Prestressed large-span laminated slab with prefabricated ECC bottom plate and post-poured GRC laminated layer and construction method of prestressed large-span laminated slab with prefabricated ECC bottom plate and post-poured GRC laminated layer

Abstract

The invention discloses a prestressed large-span laminated slab with a prefabricated ECC bottom plate and a post-poured GRC laminated layer and a construction method of the prestressed large-span laminated slab. A prestressed large-span laminated slab with a prefabricated ECC bottom plate and a post-poured GRC laminated layer comprises a bottom plate and a post-poured layer, and the bottom plate is formed by integrally pouring an ECC material and a bottom plate stranded wire net composed of transverse stranded wires and longitudinal stranded wires; rectangular ribs are integrally arranged on the bottom plate and are formed by integrally pouring truss steel bars and the bottom plate; the truss steel bars and the bottom plate stranded wire net are bound through binding wires. Good crack control and dispersion capacity and higher toughness and ductility of the ECC-high-strength stainless steel stranded wires / SMA stranded wires are utilized, so that the bottom plate can be thinner, the self weight is reduced, the concrete dosage is reduced, and the span of the prefabricated laminated plate is increased; the rectangular ribs of the truss steel bar structure improve the rigidity, the shear capacity, the bearing capacity and the bending resistance of the bottom plate, so that the laminated plate can meet the requirements of a large-span structure and a high load.

Description

Technical Field

[0001] The invention relates to a prefabricated composite slab structure and a construction method, and in particular to a prefabricated composite slab of ECC-high-strength stainless steel stranded wire / SMA stranded wire with rectangular rib-truss steel bars and post-cast recycled concrete and a construction method. Background Art

[0002] Prefabricated composite panels have always been widely used in construction projects as an important building structural component due to their efficient construction methods, good mechanical properties and economy. Traditional prefabricated composite panels mostly use ordinary steel bars and conventional concrete structures. Although they can meet the bearing requirements of general buildings, in large-span, high-load structural applications, ordinary reinforced concrete has limited bearing capacity, crack resistance and durability, and it is difficult to cope with long-term loads and harsh environments. In addition, with the shortage of resources and the increase in environmental protection needs, the sustainability and recycling of building materials have also received more and more attention.

[0003] In recent years, in order to improve the performance of prefabricated composite panels, the use of new high-strength materials and structural forms has become a research hotspot. For example, engineered cementitious composites (ECC) have gradually been used in high-performance prefabricated components due to their excellent crack resistance, tensile strength and durability. At the same time, the application of stainless steel strands and shape memory alloy (SMA) strands provides a new technical path for improving the durability, corrosion resistance and seismic performance of components. The introduction of these high-performance materials, combined with the green and environmentally friendly characteristics of post-cast recycled concrete, provides a new solution for the performance optimization of prefabricated composite panels. However, the current common prefabricated composite panel design still has many limitations, such as heavy plate weight, insufficient overall stiffness, limited bending and shear resistance, and cracks and excessive deformation are prone to occur under large span and high load conditions. In addition, the traditional steel bar arrangement form is difficult to give full play to the mechanical properties of the material in some cases, resulting in uneven structural force and material waste.

[0004] In current prefabricated composite panels, problems often occur at the joints of the composite panels. The joints between prefabricated composite panels and prefabricated composite beams are easy to handle, but the joints between prefabricated composite panels are prone to problems, such as early cracking and leakage of post-casting strips. Therefore, in current actual projects, large-span prefabricated composite panels should be used first; and in actual projects, some projects actually have actual needs for large spaces, so large-span composite panels are needed. In order to achieve the design goal of large spans, the use of prefabricated prestressed composite panels has great advantages.

