A damaged bridge reinforcement method using composite thin steel plate and UHPC

Abstract

The present invention discloses a damaged bridge reinforcement method using a composite thin steel plate and UHPC. Aiming at the local recovery bearing performance requirement of the impact damaged bridge, the present invention utilizes the advantages of high tensile strength and elastic modulus of UHPC and high interface strength with existing concrete, fills UHPC in the impact damaged area and the undamaged roughened area of ​​the box beam to restore the stiffness of the damaged area, and utilizes the shear resistance of the interface between UHPC and the undamaged roughened area to convert the normal pulling force between the UHPC filled reinforcement area and the box beam webs on both sides of the UHPC filled reinforcement area into the shear force of the interface between UHPC and the undamaged roughened area, so as to ensure that the two can work together; at the same time, utilizes the advantages of high tensile strength and easy processing and forming of thin steel plates, utilizes the thin steel plates to enhance the tensile performance of the reinforcement area and uses them as permanent templates for the reinforcement area, so as to improve the reinforcement construction efficiency and save construction costs.

Description

Technical Field

[0001] The invention relates to the technical field of bridge engineering, and more particularly to a damaged bridge reinforcement method using a composite thin steel plate and UHPC. Background Art

[0002] The rapid economic development has led to the continuous expansion of cities across my country, and the ensuing problem is increasingly congested traffic, which has led to the emergence of a large number of urban cross-line overpasses. Urban bridges play a vital role in the urban transportation system, but they also pose huge safety hazards. Due to improper operation by drivers, insufficient understanding of relevant road height restrictions, and an imperfect road administration system, accidents involving overheight vehicles hitting bridge structures are common, and bridges damaged by this account for more than 20% of all damaged bridges. Related research has statistically analyzed 502 bridge collapse or serious damage accidents in 66 countries. Among the causes of the accidents, accidents caused by overheight vehicle collisions account for about 18% of the total.

[0003] The current common method for dealing with the problem of damage to the superstructure of a bridge caused by a vehicle impact is to demolish and rebuild it; however, the period for rebuilding a bridge takes 6 to 12 months or longer, and it may also require interruption of traffic above and under the bridge deck, which is bound to bring about large economic losses. After a box girder bridge is damaged by an impact, the web and bottom plate are severely damaged, and a small amount of prestressed steel strands may be broken. Conventional single-material reinforcement methods cannot restore the stiffness, bearing capacity and durability of the bridge, and it is necessary to develop applicable reinforcement technologies. At present, there is relatively little research in this field. It is necessary to conduct in-depth research on the reinforcement technology of the main beam of a bridge damaged by a vehicle impact to provide guidance for the reinforcement of subsequent bridge impact accidents that may occur.

[0004] The reinforcement requirements for impact-damaged bridges are different from the conventional reinforcement actions due to the decline in bridge performance. There is no need to improve the overall stress performance of the bridge. It is only necessary to restore the stress performance of the damaged area and ensure that the reinforcement material has enough force transmission space to ensure that it can coordinate with the existing beam body in the undamaged area. According to this demand, the composite reinforcement of thin steel plate and UHPC is a better means. The tensile strength of thin steel plate is much higher than that of concrete. Bending the thin steel plate into a U shape can not only coordinate with the tensile zone of the box beam, but also serve as a casting template for internal cement-based reinforcement materials; UHPC is a high-performance cement-based material with tensile strength, compressive strength, elastic modulus and fluidity far superior to ordinary concrete. The shear strength of the interface between UHPC and existing concrete is also sufficient to ensure that the two can work together. The composite effect of thin steel plate and UHPC can easily achieve the purpose of restoring the bearing performance of the damaged area.

