A precast concrete bridge pier with steel pipe-internally prestressed steel strand connection and its construction method

Abstract

This invention belongs to the field of bridge engineering technology, and particularly relates to a precast concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection and its construction method. This invention ensures higher structural integrity, greater connection strength, and better support stability of the precast concrete bridge pier by setting several precast segmental units on a cast-in-place pier cap unit, setting cast-in-place segmental units between adjacent precast segmental units, and setting in-pipe prestressed steel strand units on the entirety of all precast segmental units. Furthermore, this invention also provides a construction method for the above-mentioned precast concrete bridge pier, which sequentially includes the following steps: casting precast segmental units in a factory, installing in-pipe prestressed steel strand units, casting a cast-in-place pier cap unit, casting a cast-in-place segmental unit, and tensioning, anchoring, and casting in-pipe prestressed steel strand units, ensuring an orderly and efficient construction effect for the precast concrete bridge pier.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering technology, and in particular relates to a precast concrete bridge pier with steel pipe-in-pipe prestressed steel strand connection and its construction method. Background Technology

[0002] With the development of bridge construction and technological advancements, bridge building is moving towards standardized design, factory production, assembly and mechanization of construction, and information-based management. Therefore, fully prefabricated assembly technology, including segmental precast beams and piers, is expected to become one of the main construction methods for bridges in the future.

[0003] Segmented prefabricated piers are constructed by dividing a single pier into one or more segments based on its length. Furthermore, the prefabrication of different segments of the pier can be further divided into integral prefabricated piers and segmented prefabricated piers.

[0004] Segmented piers are prefabricated in a factory. After the concrete is cured, they are transported to the construction site and assembled together using post-tensioning of prestressed steel bars to form the entire pier. The externally applied prestress gives the segmented piers a certain degree of integrity and better self-resetting ability compared to cast-in-place monolithic piers. The use of segmented piers greatly reduces the construction period, reduces the land area occupied by the construction site, and effectively alleviates transportation pressure.

[0005] However, most of the current post-tensioned prestressed segmental piers are based on the original monolithic cast-in-place reinforced concrete pier design. By optimizing the layout of prestressing ducts and tensioning prestress to ensure the effectiveness of the connection between segments, problems such as discontinuity after the longitudinal reinforcing bars are broken, large vertical positioning deviation of the pre-embedded corrugated pipes, and weakening of the effective cross section of the pier under compression exist. As a result, the overall performance of the segmental piers is relatively weak, which is not conducive to their application and promotion in actual engineering.

[0006] Chinese utility model patent with patent publication number CN217104690U and publication date of August 2, 2022 discloses a hybrid self-resetting prefabricated assembled bridge pier, which includes a pier top section, several intermediate segment piers, a second bottom segment pier, a bottom segment pier, and a pier cap arranged sequentially from top to bottom.

[0007] Vertical center holes with corresponding positions are opened in the pier top section, several intermediate pier segments, the second bottom pier segment, the bottom pier segment, and the pile cap. Prestressed strands are inserted into the vertical center holes. The bottom pier segment and the pile cap are integrally formed. A viscoelastic damping layer is sandwiched between the second bottom pier segment and the bottom pier segment. Multiple vertical energy-dissipating steel bars are symmetrically inserted on the opposite two sides of the second bottom pier segment and the bottom pier segment. The two ends of the vertical energy-dissipating steel bars extend to the top surface of the second bottom pier segment and the bottom surface of the bottom pier segment, respectively.

[0008] The general operating principle of this prefabricated bridge pier is as follows: when a minor earthquake occurs, the bridge pier will sway slightly, and multiple vertical energy-dissipating steel bars can effectively dissipate energy. When the bottom segment and the second bottom segment of the pier sway, the joint between them will open, and the viscoelastic damping layer can flexibly deform to dissipate energy, reduce the vibration amplitude, and prevent the concrete at the joint from being crushed.

[0009] However, the prefabricated bridge pier still has at least two shortcomings in terms of structural integrity, which are the technical problems that this invention aims to solve.