[0005] The utility model patent with announcement number CN215164532U discloses a corrosion-resistant close-jointed bridge composite plate based on UHPC, including a prefabricated bottom plate and a cast-in-place concrete layer. The prefabricated bottom plate is cast by UHPC ultra-high performance concrete and a reinforcement grid. The bottom surface of the prefabricated bottom plate is sprayed with a cement-based composite material layer for ECC engineering; the top surface of the prefabricated bottom plate is a sandblasted rough surface or a concave-convex surface. A plurality of close-jointed grooves are respectively provided at both longitudinal ends of the prefabricated bottom plate, and L-shaped steel bars are respectively provided in the close-jointed grooves in the middle. The bottom end of the L-shaped steel bar is connected to the L-shaped steel bar on the butt-jointed prefabricated bottom plate by grouting through a grouting sleeve. This utility model can not only improve the corrosion resistance and bending resistance of the bridge composite plate, but also improve the crack resistance of the composite plate, improve the safety and reliability of the bridge, reduce the future maintenance cost of the bridge, and has the characteristics of fast connection speed and high connection accuracy between plates.

[0006] Although the above-mentioned document proposes the use of close-fitting grooves for reinforcement, they are only arranged at the two longitudinal ends of the prefabricated base plate. The design purpose is to cooperate with the L-shaped steel bars used in the design to achieve the connection between the two prefabricated plates. This has no special contribution and significance to the prefabricated composite slab itself, and it is difficult to meet the requirements of the large-span prefabricated composite slab base plate for stiffness, flexural deformation and construction load.

[0007] Therefore, it is necessary to design a prefabricated composite panel that can not only effectively enhance the overall stiffness and bending and shear resistance of the panel, but also improve the crack resistance, durability and self-healing ability of the structure through the use of high-performance materials, while meeting the application requirements of large-span and high-load structures, and taking into account resource recycling and environmental protection.

[0008] This will provide new ideas and technical support for the design and application of prefabricated building components. Summary of the invention

[0009] In view of the shortcomings of the prior art, the present invention proposes a prefabricated composite slab structure with ECC-high-strength stainless steel strands / SMA strands and post-cast recycled concrete with rectangular rib truss steel bars, which can effectively reduce the flexural deformation of the bottom plate of the prefabricated composite slab, effectively increase the stiffness of the prefabricated composite slab floor, and meet the requirements of flexural deformation and construction load of large-span prefabricated composite slabs.

[0010] The invention also proposes a construction method for the prefabricated composite slab.

[0011] The technical solution adopted by the present invention is: A prefabricated composite slab of ECC-high-strength stainless steel strand / SMA strand and post-cast recycled concrete with rectangular rib-truss steel bar, comprising a bottom plate and a post-cast layer, wherein the bottom plate comprises a bottom plate transverse strand, a bottom plate longitudinal strand, rectangular ribs, truss steel bar and ECC made of high-strength stainless steel strand / SMA strand, and the post-cast layer is recycled concrete; The transverse strands and longitudinal strands of the bottom plate are fixed to the bottom plate formwork by aluminum buckles and slipknot bolts to form a stranded wire mesh; the bottom plate stranded wire mesh is made of high-strength stainless steel strands or SMA strands are used to partially replace high-strength stainless steel strands, and the number of replacements should be adjusted according to specific design requirements.

[0012] The rectangular ribs are arranged at the truss steel bars on the bottom plate; the truss steel bars and the bottom stranded wire mesh are bound together by binding wires.

[0013] The one-way slab is provided with truss steel bars and rectangular ribs in the longitudinal direction, and the two-way slab is provided with truss steel bars and rectangular ribs in both the transverse and longitudinal directions; the width of the rectangular ribs is 100 to 250 mm, the height of the rectangular ribs is 40 mm, and the truss steel bars are 10 to 20 mm higher than the rectangular ribs.

[0014] The diameter of the high-strength stainless steel stranded wire and the SMA stranded wire is not less than 3.6 mm and not more than 6 mm. The diameter of the transverse stranded wire of the one-way plate bottom plate is smaller than the diameter of the longitudinal stranded wire of the bottom plate. The diameter of the transverse stranded wire of the two-way plate bottom plate is the same as the longitudinal stranded wire of the bottom plate.