[0005] Therefore, how to provide a damaged bridge reinforcement method using a composite thin steel plate and UHPC is one of the technical problems that technicians in this field need to solve urgently. Summary of the invention

[0006] In view of this, in order to solve the problems mentioned in the above background technology, the present invention provides a damaged bridge reinforcement method using a composite thin steel plate and UHPC.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A damaged bridge reinforcement method using a composite thin steel plate and UHPC comprises the following steps:

[0009] Step 1) Determine the impact damage area of ​​the box girder, and clean the broken or possibly loose concrete in the impact damage area of ​​the box girder; after the concrete cleaning is completed, the web chiseling surface on the left side of the impact damage area of ​​the box girder, the web chiseling surface above the impact damage area, and the web chiseling surface on the right side of the impact damage area are all chiseled; repair welding of ordinary steel bars that have yielded or are obviously deformed due to impact, and attention should be paid to separating the exposed steel strands during welding operations;

[0010] Step 2) determine the scope of the UHPC filling and reinforcement area, chisel out the undamaged area of ​​the bottom plate, and roughen the roughened surface of the undamaged area. At the same time, implant web reinforcement above the UHPC filling and reinforcement area, use a high-power hair dryer to remove dust from the UHPC filling and reinforcement area, and use clean water to rinse the UHPC filling and reinforcement area to make it saturated and wet; install the internal wooden formwork of the impact damage area;

[0011] Step 3), processing and preparing the U-shaped steel plate: using the steel plate through the longitudinal length, placing the splicing welds between different steel plates at the junction of the box beam bottom plate and the box beam web, so as to form a U-shaped steel bottom plate and a U-shaped steel web; and correspondingly welding the U-shaped steel bottom plate steel bar connector and the U-shaped steel web steel bar connector in the U-shaped steel bottom plate and the U-shaped steel web, and then splicing the U-shaped steel bottom plate and the U-shaped steel webs on both sides into a whole;

[0012] Step 4), after the U-shaped steel plate is installed in place, the open ends of the U-shaped steel bottom plate and the U-shaped steel web are closed with wooden formwork; then UHPC is poured through the gap above the U-shaped steel web on one side, and the excellent fluidity of UHPC is used to make it flow from the U-shaped steel web on one side to the U-shaped steel web on the other side until the UHPC on both sides are flush with the upper edge of the U-shaped steel web;

[0013] Step 5) After the UHPC reaches the designed strength, remove the U-shaped steel web and the support parts under the U-shaped steel bottom plate to complete the reinforcement work.

[0014] Preferably, in step 2), the box girder web reinforcement area of ​​the UHPC filled reinforcement area is set as a hexagon that is narrow at the top and wide at the bottom, and its upper and lower horizontal sides are parallel to each other, the left and right vertical sides are parallel to each other, and the left and right oblique sides are symmetrical about the center line of the UHPC filled reinforcement area. The width of the narrow side above the hexagon is ≥ the sum of the width of the box girder impact damage area and 1.5 times the thickness of the box girder web, the width of the wide side below the hexagon is ≥ the sum of the width of the box girder impact damage area and 8 times the thickness of the box girder web, and the height of the left and right vertical sides of the hexagon is ≥ 2 times the thickness of the box girder bottom plate; the box girder bottom plate reinforcement area of ​​the UHPC filled reinforcement area is set as a rectangle, and the length of the box girder bottom plate reinforcement area is equal to the length of the wide side below the box girder web reinforcement area.

[0015] The beneficial effect of the above technical solution is that it can better ensure the gradual change of stiffness and smooth force transmission of the reinforced box girder from the impact damage area of ​​the box girder to the edge of the UHPC filled reinforcement area.

[0016] Preferably, in step 3), the U-shaped steel web is arranged in parallel with the box girder web; and the U-shaped steel bottom plate is arranged in parallel with the box girder bottom plate.

