Prefabricated concrete pier column formwork and preparation method thereof
Through the factory production and on-site application of precast concrete pier column mold shells, the problem of weather-affected pier column construction is solved, efficient and stable pier column construction is achieved, and construction quality and efficiency are improved.
Patent Information
- Application Number
- CN202510785569.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-08-15
AI Technical Summary
The construction of cast-in-place bridge pier columns is easily affected by bad weather, resulting in unstable construction quality and extended construction period. It is difficult to build on-site steel cages, which affects construction efficiency and cost.
Precast concrete pier column mold shells are used, including an annular outer shell, longitudinal reinforcement components and stirrup components. They are prepared in the factory and transported to the site for use. The mold shell structure can support concrete and resist shear force, improve the strength and seismic performance of the pier columns, and avoid on-site mold support and mold removal processes.
It can still be constructed normally in bad weather, ensure the progress of the construction period, reduce the generation of cracks, improve construction efficiency and quality, and reduce labor intensity and construction costs.
Smart Images
Figure CN120481066A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of bridge engineering, and in particular to a precast concrete pier column formwork and a preparation method thereof. Background Art
[0002] As an important supporting structure of bridges, bridge piers have evolved from simple to complex, and from single materials to composite materials. Ancient bridge piers were mostly made of stone or wood, relying on gravity for stability. After the Industrial Revolution, reinforced concrete became the mainstream material, and the design of bridge piers became more scientific. Modern bridge piers consider using materials such as concrete and carbon fiber to improve the strength, durability and construction efficiency of bridge piers.
[0003] At present, the construction of cylindrical bridge piers is mostly achieved by cast-in-place technology. At present, cast-in-place concrete bridge piers are inseparable from the forming components for forming and reinforcing the concrete. At present, the components for forming the bridge piers usually include several steel bars, bundled steel wire strips, steel formwork or wooden formwork. Multiple steel bars are positioned at the bridge piers, and multiple steel bars are distributed vertically and horizontally. During construction, multiple steel bars are accurately positioned at the bridge piers, and the steel bars are arranged longitudinally and form a spatial grid structure with the transverse stirrups. The cross nodes of each steel bar are reliably connected by tying steel wire, and finally a steel skeleton system is formed. The formwork system is connected by high Strong bolts are connected end to end, surrounding the outside of the steel skeleton to form a closed mold cavity that matches the design outline of the pier column. Specifically, multiple templates are fixed by means of locks and the like. When in use, workers build and bundle the steel cage on the pier to firmly fix the steel cage to the lower pier, and then install the template on the pier to form a sealed plate group with only the upper part open. At this time, it is only necessary to use a pump or bucket transportation method to continuously pour concrete into the semi-sealed cavity formed in the plate group. During the process, vibration is performed to eliminate bubbles in the concrete, and then the concrete is left to form and solidify into a pier column.
[0004] However, the construction quality of cast-in-place bridge piers is easily affected by the on-site maintenance and construction environments. For example, severe weather such as rain and snow will cause construction interruptions, affecting the progress of the construction period. At the same time, severe weather will seriously affect the molding and maintenance quality of concrete, which will lead to insufficient structural strength or shrinkage cracks. When the construction site is limited or the terrain is complex, the difficulty of construction workers in building steel cages increases sharply, and it is difficult to quickly ensure the accuracy of the spacing between each steel bar. Multiple quality inspections are required, which will undoubtedly affect the construction period. In addition, the bridge piers cast on site must wait until the concrete strength reaches the strength standard before the next step can be carried out, which further extends the construction period and increases the overall cost. Summary of the Invention
[0005] The present invention provides a precast concrete pier column formwork and a preparation method thereof, which can ensure the construction period and accelerate the construction speed while also improving the quality of the pier column forming.