[0015] The base plate template includes a steel plate, a limiting angle steel and a fixed angle steel. The limiting angle steel and the fixed angle steel are fixed to the steel plate with bolts. The limiting angle steel is provided with a limiting hole, and the fixed angle steel is provided with a fixing slot. The fixed angle steel is arranged along the periphery of the limiting angle steel and a spacing of not less than 80 mm is left between the two.

[0016] A construction method of a prefabricated composite slab of ECC-high-strength stainless steel stranded wire / SMA stranded wire with rectangular rib-truss steel bars and post-cast recycled concrete, comprising the following steps: S1: Fix the limit angle steel and the fixed angle steel on the steel plate according to the design dimensions, pass the stranded wire ends through the limit holes of the limit angle steel, and fix the stranded wire ends to the fixed slots on the fixed angle steel with aluminum buckles and slipknot bolts. In this way, alternately fix the bottom plate transverse stranded wires and bottom plate longitudinal stranded wires on the bottom plate formwork, and finally tie the truss steel bars and the bottom plate stranded wire mesh with wire ties; S2: Place concrete protective layer pads at the bottom of the bottom plate stranded wire mesh. After confirmation, pour the prepared ECC to the height of the bottom plate. Fill the remaining positions of the rectangular ribs on the bottom plate with long wooden strips. Finally, pour the prepared ECC to the height of the rectangular ribs in the vacant positions of the long wooden strips. S3: After the initial setting of the ECC surface, the surface of the specimen is artificially roughened using a wooden sawtooth brush to meet the rough surface requirements in the design specifications.

[0017] S4: Use the prefabricated bottom plate as the bottom formwork, and place side formwork around it as the formwork for pouring the post-casting layer of concrete. Then tie and fix the structural steel mesh in the post-casting layer, and pour the prepared recycled concrete on the bottom plate.

[0018] Beneficial effects of the invention: 1. The prefabricated composite slab of the present invention uses a combination of truss steel bars and ribbed strips on the bottom plate, which can effectively improve the bending resistance and cross-sectional stiffness of the prefabricated composite slab floor. The truss steel bars provide structural stiffness and shear resistance, while the rib beams enhance the bearing capacity and bending resistance, so that the slab can cope with large-span structures and higher load requirements; at the same time, the use of recycled concrete is in line with the concept of green environmental protection. The use of truss steel bars for construction is more convenient and reasonable.

[0019] 2. The prefabricated composite slab of the present invention uses a combination of ECC and SMA strands / steel strands for the bottom plate, and uses SMA strands / reinforcement materials for prestressing. The two as a combination of materials can significantly improve its crack control ability and crack dispersion ability. The deflection of the prefabricated composite slab during the construction stage can be effectively reduced. When used in combination with SMA strand prestressing (SMA strands can be used to replace part of the high-strength stainless steel strands according to different working conditions), the deflection of the prefabricated composite slab during the construction stage can be effectively reduced, and it is particularly suitable for use as a floor slab of a large-span prefabricated composite slab.

[0020] After the construction is completed, the SMA (shape memory alloy) strands can be heated by alternating current to generate prestress in the SMA strands, thereby applying prestress to the prefabricated composite slab bottom plate, which can improve the crack resistance of the prefabricated composite slab floor and to a certain extent cause the prefabricated composite slab bottom plate to produce a "back-supply effect", which can significantly reduce the flexural deformation of the prefabricated composite slab bottom plate and meet the flexural deformation requirements of the large-span composite slab after construction.

[0021] 3. The present invention adopts rectangular ribs (beams) running through the upper part of the entire prefabricated composite slab bottom plate, and is used in combination with truss steel bars, which can effectively increase the stiffness and performance of the prefabricated composite slab bottom plate, improve the stiffness of the prefabricated composite slab floor, and can well meet the requirements of deflection and construction load of large-span prefabricated composite slabs.