[0017] Preferably, in step 4), the U-shaped steel bottom plate steel bar connector and the U-shaped steel web steel bar connector are both configured to be wavy; the bottom wall of the U-shaped steel bottom plate steel bar connector is connected to the U-shaped steel bottom plate by a fillet weld, and its oblique side wall and upper wall are buried in the UHPC filling and reinforcement area; the bottom wall of the U-shaped steel web steel bar connector is connected to the U-shaped steel web by a fillet weld, and its oblique side wall and upper wall are buried in the UHPC filling and reinforcement area; used to enhance the interface strength of the U-shaped steel bottom plate, the U-shaped steel web and the UHPC filling and reinforcement area.

[0018] Preferably, the U-shaped steel web steel bar connector is set to two corrugated heights, with a small height in the roughened area of ​​the box girder web and a large height in the impact damaged area of ​​the box girder; the U-shaped steel bottom plate steel bar connector is set to a variety of gradually varying corrugated heights, with a large height in the impact damaged area of ​​the box girder and a gradually decreasing height in the bottom plate chiseled area of ​​the undamaged area; thereby ensuring that the U-shaped steel web steel bar connector and the U-shaped steel bottom plate steel bar connector are buried in the UHPC filling reinforcement area to the greatest extent, thereby increasing the reliability of the reinforcement interface.

[0019] Preferably, the U-shaped steel bottom plate and the U-shaped steel webs on both sides cover the entire UHPC filling and reinforcement area.

[0020] Preferably, the thickness of the U-shaped steel bottom plate and the U-shaped steel webs on both sides is 4-8 mm.

[0021] Preferably, in step 2), the thickness of the UHPC filled in the chiseled area of ​​the bottom plate in the undamaged area is 30-40 mm.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] In view of the local recovery bearing performance requirements of the impact-damaged bridge, the present invention utilizes the advantages of UHPC's high tensile strength and elastic modulus and high interface strength with existing concrete, fills UHPC in the impact-damaged area and the undamaged roughened area of ​​the box girder to restore the stiffness of the damaged area, and at the same time utilizes the shear resistance of the interface between UHPC and the undamaged roughened area to convert the normal tensile force between the UHPC-filled reinforcement area and the box girder web of the UHPC-reinforced area into the shear force of the interface between UHPC and the undamaged roughened area, thereby ensuring that the two can work together; at the same time, utilizing the advantages of thin steel plates' high tensile strength and easy processing and forming, while utilizing the thin steel plates to enhance the tensile performance of the reinforcement area, they are used as permanent templates for the reinforcement area, thereby improving the efficiency of reinforcement construction and saving construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the facade structure of the bridge damaged by the impact;

[0025] Figure 2 This is a schematic diagram of the cross-sectional structure of the damaged area of ​​the impact-damaged bridge;

[0026] Figure 3 This is the elevation layout of the impact-damaged bridge before reinforcement;

[0027] Figure 4 This is the elevation layout of the impact-damaged bridge after reinforcement;

[0028] Figure 5 This is the AA section of the impact-damaged bridge after reinforcement;

[0029] Figure 6 This is the BB section diagram of the impact-damaged bridge after reinforcement;

[0030] Figure 7 It is the cross-section layout diagram of the U-shaped steel plate;

[0031] Figure 8 This is the layout of the reinforcement connections for the web of the U-shaped steel plate;

[0032] Fig. 9 This is the layout diagram of the steel bar connectors for the U-shaped steel plate base.

[0033] Figure 1-9 Middle: 1. Box girder top plate; 2. Box girder web; 3. Box girder impact damage area; 4. Box girder web roughening area; 5. Web reinforcement; 6. Web roughening surface on the left side of the impact damage area; 7. Web roughening surface above the impact damage area; 8. Web roughening surface on the right side of the impact damage area; 9. Bottom plate roughening surface of the undamaged area; 10. Bottom plate chiseling area of ​​the undamaged area; 11. UHPC filling and reinforcement area; 12. U-shaped steel web; 13. U-shaped steel bottom plate; 14. U-shaped steel web reinforcement connector; 15. U-shaped steel bottom plate reinforcement connector. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example

[0036] Reference Figure 1-9 A damaged bridge reinforcement method using a composite thin steel plate and UHPC is shown, comprising the following steps:

