Construction method for wet joint of prefabricated bridge deck slab

Abstract

The invention relates to a construction method for a wet joint of a prefabricated bridge deck slab, and belongs to the technical field of construction of bridge engineering, hydraulic engineering and the like. Firstly, a prefabricated bridge deck slab is manufactured, and straight steel bar heads extend out of the bridge deck slab; and a mold is installed on the steel bar head, and UHPC grout is injected into the mold through a grout inlet of the mold till the UHPC grout overflows from a grout outlet. After the UHPC slurry is solidified, the mold is dismantled, and the UHPC wrapping head is maintained; and then, the prefabricated bridge deck slabs are hoisted to a construction site, the prefabricated bridge deck slabs are assembled, and joint concrete is poured. The UHPC wrapping head is manufactured in a prefabricating field, operation is simple, and only common concrete needs to be used for pouring joints in a bridge construction site. The construction quality of the UHPC wrapping head is guaranteed, the binding power of steel bars at the joint is enhanced, the anchoring length is reduced, the width of the post-cast strip is reduced, and therefore the use amount of concrete on site is reduced. And workers with special skills and special materials are not needed on site, so that the cost is saved.

Description

Technical Field

[0001] The invention relates to a construction method of a bridge deck, in particular to a construction method of a wet joint of a prefabricated bridge deck, and belongs to the technical field of construction of bridge engineering, water conservancy engineering and the like. Background Art

[0002] The connection of prefabricated components is a weak link in prefabrication and assembly construction. The connection part is not only the key hub for force transmission between prefabricated components, but also the core factor affecting the overall performance of the structure. Design defects in this part may lead to serious consequences such as local cracking, force transmission failure and even collapse of the entire structure. Its reliability directly determines the bearing capacity, overall stiffness and stability of the structure.

[0003] Precast bridge decks are directly installed on the upper flanges of steel beams, and wet joints are the most common form of connection. The flanges serve as the bottom formwork for pouring concrete, and the connection is formed by pouring concrete in the joints between precast bridge decks. This connection is called a wet joint, also often called a post-cast strip.

[0004] The arrangement of steel bars in wet joints needs to consider anchoring force transmission and the convenience of concrete pouring. In the past, ordinary concrete was used in wet joints of precast bridge decks, which required a wider post-casting strip, generally about 50 cm, which resulted in a larger amount of concrete poured on site and increased the workload on the construction site. In order to reduce the amount of concrete poured on site, ultra-high performance concrete (UHPC) has been used as a joint pouring material in recent years.

[0005] Ultra-high performance concrete (UHPC) is a new type of cement-based composite material that achieves high strength, high toughness and excellent durability by highly optimizing the raw material composition and microstructure. Due to its light weight, high strength and good durability, it is widely used in key parts of bridge decks, piers, beams, etc. Compared with ordinary concrete (NC) materials, UHPC has stronger compressive resistance, better adhesion with steel bars, and good bonding performance with NC. At the same time, the high tensile strength of UHPC can increase the cracking load of the structure, the low porosity can improve the corrosion resistance and durability of the structure, the anti-corrosion performance can provide protection for the concrete structure in harsh environments such as humidity, and the high toughness enables the concrete structure to maintain normal operation under overload environments or earthquakes. Based on these excellent properties, UHPC materials have begun to be used as materials for wet joints. After using UHPC, the width of the joint can be reduced.

[0006] However, UHPC is expensive, and it is difficult to mix, pour and maintain on site. It is not easy to achieve ideal performance of UHPC and the quality requirements of wet joints cannot be guaranteed. Summary of the invention

[0007] In order to overcome the deficiencies in the prior art, the present invention has developed a construction method for wet joints of prefabricated bridge panels, with the aim of using ordinary concrete to cast the joints on site while meeting the connection strength between the prefabricated bridge panels, and significantly reducing the joint width to facilitate construction and reduce construction costs.

[0008] The construction method of the present invention comprises the following specific steps: S1. Prefabricated bridge deck: the prefabricated bridge deck is manufactured according to a conventional method, and the protruding steel bar is a straight steel bar head; S2. Prepare grouting operation: make molds for grouting, prepare high-strength grouting materials, and grouting equipment; S3, making a wrapped head: prepare high-strength slurry with high-strength grouting material; install a mold on the steel bar head, connect the slurry outlet pipe on the grouting equipment with the slurry inlet on the mold, turn on the grouting equipment to perform grouting operations until the high-strength slurry overflows from the slurry outlet of the mold; wait for the high-strength slurry in the mold to solidify, remove the mold, form a wrapped head of the steel bar head, and maintain for a set number of days; S4. Assembling prefabricated bridge panels: transporting the prefabricated bridge panels to the bridge construction site; assembling the prefabricated bridge panels on site; S5. Casting joints: prepare for casting at the joints; pour the joint concrete and maintain.

