A prestressed composite prefabricated staircase

Abstract

The utility model discloses a prestressed composite prefabricated staircase, comprising a cast-in-place staircase and a prefabricated base plate, wherein the upper surface of the prefabricated base plate is fitted with the bottom surface of the cast-in-place staircase, prestressed steel bars are arranged in the prefabricated base plate, and the two ends of the prestressed steel bars extend from two opposite width surfaces of the prefabricated base plate respectively, a steel mesh is arranged in the cast-in-place staircase, and the two ends of the prestressed steel bars extend into rectangular steel cages at the two ends of the steel mesh; the prefabricated base plate is made of prestressed steel bars and transverse steel bars cast in concrete after tensioning, and the cast-in-place staircase is built into an integrated structure with the prefabricated base plate by casting concrete; the utility model arranges prestressed steel bars in the prefabricated base plate of the prefabricated staircase, and when in use, the use load of the staircase first offsets the existing prestress in the concrete, and then as the load increases, the concrete is pulled and cracks appear, thereby improving the strength of the prefabricated staircase and reducing the generation of transverse cracks.

Description

Technical Field

[0001] The utility model belongs to the technical field of prefabricated stairs, and in particular relates to a prestressed composite prefabricated staircase. Background Art

[0002] The statements herein merely provide background art related to the present invention and do not necessarily constitute prior art.

[0003] With the development of society, prefabricated buildings are becoming more and more widely used in the construction field. As an important part of prefabricated buildings, prefabricated concrete stairs are also becoming more and more widely promoted and applied in prefabricated buildings. Compared with the traditional cast-in-place staircase production method, prefabricated stairs have significant advantages.

[0004] At present, precast concrete stairs are prefabricated as a whole in a component factory, and then transported to the construction site for hoisting and installation. The manufacturing process of precast concrete stairs is: first, steel bars are laid in the template, then concrete is poured into the template, and finally the precast concrete stairs are cured. During the manufacturing process, more steel bars are usually laid in the template to ensure the strength of the stairs, but this leads to more steel bar consumables and increased costs. Prestressed precast stairs are proposed in the prior art, such as Chinese invention patent CN108360766A, which discloses a prefabricated prestressed plate-type staircase, in which the staircase plate adopts a double T plate, and two ribs are arranged under the plate surface of the double T plate, and the lower part of the rib is provided with prestressed steel bars. Although this method reduces the deadweight of the stairs to a certain extent, since there is usually a large tensile stress at the bottom of the staircase plate, the bottom of the stairs will crack and produce transverse cracks, and although prestressed steel bars are set, since the prestressed steel bars are set in the ribs under the staircase plate surface, there are problems such as difficulty in implementing prestressed tensioning, poor control of prestress loss, and high tensioning cost.

[0005] Therefore, the inventors found that in the actual application of prefabricated stairs, the bottom of the prefabricated stairs often cracks and produces transverse cracks. Some split stairs have the problem of loose connections, which increases the potential risks. Although prestressed steel bars are provided in the existing prestressed stairs, there is prestress loss. Due to the structure of the stairs, there are problems such as difficulty in implementing prestressing tensioning and high tensioning costs. Utility Model Content

[0006] The purpose of the utility model is to provide a prestressed composite prefabricated staircase, which improves the strength of the prefabricated staircase and reduces the generation of transverse cracks. At the same time, the staircase structure is divided into two parts: a cast-in-place stair tread and a prefabricated bottom slab, which can reduce the cross-sectional thickness of the staircase and reduce the difficulty of production, and can realize mass production of prestress in prefabricated stairs.

[0007] In order to achieve the above purpose, the utility model is implemented through the following technical solutions:

[0008] In the first aspect, an embodiment of the utility model provides a prestressed composite prefabricated staircase, comprising a cast-in-place stair tread and a prefabricated base plate, the upper surface of the prefabricated base plate being in contact with the bottom surface of the cast-in-place stair tread, prestressed steel bars being arranged in the prefabricated base plate, and the two ends of the prestressed steel bars respectively extending from two opposite width surfaces of the prefabricated base plate, a steel mesh being arranged in the cast-in-place stair tread, and the two ends of the prestressed steel bars extending into the steel mesh; the prefabricated base plate is made of cast concrete with tensioned prestressed steel bars, and the cast-in-place stair tread is built into an integrated structure with the prefabricated base plate by pouring concrete.

