Prefabricated building formwork suitable for column or beam cast-in-place construction

Abstract

The utility model discloses a prefabricated building formwork suitable for column or beam cast-in-place construction, which comprises a cylindrical formwork shell and stirrups fixed on the formwork shell, and the upper end and the lower end of the formwork shell are provided with connection matching parts matched with the adjacent formwork shell; the formwork shell is defined by steel plates, and the stirrups are jointly composed of the steel plates and rod-shaped pieces fixedly connected to the inner side faces of the steel plates. A stress test result proves that a column and beam component formed by the prefabricated formwork can better form a restraining effect on internally-poured concrete, particularly a restraining area is enlarged, so that the overall shearing resistance and the bearing capacity of a building are improved, and the prefabricated formwork has important significance on earthquake resistance of the building under the earthquake condition.

Description

[0001] This utility model claims priority to Chinese Patent Application No. 202420340411.4, filed on February 23, 2024, entitled "A Cast-in-Place Precast Building Template Applicable to Columns or Beams". Technical Field

[0002] This utility model belongs to the field of construction, specifically relating to a precast building formwork suitable for cast-in-place construction, particularly a formwork suitable for columns or beams. Background Technology

[0003] In reinforced concrete building structures, especially frame beam-column structures, longitudinal steel bars and transverse stirrups spaced along the longitudinal direction are usually provided. The transverse stirrups bear the structural shear force on the one hand, and restrain the longitudinal steel bars and concrete on the other hand, so as to improve the structural bearing capacity and seismic performance.

[0004] Traditional stirrups include, but are not limited to, the following forms: Closed stirrups are the simplest form of stirrups, usually rectangular stirrups or composite stirrups made up of multiple rectangular stirrups, used to improve the shear resistance and seismic performance of building structures; Circular stirrups are also a commonly used form of stirrups, used for columns with circular cross-sections; Spiral stirrups are spiral-shaped stirrups, usually used for circular or irregularly shaped columns, which can provide good lateral restraint for building structures; Transverse hook stirrups are stirrups located in beams and columns, which can increase the shear strength and seismic performance of concrete beams and columns.

[0005] In building construction, formwork is the primary material for shaping the structure. Traditional construction methods involve first erecting scaffolding, positioning and tying reinforcing bars, then using sheet metal to construct the structural beams and columns, followed by concrete pouring, and finally removing the formwork after the concrete has solidified. Another traditional method involves setting up formwork on-site, connecting stirrups and longitudinal reinforcing bars with tying or welding to form a reinforcing cage, pouring concrete, and then removing the formwork after the building is complete. When there are many densely packed reinforcing bars at the joints of building components, on-site processing of the reinforcing cage, whether by tying or welding, is not only inefficient but also results in numerous instances of repeated bending of the reinforcing bars on-site, leading to inconsistent spacing and reduced load-bearing capacity.

[0006] In the currently popular prefabricated construction, building components and accessories (such as floor slabs, beams, wall panels, stairs, balconies, etc.) are prefabricated in factories, then transported to the construction site, and assembled into a complete building on-site using traditional connection methods (such as welding or sleeve grouting connections). Construction sites typically no longer require additional formwork. However, because these prefabricated components are pre-cast reinforced concrete structures, especially load-bearing columns or beams, their overall weight and volume are relatively large if they are also prefabricated in the factory. On-site construction requires specialized and expensive installation equipment, and the installation process is extremely inconvenient and poses significant safety hazards. Hoisting operations are almost always high-altitude work, and there are considerable risks during component transportation, secondary transfer, and hoisting. For example, whether the embedded lifting points of the components are securely installed, and whether the lifting claws and wire ropes can withstand the weight of the components are all important safety hazards in prefabricated construction. In addition, if all prefabricated components meet cast-in-place concrete, the construction joints that exist at the interface often result in problems such as cold joints, cracking, and leakage due to insufficient bonding between dry and wet concrete, coupled with the load disturbance from equipment and operators during the pouring process. The strength, sealing, and stability of these joints are all questionable.

[0007] Furthermore, in existing technologies, the stirrups for columns or beams are prefabricated by processing steel bars into the required shapes and then welding them, or they are tied on-site to form an interlaced steel cage. This cage is then molded into the building structure using on-site formwork and cast-in-place concrete. Alternatively, prefabricated reinforced concrete building components are assembled on-site to form the entire building. On-site tying of steel bars is time-consuming and labor-intensive, requires manual operation leading to inconsistent standards, and results in highly unstable connections. In contrast, the stirrup structures used in prefabricated buildings are formed within the prefabricated reinforced concrete building components, resulting in a larger overall weight and volume. On-site construction requires specialized and expensive installation equipment, and the installation process is extremely inconvenient and poses significant safety hazards.

[0008] For example, Chinese patent application CN102535745A discloses a permanent formwork component for column construction, which includes a stirrup structure and a permanent formwork component for column construction. The stirrup includes an outer frame bar, with one or more inner bars inside the outer frame bar. The two ends of the inner bars are connected to the outer frame bar to form a multi-limb mesh stirrup. This stirrup structure is created by pre-forming multi-limb mesh stirrups and then pre-forming multiple layers of multi-limb mesh stirrups into a concrete formwork shell. The outer frame of the multi-limb mesh stirrup is completely embedded in the formwork shell. Both the outer frame bar and the inner bars are composed of ring bars, each ring bar being formed by welding and bending the ends of a steel bar. The contact points between the steel bars are welded together, allowing the longitudinal bars to be fixed within the constraint holes or closed rings formed by the steel bars during construction. The patent document discloses a method of pre-embedding precast steel cages into concrete molds to form precast templates. These templates can be mass-produced in factories, transported to the site for assembly, and then concrete is poured to form modular structural components. This method allows for rapid construction and eliminates the need for on-site formwork support. The template components can be used as construction formwork and do not need to be removed after construction.

[0009] This technology can address the issues of lightweighting and standardization of formwork to some extent. However, it still requires concrete as formwork to support the stirrup structure, meaning that both the formwork and stirrups must function independently as building components. The prefabrication process of the concrete formwork is time-consuming and labor-intensive, hindering large-scale and standardized production. Furthermore, the confinement effect on the concrete, especially in the confinement area, is solely provided by the internal stirrups. The concrete formwork only provides support for the embedded reinforcing bars and does not substantially improve the confinement effect and area of ​​the cast-in-place concrete by the stirrups in the form of a reinforcing cage. Whether it's the precast cast-in-place components used in prefabricated buildings or the on-site cast-in-place formwork provided by this patented technology, the confinement effect and area of ​​the external stirrups and their concrete formwork on the internal concrete are also limited. They cannot truly withstand the longitudinal pressure and lateral expansion stress of the cast-in-place concrete. When the building's load-bearing capacity exceeds a certain limit, such as in high-rise buildings or during earthquakes, damage can easily occur. The strength of buildings constructed in these ways is at great risk.