[0010] First, the segments of the piers, and the segments of the piers and the caps, are not connected, whether by steel reinforcement or concrete. They are only connected by the added vertical energy-dissipating steel bars, which is far from sufficient in strength.

[0011] Secondly, the prestressed strands are not connected to the segmental piers or caps at all; they are only anchored and tensioned. In other words, if the anchor plate fails, the tensioning effect of the prestressed strands is completely lost, and the connection strength and structural integrity are far from sufficient.

[0012] Therefore, in summary, there is an urgent need for a new type of prefabricated concrete bridge pier with better overall integrity, stronger structural connections, and better support stability. Summary of the Invention

[0013] This invention provides a prefabricated concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection. By setting several precast segment units on the cast-in-place pier cap unit, setting cast-in-place segment units between adjacent precast segment units, and setting in-pipe concrete steel strand units on the whole of all precast segment units, the prefabricated concrete bridge pier can ensure higher structural integrity, greater connection strength, and better support stability.

[0014] In addition, the present invention also provides a construction method for the above-mentioned prefabricated concrete bridge pier, which includes the following steps in sequence: casting prefabricated segmental units in the factory, installing concrete steel strand units in the pipe, casting cast-in-place pier cap units, casting cast-in-place segmental units, and tensioning, anchoring, and casting concrete steel strand units in the pipe, so as to ensure the orderly and efficient construction effect of the prefabricated concrete bridge pier.

[0015] The technical solution adopted by the present invention to solve the above problems is: a precast concrete bridge pier with steel pipe-in-pipe prestressed steel strand connection, the structure including cast-in-place pier unit, a plurality of precast segment units set on the cast-in-place pier unit, cast-in-place segment units set between two adjacent precast segment units, and in-pipe concrete steel strand units with their lower ends set in the cast-in-place pier unit and used for tensioning all the precast segment units.

[0016] A further preferred technical solution is that the cast-in-place foundation unit includes a steel mesh cage that connects the precast segment unit and the in-pipe concrete steel strand unit, and foundation concrete set on the steel mesh cage.

[0017] A further preferred technical solution is that: the precast segmental unit includes segmental concrete, which is disposed on the segmental concrete and is fully exposed at both ends, and is used to insert and install the steel pipe of the in-pipe concrete steel strand unit, annular stirrups disposed in the segmental concrete, and reinforcing bars disposed on the segmental concrete and fully exposed at both ends.

[0018] A further preferred technical solution is that the prefabricated segment unit further includes a perforated steel plate disposed on the outer ring surface of the steel pipe and used for inserting the reinforcing mesh cage and / or annular stirrups.

[0019] A further preferred technical solution is that several of the steel bars are distributed in a staggered manner on the concrete segment.

[0020] A further preferred technical solution is that the cast-in-place segmental unit includes an outer pipe with two steel pipes respectively sleeved at both ends, a welded block connecting the two steel bars, and cast-in-place concrete connecting the upper and lower segmental concrete.

[0021] A further preferred technical solution is that: the in-pipe concrete steel strand unit includes steel strands passing through all the steel pipes and the outer pipe, anchor plates respectively set at both ends of the steel strands, and in-pipe concrete set inside all the steel pipes and the outer pipe.

[0022] A further preferred technical solution is that the anchor plate includes a bottom circular block, a middle circular block disposed on the bottom circular block, threaded holes disposed on the bottom circular block and the middle circular block, and a rectangular hole disposed on the bottom circular block for passing through the longitudinal steel bar segment of the steel mesh cage and for pouring concrete into the pipe.

[0023] A construction method for a precast concrete bridge pier with a steel pipe-prestressed steel strand connection includes the following steps:

[0024] S1. Casting and molding in the factory to obtain all the prefabricated segmental units;

[0025] S2. Pass the in-tube concrete steel strand unit through one of the precast segment units to obtain the bottom segment;

[0026] S3. Tie steel bars to the bottom segment and pour concrete to form the cast-in-place foundation unit, and obtain the bottom segment-foundation combination.

