Method and system for constructing precast concrete member through combination of pre-tensioning method and post-tensioning method

Abstract

The invention relates to the technical field of concrete prefabrication, and discloses a method and a system for constructing a precast concrete member by combining a pre-tensioning method and a post-tensioning method, the process compositely realizes the effects of a peripheral post-tensioning method and a core pre-tensioning method on a single member, and comprises the following steps: mounting a reinforcement cage with an embedded iron part and a prestressed reinforcement, and erecting an inner template and an outer template; after the outer side formwork is cast at a time and maintained to the strength, the prestressed steel bars are fixed through anchoring clamps and tensioned through tensioning equipment; then, the inner side formwork is poured for the second time in the steel bar tensioning state; and after the concrete reaches the strength, the inner side formwork is dismantled, the anchoring clamp and the tensioning equipment are dismantled, and the ends of the prestressed steel bars are cut. Internal components are pre-tensioned to provide pre-stress, so that the crack resistance and the bearing capacity of the concrete are improved; the external member post-tensioning further increases the pre-stress of the member after the concrete is completely hardened, and further reinforces the member; after combined use, the prestress distribution is more reasonable, and the bearing capacity is comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of precast concrete technology, and in particular to a method and system for constructing precast concrete components using a combination of pre-tensioning and post-tensioning methods. Background Technology

[0002] Early structural components mainly used cast-in-place formwork and were mostly non-prestressed structures. However, with the development and progress of science and technology, the main components of engineering structures have been centrally produced in factories. This has not only improved the construction environment and saved raw materials, but also significantly improved the quality of components and shortened the construction cycle of corresponding projects.

[0003] Pre-tensioning and post-tensioning are the main construction methods for prestressed structures and are widely used in building structures and engineering. Pre-tensioning involves tensioning the prestressing tendons before pouring concrete, allowing the tendons and concrete to form a unified whole. This method is suitable for small to medium-sized components, such as bridges, roofs, and walls. The advantages of pre-tensioning are its simple construction, lower cost, and ability to effectively improve the crack resistance and stiffness of the components. However, pre-tensioning also has some disadvantages, such as limitations on the location and number of prestressing tendons, making it difficult to form complex prestressed structures; additionally, the corrosion and fire resistance of the prestressing tendons is relatively poor. Post-tensioning involves fabricating the concrete component first, then drilling holes or pre-drilling ducts in the concrete component, inserting the prestressing tendons into the ducts, and finally tensioning and anchoring them. Post-tensioning is suitable for large components, such as bridges and high-rise buildings. The advantages of post-tensioning are that it can form complex prestressed structures, the location and number of prestressing tendons are not limited, and the corrosion and fire resistance of the prestressing tendons is better. However, post-tensioning also has some drawbacks, such as complex construction, high cost, and the need for specialized equipment and skills.

[0004] To further increase the crack resistance and stiffness of precast concrete components, as well as their corrosion and fire resistance, while reducing construction costs, it is necessary to improve the pre-tensioning and post-tensioning methods, combining their advantages and compensating for their shortcomings. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for the combined construction of precast concrete components using pre-tensioning and post-tensioning methods. This method not only achieves two prestressing effects in different areas on the same component, but also enables the component to form a self-anchored whole through unique "force system conversion" and "two-stage grouting" processes, thereby combining the advantages of the two traditional processes while overcoming their disadvantages.

[0006] The solution of the present invention is: A method for constructing precast concrete components using a combination of pre-tensioning and post-tensioning methods, characterized by comprising the following steps: S1. Preparation and installation: Clean the concrete platform of the horizontal beam, apply release agent to the concrete platform, fix the prestressed steel bars and steel cage on the platform to obtain the steel cage; place the embedded iron parts in the formed steel cage, and install the outer template of the outer contour of the component and the inner template of the reserved area in the center of the component. S2. One-time pouring and curing: Concrete is poured onto the outer formwork, and then the cast-in-place concrete is cured until it reaches the predetermined strength, after which the outer formwork is removed. S3. Tensioning and anchoring: Place the prestressed steel bars into the anchoring clamps to fix them, and then use the tensioning equipment to tension the prestressed steel bars. Stop the tensioning equipment when the set tension force is reached. S4. Secondary pouring and curing: While the prestressed steel bars are kept in tension and anchored, concrete is poured onto the inner formwork. After pouring, the reserved holes are grouted to obtain the concrete component. S5. When the concrete component reaches 70% of its theoretical design strength, remove the inner formwork, remove the anchoring clamps and tensioning equipment, and cut the ends of the prestressed steel bars; then lift and stack the concrete component for continued curing. S6. After the concrete component reaches its design strength, further pressing is carried out.