[0010] Chinese patent application CN216196563U discloses a quick-assembly, non-removable formwork assembly, comprising two prefabricated non-removable formwork panels on both sides and multiple sets of quick-connecting components connecting the two prefabricated non-removable formwork panels. The prefabricated non-removable formwork panels are prefabricated by cast concrete and contain reinforcing mesh. Connecting slots are pre-embedded on the upper and lower ends of the prefabricated non-removable formwork panels during casting. Each set of quick-connecting components includes a connecting rod and two inserts, with the inserts fixedly installed at both ends of the connecting rod. The inserts are inserted into the connecting slots. When the prefabricated non-removable formwork is multi-layered, the lower half of the insert is inserted into the connecting slot on the upper end of the lower layer of prefabricated non-removable formwork, and the upper half is inserted into the connecting slot on the lower end of the upper layer of prefabricated non-removable formwork. The inner surface of the prefabricated non-removable formwork is provided with crisscrossing reinforcing ribs, with reinforcing ribs distributed opposite each connecting slot. The reinforcing ribs significantly improve the structural strength of the prefabricated non-removable formwork, enabling it to withstand greater casting impact.

[0011] The document discloses a precast concrete formwork structure with internal steel mesh, which requires both formwork and stirrups. However, the reinforcing ribs do not function as stirrups, indicating that the aforementioned technical problem of concrete constraint still exists. Moreover, this technology is clearly only applicable to cast wall structures and not to beam or column structures.

[0012] Chinese patent document CN209509476U discloses a non-removable steel formwork, characterized by: multiple thin steel plates forming a casting cavity, the shape of which matches the shape of the component to be cast; the steel plates are fixed by welding at the joints; and since it is a steel formwork, spot welding can be used for slight fixation at the joints. Specifically, the non-removable steel formwork for vertical components disclosed in this document consists of four steel plates, each with multiple stiffening ribs on the inner side of the formwork. Each stiffening rib has a pre-drilled small round hole for inserting short reinforcing bars to ensure that the steel formwork will not fall off after casting. The short reinforcing bars are sourced locally, such as scrap steel bar ends from the construction site. After the small reinforcing bars on the steel plates are installed, the formwork can be assembled. After the formwork is assembled, supporting timber is installed to reinforce the outside of the formwork, and then supporting steel pipes are erected. Concrete can be poured after the erection is complete. The steel formwork is integrated with the cast-in-place component, eliminating the conventional formwork removal process during on-site casting. In addition, the formwork is pre-embedded in the concrete at multiple points using short steel bars, ensuring the firmness of the connection between the formwork and the precast component, and increasing the strength and safety of the component.

[0013] Although the document discloses that the steel plate is used as a formwork for cast-in-place concrete and is exempt from removal, the small round holes reserved in the stiffening ribs on its inner side for inserting short steel bars are only to ensure that the steel formwork will not fall off after the casting is completed, and do not provide additional assistance for the most important confinement of the cast-in-place concrete; moreover, the steel plate is only used as a formwork and functions as a building component independently from the internal steel bars, that is, separate formwork and separate stirrups are still required, and only the internal stirrups are effective for the confinement effect, especially in the confinement area.

[0014] Furthermore, as part of the building construction process, whether it is on-site formwork construction or prefabricated building component installation, surface treatment is required after the main structure of the building is completed. This includes surface plastering and leveling, surface decoration, fireproofing, insulation, and waterproofing. Chinese patent application document CN 111576667A discloses a shear wall, including: an inner leaf wall panel, comprising a first part and a second part set at a first angle; a middle wall panel, comprising a first part and a second part set at a second angle, wherein the middle wall panel is connected to the inner leaf wall panel by a plurality of first tie members and forms a first cavity with the inner leaf wall panel, and the first cavity contains wall structure reinforcement; and an outer leaf wall panel, comprising a first part and a second part set at a third angle, wherein the outer leaf wall panel is connected to the middle wall panel by a plurality of second tie members and forms a second cavity with the middle wall panel, wherein the second cavity contains an insulation wall panel, and the insulation wall panel is connected to the second tie members. The inner leaf wall panel and the middle wall panel are tensile wall panels, and the materials used include, but are not limited to, cement-based composite materials, metals, and synthetic composite materials; the processing material of the first tie member has a certain tensile strength, including but not limited to metals or synthetic composite materials; the second tie member can be made of a material with a low heat transfer coefficient, such as stainless steel.

[0015] The patented technology claims that the shear wall is a prefabricated component with a hollow structure, consisting of two functional areas: a structural functional area and an insulation functional area. It integrates external wall insulation and the structural steel reinforcement of the shear wall. The shear wall is fabricated in a factory, and after hardening, it is demolded and cured before being transported to the site for assembly. The wall is then hoisted into place, and concrete is poured into its cavity to form the building wall. This technology eliminates the need for manual formwork erection and dismantling, insulation and waterproofing work on the construction site, and even eliminates the need for subsequent manual plastering.

[0016] However, this patented technology still falls under the category of "no-removal formwork," merely prefabricating the insulation layer during the formwork fabrication process. It still requires separate formwork and internal reinforcing steel, and for constraint purposes, especially in constrained areas, the formwork and its accompanying insulation layer do not play a substantial role. Furthermore, this technology is explicitly only applicable to shear wall structures and not to beam or column structures. Utility Model Content

[0017] To address the problems existing in the prior art, and taking CN102535745A as the closest prior art, this utility model provides a precast building formwork suitable for cast-in-place construction of columns or beams. This utility model provides the following specific technical solutions:

[0018] A precast building formwork suitable for cast-in-place column or beam construction includes a cylindrical formwork shell and stirrups fixed on the formwork shell. The upper and lower ends of the formwork shell are provided with connecting parts that mate with adjacent formwork shells. The formwork shell is characterized by being enclosed by steel plates, and the stirrups are composed of the steel plates and rod-like members fixed to the inner surface of the steel plates. The novel precast building formwork obtained through this basic technical solution forms a structural unit through the appropriate cooperation of the steel plate enclosure structure and the rod-like members, thus fulfilling the dual functions of construction formwork and structural stirrups in traditional construction processes. During building construction, additional formwork and stirrup binding are no longer required, saving production costs and reducing difficulties in processing and construction. More importantly, by using a steel plate enclosure structure and its internal rod-like members instead of traditional formwork and stirrup structures, the precast building formwork of this invention can provide stronger restraint on the cast-in-place concrete and longitudinal reinforcement, particularly increasing the restraint range on the concrete, thereby improving the overall shear bearing capacity and seismic performance of the building.

[0019] Preferably, the steel plate of this invention is formed by fixing and connecting multiple steel plates that are longitudinally separated along its enclosing center. In this further preferred embodiment, during the factory prefabrication process, the separated multiple steel plates can be further processed to form the enclosing steel plate required in the final prefabricated component. This measure not only saves materials but also facilitates the standardization, generalization, and large-scale production of the product.

[0020] Preferably, the fixed connection of multiple steel plates in this invention is formed by spot welding. In this further preferred technical solution, compared with directly connecting multiple steel plates as a whole, connecting the steel plates by spot welding can not only satisfy the integrity of the prefabricated building components, but also better separate the stress of each steel plate, avoid the steel plates participating in the longitudinal stress of the component, ensure the uniformity of the longitudinal bending stiffness of the component, and also facilitate standardized and large-scale production on factory assembly lines.