[0022] When the span of the precast composite slab is large or the thickness of the precast composite slab bottom plate is small, the stiffness of the precast composite slab bottom plate is relatively small, which will cause the deflection of the precast composite slab bottom plate to be too large during hoisting construction, or fail to meet the requirements of construction loads such as upper concrete pouring or construction machinery. Therefore, it is necessary to design rectangular ribs (beams) according to the design calculation to meet the requirements of the large-span precast composite slab bottom plate for stiffness, deflection and construction load.

[0023] 4. The present invention utilizes the good crack control and dispersion capabilities, high toughness and ductility of the ECC-high-strength stainless steel stranded wire / SMA stranded wire high-performance composite material, so that the base plate can be made thinner than the traditional base plate, reducing the dead weight and the amount of concrete, increasing the span of the prefabricated composite plate, and effectively achieving the design goal of a large span of the prefabricated composite plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure shows a three-dimensional structure schematic diagram of the prefabricated composite panel of the present invention; Figure 2 The figure shows a three-dimensional structure schematic diagram of the bottom plate of the one-way plate of the present invention; Figure 3 The figure shows a three-dimensional structure schematic diagram of the bottom plate of the two-way plate of the present invention; Figure 4 The figure shows a three-dimensional structure diagram of the truss steel bar of the present invention; Figure 5 The figure shows a three-dimensional structure diagram of the base plate template of the present invention; Figure 6 Shown is a top view schematic diagram of the stranded wire fixing method of the present invention.

[0025] In the figure: 1. bottom plate; 101. bottom plate transverse strand; 1011. bottom plate transverse steel strand; 1012. bottom plate transverse SMA strand; 102. bottom plate longitudinal strand; 1021. bottom plate longitudinal steel strand; 1022. bottom plate longitudinal SMA strand; 103. rectangular rib; 104. truss reinforcement; 105. ECC; 2. post-cast slab; 3. bottom plate formwork; 301. steel plate; 302. limiting angle steel; 303. limiting hole; 304. fixing angle steel; 305. fixing slot; 401. slipknot screw; 402. nut; 403. aluminum buckle. DETAILED DESCRIPTION

[0026] In order to make the technical concept and advantages of the present invention more clearly understood, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the following embodiments are only used to explain and illustrate the preferred implementation methods of the present invention, and should not be regarded as and do not constitute a limitation on the scope of patent protection claimed by the present invention. Example 1

[0027] See also Figure 1 , Figure 2 The prestressed large-span composite slab of the prefabricated ECC bottom slab-post-cast GRC superimposed layer of the present invention comprises a bottom slab 1 and a post-cast layer 2, wherein the bottom slab 1 is integrally cast with an ECC material and a bottom slab stranded wire mesh, wherein the bottom slab stranded wire mesh is formed by fixing transverse stranded wires and longitudinal stranded wires on a bottom slab formwork through aluminum buckles and slipknot bolts; The bottom plate 1 is provided with a rectangular rib 103, which is integrally cast by the truss steel bar 104 and the bottom plate; Figure 4 As shown, the truss reinforcement 104 and the bottom plate stranded wire mesh are tied together by tying wire; The post-cast layer 2 is located above the base plate 1 and is cast using concrete or recycled concrete.

[0028] The bottom plate stranded wire mesh is made of high-strength stainless steel stranded wire.

[0029] There is no research report on the combination of truss steel bars and rectangular ribs. The use of truss steel bars can improve the overall performance and stress performance of prefabricated composite slabs, that is, the prefabricated composite slabs and the upper post-cast concrete form a whole and bear the stress together; and the use of rectangular rib-truss steel bars, in addition to the above advantages, can also increase the stiffness of the prefabricated composite slabs, achieve the design goal of large spans and reduce deflection, and can further improve the stiffness and overall performance of the prefabricated composite slabs after construction is completed.