[0009] As a further technical solution, the precast base plate is a rectangular concrete slab structure, and a plurality of prestressed steel bars are arranged in parallel in the width direction of the precast base plate, and a certain distance is separated between two adjacent prestressed steel bars.

[0010] As a further technical solution, the length of the prestressed steel bars is greater than the length of the prefabricated bottom plate, both ends of the prestressed steel bars extend out of the prefabricated bottom plate, and the prestressed steel bars extending out of one end are parallel to the prefabricated bottom plate, and the prestressed steel bars extending out of the other end are bent and set to form a certain angle with the prefabricated bottom plate, so as to realize the prestressed steel bars being arranged in a zigzag manner along the inclined section and two straight sections of the stairs.

[0011] As a further technical solution, a plurality of prestressed steel bars are connected by transverse steel bars, and the prestressed steel bars and the transverse steel bars are located at the lower part of the prefabricated bottom plate and the axis.

[0012] As a further technical solution, both ends of the cast-in-place stair tread are provided with mounting holes, wherein the upper end of the cast-in-place stair tread is mounted on the upper stair beam through the mounting holes, and the lower end of the cast-in-place stair tread is mounted on the lower stair beam through the mounting holes.

[0013] As a further technical solution, the steel mesh in the cast-in-place stair slab is a steel mesh woven with longitudinal steel bars and transverse steel bars, and rectangular steel cages are arranged at both ends of the steel mesh, which anchor the prefabricated base plate and the cast-in-place stair slab together.

[0014] As a further technical solution, the rectangular steel cages at both ends of the steel mesh are respectively located inside the two ends of the cast-in-place ladder slab.

[0015] As a further technical solution, the cast-in-place stair tread is provided with hanging holes, and the sides of the cast-in-place stair tread are provided with hanging ears.

[0016] As a further technical solution, the steel mesh is spaced a certain distance from the bottom surface of the cast-in-place stair slab.

[0017] As a further technical solution, the thickness of the prefabricated base plate is 3-15 cm.

[0018] The beneficial effects of the above-mentioned embodiments of the utility model are as follows:

[0019] The prestressed composite prefabricated stairs provided by the utility model are divided into two structures: a cast-in-place stair tread and a prefabricated bottom plate. The prefabricated bottom plate can be standardized and mass-produced through a prestressed long line platform. Compared with the single prestressing loss value, the prestressed steel bars are effectively controlled, and the prestressed steel bars are arranged in a zigzag shape along the inclined section and two straight sections of the stairs, so that the prestressed staircase process is technically realized and the production cost is reduced. The steel bars in the bottom plate of the prefabricated staircase and the cast-in-place stair tread are deeply inserted into the rectangular steel bar cages at both ends for reliable and effective anchoring, so that the two parts form a structure.

[0020] The prestressed composite prefabricated staircase provided by the utility model is divided into two structures: a cast-in-place stair tread and a prefabricated bottom plate. Prestressed steel bars are arranged in the prefabricated bottom plate, and a steel mesh is arranged in the cast-in-place stair tread. The prestressed steel bars are tensioned first and then concrete is poured to form the prefabricated bottom plate. When in use, the use load of the staircase first offsets the existing prestress in the concrete, and then as the load increases, the concrete is stretched and cracks appear, thereby improving the strength of the prefabricated staircase and reducing the generation of transverse cracks.

[0021] The prestressed composite prefabricated staircase provided by the utility model has prestressed steel bars arranged in the prefabricated bottom plate and ordinary steel bars arranged in the cast-in-place stair slab. Compared with ordinary steel bars, the prestressed steel bars have a smaller diameter and higher strength. Compared with the existing method of casting entirely with ordinary steel mesh, the use of steel can be reduced.

[0022] The prestressed composite prefabricated staircase provided by the utility model first casts the prefabricated base plate and then casts the cast-in-place stair tread. When casting the cast-in-place stair tread, the two ends of the prestressed steel bars in the prefabricated base plate can extend into the interior of the two ends of the steel mesh, and the cast-in-place stair tread and the prefabricated base plate can be directly cast into an integrated structure. Therefore, no other connecting parts are required to connect the prefabricated base plate and the cast-in-place stair tread, thereby improving the stability of the connection between the prefabricated base plate and the cast-in-place stair tread.