[0021] Preferably, the outer surface of the steel plate of this invention is further provided with a reinforcing layer, which is a magnesium phosphate-based material layer fixedly connected to the outer surface of the steel plate. In this further preferred embodiment, by adding a reinforcing layer, particularly a magnesium phosphate-based cementitious material layer, to the outer side of the steel plate enclosure structure of the building component of this invention, the reinforcing layer provides better bonding and support to the steel plate, thereby enhancing the steel plate's resistance to the outward transverse stress generated by the cast-in-place concrete, further strengthening the constraint effect on the cast-in-place concrete, and particularly reducing the area of ​​the unconstrained zone. Of course, in addition to using a magnesium phosphate-based material layer as a reinforcing layer, it is also possible to use a steel mesh reinforced with concrete, as long as the constraint effect can be enhanced through better bonding with the enclosing steel plate.

[0022] Preferably, the steel plate of this invention has inwardly recessed grooves on opposite outer surfaces, and protrusions corresponding to the grooves are formed in the enclosed hollow area. Both ends of the rod-shaped member extend through the protrusions into the grooves, and connecting fasteners are provided at both ends of the rod-shaped member. The connecting fasteners are located within and fitted to the corresponding grooves. Both the connecting fasteners and the ends of the rod-shaped member are located within the grooves and do not protrude from the outer surface of the steel plate. In this further preferred embodiment, the interlocking concave-convex structure allows the rod-shaped member to fit tightly against the enclosing steel plate, achieving the function of traditional stirrups with significantly better restraint. This not only greatly increases the restraint range of the internal concrete but also provides better restraint for the longitudinal reinforcing bars. Furthermore, this design ensures that both ends of the rod-shaped member are located within the enclosing steel plate without protruding to the outside, thus not affecting the appearance of the building component's outer surface and avoiding obstacles caused by adding other functional layers to the outer surface of the steel plate. It is also more ideal for production, packaging, and transportation during factory prefabrication.

[0023] Preferably, one end of the rod-shaped member of this invention has a upset anchor head, and the other end has an external thread that can be connected to a nut. The upset anchor head and the nut respectively form the connecting and fixing parts at both ends of the rod-shaped member. In this further preferred technical solution, the design of the upset anchor head at one end of the rod-shaped member allows the rod-shaped member to cooperate with the enclosing steel plate to play the role of a traditional stirrup, and its restraining effect is significantly better than that of a traditional stirrup. The upset anchor head can better resist the stress of the poured concrete on one side of the steel plate, which can not only greatly increase the restraining range of the internal concrete, but also have a better restraining effect on the longitudinal reinforcement. The other end of the rod-shaped member uses a threaded connection, which makes it easy to insert the rod-shaped member into the corresponding groove on the steel plate. The upset anchor head at one end will not move. As long as the threaded nut is tightened on the other side, the rod-shaped member and the steel plate can be tightly fitted. This is more ideal for production, packaging and transportation in the factory prefabrication process.

[0024] Preferably, both ends of the rod-shaped member of this invention have external threads that can be connected to nuts, forming connecting and fixing components at both ends of the rod-shaped member. In this further preferred technical solution, considering the difficulty of the upset anchor head processing technology, using threaded connections at both ends as connecting and fixing components can reduce processing difficulty, reduce processing costs, increase product qualification rate, and facilitate its large-scale production.

[0025] Preferably, the upset anchor head of this utility model includes an anchor head body with a diameter larger than that of the rod-shaped member, which protrudes outward to form a fitting portion, the fitting portion being able to fit with the groove; or the anchor head body fits with the groove through a washer provided on the rod-shaped member, the diameter of the washer being larger than that of the anchor head body. In this further preferred technical solution, the fitting portion on the upset anchor head of the rod-shaped member or the added washer further enhances the rigid constraint range of the anchor head, while allowing the rod-shaped member and the surrounding steel plate to fit more tightly, thus playing the role of traditional stirrups, and its constraint effect is significantly better than that of traditional stirrups. The tight fit allows the rod-shaped member and the steel plate to better form an integral force-bearing structure, which helps to better resist the stress of the poured concrete, not only greatly increasing the constraint range of the internal concrete, but also providing better constraint for the longitudinal reinforcement.

[0026] Preferably, the angle between the sidewall and bottom of the groove in this invention is 30-60°; the diameter of the protrusion is 2-5 times the diameter of the rod-shaped member. In this further preferred embodiment, the groove structure is designed to be larger on the outside and smaller on the inside, and its size is larger than the diameter of the rod-shaped member. This allows the rod-shaped member to be smoothly inserted from one side of the steel plate to the other, enabling a tighter fit with the enclosing steel plate to function as a traditional stirrup. Its clamping effect is significantly better than that of traditional stirrups, helping to better resist the stress of the poured concrete. This not only greatly increases the restraint range of the internal concrete but also provides better restraint for the longitudinal reinforcing bars.

[0027] Preferably, the connecting mating part at one end of the template can fit tightly with the corresponding connecting mating part of the adjacent template, allowing the two templates to be joined together with their outer surfaces flush. In this further preferred embodiment, the connecting mating part eliminates the need for prefabricating bulky complete components as in traditional prefabricated buildings. Simultaneously, multiple template components can be easily assembled into the required complete component on-site. The connecting mating part can be processed into a standard interface, which greatly improves efficiency for large-scale prefabrication of standard components in factories, reduces the technical requirements for installation workers, and provides a good foundation for the application of intelligent construction technology.

[0028] Preferably, the connecting and mating part of this utility model is a slot mating or a plug-in mating form. In this further preferred embodiment, the assembly of multiple template components can use any known suitable mating form. Slot mating or plug-in mating is the most convenient method for on-site operation and is also ideal for factory processing. However, other suitable mating forms can also be used as long as they serve the purpose of connection and mating.

[0029] Preferably, the rod-shaped members of this invention are arranged in multiple layers longitudinally along the enclosing center of the steel plate. The rod-shaped members in the same layer are arranged parallel to each other in the same plane, while the rod-shaped members in adjacent layers are arranged perpendicularly or intersecting in parallel directions at different positions. In this further preferred embodiment, the arrangement of multiple rod-shaped members, multiple layers of rod-shaped members, and rod-shaped members in different directions provides constraint on the cast-in-place concrete at different locations and in different directions within the enclosing steel plate. This helps to better resist the stress and structural shear force of the cast-in-place concrete, greatly increasing the constraint range on the internal concrete and simultaneously providing better constraint on the longitudinal reinforcing bars. The distance between each layer or each rod-shaped member can be appropriately set according to different building components, building parts, building types, etc., and those skilled in the art can optimize the selection based on specific construction requirements.

[0030] Preferably, the steel plate is made of seamless steel pipe or formed by laterally bending steel plates. In this further preferred embodiment, the enclosing formwork of this invention, formed by bending steel plates, is typically used for columns and beams in concrete structures. It replaces traditional construction formwork and external stirrups in concrete structures, resisting lateral pressure during concrete pouring and participating in structural stress during use, primarily bearing structural shear force. The prefabricated building formwork of this invention, made by bending and welding steel plates into rectangular, T-shaped, cross-shaped, L-shaped, and circular shapes, is easily manufactured in a factory, resulting in low processing costs and facilitating automated production lines.