[0009] Preferably, the length of the steel bar head is 10 cm to 30 cm.

[0010] Preferably, the mold is assembled from an upper mold and a lower mold, and has a slurry inlet and a slurry outlet; one end of the mold has a through hole reserved for the steel bar head, and the other end has a groove on the inner side; when installing the mold in step S3, the mold is assembled into a whole so that the steel bar head passes through the through hole and the end of the steel bar head is placed in the groove.

[0011] Preferably, the high-strength grouting material is a solid powder for preparing ultra-high performance concrete; the high-strength slurry is an ultra-high performance concrete slurry, which is prepared by mixing the solid powder with a specified amount of water and additives and stirring, without adding fibers.

[0012] Preferably, in step S3, after the mold is removed, the wrapping head is steam cured.

[0013] Preferably, the joint concrete is ordinary concrete or steel fiber concrete.

[0014] Preferably, in step S5, before pouring the joint concrete, the side surfaces of the prefabricated bridge deck at the wet joint are roughened.

[0015] Preferably, in step S1, during the stage of tying the steel bars of the prefabricated bridge deck, the positions of some steel bars are adjusted so that after the prefabricated bridge deck is assembled on site, the wrapping heads on both sides of the same joint are staggered, and the end of the wrapping head on one side of the joint is close to the side of the prefabricated bridge deck on the other side of the joint, with a distance of less than 8 cm.

[0016] Preferably, the inner cavity of the mold is cylindrical, and the inner surface has concave patterns, so that the outer side surface of the wrapping head has a convexity.

[0017] Preferably, the protrusion is columnar, or spiral along the axial direction of the wrapping head.

[0018] The beneficial effects of the present invention include the following aspects: (1) In the present invention, the steel bars protruding from the prefabricated bridge deck are wrapped with UHPC and then concrete is poured. The bonding force between the UHPC layer and the steel bars is strong, so that the length of the steel bar head can be reduced, the width of the wet joint can be reduced, and the amount of concrete used on site can be reduced. This method does not change the previous working habits of pouring wet joints on site, facilitates construction, and speeds up the progress of on-site construction. (2) Compared with the conventional method, the present invention only adds grouting operation, which requires relatively small equipment and does not require large or bulky construction tools and machinery. It has low labor intensity and is convenient and easy to operate. The additional materials and labor required in the prefabrication site are very small. (3) The present invention only adds a small amount of UHPC to the prefabrication site, making efficient use of the expensive UHPC; (4) The UHPC wrapped head of the present invention effectively protects the steel bar head, slows down the corrosion of the steel bar head, and increases the durability of the wet joint; (5) The prefabricated bridge deck of the present invention has elongated straight steel bar heads, which facilitates prefabrication operations because the end formwork is simple in form and is convenient for erecting and removing the formwork; (6) The mold in the present invention facilitates the positioning of the steel bar head so that the steel bar head is symmetrically wrapped in the middle of the wrapped head; (7) In the present invention, protrusions are formed on the outer surface of the wrapping head, thereby enhancing the bonding strength between the wrapping head and the ordinary concrete poured subsequently. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the end of the precast bridge deck; Figure 2 Overall schematic diagram of the UHPC wrapped head production mold; Figure 3 Schematic diagram of the lower half of the mold; Figure 4 Schematic diagram of the fabrication of the UHPC wrapping head at the end of the precast bridge deck; Figure 5Schematic diagram of the end of the precast bridge deck after the UHPC wrapping head is completed; Figure 6 Schematic diagram of the precast bridge deck on site before pouring the wet joints; Figure 7 Schematic top view of the precast bridge deck before wet joint pouring on site; Figure 8 Schematic diagram after wet joint pouring is completed; Fig. 9 A partially enlarged schematic diagram of the UHPC wrapped head.