[0006] The present invention provides a precast concrete pier column formwork, comprising: an outer shell, a longitudinal reinforcement assembly, and a stirrup assembly. The outer shell is annular, with a cavity for pouring concrete reserved in the middle of the outer shell. The longitudinal reinforcement assembly includes a plurality of longitudinal reinforcement rods, the centerline of each longitudinal reinforcement rod is parallel to the centerline of the outer shell, each longitudinal reinforcement rod is vertically distributed in the circumference of the outer shell, and each longitudinal reinforcement rod is inserted through the outer shell. The stirrup assembly includes a plurality of stirrup rings, each of which is annular, and the plurality of stirrup rings are horizontally arranged. Each stirrup ring is fixedly connected to the middle position of the outer shell, each stirrup ring is bundled and sleeved on the outside of each longitudinal reinforcement rod, and each stirrup ring is arranged and distributed in sequence along the centerline direction of the outer shell.
[0007] Furthermore, the longitudinal ribs are evenly distributed in the circumference of the outer shell.
[0008] Furthermore, each stirrup ring is evenly distributed along the center line of the outer shell.
[0009] Furthermore, each stirrup ring is unevenly distributed along the center line of the outer shell.
[0010] Furthermore, the hoop reinforcement rings near the top of the outer shell form a reinforced area, and the hoop reinforcement rings located below the reinforced area form a non-reinforced area. The spacing between the hoop reinforcement rings in the reinforced area is the same, and the spacing between the hoop reinforcement rings in the non-reinforced area is the same. The spacing between the hoop reinforcement rings in the reinforced area is smaller than the spacing between the hoop reinforcement rings in the non-reinforced area.
[0011] Furthermore, the encrypted area accounts for 1 / 6 to 1 / 3 of the total axial length of the outer shell.
[0012] Furthermore, the upper and lower ends of each longitudinal reinforcement rod respectively pass through and extend out of the outer shell for subsequent connection with the upper cap beam and the lower pedestal pile foundation of the bridge.
[0013] Furthermore, the outer shell is made of ultra-high performance concrete and is prepared by a centrifugal method.
[0014] Furthermore, the wall thickness of the outer shell is 150 mm to 200 mm.
[0015] Furthermore, the diameter of the cavity in the middle of the outer shell is 4 to 8 times the thickness of the outer shell wall.
[0016] The present invention also provides a method for preparing a precast concrete pier column formwork, comprising the following steps:
[0017] S1. Forming and fixing the longitudinal reinforcement assembly and stirrup assembly: each stirrup ring is placed outside each longitudinal reinforcement rod and tied to form a reinforcement cage, and the tied reinforcement cage is placed in the lower mold and fixed;
[0018] S2. Preparation of the outer shell: The premix, water, water-reducing agent, and steel fiber weighed according to the mix ratio are sequentially added to a mixer and mixed evenly. The mixed slurry is evenly filled along the lower mold. The upper mold is hoisted above the lower mold, aligned, clamped, and sealed. The upper and lower molds are fixed with mold bolts. The spliced mold is hoisted above the centrifuge and prepared in a stepwise acceleration manner of low, medium, and high speeds to ensure that the outer shell is finally formed densely. After centrifugation, it is allowed to stand for about 2 hours;
[0019] S3. Steam initial curing: After standing still, the mold is hoisted into the steam curing tank for normal pressure steam curing at 50℃~60℃ and ambient humidity above 95%RH, so that the outer shell reaches the demoulding strength before demoulding;
[0020] S4. Steam final curing: Place the demoulded outer shell into an autoclave for high-temperature steam curing at a temperature of 160°C to 180°C and a saturated steam pressure of 1.0MPa to 1.2MPa for 6h to 12h.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: compared with existing concrete piers, the formwork of the present invention can support the concrete cast on site, does not require the support of on-site formwork, and is more convenient to use. Specifically, the longitudinal reinforcement rods in the present formwork structure can bear tensile stress and compressive stress, the stirrup rings can effectively resist shear force, and the outer shell can effectively restrain the concrete cast in the core of the cavity area, reducing the generation and development of cracks and enhancing the ductility and seismic performance of the pier column. The outer shell, combined with the longitudinal reinforcement rods and stirrup rings and the core concrete of the cavity area, can significantly improve the strength and rigidity of the pier column compared with traditional cast-in-place concrete piers.