[0030] The prestressed large-span composite slab of the prefabricated ECC bottom slab-post-cast GRC composite layer of the present invention can not only effectively enhance the overall rigidity and bending and shearing resistance of the slab, but also improve the crack resistance, durability and self-healing ability of the structure through the use of high-performance materials, meet the application requirements of large-span and high-load structures, and take into account resource recycling and environmental protection. Example 2

[0031] like Figure 3 As shown, the prestressed large-span composite slab of prefabricated ECC bottom slab-post-cast GRC composite layer of this embodiment is different from that of Embodiment 1 in that: the bottom slab stranded wire mesh adopts a combination of high-strength stainless steel stranded wire and SMA stranded wire at intervals.

[0032] The use of a combination of ECC and SMA strands / steel strands, and the use of SMA strands to replace some high-strength stainless steel strands, can increase the prestressed tensile strength of the base plate and significantly improve the crack control and crack dispersion capabilities of the composite slab.

[0033] The number of SMA strands used is adjusted according to specific design requirements.

[0034] The diameter of the high-strength stainless steel strand and the SMA strand is not less than 3.6 mm and not more than 6 mm. The diameter of the transverse strand of the bottom plate of the one-way plate is smaller than the diameter of the longitudinal strand of the bottom plate. The diameter of the transverse strand of the bottom plate of the two-way plate is the same as the longitudinal strand of the bottom plate. The one-way plate is arranged with truss steel bars and rectangular ribs in the longitudinal direction, and the two-way plate is arranged with truss steel bars and rectangular ribs in both the transverse and longitudinal directions.

[0035] SMA stranded wire is composed of shape memory alloy wires. The area design of SMA stranded wire adopts the method of equal area or equal strength to replace steel stranded wire. When equal area replacement, SMA stranded wire is preferably used with the same diameter as steel stranded wire, and the replacement area is not more than 50%. When strength is used to replace steel stranded wire, the diameter of SMA stranded wire should be larger than that of steel stranded wire to ensure the same number of replacements. Example 3

[0036] The prestressed large-span composite slab of the prefabricated ECC bottom plate-post-cast GRC composite layer of this embodiment is different from that of Embodiment 1 and Embodiment 2 in that: the width of the rectangular rib 103 is 100-250 mm, and the height of the rectangular rib is 40 mm; the number of rectangular ribs on the prefabricated composite slab is determined according to the invention, the number of rectangular ribs on the one-way slab should not be less than 3, and the spacing between the rectangular ribs is 400 mm-700 mm; the rectangular ribs in the main force direction of the two-way slab should be appropriately encrypted, the spacing between the rectangular ribs of the two-way slab should not be greater than 500 mm, and the number should not be less than 4, and the outermost rectangular ribs of the one-way slab and the two-way slab should not be greater than 200 mm from the edge of the composite slab.

[0037] The truss steel bars are 10 to 20 mm higher than the rectangular ribs.

[0038] like Figure 5 As shown, the base plate template 3 includes a steel plate, a limiting angle steel and a fixed angle steel. The limiting angle steel and the fixed angle steel are fixed to the steel plate with bolts. The limiting angle steel is provided with a limiting hole, and the fixed angle steel is provided with a fixing slot. The fixed angle steel is arranged along the periphery of the limiting angle steel and a spacing of not less than 80 mm is left between the two. Example 4