[0007] As a preferred technical solution, the predetermined strength in step S2 is 70% of the design compressive strength.

[0008] As a preferred technical solution, the prestressed steel bars are provided in three pieces, with both ends fixed to one end of the oppositely arranged angle steel, and the other end of the angle steel fixed to the horizontal beam.

[0009] As a preferred technical solution, the system for the combined pre-tensioning and post-tensioning construction of precast concrete components includes a horizontal beam with a concrete platform at the top; angle steel is fixed to both ends of the horizontal beam; both ends of the prestressed steel bars are fixed to the angle steel; and the ends of the prestressed steel bars pass through anchoring clamps and are connected to the tensioning equipment.

[0010] As a preferred technical solution, the angle steel is fixed to the horizontal beam by pre-embedded bolts.

[0011] Compared with the prior art, the advantages of the present invention are: 1. This invention patent employs a segmented casting method, which effectively compensates for the shortcomings of post-tensioning. By casting the outer formwork and tensioning the concrete once it reaches its design strength, it achieves the effect of post-tensioning. Subsequently, the inner formwork in the middle section is cast, and once it reaches its design strength, the tensioning equipment releases the prestressed steel bars. Then, grouting is performed on the pre-reserved holes, allowing the outer concrete to utilize the post-tensioning effect while the inner concrete utilizes the pre-tensioning effect, simultaneously acting as an anchor for the outer post-tensioning method.

[0012] 2. This invention combines the advantages of pre-tensioning and post-tensioning methods. The basic principle is to first pour the external concrete (post-tensioning for the external concrete), then tension the prestressed steel bars, and finally pour the internal concrete (pre-tensioning for the internal concrete). The pre-tensioning of the internal components provides prestress, improving the crack resistance and load-bearing capacity of the concrete. The post-tensioning of the external components further increases the prestress of the components after the concrete has fully hardened, further strengthening them. When used in combination, the prestress distribution can be more reasonable, and the load-bearing capacity can be comprehensively improved. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0014] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a front view schematic diagram of the structure according to an embodiment of the present invention; Figure 3 This is a perspective view of concrete construction according to an embodiment of the present invention; In the diagram: 1-Horizontal beam; 2-Embedded bolt; 3-Concrete platform; 4-Angle steel; 5-Concrete component; 6-Prestressed steel bar; 601-Prestressed steel bar No. 1; 602-Prestressed steel bar No. 2; 603-Prestressed steel bar No. 3; 701-Inner side plate No. 1; 702-Inner side plate No. 2; 703-Inner side plate No. 3; 704-Inner side plate No. 4; 801-Outer side plate No. 1; 802-Outer side plate No. 2; 803-Outer side plate No. 3; 804-Outer side plate No. 4. Detailed Implementation

[0015] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0016] A combined construction method for precast prestressed beams S1: Construction Preparation and Installation like Figure 2 , Figure 3As shown, the concrete platform 3 at the top of the horizontal beam 1 is cleaned and coated with a release agent; prestressed steel bars 6 and steel cages are arranged and tied to prepare a steel cage. Embedded iron parts are placed in the steel cage. After applying a release agent to the formwork, the outer and inner formwork are installed, with the inner formwork enclosing the core post-cast area. Outer plate 1 (801), outer plate 2 (802), outer plate 3 (803), and outer plate 4 (804) form the outer formwork; inner plate 1 (701), inner plate 2 (702), inner plate 3 (703), and inner plate 4 (704) form the inner formwork. S2: Preparation for primary pouring and tensioning Concrete was mixed on-site, and the outer formwork was poured for the first time. The cast-in-place concrete was then cured until it reached 70% of its design strength. The outer formwork was then removed, and the tensioning equipment was inspected. The initial stress was adjusted, and the anchoring clamps were checked. The prestressed steel bars 6 were then placed into the anchoring clamps, and cones and toothed plates were embedded to prevent slippage. The anchoring clamps were then fixed to the tensioning equipment by welding or other methods. The prestressed steel bars 6 were then tensioned. The tensioning force was controlled by adjusting the rotation speed of the tension sensor in real time using feedback signals. The tensioning equipment was stopped when the set tensioning force was reached.