[0027] S4. On the bottom segment-pier assembly, the remaining precast segment units are inserted into the in-tube concrete steel strand units, and all the cast-in-place segment units are poured at intervals to obtain the pier body.

[0028] S5. First, tension and anchor the concrete steel strand unit inside the pipe, and finally pour and cure the concrete inside the pipe. The construction of the entire pier is then completed.

[0029] A further preferred technical solution is that, in S5, the tension strength of the concrete steel strand unit inside the pipe is 10-30% of the design standard strength of the concrete steel strand unit inside the pipe. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the prefabricated concrete bridge pier in this invention.

[0031] Figure 2 This is a schematic diagram of the structure of the prefabricated segmental unit in this invention.

[0032] Figure 3 This is a schematic diagram of the structure in which the steel bars are staggered vertically in this invention.

[0033] Figure 4 This is a schematic diagram showing the position of the steel pipe in this invention.

[0034] Figure 5 This is a schematic diagram of the location and structure of the cast-in-place foundation unit in this invention.

[0035] Figure 6 This is a schematic diagram of the location and structure of the cast-in-place segmental unit in this invention.

[0036] Figure 7 This is a schematic diagram of the location and structure of the concrete steel strand unit inside the tube in this invention.

[0037] Figure 8 This is a schematic diagram illustrating the usage of the anchor plate in this invention.

[0038] The meanings of the labels in the attached diagram are as follows.

[0039] Cast-in-place foundation unit 1, precast segment unit 2, cast-in-place segment unit 3, and in-pipe concrete steel strand unit 4.

[0040] 101 Reinforcing mesh cage, 102 Foundation concrete, 201 Segmental concrete, 202 Steel pipe, 203 Ring stirrup, 204 Reinforcing bar, 205 Perforated steel plate, 301 Outer pipe, 302 Welded block, 303 Cast-in-place concrete, 401 Steel strand, 402 Anchor plate, 403 Concrete inside the pipe.

[0041] Bottom circular block 402a, middle circular block 402b, threaded hole 402c, rectangular hole 402d. Detailed Implementation

[0042] The following description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

[0043] As attached Figure 1-8 As shown, a precast concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection includes a cast-in-place pier unit 1, a plurality of precast segment units 2 disposed on the cast-in-place pier unit 1, a cast-in-place segment unit 3 disposed between two adjacent precast segment units 2, and an in-pipe concrete steel strand unit 4 disposed at the lower end in the cast-in-place pier unit 1 and used for tensioning all the precast segment units 2.

[0044] In this embodiment, the function and structural strength requirements of the bottommost precast segment unit 2 are different from those of all other precast segment units 2. Therefore, the bottommost precast segment unit 2 needs further reinforcement with the steel reinforcement structure of the cast-in-place foundation unit 1, through methods such as binding, welding, and splicing.

[0045] Furthermore, the prefabricated concrete bridge pier in this embodiment is essentially "partially prefabricated" because the cast-in-place segmental unit 3 and the cast-in-place pier cap unit 1 need to be cast on-site at the bridge construction site.

[0046] Finally, the advantages of the in-tube concrete steel strand unit 4 compared with ordinary anchored steel strands are: First, the steel strands are not merely interlocked with the pier, but are embedded in the concrete. In other words, even if the anchor is lost, the tensioning effect on the pier is still partially maintained. Second, the unit also integrates steel pipes, which are connected by the cast-in-place segment units 3. Therefore, the overall structure of the prefabricated concrete pier is higher.

[0047] The cast-in-place foundation unit 1 includes a steel mesh cage 101 that connects the precast segment unit 2 and the in-pipe concrete steel strand unit 4, and a foundation concrete 102 set on the steel mesh cage 101.

[0048] In this embodiment, the steel mesh cage 101 is cubic or cylindrical in shape, and includes steel bars in at least three directions: horizontal, vertical, and longitudinal, which are fully tied together. A generally circular groove is provided at the insertion position of the prefabricated segment unit 2, and the horizontal and vertical steel bars protrude appropriately within this groove to accommodate the openings on the prefabricated segment unit 2, ensuring a more complete connection.