[0023] The prestressed composite prefabricated staircase provided by the utility model has a simple structure and is easy to produce. It can truly give play to the prestressing effect of the prestressed steel bars, convert the prestress of the steel bars into the crack resistance, strength and shear resistance of the prefabricated staircase, improve the performance of the prefabricated staircase, and reduce the occurrence of cracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0025] Figure 1 It is a front view of the prestressed composite prefabricated staircase of the utility model;

[0026] Figure 2 It is the reinforcement diagram inside the prestressed composite prefabricated staircase of the utility model;

[0027] Figure 3 It is a schematic diagram of the disassembled prestressed composite prefabricated staircase of the utility model;

[0028] Figure 4 It is a top view of the prestressed composite prefabricated staircase of the utility model;

[0029] Figure 5 It is a top view of the prefabricated bottom plate of the utility model;

[0030] Figure 6 It is a front view of the prefabricated base plate of the utility model;

[0031] Figure 7 It is a reinforcement diagram inside the prefabricated bottom plate of the utility model;

[0032] Figure 8 yes Figure 1 Sectional view at AA in the middle;

[0033] Fig. 9 yes Figure 2 Cross-section at the middle BB;

[0034] Fig.10 yes Figure 2 Cross-section view at CC.

[0035] The schematic diagram is for illustrative purposes only;

[0036] Among them, 1. cast-in-place stair slab; 101. steel mesh; 1011. longitudinal steel bar; 1012. first transverse steel bar; 1013. lower end steel cage; 1014. upper end steel cage; 102. groove; 103. mounting hole; 104. lifting ear; 105. lifting hole; 2. prefabricated bottom plate; 201. prestressed steel bar; 202. second transverse steel bar. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] Example 1

[0039] In a typical implementation of the present invention, Figure 1-3As shown, a prestressed composite prefabricated staircase is provided, comprising a cast-in-place stair tread 1 and a prefabricated base plate 2, the upper surface of the prefabricated base plate 2 being fitted with the bottom surface of the cast-in-place stair tread 1, prestressed steel bars 201 being arranged in the prefabricated base plate 2, and the two ends of the prestressed steel bars 201 respectively extending from two opposite width surfaces of the prefabricated base plate 2, a steel mesh 101 being arranged in the cast-in-place stair tread 1, and the two ends of the prestressed steel bars 201 extending into the lower steel cage 1013 and the upper steel cage 1014 at the two ends of the steel mesh 101; the prefabricated base plate 2 is made of poured concrete by tensioning the prestressed steel bars 201 and the second transverse steel bars 202, and the cast-in-place stair tread 1 is built into an integrated structure with the prefabricated base plate 2 by pouring concrete.

[0040] In this embodiment, the cast-in-place stair tread 1 serves as the main structure of the prefabricated staircase, and steps are arranged on the upper surface of the cast-in-place stair tread. During the casting, the bottom surface of the cast-in-place stair tread forms a groove 102 due to the placement of the prefabricated bottom plate 2, thereby achieving the cast-in-place stair tread wrapping the prefabricated bottom plate on three sides.

[0041] like Figure 5 As shown, the prefabricated bottom plate 2 is a rectangular concrete plate structure, and a plurality of prestressed steel bars 201 are arranged in parallel in the width direction of the prefabricated bottom plate 2, and a certain distance is separated between two adjacent prestressed steel bars. In a specific implementation of this embodiment, the distance between two adjacent prestressed steel bars can be 5-15 cm, which can ensure high strength and reduce the use of steel bars to a certain extent.