[0031] Beneficial effects

[0032] In summary, compared with the prior art, this utility model has the following beneficial effects:

[0033] This utility model of prefabricated building formwork, through the appropriate cooperation of steel plate enclosure structures and the rod-like members between them, forms a building structure that simultaneously functions as both formwork and stirrups. During construction, there is no need for formwork supports and stirrup tying, saving production costs and reducing the difficulty of processing and construction. Using steel plate enclosure structures and their internal rod-like reinforcements instead of traditional construction formwork and stirrup structures provides better constraint on the poured concrete, particularly increasing the constrained area, thereby improving the overall shear resistance and load-bearing capacity of the building.

[0034] In this precast building formwork, controlling the thickness of the steel plate enclosure structure increases the distance between the component and the internal longitudinal reinforcement and concrete. The multi-layered internal constraint components (including groove and protrusion designs, and anchor heads) working in conjunction with the steel plate enclosure structure not only significantly increase the constraint range on the internal concrete but also provide better constraint on the longitudinal reinforcement. The improved bonding between the outer reinforcing layer of the steel plate enclosure structure and the steel plate enhances the steel plate's resistance to lateral stress in the internal concrete. The integral steel plate formed by segmented welding significantly reduces the unevenness of the longitudinal pressure exerted on the steel plate by the building structure at different locations. These structural features of the precast building formwork of this invention provide better constraint on the poured concrete, particularly increasing the constraint area.

[0035] This utility model of prefabricated building formwork uses a steel plate enclosure structure and rod-like members between them to form a building structure that simultaneously functions as formwork and stirrups. The connection parts use a special connection and fixing structure, which facilitates the prefabrication of this utility model's prefabricated building formwork in advance. Whether in the prefabrication process or on-site construction process, there is no need for binding or welding procedures. It can be directly prefabricated in the factory according to standard specifications in batch production, which not only improves efficiency, but also avoids inconsistencies in the process of construction, shortens the construction cycle and construction requirements.

[0036] This invention relates to a precast building formwork that, through a steel plate enclosure structure and the inter-bracing rods, forms a building structure that simultaneously functions as both formwork and stirrups, eliminating the need for separate construction formwork (whether traditionally erected wooden formwork or precast concrete formwork). On the construction site, longitudinal reinforcing bars can be directly inserted into the precast formwork, requiring only tying or welding at the ends to the steel plate enclosure structure and / or the rods (the middle section can also be secured using the fixing holes within the formwork). After the cast-in-place concrete has solidified, the precast formwork remains intact and can simultaneously function as part of the reinforced concrete structure, bearing stress along with the internal rods and stirrups, thus increasing the confinement area for the concrete.

[0037] This utility model's prefabricated building formwork can be prefabricated into standard components at the smallest unit, which are then assembled through connecting parts at both ends to form a complete building formwork of the required size. Compared with prefabricated building components, this utility model's prefabricated building formwork is lighter, making transportation, hoisting, and installation more convenient. Furthermore, since concrete is poured on-site after installation, it avoids the shortcomings in strength, sealing, and stability of pre-cast integral prefabricated building components. It also facilitates large-scale factory production, convenient on-site installation, and integrated decoration and finishing, eliminating the need for plastering, puttying, and painting. The miniaturization, lightweighting, standardization, and integration of building components facilitate the application of artificial intelligence technology, achieving effects such as reduced construction costs, shortened construction time, and improved quality. Attached Figure Description

[0038] Figure 1 This image shows a perspective view of the prefabricated building column template of Embodiment 1 of this utility model.

[0039] Figure 2 for Figure 1 Cross-sectional view.

[0040] Figure 3 for Figure 2 A magnified view of the upset anchor head structure at part B.

[0041] Figure 4 The diagram shows the connection and mating parts and the reinforcing layer of the prefabricated building column formwork in Embodiment 1 of this utility model.

[0042] Figure 5 A schematic diagram of the prefabricated U-shaped beam formwork of Embodiment 2 of this utility model is shown.

[0043] Figure 6 The diagram shows a comparison of the longitudinal constraint zones of the prefabricated building formwork of this utility model and the traditional formwork-stirrup concrete column structure.

[0044] Figure 7 The diagram shows a comparison of the lateral constraint zones of the prefabricated building formwork of this utility model and the traditional formwork-stirrup concrete column structure.

[0045] Explanation of reference numerals in the attached drawings: 1 is steel plate; 2 is rod-shaped member; 3 is reinforcing layer; 4 is longitudinal steel reinforcement restraint structure; 5 is groove; 6 is protrusion; 7 is upset anchor head; 8 is anchor head body; 9 is nut; 10 is fitting part; 11 is washer; 12 is insertion interface; 13 is socket end; 14 is weld seam.

[0046] Figure 8The image shows a comparison of the load-displacement curves of axially compressed members of a traditional reinforced concrete column and the precast formwork column of this invention. The blue curve represents the traditional reinforced concrete column, and the red curve represents the data for the precast formwork column of this invention.

[0047] Figure 9 The diagram shows a comparison of hysteresis curves in low-cycle reciprocating tests between a conventional reinforced concrete column and the precast formwork column component of this invention. The blue curve represents the conventional reinforced concrete column, and the red curve represents the data for the precast formwork column component of this invention.

[0048] Figure 10 The results of bending tests (mid-span deflection - mid-span bending moment) for conventional reinforced concrete beams and the precast formwork beams of this invention are shown. The blue curve represents a conventional reinforced concrete column, and the red curve represents the data for the precast formwork column of this invention.

[0049] Figure 11 The torque-rotation curve of the prefabricated template beam component of this utility model is shown. Detailed Implementation

[0050] The following detailed description provides further details through specific embodiments. However, it should be noted that the embodiments described below are merely for better illustrating the content of this utility model, and do not represent that the content of this utility model is limited to the described embodiments. Therefore, non-essential improvements and adjustments made to the implementation schemes by those skilled in the art based on the above-described utility model content still fall within the protection scope of this utility model, and the protection scope of the appended claims shall prevail.

[0051] Unlike existing technologies that require both formwork and stirrups, this invention uses a single structure that performs the functions of both, and both simultaneously contribute to the substantial restraint of the concrete.

[0052] The steel plate of this invention has a thickness of 0.8-10 mm, more preferably 1-1.5 mm, and a length of 40-1000 mm, more preferably 100-300 mm, along its longitudinal direction.

[0053] The term "enclosure" or "enclosed steel plate" used in this utility model refers to a structure in which a steel plate or other surface structure is bent inward along a certain axis and then enclosed and tends to close, for example by welding. The enclosed structure referred to in this utility model can be a fully enclosed structure or a semi-enclosed structure with partial openings. Its cross-sectional shape can be a closed square, rectangle, circle, polygon or a semi-enclosed U-shape, cross shape, L-shape, T-shape, etc.

[0054] Example 1

[0055] A type of precast column formwork suitable for cast-in-place construction, such as Figure 1-4 As shown, a closed rectangle is formed by steel plates 1 with a thickness of 1.5 mm. The length of steel plate 1 along the longitudinal direction of the enclosure center is 200 mm. The opposite faces of the enclosing steel plates 1 are connected by rod-like members 2 in the form of screws that are vertically fixed to the inner side of the enclosing steel plates 1. The steel plate 1 is formed by fixing and connecting multiple segments of steel plate 1 that are longitudinally separated along its enclosure center. Figure 1 The welding connection of the two steel plates is shown, with 14 representing the weld seam. The rod-like members 2 have multiple layers, preferably an even number; this embodiment shows four layers. Each layer of rod-like members 2 includes 10 coplanar rod-like members 2 arranged parallel to each other at intervals. The length directions of adjacent layers of rod-like members 2 are perpendicular to each other, alternating longitudinally and transversely. A reinforcing layer 3 covers and connects to the outer surface of the enclosing steel plate 1. The enclosing steel plate 1 has pouring holes (not shown) for pouring concrete from the outside into the internal hollow area formed by the enclosing steel plate 1; the enclosed area also includes a structure for inserting and fixing longitudinal reinforcing bars (not shown).