[0037] Step 1), determine the impact damage area 3 of the box girder, clean the broken or possibly loose concrete in the impact damage area 3 of the box girder; after the concrete cleaning is completed, the web chiseling surface 6 on the left side of the impact damage area of ​​the box girder impact damage area 3, the web chiseling surface 7 on the upper side of the impact damage area, and the web chiseling surface 8 on the right side of the impact damage area are all chiseled; repair welding of ordinary steel bars that have yielded or are obviously deformed due to impact, and attention should be paid to separating the exposed steel strands during welding operations;

[0038] Step 2), determine the scope of the UHPC filling and reinforcement area 11, chisel out the chiseling area 10 of the undamaged area bottom plate, and chisel the chiseling surface 9 of the undamaged area bottom plate formed, and at the same time implant the web embedding reinforcement 5 above the UHPC filling and reinforcement area 11, use a high-power hair dryer to remove dust from the UHPC filling and reinforcement area 11, and use clean water to rinse the UHPC filling and reinforcement area 11 to make it in a saturated and wet state; install the internal wooden formwork of the impact damage area;

[0039] Step 3), processing and preparing the U-shaped steel plate: using the steel plate through the longitudinal length, placing the splicing welds between different steel plates at the junction of the box beam bottom plate and the box beam web 2, so as to form a U-shaped steel bottom plate 13 and a U-shaped steel web 12; and correspondingly welding the U-shaped steel bottom plate steel bar connector 15 and the U-shaped steel web steel bar connector 14 in the U-shaped steel bottom plate 13 and the U-shaped steel web 12, and then splicing the U-shaped steel bottom plate 13 and the U-shaped steel web 12 on both sides into a whole;

[0040] Step 4), after the U-shaped steel plate is installed in place as a whole, the open ends of the U-shaped steel bottom plate 13 and the U-shaped steel web 12 are closed with a wooden formwork; then UHPC is poured through the gap above the U-shaped steel web 12 on one side, and the excellent fluidity of UHPC is used to make it flow from the U-shaped steel web 12 on one side to the U-shaped steel web 12 on the other side until the UHPC on both sides are flush with the upper edge of the U-shaped steel web 12;

[0041] Step 5) After the UHPC reaches the designed strength, the support members below the U-shaped steel web 12 and the U-shaped steel bottom plate 13 are removed to complete the reinforcement work.

[0042] As an optional or preferred method of this embodiment, in step 2), the box girder web reinforcement area of ​​the UHPC filled reinforcement area 11 is set as a hexagon that is narrow at the top and wide at the bottom, and its upper and lower horizontal sides are parallel to each other, the left and right vertical sides are parallel to each other, and the left and right oblique sides are symmetrical about the center line of the UHPC filled reinforcement area 11. The width of the narrow side above the hexagon is ≥ the sum of the width of the box girder impact damage area and 1.5 times the thickness of the box girder web, the width of the wide side below the hexagon is ≥ the sum of the width of the box girder impact damage area and 8 times the thickness of the box girder web, and the height of the left and right vertical sides of the hexagon is ≥ 2 times the thickness of the box girder bottom plate; the box girder bottom plate reinforcement area of ​​the UHPC filled reinforcement area 11 is set as a rectangle, and the length of the box girder bottom plate reinforcement area is equal to the length of the wide side below the box girder web reinforcement area. This can better ensure the gradual change in stiffness and smooth force transmission from the box girder impact damage area to the edge of the UHPC filled reinforcement area after reinforcement.

[0043] As an optional or preferred manner of this embodiment, in step 3), the U-shaped steel web 12 is arranged parallel to the box girder web 2; and the U-shaped steel bottom plate 13 is arranged parallel to the box girder bottom plate.