[0022] At the same time, compared with traditional cast-in-place concrete piers, this formwork can be manufactured and prefabricated in the factory according to the design and then transported to the construction site. It can not only ensure the process accuracy of each steel bar, but also will not be affected by the on-site maintenance environment and construction environment. It can still be produced normally even in severe weather such as rain, snow and low temperature, and there is no need to consider too much about the molding and maintenance quality of on-site concrete, thereby ensuring the progress of the construction period. At the same time, compared with the existing cast-in-place concrete piers, it can realize the simultaneous construction of multiple piers and multiple processes. During the on-site construction stage, the formwork is used as a construction template to play a supporting and shaping role, eliminating on-site formwork and dismantling processes. The construction is simple, which can reduce labor intensity, save construction costs, and speed up construction. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 A schematic diagram of a partial internal cross-section of a precast concrete pier column formwork provided in an embodiment of the present invention;
[0024] Figure 2A schematic top-view structural diagram of a precast concrete pier column formwork provided in an embodiment of the present invention;
[0025] Figure 3 A schematic diagram of the internal cross-sectional structure of a forming portion of a precast concrete pier column provided in an embodiment of the present invention;
[0026] Figure 4 A schematic diagram of a mold structure for preparing a precast concrete pier column formwork provided in an embodiment of the present invention;
[0027] Figure 5 A structural schematic diagram of a precast concrete pier column formwork preparation process provided by an embodiment of the present invention.
[0028] Description of reference numerals:
[0029] 1. Outer shell; 101. Cavity; 2. Longitudinal reinforcement assembly; 21. Longitudinal reinforcement rod; 3. Stirrup assembly; 31. Stirrup ring; 4. Mold; 41. Upper mold; 42. Lower mold; 421. Bolt hole; 43. Head plate; 44. Cavity; 46. Running wheel; 47. Annular rib; 48. Longitudinal reinforcement; 49. Clamping bolt; 5. Flange connecting plate; 6. Connecting rod; 7. Limit plate; 8. Tightening bolt. DETAILED DESCRIPTION
[0030] A specific embodiment of the present invention is described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.
[0031] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.
[0032] refer to Figure 1 and Figure 2The present invention provides a precast concrete pier column formwork, comprising: an outer shell 1, a longitudinal reinforcement assembly 2, and a stirrup assembly 3. The outer shell 1 is annular, and a cavity 101 for pouring concrete is reserved in the middle of the outer shell 1. The longitudinal reinforcement assembly 2 includes a plurality of longitudinal reinforcement rods 21, and the center line of each longitudinal reinforcement rod 21 is parallel to the center line of the outer shell 1. Each longitudinal reinforcement rod 21 is vertically distributed in the circumference of the outer shell 1, and each longitudinal reinforcement rod 21 is inserted through the outer shell 1 and fixedly connected to the inner wall of the outer shell 1. The stirrup assembly 3 includes a plurality of stirrup rings 31, each of which is annular. The plurality of stirrup rings 31 are horizontally arranged, and each stirrup ring 31 is fixedly connected to the middle position of the outer shell 1. Each stirrup ring 31 is bundled and sleeved on the outside of each longitudinal reinforcement rod 21, and each stirrup ring 31 is arranged in sequence along the center line direction of the outer shell 1.
[0033] In the above embodiments, compared with the existing concrete piers, the formwork of the present invention can support the concrete cast on site, does not require the support of on-site formwork, and is more convenient to use. Specifically, the longitudinal reinforcement rods 21 in the present formwork structure can bear tensile stress and compressive stress, and the stirrup rings 31 can effectively resist shear force. The outer shell 1 can effectively restrain the concrete cast in the core of the cavity 101 area, reduce the generation and development of cracks, and enhance the ductility and seismic performance of the pier. The outer shell 1, combined with the longitudinal reinforcement rods 21 and the stirrup rings 31 and the core concrete of the cavity 101 area, can significantly improve the strength and stiffness of the pier compared to traditional cast-in-place concrete piers.