[0056] In this embodiment, the prefabricated building column formwork is prefabricated in the factory. At the construction site, the longitudinal steel bars required for the column formwork are directly inserted into the hollow area inside the enclosing steel plate 1. The longitudinal steel bars are then welded and fixed to the steel plate 1 and the rod-shaped member 2 to form a steel cage. Concrete is then poured into the hollow area to form a reinforced concrete structure.

[0057] In this embodiment, the enclosing steel plate 1 and the rod-shaped member 2 are fixed by a special connection method. The outer side of the enclosing steel plate 1 is recessed inward to form a groove 5 corresponding to the two ends of the rod-shaped member 2, and a protrusion 6 corresponding to the groove 5 is formed on the inner side of the enclosing steel plate 1. A through hole is provided in the groove 5 so that the two ends of the rod-shaped member 2 can pass freely through the groove 5. The two ends of the rod-shaped member 2 are respectively connected to a connecting fastener, which is located in the corresponding groove 5 and fits tightly against the groove 5.

[0058] In this embodiment, the connecting fasteners at both ends of the rod-shaped member 2 are upset anchor heads 7 and nuts 9, respectively. One end of the rod-shaped member 2 has an integrally upset anchor head 7, and the other end of the rod-shaped member 2 is machined with external threads and connected to a nut 9. The upset anchor head 7 and the nut 9 respectively form the connecting fasteners at both ends of the rod-shaped member 2. By tightening the nut 9, a tight fit between the connecting fasteners at both ends and the groove 5 can be achieved. Of course, both ends can also be fixedly connected by threaded nuts.

[0059] like Figure 3As shown, when using the upset anchor head 7, the upset anchor head 7 includes an anchor head body 8 with a diameter larger than that of the rod-shaped member 2; the anchor head body 8 includes a ring of protruding fitting parts 10, which are tightly fitted with the groove 5. The groove 5 has an internal shape that is conical or frustum-shaped, and the angle formed between the groove wall and the bottom of the groove is about 45°. When the groove 5 and the protruding part 6 are stamped as a single piece, the shape of the protruding part 6 corresponding to the groove 5 is consistent with that of the groove 5, and its inner diameter can be 2-3 times the diameter of the rod-shaped member 2 passing through it. When the fitting part 10 is not integrally processed with the anchor head body 8, a washer 11 can be used instead of the fitting part 10. In this way, during the processing of the upset anchor head body 8, it is only necessary to ensure that the size of the upset anchor head 7 is larger than that of its corresponding rod-shaped member 2. It is not necessary to process the fitting part 10 on the upset anchor head body 8. Instead, a washer 11 of matching size is used separately and fitted onto the rod-shaped member 2, and then the washer 11 is tightly fitted with the groove 5. Preferably, such as Figure 3 As shown, both ends of the connecting fastener and the rod-shaped member 2 are located inside the groove 5, and do not extend to the outer side of the steel plate 1. This design ensures the flatness of the template surface, making it convenient to continue to set the reinforcing layer 3 and other functional or decorative layers on the outer side. In addition, in terms of stress, it also allows the steel plate serving as the template to be closer to the poured concrete, which helps to better and more effectively restrain the internal concrete.

[0060] When the connecting fastener uses a threaded nut, a washer 11 can also be added to the nut 9 to achieve a tight fit with the groove 5, and will not be shown separately.

[0061] like Figure 4 As shown, the reinforcing layer 3 used in this embodiment is a magnesium phosphate-based polymer material layer. Using this material can better strengthen the bond between this layer structure and the steel plate 1 of the template, helping to further effectively restrain the internal concrete. The reinforcing layer 3, connected to the outer surface of the steel plate 1, can effectively protect the outer surface of the column template. Furthermore, after the cast-in-place reinforced concrete column is formed, the reinforcing layer 3 can fit tightly against the steel plate 1, helping to alleviate the lateral pressure of the concrete borne by the steel plate 1 and further effectively restraining the internal concrete. Outside the reinforcing layer 3, additional layers such as concrete, decorative layers, thermal insulation layers, sound insulation layers, fireproof layers, and wallpaper can still be applied as needed.

[0062] In this invention, the reinforcing layer 3 can also be formed from any material known in the prior art that has good adhesion to steel plates, such as a steel mesh layer plus a concrete layer. The steel mesh layer is fixedly connected to the anchor head body 8 and / or nut 9 by spot welding, and the steel mesh layer is pressed and fixed by the anchor head body 8 and nut 9.

[0063] In this embodiment, the column formwork is provided with corresponding connection and mating parts at both ends along the longitudinal direction (the direction of longitudinal reinforcement insertion). For example... Figure 4As shown, in this embodiment, one end of the column template is provided with an insertion interface 12 extending outward along its longitudinal direction. The inner side surface of the sidewall of the other end of the column template is shaped to match the insertion interface as a receiving end 13. The insertion interface 12 of the column template and the receiving end 13 of another column template can fit tightly together so that the outer surfaces of the templates after insertion are flush with each other. Of course, other mating structures known in the art, such as slot-type mating connections, can also be used, as long as multiple column templates can be tightly fitted together and their outer surfaces can be flush with each other.

[0064] During on-site installation, the insertion end 12 of the column formwork is inserted into the corresponding socket 13 of another column formwork of the same model. A third column formwork can be inserted into the first one as needed, until the dimensions meet the requirements of the building's column structure. After the required dimensions are achieved, the column formwork used at both ends of the assembled column structure is in a form without connecting parts.

[0065] Figure 6 and 7 The diagram shows the constrained areas of reinforced concrete columns constructed using the precast column formwork of Embodiment 1 of this utility model and those constructed using the traditional stirrup-formwork method. Areas without lines represent effective constrained areas, while areas with lines represent unconstrained areas.

[0066] from Figure 6 As can be seen, in terms of longitudinal restraint effect, both the reinforced concrete column formed by traditional stirrups and formwork (left figure) and the reinforced concrete column formed by the precast building column formwork of this utility model (right figure) have unrestrained areas in the longitudinal interval between adjacent layers of bolts. However, the reinforced concrete column formed by the precast building column formwork of this utility model has a smaller unrestrained area in the corresponding region.

[0067] from Figure 7 As can be seen, in terms of lateral restraint, both the reinforced concrete column formed by traditional stirrups and formwork (left figure) and the reinforced concrete column formed by the precast building column formwork of this utility model (right figure) have unrestrained areas in the lateral space between the same layer of bolts and in the diagonal edge area. However, the reinforced concrete column formed by the precast building column formwork of this utility model has a smaller unrestrained area in the corresponding region.