[0042] like Figure 6 As shown, both ends of the prestressed steel bar 201 extend from both ends of the precast bottom plate 2 in the length direction, and the prestressed steel bar extending from one end is parallel to the precast bottom plate 2 (the left end in the figure), and the prestressed steel bar extending from the other end is bent and arranged to form a certain angle with the precast bottom plate (the right end in the figure), wherein the end of the prestressed steel bar parallel to the precast bottom plate 2 extends into the upper end steel cage 1014 of the steel mesh 101, and the end of the prestressed steel bar at a certain angle to the precast bottom plate extends into the lower end steel cage 101 of the deep steel mesh 101, thereby realizing the prestressed steel bars arranged in a broken line along the inclined section and two straight sections of the stairs, which can be referred to Figure 2 In this way, when pouring the cast-in-place stair slab concrete, the precast base plate and the cast-in-place stair slab can be cast into an integrated structure, and a stable connection between the precast base plate and the cast-in-place stair slab can be achieved without the need for other components to connect.

[0043] like Figure 7As shown, in order to further improve the strength of the precast base plate 2, multiple prestressed steel bars 201 in the precast base plate 2 are connected by a second transverse steel bar 202. The prestressed steel bars 201 and the second transverse steel bars 202 are located below the neutral axis of the precast base plate 2, wherein the second transverse steel bars are ordinary steel bars. The prestressed steel bars 201 are first tensioned and then concrete is poured to form the precast base plate. When the strength reaches the required level, the prestressed steel bars are released to allow the steel bars to shrink. In this way, when in use, the use load of the stairs first offsets the existing prestress in the concrete, and then as the load increases, the concrete is tensioned and cracks appear, thereby improving the strength of the precast stairs and reducing the occurrence of transverse cracks.

[0044] like Figure 4 As shown, mounting holes 103 are provided at both ends of the cast-in-place stair tread 1, wherein the upper end of the cast-in-place stair tread 1 is installed on the upper stair beam through the mounting holes, and the lower end of the cast-in-place stair tread 1 is installed on the lower stair beam through the mounting holes 103, so as to realize the installation of the stairs. Hanging holes 105 are provided on the cast-in-place stair tread 1, and lifting ears 104 are provided on the sides of the cast-in-place stair tread 1. The lifting ears 104 are provided to facilitate the lifting of the cast prestressed composite prefabricated stairs from the mold, and the stairs are lifted and placed on the upper stair beam and the lower stair beam through the lifting holes 105, so as to facilitate the installation of the stairs.

[0045] Combination Figure 1-3 as well as Figure 8-10 As shown, the steel mesh 101 is a steel mesh woven by longitudinal steel bars 1011 and transverse steel bars. Rectangular steel cages are arranged at both ends of the steel mesh 101, namely, a lower end steel cage 1013 and an upper end steel cage 1014. The rectangular steel cages at both ends of the steel mesh are respectively located at both ends of the cast-in-place ladder plate to pour concrete to form the two ends of the cast-in-place ladder plate. The steel bars in the steel mesh 101 are ordinary steel bars. The ordinary steel bars here refer to steel bars without prestress. Prestressed steel bars are high-strength steel bars that have been stretched. Pre-designed prestress is applied during the stretching process to make them have higher strength and toughness. Ordinary steel bars are not treated in this way, and their strength and toughness are relatively low.

[0046] In this embodiment, the steel mesh 101 is spaced a certain distance from the bottom surface of the cast-in-place ladder slab 1. Therefore, when placing the steel mesh 101 on the prefabricated bottom slab 2, reference can be made to Fig.10 , bend the two ends of the first transverse steel bar 1012 downward so that the two ends of the first transverse steel bar 1012 are supported on the upper surface of the prefabricated bottom plate 2. Similarly, bend the two ends of the second transverse steel bar 202 upward so that the two ends of the first transverse steel bar 1012 and the two ends of the second transverse steel bar 202 are butt-jointed at the upper surface of the prefabricated bottom plate.

[0047] In this embodiment, the thickness of the prefabricated base plate 2 is 3-15 cm. If the thickness of the prefabricated base plate is too thin, it will cause the base plate to arch too much, and if it is too thick, it will be difficult to hoist it into the stair mold. By limiting the thickness of the prefabricated base plate to this range, the prefabricated base plate can both play a prestressed role and be easy to hoist.