[0034] At the same time, compared with traditional cast-in-place concrete piers, this formwork can be manufactured and prefabricated in the factory according to the design and then transported to the construction site. It can not only ensure the process accuracy of each steel bar, but also will not be affected by the on-site maintenance environment and construction environment. It can still be produced normally even in severe weather such as rain, snow and low temperature, and there is no need to consider too much about the molding and maintenance quality of on-site concrete, thereby ensuring the progress of the construction period. At the same time, compared with the existing cast-in-place concrete piers, it can realize the simultaneous construction of multiple piers and multiple processes. During the on-site construction stage, the formwork is used as a construction template to play a supporting and shaping role, eliminating on-site formwork and dismantling processes. The construction is simple, which can reduce labor intensity, save construction costs, and speed up construction.
[0035] Further, refer to Figure 2 The longitudinal ribs 21 are evenly distributed around the outer shell 1 .
[0036] In the above embodiments, the longitudinal reinforcement rods 21 are evenly arranged along the distribution circumference. The longitudinal reinforcement rods 21 can be made of fiber reinforced plastic (FRP) bars or high-strength threaded steel bars and prestressed according to engineering requirements.
[0037] Furthermore, in the first embodiment, the stirrup rings 31 are evenly distributed along the center line of the outer shell 1. This embodiment continues the traditional stirrup bundling method and has relatively stable reliability.
[0038] Further, refer to Figure 1 , the second embodiment: the hoop rings 31 are non-uniformly distributed along the center line direction of the outer shell 1. Specifically, the hoop rings 31 close to the top of the outer shell 1 form a densified area, and the hoop rings 31 located below the densified area form a non-densified area. The spacing between the hoop rings 31 in the densified area is the same, and the spacing between the hoop rings 31 in the non-densified area is the same. The spacing between the hoop rings 31 in the densified area is smaller than the spacing between the hoop rings 31 in the non-densified area.
[0039] In the above embodiments, since the ends of the pier columns are areas where stress and deformation are concentrated, especially under earthquakes, plastic hinges are prone to occur at the ends, causing localized failure. Providing stirrups in the reinforced area at both ends can effectively improve shear strength, constrain the core concrete, prevent concrete spalling and steel bar buckling, thereby enhancing the structural ductility and overall seismic performance, and avoiding sudden structural collapse. Specifically, in accordance with the relevant provisions of JTG / T 2231-01-2021 "Code for Seismic Design of Highway Bridges" and CJJ 166-2011 "Code for Seismic Design of Urban Bridges", the scope of the reinforced area shall not be less than the equivalent plastic hinge length, or 1.5 times the pier diameter, or the range where the bending moment exceeds 75% of the maximum bending moment. The minimum stirrup ratio in the reinforced area shall not be less than 0.4%, the maximum stirrup spacing shall not be greater than 10 cm, or 6 times the longitudinal reinforcement diameter, or 1 / 4 the pier diameter. The stirrup spacing in the non-reinforced area shall not be greater than twice the stirrup spacing in the reinforced area, and the stirrup diameter and configuration should be the same as those in the reinforced area.
[0040] Further, refer to Figure 1 The encrypted area accounts for 1 / 6 to 1 / 3 of the total axial length of the outer shell 1.
[0041] In the above embodiments, the shear strength can be further effectively improved, the core concrete can be restrained, concrete spalling and steel bar buckling can be prevented, thereby enhancing the structural ductility and overall seismic performance, and avoiding the beneficial effect of sudden structural collapse.
[0042] Further, refer to Figure 1 and Figure 3 The upper and lower ends of each longitudinal reinforcement rod 21 respectively pass through and extend out of the outer shell 1, so as to be subsequently connected with the upper cap beam and the lower pedestal pile foundation of the bridge.
