudinal Main Reinforcement Layout and Welding: Insert longitudinal main reinforcement 8 longitudinally, and weld it to all the following reinforcement bars: bent reinforcement 4, supplementary reinforcement 12, and bent and welded reinforcement 9. The welding should be firm, forming an integral reinforcement skeleton. Figure 4 As shown in the figure, the connection relationship between the longitudinal main reinforcement 8 and each reinforcement bar can be seen; and the reinforcement density is checked to ensure that the reinforcement density in the wet joint 6 meets the design requirements. The failed reinforcement bars are compensated by the double measures of replanting reinforcement bars 12 and bending and welding reinforcement bars 9, thus ensuring the quantity of reinforcement bars in the joint. S6. Formwork Erection and Concrete Pouring: Erect the formwork and pour UHPC concrete into the wet joint 6, as follows. Figure 4 As shown, a complete steel reinforcement skeleton has been formed inside wet joint 6; S7. Subsequent construction: After the UHPC concrete reaches the design strength, the formwork will be removed and subsequent work such as restoring the bridge deck pavement layer 1 will be carried out.

[0016] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for connecting reinforcing bars when replacing old and new crash barriers, characterized in that, Includes the following steps: S1. Remove the old concrete of the crash barrier that needs to be replaced to expose the original steel bars connected to the box girder structure; S2. According to the installation elevation requirements of the new precast crash barrier and the elevation of the bridge deck pavement, if the anchorage depth of the original steel bars is sufficient, the exposed original steel bars are vertically bent at 90° to form a ring-shaped bent steel bar. S3. Hoist the new precast crash barrier into place and form a wet joint between the new precast crash barrier and the old crash barrier for pouring concrete, and insert the precast steel bars of the crash barrier into the wet joint and align and fix them with the bent steel bars; S4. Set up formwork at the junction of the old crash barrier and the new precast crash barrier to form a wet joint pouring space, and pour concrete into the wet joint pouring space. S5. After the concrete reaches the design strength, remove the formwork and carry out the bridge deck pavement restoration work.

2. The method for connecting reinforcing bars for replacing old and new crash barriers according to claim 1, characterized in that: In step S2, if the anchorage depth of the original reinforcing bar is insufficient, the following steps must be followed: S21. Drill and clean holes between the two rows of reinforcing bars pre-installed in the old crash barrier, inject adhesive into the holes, and then insert replacement reinforcing bars. S22. Cut off the original steel bars exposed on the side near the bridge deck, and weld new steel bars on the side of the original steel bars near the wet joint on the side near the bridge deck. Bend the new steel bars into the wet joint to form bent and welded steel bars. S23. Insert longitudinal main bars longitudinally, and weld the longitudinal main bars with bent bars, replanted bars and bent welded bars to form an integral steel reinforcement skeleton.

3. The method for connecting reinforcing bars for replacing old and new crash barriers according to claim 2, characterized in that: In step S21, the location of the rebar to be installed is outside the influence area of ​​the prestressed anchorage and must avoid the location of the transverse prestressing action of the box girder.

4. The method for connecting reinforcing bars for replacing old and new crash barriers according to claim 1, characterized in that: The height of the wet joint is higher than the height of the exposed bent reinforcing bars.

5. The method for connecting reinforcing bars for replacing old and new crash barriers according to claim 1, characterized in that: The concrete is UHPC concrete.

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