[0044] As an optional or preferred mode of this embodiment, in step 4), the U-shaped steel bottom plate steel bar connector 15 and the U-shaped steel web steel bar connector 14 are both configured to be wavy; the bottom wall of the U-shaped steel bottom plate steel bar connector 15 is connected to the U-shaped steel bottom plate 13 by a fillet weld, and its oblique side wall and upper wall are buried in the UHPC filling and reinforcement area 11; the bottom wall of the U-shaped steel web steel bar connector 14 is connected to the U-shaped steel web 12 by a fillet weld, and its oblique side wall and upper wall are buried in the UHPC filling and reinforcement area 11; it is used to enhance the interface strength of the U-shaped steel bottom plate 13, the U-shaped steel web 12 and the UHPC filling and reinforcement area 11.

[0045] As an optional or preferred embodiment of the present invention, the U-shaped steel web steel bar connector 14 is set to have two corrugated heights, with a small height in the box girder web roughening area 4 and a large height in the box girder impact damaged area 3; the U-shaped steel bottom plate steel bar connector 15 is set to have multiple gradually varying corrugated heights, with a large height in the box girder impact damaged area 3 and a gradually decreasing height in the bottom plate chiseled area 10 in the undamaged area; thereby ensuring that the U-shaped steel web steel bar connector 14 and the U-shaped steel bottom plate steel bar connector 15 fill the UHPC reinforcement area 11 to the greatest extent, thereby increasing the reliability of the reinforcement interface.

[0046] As an optional or preferred embodiment of this embodiment, the U-shaped steel bottom plate 13 and the U-shaped steel webs 12 on both sides cover the entire UHPC filling and reinforcement area.

[0047] As an optional or preferred embodiment of the present invention, the thickness of the U-shaped steel bottom plate 13 and the U-shaped steel webs 12 on both sides is 4 to 8 mm.

[0048] As an optional or preferred mode of this embodiment, in step 2), the thickness of the UHPC filled in the undamaged bottom plate chiseled area 10 is 30-40 mm.

[0049] In view of the local recovery bearing performance requirements of the impact-damaged bridge, the present invention utilizes the advantages of UHPC's high tensile strength and elastic modulus and high interface strength with existing concrete, fills UHPC in the impact-damaged area and the undamaged roughened area of ​​the box girder to restore the stiffness of the damaged area, and at the same time utilizes the shear resistance of the interface between UHPC and the undamaged roughened area to convert the normal tensile force between the UHPC-filled reinforced area and the box girder web of the UHPC-filled reinforced area into the shear force of the interface between UHPC and the undamaged roughened area, thereby ensuring that the two can work together; at the same time, utilizing the advantages of thin steel plates' high tensile strength and easy processing and forming, while utilizing the thin steel plates to enhance the tensile performance of the reinforced area, they are used as permanent templates for the reinforced area, thereby improving the efficiency of reinforcement construction and saving construction costs.