[0043] In the above embodiment, the length of the longitudinal reinforcement rod 21 of the outer shell 1 extending from the upper end of the outer shell 1 should not be less than 8 times the diameter of the longitudinal reinforcement rod 21, and this value should be greater than 100 mm. Considering the installation adjustment margin, it is usually extended by 10 to 12 times the diameter of the longitudinal reinforcement. The length of the longitudinal reinforcement rod 21 of the outer shell 1 extending from the lower end of the outer shell 1 is usually 6 to 8 times the diameter of the longitudinal reinforcement rod 21.
[0044] Further, refer to Figure 1 and Figure 5 The outer shell 1 is made of ultra-high performance concrete and is prepared by centrifugal method.
[0045] In the above embodiments, ultra-high performance concrete is referred to as UHPC. The UHPC material itself has ultra-high strength properties such as high compressive strength and high elastic modulus. This type of material has low porosity, low water-cement ratio, and small pores. Based on the above characteristics, the outer shell 1 can effectively prevent the corrosion of concrete and steel bars by external corrosive media during construction and use, thereby extending the service life of the structure and reducing long-term maintenance costs. Due to the ultra-high strength of the UHPC material, under the same load-bearing requirements, the cross-sectional size of its components can be designed to be smaller than that of ordinary reinforced concrete columns, thereby reducing the occupied space and reducing the deadweight of the structure. In addition, the outer shell 1 can provide lateral constraints to the concrete filled in the middle, thereby enhancing the strength and seismic resistance of the bridge pier column.
[0046] Further, refer to Figure 1 、 Figure 2 and Figure 3 The wall thickness of the outer shell 1 is 150 mm to 200 mm, and the diameter of the cavity 101 in the middle of the outer shell 1 is approximately 4 to 8 times the wall thickness of the outer shell 1.
[0047] In the above embodiments, the outer shell 1 should have different thicknesses according to different construction scenarios. In order to meet the requirements of construction stability and steel bar protective layer, special working conditions such as high corrosion environment, large-span bridge piers or impact protection, it is recommended that the shell thickness be 150mm to 200mm. The shell thickness can also be appropriately reduced through comprehensive optimization of materials, design and construction. Under normal circumstances, the minimum thickness is greater than 80mm.
[0048] The centrifugal forming device for preparing the UHPC shell 1 is a steel mold 4, which includes an upper mold 41 and a lower mold 42 with a semi-cylindrical cross-section. A semi-annular head plate 43 is welded and fixed at both ends of the upper mold 41 and the lower mold 42. After the upper mold 41 and the lower mold 42 are buckled together, a cavity 44 capable of accommodating a steel cage is formed inside. The groove wall of the mold 4 is provided with a running wheel 46 evenly distributed in the annular direction, which is used to adapt to the roller of the centrifuge and can realize the rotation of the driving steel mold 4. The groove wall of the steel mold 4 is provided with an annular rib 47 evenly distributed in the annular direction and a longitudinal reinforcing rib 48 arranged at intervals along its axial direction. In order to improve the strength of the mold 4, the outer side of the flange connecting plate 5 is welded to the connecting rod 6 as a whole. The longitudinal reinforcement in the steel cage passes through the reserved holes on the flange connecting plate 5 and is fixed by bolts. The connecting rod 6 is inserted into the circular hole of the head plate 43, and then tightened and fixed by the limit plate 7 and the clamping bolt 8. The edges of the upper mold 41 and the lower mold 42 are provided with a locking structure along the axial direction. The upper mold 41 is a convex shape and the lower mold 42 is a groove shape to achieve reliable sealing inside the mold 4 after the mold is closed. After the upper mold 41 and the lower mold 42 are buckled together, the upper mold 41 and the lower mold 42 are locked by the clamping bolt 49 through the bolt hole 421.