[0049] The precast segmental unit 2 includes segmental concrete 201, a steel pipe 202 disposed on the segmental concrete 201 with both ends exposed and used to insert and install the in-pipe concrete steel strand unit 4, annular stirrups 203 disposed in the segmental concrete 201, and steel bars 204 disposed on the segmental concrete 201 with both ends exposed.

[0050] In this embodiment, the reinforcing bar 204 is used to connect to the reinforcing bar 204 on another adjacent precast segment unit 2, or to connect to the longitudinal reinforcing bar of the reinforcing bar cage 101. The connection methods include binding, welding, etc.

[0051] In addition, the number of steel pipes 202 in a single prefabricated segment unit 2 is 2-4. If there are more, it will reduce the structural strength of the prefabricated segment unit 2 and increase the workload of the connection operation. If there are fewer, the connection strength between adjacent prefabricated segment units 2 will be insufficient.

[0052] The prefabricated segment unit 2 also includes a perforated steel plate 205 disposed on the outer ring surface of the steel pipe 202 and used for inserting the reinforcing mesh cage 101 and / or the annular stirrup 203.

[0053] In this embodiment, the perforated steel plate 205 has three application scenarios, including:

[0054] First, it is only set in the middle area of ​​the outer ring surface of the steel pipe 202 for passing through and connecting the annular stirrup 203;

[0055] Second, it is only set on the lower exposed section of the steel pipe 202 of the lowest prefabricated segment unit 2, for passing through the transverse straight steel bars, longitudinal straight steel bars, or transverse circular steel bars that connect the steel mesh cage 101.

[0056] Third, the two methods mentioned above can be used in combination.

[0057] Ultimately, the perforated steel plate 205 is introduced to reinforce the prefabricated segment unit 2, whether it is to reinforce itself or to reinforce the connection.

[0058] Several of the steel bars 204 are distributed in a staggered manner on the segmental concrete 201.

[0059] In this embodiment, the reinforcing bar 204 is generally connected to the reinforcing bar 204 of another precast segment unit 2. The bottommost reinforcing bar 204 is relatively special and is used to connect the longitudinal reinforcing bars of the reinforcing bar cage 101. The connection method can be either binding or welding.

[0060] On the other hand, the aforementioned "vertical misalignment" refers to the fact that all the steel bars 204 are of the same length, for example, each is 1m longer than the segmental concrete 201. However, some of the steel bars 204 protrude 0.3m upwards and 0.7m downwards, while the remaining ones are the opposite, protruding 0.7m upwards and 0.3m downwards. This method ensures that the binding and welding positions are staggered, preventing excessive concentration of connection points, increasing the vertical width of the effective connection area, and guaranteeing a more stable connection structure.

[0061] The cast-in-place segmental unit 3 includes an outer pipe 301 with the upper and lower steel pipes 202 respectively sleeved at both ends, a welded block 302 connecting the upper and lower reinforcing bars 204, and a cast-in-place concrete 303 connecting the upper and lower segmental concrete 201.

[0062] In this embodiment, the upper and lower ends of the outer tube 301 are fully sleeved, and due to the staggered arrangement of the reinforcing bars 204, the final welded blocks 302 are also of varying heights, ensuring strong structural stability of the staggered joint connection method.

[0063] The in-pipe concrete steel strand unit 4 includes a steel strand 401 passing through all the steel pipes 202 and the outer pipe 301, anchor plates 402 respectively set at both ends of the steel strand 401, and in-pipe concrete 403 set inside all the steel pipes 202 and the outer pipe 301.

[0064] In this embodiment, the concrete 403 inside the pipe is poured last, after the foundation concrete 102 and the cast-in-place concrete 303, and the anchor plate 402 is tightened first, and then the concrete is poured.

[0065] Finally, it is precisely because of the presence of the concrete 403 inside the tube that the tensioning effect of the steel strand 401 is not completely independent, and it also has a sufficient connection effect with the pier. In other words, even if the anchor plate 402 is lost, the concrete 403 inside the tube can still "hold" the steel strand 401, so that the concrete steel strand unit 4 inside the tube still has a certain tensioning effect.