[0068] Example 2

[0069] Precast U-shaped beam formwork suitable for cast-in-place construction, such as Figure 5As shown, a U-shaped template structure is formed by a 1 mm thick thin steel plate 1. The steel plate 1 has a longitudinal length of 100 mm along the center of the enclosure. The two opposite sides of the enclosure steel plate 1 are fixedly connected by rod-like members 2 vertically fixed to the inner side of the enclosure steel plate 1. The rod-like members 2 have multiple layers, preferably an even number. In this embodiment, there are two layers. Each layer of rod-like members 2 includes five parallel rod-like members 2 arranged in a coplanar manner. The length directions of adjacent layers of rod-like members 2 are basically the same, but the connection positions on the inner side of the enclosure steel plate can be staggered. A reinforcing layer 3 is covered and connected to the outer surface of the enclosure steel plate 1. The enclosure steel plate 1 is provided with pouring holes that allow concrete to be poured from the outside into the hollow area formed by the enclosure steel plate. The enclosure area also includes a wavy constraint structure 4 for inserting and fixing longitudinal reinforcing bars.

[0070] In this embodiment, the beam formwork is prefabricated in the factory. At the construction site, the longitudinal steel bars required for the building beam components are directly inserted into the hollow area inside the enclosing steel plate 1. The longitudinal steel bars are then welded and fixed to the steel plate 1 and the rod-shaped member 2 to form a steel cage. Concrete is then poured into the hollow area to form a reinforced concrete structure.

[0071] Similar to the column template in Example 1, the enclosing steel plate 1 and the rod-shaped member 2 are fixed by a special connection method. The outer side of the enclosing steel plate 1 is recessed inward to form a groove 5 corresponding to the two ends of the rod-shaped member 2, and a protrusion 6 corresponding to the groove 5 is formed on the inner side of the enclosing steel plate 1. Through holes are opened in the groove 5 so that the two ends of the rod-shaped member 2 can pass freely through the groove 5. The two ends of the rod-shaped member 2 are respectively connected to connecting fasteners, which are located in the corresponding grooves 5 and fit tightly against the grooves 5.

[0072] Similar to the column template in Embodiment 1, the connecting fasteners at both ends of the rod-shaped member 2 can be upset anchor heads 7 and nuts 9, respectively. One end of the rod-shaped member 2 has an integral upset anchor head 7, and the other end of the rod-shaped member 2 is machined with external threads and connected to a nut 9. The upset anchor head 7 and the nut 9 respectively form the connecting fasteners at both ends of the rod-shaped member 2. By tightening the nut 9, the connecting fasteners at both ends can be tightly fitted with the groove 5. Of course, both ends can also be fixedly connected by threaded nuts. When using an upset anchor head, the upset anchor head 7 includes an anchor head body 8 with a diameter larger than that of the rod-shaped member 2; the anchor head body 8 includes a protruding fitting portion 10, and the fitting portion 10 achieves a tight fit with the groove 5. The internal shape of the groove 5 is conical or frustum-shaped, and the angle formed by the groove wall and the groove bottom is about 45°. When the groove 5 and the protrusion 6 are integrally formed by stamping, the shape of the protrusion 6 corresponding to the groove 5 is consistent with that of the groove 5, and its inner diameter can be 2-3 times the diameter of the rod-shaped member 2 passing through it. Alternatively, a washer 11 can be used instead of the fitting part 10. In this way, during the processing of the upset anchor head body 8, only the size of the upset anchor head 7 is ensured to be larger than its corresponding rod-shaped member 2. It is unnecessary to process the fitting part 10 on the upset anchor head body 8; instead, a washer 11 of matching size is used and fitted onto the rod-shaped member 2, and then the washer 11 is tightly fitted to the groove 5. Preferably, both ends of the connecting fastener and the rod-shaped member 2 are located inside the groove 5, and do not extend outward to the outer surface of the steel plate 1 serving as the template. This design ensures the flatness of the template surface, facilitating the addition of a reinforcing layer 3 and other functional or decorative layers on the outer surface. Furthermore, in terms of stress, it allows the steel plate 1 serving as the template to be closer to the poured concrete, helping to better and more effectively constrain the internal concrete.

[0073] Similar to the column template in Example 1, when the connecting fastener uses a threaded nut, a washer 11 can also be added to the nut 9 to achieve a tight fit with the groove 5.

[0074] Similar to the column formwork in Example 1, the reinforcing layer 3 used in this example is formed of magnesium phosphate-based polymer material. Using this material better strengthens the bond between this layer structure and the steel plate 1 in the beam formwork of this invention, helping to further effectively restrain the internal concrete. The reinforcing layer 3, connected to the outer surface of the steel plate 1, effectively protects the outer surface of the beam formwork. Furthermore, after the cast-in-place reinforced concrete beam is formed, the reinforcing layer 3 can fit tightly against the steel plate 1, assisting in the lateral pressure of the concrete borne by the steel plate 1 and helping to better restrain the internal concrete. Outside the reinforcing layer 3, additional layers such as concrete, decorative layers, thermal insulation, sound insulation, fireproofing, and wallpaper can still be applied as needed.

[0075] Similar to the column formwork in Example 1, the reinforcing layer 3 in the beam formwork can also be formed by a steel mesh layer and concrete. The steel mesh layer is fixedly connected to the anchor head body 8 and / or nut 9 by spot welding, and the steel mesh layer is pressed and fixed by the anchor head body 8 and nut 9.

[0076] Similar to the column formwork in Embodiment 1, the beam formwork in this embodiment can also have corresponding connection and mating parts at both ends along the longitudinal direction (in the direction of longitudinal reinforcement insertion) of the enclosure center. One end of the beam formwork has an insertion interface 12 extending outwards along its longitudinal direction. The inner side surface of the sidewall of the other end of the beam formwork is shaped to match the insertion interface 12 as a socket end 13. The insertion interface 12 of the beam formwork and the socket end 13 of the other beam formwork can fit tightly together so that the outer surfaces of the formwork after insertion are flush. Of course, other mating structures known in the art, such as slot-type mating connections, can also be used, as long as multiple beam formworks can be tightly fitted together and their outer surfaces can be flush.

[0077] During on-site installation, the insertion end 12 of the beam formwork in this embodiment is inserted into the corresponding socket 13 of another beam formwork of the same model. A third beam formwork can be inserted into the subsequent beam formwork as needed, until the dimensions meet the requirements of the building's beam structure. After the required dimensions are achieved, the beam formwork used at both ends of the assembled beam structure is in a form without connecting parts.

[0078] Example 3: Stress Test on Column Members

[0079] According to Example 1, the precast column formwork structure was first prepared with a steel plate thickness of 1.2 mm, a column height of 960 mm, and a column cross-sectional width and height of 290 mm (considering the 30 mm outer non-stressed decorative layer thickness). Then, longitudinal reinforcement was added at a ratio of 1.8%, and concrete was poured on-site to obtain the precast formwork column component for the test. As a control, a conventional reinforced concrete column was prepared using a detachable formwork, with reinforcement tied, concrete poured, and the formwork removed to obtain a control reinforced concrete column component of the same specifications, with a column cross-sectional height and width of 320 mm. The applicant commissioned Chongqing University to conduct relevant stress tests on the above-mentioned precast formwork column component and the control conventional reinforced concrete column component, obtaining the following test data.