[0049] Specifically, refer to Figure 4 and Figure 5 The present invention also provides a method for preparing a precast concrete pier column formwork, comprising the following steps:
[0050] S1. Moulding and fixing of the longitudinal reinforcement assembly 2 and the stirrup assembly 3: Each stirrup ring 31 is sleeved outside each longitudinal reinforcement rod 21 and tied to form a reinforcement cage. The tied reinforcement cage is placed in the lower mould 42 and fixed. Specifically, the tied reinforcement cage is placed in the lower mould 42 and connected with the flange connecting plate 5 and the connecting rod 6 to form a whole. It is then clamped into the circular hole of the head plate 43 and then tightened and fixed with the limit plate 7 and the clamping bolt 8;
[0051] S2. Preparation of the outer shell 1: The premix, water, water-reducing agent and steel fiber weighed according to the mix ratio are added to the mixer in sequence and stirred evenly. The mixed slurry is evenly filled along the lower mold 42. The upper mold 41 is hung above the lower mold 42, and the upper mold 41 is gradually lowered. The upper mold 41 and the lower mold 42 are aligned, clamped and sealed. The upper mold 41 and the lower mold 42 are fixed by the mold bolts 49. The spliced mold is hung above the centrifuge and prepared in a step-by-step acceleration method of low speed, medium speed and high speed. Specifically, the speed of the low speed stage is set to 300r / min to make the UHPC mixture dispersed and reasonably Distribution and preliminary shaping, this stage lasts about 2 to 3 minutes. The speed of the medium-speed stage is set to 600 r / min, and gradually increasing the speed is conducive to the redistribution of the uneven sections of the mixture and further shaping. This stage lasts about 5 minutes. The speed of the high-speed stage is set to 1100 r / min. The huge centrifugal force generated by the high-speed rotation fully discharges and squeezes the internal moisture and voids, so that the prefabricated UHPC shell is finally formed and dense. This stage lasts about 15 minutes. After centrifugation, the steel mold 4 composed of the upper mold 41 and the lower mold 42 is left to stand on the centrifuge for about 2 hours;
[0052] S3. Steam initial curing: After standing still, the mold is hoisted into a steam curing tank for normal pressure steam curing at 50°C to 60°C and an ambient humidity of 95% RH or above, so that the outer shell 1 reaches the demolding strength before demolding. Specifically, to prevent cracks due to low strength during demolding, the initial curing time is preferably set to 4 hours to 8 hours. During demolding, the mold 4 after steam initial curing is hoisted onto the demolding table, and the upper mold 41 is removed and hoisted onto the lower mold 41 using a pneumatic wrench. Then, the outer shell 1 is hoisted for demolding, avoiding collisions during the hoisting process. The flange connecting plate 5, connecting rod 6, limit plate 7, and clamping bolts 8 are removed, and the upper and lower mold halves are cleaned.
[0053] S4. Steam final curing: Place the demoulded outer shell 1 into an autoclave for high-temperature steam curing at a temperature of 160°C to 180°C and a saturated steam pressure of 1.0MPa to 1.2MPa for 6h to 12h. After final curing, its strength can reach the design strength.
[0054] In the above embodiment, the mix ratio in step S2 is usually a conventional setting method, and most of them are provided by UHPC manufacturers, usually 1 kg premix, 94.5 g to 100 g water, 7.8 g to 8.8 g UHPC water reducer and 75 g steel fiber. The premix is first added and dry mixed for 1 min to 2 min, then water and admixtures are added and stirred for 2 min to 4 min, and then steel fiber is added and stirred for 1 min to 2 min. The total time is preferably controlled within 8 min. However, the UHPC mix ratio prepared according to different requirements will not be exactly the same, and is not limited to the above one.
[0055] The present invention also provides a method for the overall application process:
[0056] S1. According to the dimensional design requirements of the composite column, determine the outer diameter, height, thickness of the UHPC outer shell 1, and the steel grade, diameter, length, quantity, and other parameters of the internal longitudinal reinforcement rods 21, the reinforced area hoop rings 31, and the non-reinforced area hoop rings 31. These parameters need to be selected based on the on-site application environment and after measurement and evaluation, and are not specifically limited in this embodiment.