[0039] This embodiment is a construction method of the prestressed large-span composite slab as described above, and the process includes: Step S1: fix the limiting angle steel and the fixed angle steel on the steel plate according to the design size, pass the stranded wire end through the limiting hole of the limiting angle steel, and fix the stranded wire end to the fixed slot on the fixed angle steel with an aluminum buckle and a slipknot bolt. In this way, the transverse stranded wires and the longitudinal stranded wires of the bottom plate are alternately fixed on the bottom plate template, and finally the truss steel bars and the bottom plate stranded wire mesh are tied with wire ties; Step S2: Place a concrete protective layer pad at the bottom of the bottom plate stranded wire mesh. After confirming that it is correct, pour the prepared ECC to the height of the bottom plate, fill the remaining positions of the bottom plate where the rectangular ribs are set with long wooden strips, and finally pour the prepared ECC to the height of the rectangular ribs in the vacant positions of the long wooden strips; Step S3: After the initial setting of the ECC surface, the surface of the specimen is artificially roughened using a wooden sawtooth brush to meet the rough surface requirements in the design specifications; Step S4: Use the prefabricated bottom plate as the bottom formwork, and place side formwork around it as the formwork for pouring the post-casting layer concrete, then tie and fix the structural steel mesh in the post-casting layer, and pour the mixed recycled concrete on the bottom plate.

[0040] The bottom plate 1 is made of a combination of ECC and a stranded wire mesh, wherein the stranded wire mesh is made of high-strength stainless steel stranded wire or a combination of high-strength stainless steel stranded wire and SMA stranded wire at intervals; the number of SMA stranded wires used is adjusted according to specific design requirements; the area design of the SMA stranded wire adopts a method of replacing steel stranded wire with equal area or equal strength. When replacing with equal area, the SMA stranded wire is preferably of the same diameter as the steel stranded wire, and the replacement area is not greater than 50%. When replacing steel stranded wire with strength, the diameter of the SMA stranded wire should be greater than the diameter of the steel stranded wire to ensure that the number of replacements is consistent.

[0041] The method of applying prestress to prefabricated composite slabs by using SMA strands is as follows: the SMA strands are connected to the conductors before construction, and the conductors extend out of the prefabricated composite slabs. After the prefabricated composite slabs are completed, when the concrete strength of the prefabricated composite slabs reaches more than 60% of the design strength, the SMA strands are connected to the extended conductors and connected to alternating current, and the SMA strands are energized and heated, and the temperature rise range is controlled at 200-250 degrees. Driven by its shape memory effect, the SMA strands will generate prestress due to recovery deformation, and the shrinkage prestress amplitude is not more than 200MPa, thereby applying prestress to the prefabricated composite slabs.

[0042] The rectangular ribs (beams) pass through the entire upper part of the bottom plate, and the rectangular ribs are used in combination with truss steel bars; the spacing between the rectangular ribs is 400mm-700mm, the number of rectangular ribs on the one-way plate should not be less than 3, and the rectangular ribs in the main force direction of the two-way plate should be appropriately increased. The spacing between the rectangular ribs is not more than 500mm, and the number is not less than 4. The outermost rectangular ribs of the one-way plate and the two-way plate are not more than 200mm away from the edge of the composite plate. Example 5

[0043] like Figure 1 As shown, the prefabricated composite slab of ECC-high-strength stainless steel strand / SMA strand with rectangular rib-truss steel bar and post-cast recycled concrete of the present invention comprises a bottom plate 1 and a post-cast layer 2, wherein the bottom plate 1 comprises a bottom plate transverse strand 101, a bottom plate longitudinal strand 102, a rectangular rib 103, a truss steel bar 104 and an ECC 105 made of high-strength stainless steel strand / SMA strand, and the post-cast layer 2 can be recycled concrete; the rectangular rib 103 is arranged at the truss steel bar 104 on the bottom plate; the bottom plate transverse strand 101 and the bottom plate longitudinal strand 102 are fixed to the bottom plate formwork by aluminum buckles and slipknot bolts to form a strand mesh; the truss steel bar is as shown in FIG. Figure 4 As shown, the truss reinforcement and the bottom stranded wire mesh are tied together by tying wire.