[0080] 1. Axial compression test

[0081] Axial compression testing is an experiment to study the mechanical properties of vertically compressed members such as columns under axial pressure. Ideally, the axial pressure passes through the axis of the member, and the member only experiences axial pressure, without bending moment or shear force. Its basic principle is to apply gradually increasing axial pressure and observe and record the deformation, strain, and failure mode of the member during the compression process.

[0082] The test loading was performed using a 1000-ton long column compression testing machine manufactured by Changchun Testing Machine Research Institute. Strain data was collected using resistance strain gauges, and displacement was measured using resistance displacement gauges with a measurement accuracy of 0.001 mm. Load, strain, and displacement data were collected using a DH5922D dynamic strain acquisition system manufactured by Donghua Testing. Geometric alignment was used to ensure the load center passed through the centroid of the component. Before the formal test began, a pre-loading method was used to eliminate the gap between the testing machine's pressure plate and the component. Formal loading then commenced. Before reaching 70% of the calculated bearing capacity, a graded load control method was used, with each grade applying a load of 50 kN. After each grade was completed, the load was maintained for 5 minutes until strain and displacement stabilized before proceeding to the next grade. After reaching 70% of the calculated bearing capacity, a displacement recording control method was used, with each displacement increment being 0.01 mm. After load, displacement, and strain data stabilized, the next grade was applied. The component was considered to have failed when the load decreased to 85% of the ultimate load, and the test was stopped. Displacement, strain, and load data were monitored and recorded in real time throughout the entire loading process.

[0083] The results are shown in Table 1 below. Figure 8 The comparison shows the load-displacement curves of axially compressed components of traditional reinforced concrete columns and precast formwork columns of this invention.

[0084] Table 1. Axial compression tests of traditional reinforced concrete column members and precast formwork column members of this utility model.

[0085]

[0086] The test results show that after traditional reinforced concrete columns reach their ultimate bearing capacity, significant spalling of the concrete occurs, leading to a rapid decrease in bearing capacity and a rapid increase in displacement, exhibiting clear brittle failure. Conversely, for the precast formwork column members of this invention, after reaching their ultimate bearing capacity, the bearing capacity decreases slowly with increasing displacement, demonstrating very clear ductile failure. The tests show that, using the same design method, the axial compressive bearing capacity of the precast formwork column members is approximately 20% higher than that of traditional reinforced concrete columns. Under axial pressure, the precast formwork column members outperform traditional reinforced concrete columns in both bearing capacity and ductility.

[0087] 2. Column low-cycle reciprocating test

[0088] Low-cycle cyclic loading tests on columns are primarily used to study the mechanical properties of columns under repeated horizontal loads, such as earthquakes. During an earthquake, building columns are subjected to repeated tensile, compressive, and bending deformations. This low-cycle cyclic loading test can simulate the stress state of columns under seismic loading. The test yields the hysteresis curve of the column, which reflects important mechanical performance indicators such as energy dissipation capacity, strength, and stiffness.

[0089] The horizontal load on the column was applied using a JSF-Ⅱ high-precision static servo hydraulic control console manufactured by Chengdu Servo Hydraulic Equipment Co., Ltd. The vertical load was applied using a ZB4-500 electric oil pump manufactured by Liuzhou Ruike Machinery Co., Ltd., in conjunction with a QF-200T hydraulic jack manufactured by Dezhou Junda Hydraulic Equipment Co., Ltd., to apply the vertical load in one go. After the vertical load was applied, a small-tonnage horizontal load was used to check the alignment of the component. Once alignment was confirmed, horizontal displacement was applied according to a predetermined system using displacement control. The displacement loading system is shown in the figure below. During the test, a DH5922D dynamic strain acquisition system manufactured by Donghua Testing was used to monitor and record the vertical load, horizontal load, and horizontal displacement of the component in real time.

[0090] Mechanical data, including longitudinal steel bar yield strength, concrete cube compressive strength, and horizontal ultimate bearing capacity, were measured in low-cycle cyclic tests on the precast building formwork column of this invention and a conventional reinforced concrete column as a control. The results are shown in Table 2 below. Figure 9 The comparison shows the hysteresis curves of traditional reinforced concrete columns and the precast formwork column components of this utility model in low-cycle reciprocating tests.

[0091] Table 2 Low-cycle cycling tests of traditional reinforced concrete columns and precast formwork column components of this utility model.

[0092]

[0093] The results above show that, under the same axial pressure level, the ultimate horizontal thrust of the precast formwork column component of this invention is greater than that of the traditional reinforced concrete column, indicating that the precast formwork component has stronger shear bearing capacity. From the hysteresis curve morphology, the hysteresis curve of the precast formwork column component is fuller, indicating stronger energy dissipation capacity. This demonstrates that under seismic loading, the precast formwork component of this invention has superior energy dissipation capacity and seismic performance.

[0094] In summary, under seismic loading, precast formwork components outperform traditional reinforced concrete components in both load-bearing capacity and energy dissipation capacity.

[0095] Example 4: Stress Test of Beam Members

[0096] According to Example 2, the precast beam formwork structure was first prepared with a steel plate thickness of 1.2 mm. The beam cross-section width and height were 160*380 mm. Three 25 mm diameter HRB400 steel bars were placed at the bottom of the beam, and two 12 mm diameter HRB400 steel bars were placed at the top. After the steel bars were placed inside the formwork, concrete was poured on site to obtain the precast formwork beam component for the test. As a control, the conventional reinforced concrete beam was prepared by tying the steel bars with a detachable formwork, pouring concrete, and then removing the formwork to obtain the same specifications. The beam cross-section size was 200*400 mm. Two 12 mm diameter HRB400 steel bars were placed at the top of the beam, and three 25 mm diameter HRB400 steel bars were placed at the bottom. The stirrups were two-legged stirrups with a diameter of 10 mm and a spacing of 150 mm. The applicant commissioned Chongqing University to conduct relevant stress tests on the above precast formwork beam components and obtained the following test data.

[0097] 1. Beam bending test

[0098] In building structures, beams are the primary bending members. Bending beam member tests aim to study the mechanical properties of beams under bending loads, including bending capacity, deformation characteristics, crack propagation patterns, and failure modes.

[0099] The test loading employed a ZB4-500 electric oil pump manufactured by Liuzhou Ruike Machinery Co., Ltd., in conjunction with a QF-200T hydraulic jack manufactured by Dezhou Junda Hydraulic Equipment Co., Ltd. The jack applied the vertical load onto a rigid beam, which in turn applied it to the test member. Strain measurement was performed using resistance strain gauges, and displacement measurement was performed using resistance displacement gauges. Strain data, displacement data, and load data were all dynamically acquired in real-time using a DH5922D dynamic strain acquisition system manufactured by Donghua Testing.

[0100] The test procedure is as follows: The test beam was correctly installed on the testing machine support. The beam's axis was checked for horizontality and the loading point was verified for accuracy. Preloading was then initiated to eliminate horizontal gaps, ensuring the load passed through the beam's center. After preloading, formal loading began. The test loading employed a segmented loading method. Before the load reached 70% of the estimated load, load-controlled loading was used, with each level loading 10 kN. After each loading, the load was held for 5 minutes until the displacement and strain data stabilized before proceeding to the next level. After the load reached 70% of the estimated load, displacement-controlled loading was used. Before reaching the ultimate load, each displacement level was increased by 0.01 mm. After reaching the ultimate displacement, each displacement level was increased by 0.05 mm until the load decreased to 85% of the ultimate load, at which point the test was stopped. Load, displacement, and strain data of the beam were recorded throughout the test.