[0057] S2. Produce a formwork corresponding to the requirements according to the method for preparing a precast concrete pier column formwork. The centrifugal process steps include tying and fixing the steel cage, installing and fixing the formwork, calculating the amount of UHPC mixture, stirring the UHPC mixture, placing the mixture in the lower mold 42 of the steel mold 4, closing the mold, and then centrifugation. The mixture then undergoes initial steam curing, demolding, and final steam curing. The specific process steps are as described in the above-mentioned method for preparing a precast concrete pier column formwork.
[0058] S3. Transport the prefabricated outer shell 1 to the construction site. Then, connect the pier columns and the abutment pile foundation using wet joints. Connect the longitudinal reinforcement rods 21 exposed at the lower end of the outer shell 1 to the steel bars in the cap beam or the abutment pile foundation. Then, pour concrete. During the pouring process, the concrete needs to be vibrated and cured as required.
[0059] Construction steps for wet joint connection between pier columns and abutment pile foundations: Use slightly expansive concrete with a concrete grade no lower than that used for the abutment pile foundations, roughen the contact surface of the abutment piles to ensure a rough and clean surface to enhance bonding strength, mechanically connect the pier column reinforcement to the exposed reinforcement of the abutment pile foundations, increase the number of stirrups in the joint area to improve shear resistance, install reinforced formwork, and ensure the sealing and stability of the joints. Concrete should be poured in layers and vibrated thoroughly to ensure compaction. Cover and maintain the concrete after pouring to keep it moist. Perform non-destructive testing to verify construction quality when necessary.
[0060] S4. Use the cavity 101 area enclosed by the UHPC shell 1 as the pouring space, pour concrete into the pouring space, and vibrate during the pouring process to ensure dense pouring. After hardening, the core concrete and the shell 1 form an integrated concrete composite column, and then perform curing as required;
[0061] S5. After the core concrete reaches a certain strength, the exposed steel bars at the upper end of the shell are inserted into the grouting sleeves reserved in the cap beam, and then grouting and anchoring are carried out, and maintenance is carried out as required. Specifically, according to the conventional grouting process and equipment, the grouting sleeve is a full grouting sleeve, which usually includes a sleeve body, a grouting port, and a grouting port. During the prefabrication stage of the cap beam, the grouting sleeve is inserted into the lower end of the steel bar and pre-buried in the cap beam, corresponding to the position of the longitudinal reinforcement rod 21 in the pier column, and temporarily fixed by means of binding, spot welding or positioning brackets to ensure that it does not shift during the concrete pouring process. The sleeve port, grouting port and grouting port are sealed with rubber plugs, plastic covers or foam glue, and the core concrete is poured in layers to ensure that the concrete It will wrap around the outer wall of the sleeve but will not enter the interior. After pouring, check whether the inside of the sleeve is clean to ensure that there is no residue for subsequent on-site grouting connection. During the pier construction phase, use lifting equipment to lift the cap beam to the top of the pier and slowly lower it, and cooperate with the operating personnel to assist in positioning so that the longitudinal reinforcement rod 21 in the pier column is aligned with the embedded sleeve in the cap beam. After the steel bar in the pier column is inserted into the sleeve, high-strength non-shrinkage grouting material is injected from the grouting port of the sleeve until the grouting port overflows from the upper end. After the grouting is completed, it needs to be left to stand for more than 24 hours to ensure the initial strength stability. During this period, it is strictly forbidden to apply any load or vibration to the connection part. After the grouting reaches the design strength, a rigid connection between the abutment and the pier column can be formed.
[0062] The above disclosures are only a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.