[0066] The anchor plate 402 includes a bottom circular block 402a, an intermediate circular block 402b disposed on the bottom circular block 402a, a threaded hole 402c disposed on the bottom circular block 402a and the intermediate circular block 402b, and a rectangular hole 402d disposed on the bottom circular block 402a for passing through the longitudinal steel bar segment of the steel mesh cage 101 and for pouring the concrete 403 inside the pipe.

[0067] In this embodiment, the steel strand 401 is tensioned as needed before concrete is poured. Therefore, existing ordinary anchors cannot meet this requirement. Once the existing anchors are tightened, there is no entrance for pouring concrete.

[0068] Therefore, the rectangular hole 402d ensures that the concrete 403 inside the pipe can be added from there without affecting the tightening effect of the anchor plate 402.

[0069] Finally, the anchor plate 402 below is located inside the cast-in-place foundation unit 1, so the rectangular hole 402d is used to insert the longitudinal bars of the steel mesh cage 101 to further reinforce the anchor plate 402 and the concrete steel strand unit 4 inside the pipe.

[0070] Specifically, the rectangular hole 402d is a chamfered rectangle that spans the steel pipe 202, ensuring that the inner radial side is used for adding concrete and the outer radial side is used for the longitudinal bars passing through the steel mesh cage 101.

[0071] A construction method for a precast concrete bridge pier with a steel pipe-prestressed steel strand connection includes the following steps:

[0072] S1. Casting and molding in the factory to obtain all the prefabricated segmental units 2;

[0073] S2. Pass the in-tube concrete steel strand unit 4 through one of the precast segment units 2 to obtain the bottom segment;

[0074] S3. Tie steel bars to the bottom segment and pour concrete to form the cast-in-place foundation unit 1, and obtain the bottom segment-foundation combination.

[0075] S4. On the bottom segment-pier assembly, the remaining precast segment units 2 are inserted into the in-pipe concrete steel strand unit 4, and all the cast-in-place segment units 3 are poured at intervals to form the main body of the pier.

[0076] S5. First, tension and anchor the concrete steel strand unit 4 inside the pipe, and finally pour and cure the concrete inside the pipe. The construction of the entire pier is completed.

[0077] In this embodiment, S1 includes the sequential connection of the reinforcing bar 204 and the annular stirrup 203 to form a segmental reinforcing cage; the annular stirrup 203 and the steel pipe 202 are positioned and connected to each other; concrete is poured and cured to form the segmental concrete 201.

[0078] In S2, the height of the concrete 102 of the cast-in-place foundation unit 1 is appropriately high, covering a portion of the length of the lowest precast segment unit 2.

[0079] In S5, the tension strength of the concrete steel strand unit 4 inside the pipe is 10-30% of the design standard strength of the concrete steel strand unit 4 inside the pipe.

[0080] Finally, this embodiment has the following advantages.

[0081] First, the prefabricated concrete bridge pier is essentially "partially prefabricated," thus combining the advantages of both prefabricated and cast-in-place methods, achieving a good balance between the structural strength of the bridge pier and the amount of on-site construction work.

[0082] Secondly, the cast-in-place segmental unit 3 includes the connection effect of steel bar 204, the sleeve effect of steel pipe 202, and finally the cast-in-place concrete 303, ensuring that the two adjacent precast segmental units 2 can be fully connected and fixed.

[0083] Third, there are also multiple connection points between the precast segment unit 2 at the bottom and the cast-in-place foundation unit 1, such as steel pipe insertion, steel bar connection, and concrete pouring, to ensure that this connection is also of high strength.

[0084] Fourth, for the concrete steel strand unit 4 inside the pipe, its structure from the outside to the inside consists of steel pipe, concrete, and steel strand. Therefore, its tensioning effect is to fix the entire pier, and the tensioning strength is greater and the tensioning effect is less likely to be reduced.