[0050] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for reinforcing a damaged bridge by composite application of thin steel plate and UHPC, characterized in that: The following steps are involved: Step 1), determining the impact damage area (3) of the box girder, and cleaning the broken or possibly loose concrete in the impact damage area (3) of the box girder; after the concrete cleaning is completed, roughening the web roughening surface (6) on the left side of the impact damage area, the web roughening surface (7) above the impact damage area, and the web roughening surface (8) on the right side of the impact damage area of ​​the box girder impact damage area (3); repair welding ordinary steel bars that have yielded or are obviously deformed due to impact, and care should be taken to separate the exposed steel strands when carrying out the welding operation; Step 2), determine the scope of the UHPC filling and reinforcement area (11), chisel out the undamaged area bottom plate chiseling area (10), and chisel the undamaged area bottom plate chiseling surface (9), and at the same time implant web reinforcement (5) above the UHPC filling and reinforcement area (11), use a high-power hair dryer to remove dust from the UHPC filling and reinforcement area (11), and use clean water to rinse the UHPC filling and reinforcement area (11) to make it in a saturated and wet state; install the internal wooden formwork of the impact damage area; Step 3) Processing and preparing the U-shaped steel plate: using the steel plate in the longitudinal direction, placing the joint welds between different steel plates at the junction of the box beam bottom plate and the box beam web (2), thereby forming a U-shaped steel bottom plate (13) and a U-shaped steel web (12); and correspondingly welding the U-shaped steel bottom plate steel bar connector (15) and the U-shaped steel web steel bar connector (14) in the U-shaped steel bottom plate (13) and the U-shaped steel web (12), respectively, and then splicing the U-shaped steel bottom plate (13) and the U-shaped steel web (12) on both sides into a whole; Step 4), after the U-shaped steel plate is installed in place, the open ends of the U-shaped steel bottom plate (13) and the U-shaped steel web (12) are closed by using a wooden formwork; then UHPC is poured through the gap above the U-shaped steel web (12) on one side, and the excellent fluidity of UHPC is used to make it flow from the U-shaped steel web (12) on one side to the U-shaped steel web (12) on the other side until the UHPC on both sides are flush with the upper edge of the U-shaped steel web (12); Step 5), after the UHPC reaches the designed strength, the support members below the U-shaped steel web (12) and the U-shaped steel bottom plate (13) are removed to complete the reinforcement work; In step 4), the U-shaped steel bottom plate steel bar connector (15) and the U-shaped steel web plate steel bar connector (14) are both configured to be wavy; the bottom straight bar section of the U-shaped steel bottom plate steel bar connector (15) is connected to the U-shaped steel bottom plate (13) by a fillet weld, and its oblique bar section and upper straight bar section are buried in the UHPC filling and reinforcement area (11); the bottom straight bar section of the U-shaped steel web plate steel bar connector (14) is connected to the U-shaped steel web plate (12) by a fillet weld, and its oblique bar section and upper straight bar section are buried in the UHPC filling and reinforcement area (11).

2. The damaged bridge reinforcement method using a composite thin steel plate and UHPC according to claim 1 is characterized in that: In step 2), the web reinforcement area of ​​the UHPC filling reinforcement area (11) is set to be a hexagon that is narrow at the top and wide at the bottom, and its upper and lower horizontal sides are parallel to each other, its left and right vertical sides are parallel to each other, and its left and right oblique sides are symmetrical about the center line of the UHPC filling reinforcement area (11); the bottom plate reinforcement area of ​​the UHPC filling reinforcement area (11) is set to be a rectangle.

3. The damaged bridge reinforcement method using a composite thin steel plate and UHPC according to claim 1 is characterized in that: In step 3), the U-shaped steel web (12) is arranged parallel to the box girder web (2); and the U-shaped steel bottom plate (13) is arranged parallel to the box girder bottom plate.

4. The damaged bridge reinforcement method using a composite thin steel plate and UHPC according to claim 3 is characterized in that: The U-shaped steel web reinforcement connector (14) is set to have two wave heights, with a small height in the box girder web roughening area (4) and a large height in the box girder impact damaged area (3); the U-shaped steel bottom plate reinforcement connector (15) is set to have multiple gradually changing wave heights, with a large height in the box girder impact damaged area (3) and a gradually decreasing height in the bottom plate chiseled area (10) in the undamaged area.

5. The damaged bridge reinforcement method using a composite thin steel plate and UHPC according to claim 1 is characterized in that: The U-shaped steel bottom plate (13) and the U-shaped steel web plates (12) on both sides cover the entire UHPC filling and reinforcement area (11).

6. The damaged bridge reinforcement method using a composite thin steel plate and UHPC according to claim 1 is characterized in that: The thickness of the U-shaped steel bottom plate (13) and the U-shaped steel web plates (12) on both sides is 4 to 8 mm.

7. The damaged bridge reinforcement method using a composite thin steel plate and UHPC according to claim 1 is characterized in that: In step 2), the thickness of the UHPC filled in the undamaged bottom plate chiseled area (10) is 30 to 40 mm.

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