[0017] S3: Secondary pouring While maintaining the tension of the reinforcing bars, a second pour is made on the inner formwork. After the second pour, the pre-reserved holes are grouted to obtain concrete component 5. Concrete component 5 is then cured. Subsequently, the inner formwork is removed, the anchoring clamps are adjusted, and the test blocks are pressed. Prestressed steel bars 6 are then released. When concrete component 5 reaches 70% of its design strength, the component is lifted and stacked for continued curing. Once it has fully reached its strength, the concrete component is then pressed. The system used in the above method, such as Figure 2 As shown, the structure includes a horizontal beam 1, with a concrete platform 3 at its top; angle steel 4 is fixed to both ends of the horizontal beam 1; prestressed steel bars 6 are fixed to the angle steel 4 at both ends; and the ends of the prestressed steel bars 6 pass through anchoring clamps and are connected to the tensioning equipment. The angle steel 4 is fixed to the horizontal beam 1 by pre-embedded bolts 2, and the horizontal beam 1 and the concrete platform 3 together form a stable load-bearing foundation.

[0018] It should be noted that existing technologies are used for the unmodified parts, such as anchoring clamps, tensioning equipment, and concrete curing.

[0019] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing precast concrete components using a combination of pre-tensioning and post-tensioning methods, characterized in that, Includes the following steps: S1. Preparation and installation: Clean the concrete platform of the horizontal beam, apply release agent to the concrete platform, fix the prestressed steel bars and steel cage on the platform to obtain the steel cage; place the embedded iron parts in the formed steel cage, and install the outer template of the outer contour of the component and the inner template of the reserved area in the center of the component. S2. One-time pouring and curing: Concrete is poured onto the outer formwork, and then the cast-in-place concrete is cured until it reaches the predetermined strength, after which the outer formwork is removed. S3. Tensioning and anchoring: Place the prestressed steel bars into the anchoring clamps to fix them, and then use the tensioning equipment to tension the prestressed steel bars. Stop the tensioning equipment when the set tension force is reached. S4. Secondary pouring and curing: While the prestressed steel bars are kept in tension and anchored, concrete is poured onto the inner formwork. After pouring, the reserved holes are grouted to obtain the concrete component. S5. When the concrete component reaches 70% of its theoretical design strength, remove the inner formwork, remove the anchoring clamps and tensioning equipment, and cut the ends of the prestressed steel bars; then lift and stack the concrete component for continued curing. S6. After the concrete component reaches its design strength, further pressing is carried out.

2. The method for constructing precast concrete components using a combination of pre-tensioning and post-tensioning methods as described in claim 1, characterized in that: In step S2, the predetermined strength is 70% of the design compressive strength.

3. The method for constructing precast concrete components using a combination of pre-tensioning and post-tensioning methods as described in claim 1, characterized in that: The prestressed steel bars are provided in three sections, with each end fixed to one end of an angle steel arranged opposite to the other, and the other end of the angle steel fixed to the horizontal beam.

4. A system for a method of constructing precast concrete components using a combination of pre-tensioning and post-tensioning methods as described in any one of claims 1 to 3, characterized in that: It includes a horizontal beam with a concrete platform on top; angle steel is fixed at both ends of the horizontal beam; the prestressed steel bars are fixed at both ends to the angle steel; and the ends of the prestressed steel bars pass through anchoring clamps and are connected to the tensioning equipment.

5. The system as described in claim 4, characterized in that: The angle steel is fixed to the horizontal beam by pre-embedded bolts.

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