[0020] Figure numerals: prefabricated bridge deck 1, steel bar head 2, upper half mold 3, lower half mold 4, connecting hinge 5, slurry inlet 6, slurry outlet 7, bolt hole 8, groove 9, steel bar through hole 10, mold 11, UHPC wrapping head 12, post-casting strip 13. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] The directional words in the embodiments are based on the customary terms in engineering and are not strictly defined. For example, "upper" means the upper surface of the built part of the structure, and also includes the upper surface of the auxiliary components located obliquely above its influence range; when indicating the direction, "upper" includes both directly above and obliquely above. Directional words such as "left" and "right", "upper" and "lower" are only used to facilitate the description in conjunction with the drawings. The directional words used are only for the convenience of describing this patent, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore cannot be understood as a limitation on this patent. Example

[0023] The bridge in this embodiment is a single-span simply supported composite beam with a span of 30m and a superstructure width of 17.5m. The main beam is made of I-beam, the cross beam is also made of I-beam, and the bridge deck is made of prefabricated bridge deck. The longitudinal and transverse joints of the prefabricated bridge deck are set on the flange plates of the main beam and the cross beam. The main beam has 2 side beams and 4 middle beams; in addition to the 2 end beams, there are 3 middle beams in the span. The bridge deck is divided into 5 sections horizontally and 4 sections longitudinally, with a total of 20 areas, and each area corresponds to a prefabricated bridge deck. Studs are welded on the flange plates to strengthen the connection between the prefabricated bridge deck and the steel beam and bear the force together. The construction of the wet joints of the bridge deck of this bridge includes the following steps: S1. Prefabricated bridge deck: According to the design drawings of the bridge deck, the bridge deck reinforcement is tied on the pedestal in the prefabrication yard, and the connecting reinforcement extending from the end is in the form of a straight reinforcement segment. After the reinforcement mesh after the support is tied, the bridge deck concrete is poured and cured to obtain the prefabricated bridge deck 1, and the reinforcement segment at the end is called the reinforcement head 2, see Figure 1 . At this stage, considering the characteristics of the later on-site installation, the relative steel bar heads 2 in the wet joints should be staggered by a distance, and the positions of some steel bars in each prefabricated bridge deck 1 need to be planned and adjusted in advance. According to the stress characteristics of the prefabricated bridge deck 1 during service, in this embodiment, only the steel bars along the longitudinal direction of the bridge are adjusted, also known as the longitudinal bars of the bridge deck. Correspondingly, in this embodiment, the steel bars along the transverse direction of the bridge are called transverse bars, also known as the transverse bars of the bridge deck. The transverse bars are on the outside, close to the top and bottom surfaces of the prefabricated bridge deck 1; the longitudinal bars are on the inside. The position of the transverse bars does not need to be adjusted, only the longitudinal bars need to be adjusted, and the transverse bars are no longer shown in the drawings. Therefore, along the span direction of the bridge, the longitudinal bars in each prefabricated bridge deck 1 in the first and third sections are placed and tied according to the standard, and the longitudinal bars in each prefabricated bridge deck 1 in the second and fourth sections have a corresponding transverse offset, which is 10 cm in this embodiment. The diameter of the longitudinal bars is 25 mm, the diameter of the transverse bars is 16 mm, and the thickness of the fine protective layer is 25 mm. The designed wet joint width is 25 cm and the length of the steel bar head 2 is 23 cm.

[0024] S2, prepare grouting operation: make the mold 11 for grouting, and the grouting equipment, prepare the UHPC grouting material, and prepare the UHPC slurry. The mold 11 is assembled from the upper mold 3 and the lower mold 4, see Figure 2 and Figure 3 . There is a connecting hinge 5 at the joint on one side of the mold 11, and the joint on the other side is clamped by bolts through bolt holes 8; the mold 11 has a slurry inlet 6 and a slurry outlet 7. A steel bar through hole 10 is opened at one end of the mold 11 for the steel bar head 2 to pass through, and a groove 9 is provided on the inner side of the other end to fix the steel bar head 2. A layer of rubber gasket is padded in the joint between the lower half mold 3 and the upper half mold 4 to prevent the UHPC slurry from seeping out. The inner cavity of the mold 11 is cylindrical as a whole, and the inner surface can be specially treated so that the outer side of the UHPC wrapped head 12 after casting has spiral protrusions. These protrusions can improve the bonding ability between the UHPC wrapped head 12 and the joint concrete, see Fig. 9 The mold 11 in this embodiment has the same specifications and dimensions. The material of the mold 11 is cast steel, and rubber or synthetic rubber can also be used. The cross-sectional diameter of the inner cavity of the mold 11 is 75 mm and the length is 200 mm. UHPC grouting material is a solid powder material for preparing ultra-high performance concrete.