Claims
1. A precast concrete pier column formwork, characterized in that: include: The outer shell (1) is annular, and a cavity (101) for pouring concrete is reserved in the middle of the outer shell (1); A longitudinal reinforcement assembly (2) includes a plurality of longitudinal reinforcement rods (21), wherein the center line of each longitudinal reinforcement rod (21) is parallel to the center line of the outer shell (1), each longitudinal reinforcement rod (21) is vertically distributed in the circumferential direction of the outer shell (1), and each longitudinal reinforcement rod (21) is inserted through the outer shell (1); The stirrup assembly (3) comprises a plurality of ring-shaped stirrup rings (31), wherein the plurality of stirrup rings (31) are arranged horizontally, each of the stirrup rings (31) is fixedly connected to a central position in the outer shell (1), each of the stirrup rings (31) is bundled and sleeved on the outside of each of the longitudinal reinforcement rods (21), and each of the stirrup rings (31) is arranged and distributed in sequence along the centerline direction of the outer shell (1).
2. The precast concrete pier column formwork according to claim 1, characterized in that: The longitudinal ribs (21) are evenly distributed in the circumferential direction of the outer shell (1).
3. The precast concrete pier column formwork according to claim 1 or 2, characterized in that: The stirrup rings (31) are all non-uniformly distributed along the center line direction of the outer shell (1).
4. The precast concrete pier column formwork according to claim 3, characterized in that: The hoop reinforcement rings (31) located above the outer shell (1) form a densified area, and the hoop reinforcement rings (31) located below the densified area form a non-densified area. The hoop reinforcement rings (31) in the densified area have the same spacing, and the hoop reinforcement rings (31) in the non-densified area have the same spacing. The spacing between the hoop reinforcement rings (31) in the densified area is smaller than the spacing between the hoop reinforcement rings (31) in the non-densified area.
5. The precast concrete pier column formwork according to claim 4, characterized in that: The encrypted area accounts for 1 / 6 to 1 / 3 of the total axial length of the outer shell (1).
6. The precast concrete pier column formwork according to claim 1, characterized in that: The upper and lower ends of each longitudinal reinforcement rod (21) respectively penetrate and extend out of the outer shell (1) for subsequent connection with the upper cap beam and the lower pedestal pile foundation of the bridge.
7. The precast concrete pier column formwork according to claim 5, characterized in that: The outer shell (1) is made of ultra-high performance concrete and is prepared by a centrifugal method.
8. The precast concrete pier column formwork according to claim 7, characterized in that: The wall thickness of the outer shell (1) is 150 mm to 200 mm.
9. The precast concrete pier column formwork according to claim 8, characterized in that: The diameter of the central cavity (101) of the outer shell (1) is 4 to 8 times the wall thickness of the outer shell (1).
10. A method for preparing a precast concrete pier column formwork according to claim 9, characterized in that: The following steps are involved: S1, mold installation and fixing: each stirrup ring (31) is placed outside each longitudinal reinforcement rod (21) and tied to form a reinforcement cage, and the tied reinforcement cage is placed in the lower mold (42) and fixed; S2. Preparation of the outer shell (1): The premix, water, water-reducing agent and steel fiber weighed in accordance with the mixing ratio are sequentially added to the mixer and stirred evenly, the mixed slurry is evenly filled along the lower mold (42), the upper mold (41) is hung above the lower mold (42), aligned, clamped and sealed, the upper mold (41) and the lower mold (42) are fixed by the mold bolts (49), the spliced mold is hung above the centrifuge, and centrifuged in a step-by-step acceleration manner to make the outer shell (1) finally compact and compact, and the outer shell (1) is allowed to stand for about 2 hours after centrifugation; S3. Steam initial curing: hoist the mold after standing still into a steam curing tank for normal pressure steam curing at 50°C to 60°C and an ambient humidity of 95% RH or above, so that the outer shell (1) reaches the demoulding strength before demoulding; S4. Steam final curing: Place the demoulded outer shell (1) into an autoclave for high-temperature steam curing at a temperature of 160° C. to 180° C. and a saturated steam pressure of 1.0 MPa to 1.2 MPa for 6 h to 12 h.