[0101] The results are shown in Table 3 below. Figure 10The results of bending tests on traditional reinforced concrete beams and precast formwork beams of this invention are shown.

[0102] Table 3. Bending tests of traditional reinforced concrete beams and precast formwork beams.

[0103]

[0104] The test results show that the deflection corresponding to the ultimate load of the precast formwork beam is 22 mm, which is 1 / 140 of the span, while the deflection corresponding to the ultimate load of the traditional reinforced concrete beam is 16 mm, which is 1 / 180 of the span. After the precast formwork beam reaches its ultimate bearing capacity, it can still maintain a certain bearing capacity as the deflection continues to increase. When the mid-span deflection reaches 37 mm, which is 1 / 83 of the span, its bearing capacity is still 89% of the ultimate bearing capacity. It is evident that under bending moment, the ductility and bearing capacity of the precast formwork beam are superior to those of the traditional reinforced concrete beam.

[0105] 2. Torsional member test

[0106] The cross-section and reinforcement of the torsional specimen were the same as those of the bending member. The loading of the torsional member was performed using a JSF-Ⅱ high-precision static servo hydraulic control system manufactured by Chengdu Servo Hydraulic Equipment Co., Ltd. Strain measurement used resistance strain gauges, and displacement measurement used resistance displacement gauges. Strain data, displacement data, and load data were all dynamically acquired in real time using a DH5922D dynamic strain acquisition system manufactured by Donghua Testing. After the prefabricated template component of this invention was installed, a pre-loading was performed to eliminate installation gaps. Then, the load was zeroed, and formal loading began. Loading was divided into two stages. Before reaching 70% of the estimated torque, load-controlled loading was used, with each stage having a torque of 1 kN·m. After each stage, the load was held for 5 minutes until the displacement and strain data stabilized before proceeding to the next stage. After the load reached 70% of the estimated torque, displacement-controlled loading was used, with each stage having a torsional displacement angle of 0.05°. When the torque reached 85% of the ultimate torque, the component was considered to have failed, and the test was stopped. Load, displacement, and strain data of the beam component were recorded throughout the test.

[0107] The experimental results are shown in Table 4 below. Figure 11 The torque-rotation curve of the prefabricated template beam component of this utility model is shown.

[0108] Table 4 Torsional test results of precast formwork beams of this utility model

[0109]

[0110] The results show that when the component rotation angle is 1.5°, the component reaches its elastic limit, corresponding to a torque of approximately 25 kN·m. When the rotation angle reaches about 9°, the precast formwork component reaches its ultimate torque of 45.8 kN·m. According to the standard, the ultimate torsional bearing capacity of the component is 34.2 kN·m, and the experimentally obtained ultimate bearing capacity is about 30% higher than the calculated value. Even as the component rotation angle continues to increase, the ultimate torque remains almost unchanged. Even when the loading actuator reaches its maximum stroke and the displacement gauge reaches its maximum range, the component's bearing capacity does not show a significant decrease. Therefore, under torque, the ductility and bearing capacity of the precast formwork component are superior to those of traditional reinforced concrete torsional members.

[0111] In summary, the stress test results demonstrate that the precast templates of this invention can better constrain the cast-in-place concrete, especially by increasing the constrained area, thereby improving the overall shear strength and bearing capacity of the building. This is of great significance for earthquake resistance of buildings under seismic conditions.

[0112] The above descriptions are merely embodiments of this utility model. Commonly known structures and characteristics are not described in detail here. Those skilled in the art possess all the general technical knowledge of the field prior to the application date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Therefore, those skilled in the art can, based on the guidance provided in this application, improve and implement this solution in conjunction with their own capabilities. Typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of this utility model. These modifications and improvements should also be considered within the scope of protection of this utility model and will not affect the effectiveness of the implementation of this utility model or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A precast building formwork suitable for cast-in-place construction of columns or beams, comprising a cylindrical formwork shell and stirrups fixed on the formwork shell, wherein the upper and lower ends of the formwork shell are provided with connecting parts that mate with adjacent formwork shells; characterized in that: The steel plate (1) is fixedly connected by multiple steel plates which are divided along the longitudinal direction of the enclosed center.

2. The precast architectural formwork of claim 1, wherein, The fixed connection is formed by spot welding.

3. The precast architectural formwork of claim 2, wherein, The outer side of the steel plate (1) is further provided with a reinforcing layer (3), which is a magnesium phosphate-based material layer fixedly connected to the outer side of the steel plate (1).

4. The precast architectural formwork according to any one of claims 1-3, wherein, The opposite outer sides of the steel plate (1) are respectively recessed inward to form grooves (5), and a protruding portion (6) corresponding to the groove (5) is formed in the hollow region enclosed by the steel plate (1), the two ends of the rod-shaped member (2) respectively pass through the protruding portion (6) and protrude into the groove (5), and the connecting fixing member is located in the corresponding groove (5) and is attached thereto; the connecting fixing member and the end of the rod-shaped member (2) are located in the groove (5) and do not protrude from the outer side of the steel plate (1).

5. The precast architectural formwork of claim 1, wherein, The rod-shaped member (2) has a upset anchor head (7) at one end and an outer thread for connecting a nut (9) at the other end, and the upset anchor head (7) and the nut (9) are respectively formed as the connecting fixing member at the two ends of the rod-shaped member (2).

6. The precast architectural formwork of claim 5, wherein, The rod-shaped member (2) has an outer thread for connecting a nut (9) at both ends, which are respectively formed as the connecting fixing member at the two ends of the rod-shaped member (2).

7. The precast architectural formwork of claim 5, wherein, The anchor head includes an anchor head body (8) with a diameter greater than that of the rod-shaped member, which protrudes outward to form a ring-shaped attachment portion (10) that can be attached to the groove (5); or the anchor head body (8) is attached to the groove (5) through a gasket (11) provided on the rod-shaped member (2), and the diameter of the gasket (11) is greater than that of the anchor head body (8).

8. The precast architectural formwork of claim 6, wherein, The angle between the side wall and the bottom of the groove (5) is 30-60°; the diameter of the protruding portion (6) is 2-5 times the diameter of the rod-shaped member (2).

9. The precast architectural formwork of claim 5, wherein, The connecting fitting portion of one end of the formwork can be tightly attached to the corresponding connecting fitting portion of the adjacent formwork, so that the two formworks can be spliced and their outer sides are flush with each other.

10. The precast architectural formwork of claim 1, wherein, The connecting fitting portion is in the form of a clamping groove or a plug-in fitting.

11. The precast architectural formwork of claim 10, wherein, The rod-shaped member (2) is provided in multiple layers along the longitudinal direction of the enclosed center of the steel plate (1), the rod-shaped members (2) in the same layer are coplanar and parallel, and the rod-shaped members (2) in adjacent layers are vertically crossed or crossed in parallel at different positions.

12. The precast architectural formwork of any one of claims 1-3 or 5-11, wherein, The steel plate (1) is made of a seamless steel pipe or is formed by folding a steel plate laterally.

13. The precast architectural formwork of any one of claims 1-3 or 5-11, wherein, ​

Images