[0048] The processing method of the prestressed composite prefabricated staircase provided in this embodiment is as follows:

[0049] Step 1: tensioning prestressed steel bars and pouring concrete to form a prefabricated base plate;

[0050] Step 2: Place the prefabricated base plate with prestressed steel bars in the stair mold, and place a steel mesh on the prefabricated base plate; make the prestressed steel bars exposed at both ends of the prefabricated base plate extend into the rectangular steel cages at both ends of the steel mesh;

[0051] Step 3: Pour concrete to form a cast-in-place staircase. Connect the bottom plate and the staircase together through the rectangular steel cages at both ends of the steel mesh. After pouring the concrete, anchor the two parts securely so that the cast-in-place staircase and the prefabricated bottom plate are cast into an integrated structure.

[0052] Step 4: After curing the stairs for a period of time, demoulding is performed to obtain a prestressed composite prefabricated staircase.

[0053] The prestressed composite prefabricated staircase provided in this embodiment is divided into two structures: a cast-in-place stair tread and a prefabricated base plate. Prestressed steel bars are arranged in the prefabricated base plate, and a steel mesh is arranged in the cast-in-place stair tread. The prestressed steel bars are first tensioned and then concrete is poured to form the prefabricated base plate. When in use, the use load of the staircase first offsets the existing prestress in the concrete, and then as the load increases, the concrete is stretched and cracks appear, thereby improving the strength of the prefabricated staircase and reducing the occurrence of transverse cracks.

[0054] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A prestressed composite prefabricated staircase, characterized in that: It includes a cast-in-place stair slab and a precast base plate, the upper surface of the precast base plate is in contact with the bottom surface of the cast-in-place stair slab, prestressed steel bars are arranged in the precast base plate, and the two ends of the prestressed steel bars extend from two opposite width surfaces of the precast base plate respectively, and a steel mesh is arranged in the cast-in-place stair slab, and the two ends of the prestressed steel bars extend into the steel mesh; the precast base plate is made of cast concrete with tensioned prestressed steel bars, and the cast-in-place stair slab is built into an integrated structure with the precast base plate by pouring concrete.

2. The prestressed composite prefabricated staircase according to claim 1, characterized in that: The prefabricated bottom plate is a rectangular concrete plate structure. A plurality of prestressed steel bars are arranged in parallel in the width direction of the prefabricated bottom plate, and a certain distance is spaced between two adjacent prestressed steel bars.

3. The prestressed composite prefabricated staircase according to claim 2, characterized in that: The length of the prestressed steel bars is greater than the length of the prefabricated bottom plate, both ends of the prestressed steel bars extend out of the prefabricated bottom plate, and the prestressed steel bars extending out of one end are parallel to the prefabricated bottom plate, and the prestressed steel bars extending out of the other end are bent and arranged at a certain angle to the prefabricated bottom plate, so as to realize the prestressed steel bars being arranged in a zigzag manner along the inclined section and two straight sections of the stairs.

4. The prestressed composite prefabricated staircase according to claim 2, characterized in that: A plurality of prestressed steel bars are connected by transverse steel bars, and the prestressed steel bars and the transverse steel bars are located at the lower part of the precast bottom plate and the axis.

5. The prestressed composite prefabricated staircase according to claim 1, characterized in that: Both ends of the cast-in-place stair tread are provided with mounting holes, wherein the upper end of the cast-in-place stair tread is mounted on the upper stair beam through the mounting holes, and the lower end of the cast-in-place stair tread is mounted on the lower stair beam through the mounting holes.

6. The prestressed composite prefabricated staircase according to claim 1, characterized in that: The steel mesh in the cast-in-place stair slab is a steel mesh woven from longitudinal steel bars and transverse steel bars. Rectangular steel cages are provided at both ends of the steel mesh, and the rectangular steel cages anchor the prefabricated bottom plate and the cast-in-place stair slab together.

7. The prestressed composite prefabricated staircase according to claim 6, characterized in that: The rectangular steel cages at both ends of the steel mesh are located inside the two ends of the cast-in-place ladder slab respectively.

8. The prestressed composite prefabricated staircase according to claim 1, characterized in that: The cast-in-place ladder plate is provided with hanging holes, and the sides of the cast-in-place ladder plate are provided with hanging ears.

9. The prestressed composite prefabricated staircase according to claim 1, characterized in that: The steel mesh is spaced a certain distance from the bottom surface of the cast-in-place ladder slab.

10. The prestressed composite prefabricated staircase according to claim 1, characterized in that: The thickness of the prefabricated bottom plate is 3-15 cm.

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