[0025] S3. Making the wrapped head: prepare UHPC slurry, which is formed by mixing UHPC grouting material with a specified amount of water and liquid additives, and stirring, without adding fibers. Install the mold 11 on the steel bar head 2. Before installing the mold 11, first grind the steel bar head 2 to remove the rust on it, and then insert the steel bar head 2 from the side of the steel bar through-hole 10 of the clamped mold 11 until the steel bar head 2 rests on the groove 9. Wrap an elastic rubber strip around the exposed part of the steel bar head 2 near the steel bar through-hole 10 to ensure that there is no leakage. Then connect the slurry outlet pipe on the grouting equipment to the slurry inlet 6 on the mold 11, turn on the grouting equipment to carry out grouting operations, until the UHPC slurry overflows from the slurry outlet 7 of the mold 11; then stop grouting, wait for the UHPC slurry in the mold 11 to solidify, remove the mold 11, and perform steam curing for the set number of days. Figure 4 , Figure 5 The thickness of the wrapping layer of the UHPC wrapping head 12 on the steel bar is 25 mm.

[0026] S4, assembling prefabricated bridge deck: transporting the prefabricated bridge deck 1 to the bridge construction site; assembling the prefabricated bridge deck 1 on site, see Figure 6 , Figure 7 The UHPC wrapping heads 12 of adjacent prefabricated bridge panels 1 in the joint are arranged in a staggered manner, and the design distance between two adjacent UHPC wrapping heads 12 is 25 mm, which makes the corresponding UHPC wrapping heads 12 close to each other, but also reserves a certain construction error.

[0027] S5. Casting joints: prepare for the casting operation at the joints. Before casting the joint concrete, the sides of the wet joints of the precast bridge deck 1 need to be roughened to make the surface rough and enhance the bonding strength of the joint surface. Then, steel fiber concrete is cast at the joints and cured. After completing all the steps, the post-casting strip 13 can be formed. Figure 8 In this step, a steel bar perpendicular to the direction of the steel bar head 2 can be inserted into the joint to serve as the transverse steel bar of the joint.

[0028] The preferred embodiments listed above further illustrate the objectives, technical solutions and advantages of the present invention in detail. It should be understood that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A construction method for wet joints of prefabricated bridge decks, characterized in that: The construction includes the following specific steps: S1. Prefabricated bridge deck: the prefabricated bridge deck is manufactured according to a conventional method, and the protruding steel bar is a straight steel bar head; S2. Prepare grouting operation: make molds for grouting, prepare high-strength grouting materials, and grouting equipment; S3, making a wrapped head: prepare high-strength slurry with high-strength grouting material; install a mold on the steel bar head, connect the slurry outlet pipe on the grouting equipment with the slurry inlet on the mold, turn on the grouting equipment to perform grouting operations until the high-strength slurry overflows from the slurry outlet of the mold; wait for the high-strength slurry in the mold to solidify, remove the mold, form a wrapped head of the steel bar head, and maintain for a set number of days; S4. Assembling prefabricated bridge panels: transporting the prefabricated bridge panels to the bridge construction site; assembling the prefabricated bridge panels on site; S5. Casting joints: prepare for casting at the joints; pour the joint concrete and maintain.

2. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: The length of the steel bar head is 10 cm to 30 cm.

3. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: The mold is assembled from an upper mold and a lower mold, and has a slurry inlet and a slurry outlet; one end of the mold has a through hole reserved for the steel bar head, and the inner side of the other end has a groove; when installing the mold in step S3, the mold is assembled into a whole, so that the steel bar head passes through the through hole, and the end of the steel bar head is against the groove.

4. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: The high-strength grouting material is a solid powder for preparing ultra-high performance concrete; the high-strength slurry is an ultra-high performance concrete slurry, which is prepared by mixing the solid powder with a specified amount of water and additives and stirring, without adding fibers.

5. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: In step S3, after the mold is removed, the wrapping head is steam cured.

6. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: The joint concrete is ordinary concrete or steel fiber concrete.

7. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: In step S5, before pouring the joint concrete, the side surfaces of the prefabricated bridge deck at the wet joint are roughened.

8. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: In step S1, during the stage of tying the steel bars of the prefabricated bridge deck, the positions of some steel bars are adjusted so that after the prefabricated bridge deck is assembled on site, the wrapping heads on both sides of the same joint are staggered, and the end of the wrapping head on one side of the joint is close to the side of the prefabricated bridge deck on the other side of the joint, with a distance of less than 8 cm.

9. The construction method of a prefabricated bridge deck wet joint according to claim 1, characterized in that: The inner cavity of the mold is cylindrical, and the inner surface has concave lines, so that the outer side surface of the wrapping head has a bulge.

10. A construction method for wet joints of prefabricated bridge decks according to claim 9, characterized in that: The protrusion is columnar or spiral along the axial direction of the wrapping head.

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