[0085] Fifth, the anchor plate 402 below can also be inserted into the longitudinal steel bars of the steel mesh cage 101, so that there is a connection between the concrete steel strand unit 4 in the pipe and the cast-in-place foundation unit 1, which can further strengthen the concrete steel strand unit 4 in the pipe and strengthen the precast segment unit 2.

[0086] Sixth, the anchor plate 402 has appropriate openings for pouring concrete 403 into it to form the inner concrete 403, which is used to insert the longitudinal steel bars of the steel mesh cage 101, thus achieving a high degree of integration in structure and function.

[0087] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various modifications can be made without departing from the spirit of the present invention. These are non-inventive modifications and are protected by patent law as long as they fall within the scope of the claims of the present invention.

Claims

1. A precast concrete bridge pier with a steel pipe-prestressed steel strand connection, characterized in that: The structure includes a cast-in-place foundation unit (1), several precast segment units (2) disposed on the cast-in-place foundation unit (1), a cast-in-place segment unit (3) disposed between two adjacent precast segment units (2), and an in-tube concrete steel strand unit (4) disposed at the lower end in the cast-in-place foundation unit (1) and used for tensioning all the precast segment units (2). The cast-in-place foundation unit (1) includes a steel mesh cage (101) that is inserted into the precast segment unit (2) and the in-pipe concrete steel strand unit (4), and a foundation concrete (102) set on the steel mesh cage (101). The precast segmental unit (2) includes segmental concrete (201), a steel pipe (202) disposed on the segmental concrete (201) with both ends exposed, and used to insert and install the in-pipe concrete steel strand unit (4), annular stirrups (203) disposed in the segmental concrete (201), and steel bars (204) disposed on the segmental concrete (201) with both ends exposed. The cast-in-place segmental unit (3) includes an outer pipe (301) with the upper and lower steel pipes (202) respectively sleeved at both ends, a welded block (302) connecting the upper and lower reinforcing bars (204), and cast-in-place concrete (303) connecting the upper and lower segmental concrete (201). The in-pipe concrete steel strand unit (4) includes a steel strand (401) passing through all the steel pipes (202) and the outer pipe (301), anchor plates (402) respectively set at both ends of the steel strand (401), and in-pipe concrete (403) set in all the steel pipes (202) and the outer pipe (301). The anchor plate (402) includes a bottom circular block (402a), an intermediate circular block (402b) disposed on the bottom circular block (402a), a threaded hole (402c) disposed on the bottom circular block (402a) and the intermediate circular block (402b), and a rectangular hole (402d) disposed on the bottom circular block (402a) for passing through the longitudinal steel bar segment of the steel mesh cage (101) and for pouring the concrete (403) inside the pipe.

2. The precast concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection according to claim 1, characterized in that: The prefabricated segment unit (2) also includes a perforated steel plate (205) disposed on the outer ring surface of the steel pipe (202) and used to insert the steel mesh cage (101) and / or the annular stirrup (203).

3. The precast concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection according to claim 1, characterized in that: Several of the steel bars (204) are distributed in an alternating manner on the segmental concrete (201).

4. A construction method for a precast concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection as described in claim 1, characterized in that... The steps are as follows: S1. Casting and molding in the factory to obtain all the prefabricated segmental units (2). S2. The bottom segment is obtained by passing the in-tube concrete steel strand unit (4) through one of the precast segment units (2); S3. Tie steel bars on the bottom segment and pour concrete to form the cast-in-place foundation unit (1) and obtain the bottom segment-foundation combination. S4. On the bottom segment-pier assembly, use the in-pipe concrete steel strand unit (4) to insert all the remaining precast segment units (2), and pour at intervals to form all the cast-in-place segment units (3) to obtain the pier body; S5. First, tension and anchor the concrete steel strand unit (4) inside the pipe, and finally pour the concrete inside the pipe and cure it. The construction of the entire pier is completed.

5. The construction method of a precast concrete bridge pier with a steel pipe-in-pipe prestressed steel strand connection according to claim 4, characterized in that: In S5, the tension strength of the concrete steel strand unit (4) inside the pipe is 10-30% of the design standard strength of the concrete steel strand unit (4) inside the pipe.

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