[0044] like Figures 2-3As shown, the bottom plate stranded wire mesh is made of high-strength stainless steel stranded wire or partially replaced by SMA stranded wire, and the number of replacements should be adjusted according to specific design requirements; therefore, the bottom transverse stranded wire includes bottom transverse steel stranded wire and bottom transverse SMA stranded wire, and the bottom longitudinal stranded wire includes bottom longitudinal steel stranded wire and bottom longitudinal SMA stranded wire; as shown Figure 2 As shown in FIG. 1 , part of the longitudinal steel strands of the one-way slab are replaced by SMA strands; Figure 3 As shown, part of the longitudinal steel strands and part of the transverse steel strands of the two-way slab are replaced by SMA strands.

[0045] like Figures 2-3 As shown, the one-way slab is arranged with truss steel bars and rectangular ribs in the longitudinal direction, and the two-way slab is arranged with truss steel bars and rectangular ribs in both the transverse and longitudinal directions; the width of the rectangular ribs is 100 to 250 mm, and the height of the rectangular ribs is 40 mm; the truss steel bars are 10 to 20 mm higher than the rectangular ribs.

[0046] The diameter of the high-strength stainless steel stranded wire and the SMA stranded wire is not less than 3.6 mm and not more than 6 mm. The diameter of the transverse stranded wire of the one-way plate bottom plate is smaller than the diameter of the longitudinal stranded wire of the bottom plate. The diameter of the transverse stranded wire of the two-way plate bottom plate is the same as the longitudinal stranded wire of the bottom plate.

[0047] like Figure 5 As shown, the base plate template includes a steel plate, a limiting angle steel and a fixed angle steel. The limiting angle steel and the fixed angle steel are fixed to the steel plate with bolts. The limiting angle steel is provided with a limiting hole, and the fixed angle steel is provided with a fixing slot. The fixed angle steel is arranged along the periphery of the limiting angle steel and a spacing of not less than 80 mm is left between the two.

[0048] like Figure 6 As shown, when fixing the base plate stranded wire, first pass the stranded wire end through the limiting hole of the limiting angle steel, fix the slipknot bolt to the stranded wire end with an aluminum buckle, then put the slipknot bolt threaded section into the fixing slot on the fixing angle steel and tighten it with a nut until the stranded wire is tight. In this way, the base plate transverse stranded wire and the base plate longitudinal stranded wire are alternately fixed on the base plate template to form a stranded wire net. Example 6

[0049] A construction method of a prefabricated composite slab of ECC-high-strength stainless steel stranded wire / SMA stranded wire with rectangular rib-truss steel bars and post-cast recycled concrete, wherein the construction process comprises the following steps: Step S1: fix the limiting angle steel and the fixed angle steel on the steel plate according to the design size, pass the stranded wire end through the limiting hole of the limiting angle steel, and fix the stranded wire end to the fixed slot on the fixed angle steel with an aluminum buckle and a slipknot bolt. In this way, the transverse stranded wires and the longitudinal stranded wires of the bottom plate are alternately fixed on the bottom plate template, and finally the truss steel bars and the bottom plate stranded wire mesh are tied with wire ties; Step S2: Place a concrete protective layer pad at the bottom of the bottom plate stranded wire mesh. After confirming that it is correct, pour the prepared ECC to the height of the bottom plate, fill the remaining positions of the bottom plate where the rectangular ribs are set with long wooden strips, and finally pour the prepared ECC to the height of the rectangular ribs in the vacant positions of the long wooden strips; Step S3: After the initial setting of the ECC surface, the surface of the specimen is artificially roughened using a wooden sawtooth brush to meet the rough surface requirements in the design specifications.

[0050] Step S4: Use the prefabricated bottom plate as the bottom formwork, and place side formwork around it as the formwork for pouring the post-casting layer concrete, then tie and fix the structural steel mesh in the post-casting layer, and pour the mixed recycled concrete on the bottom plate.

[0051] Compared with the prior art, the present invention adopts a combination of truss steel bars and rib strips, which can effectively improve the bending resistance and cross-sectional stiffness of the prefabricated composite slab floor; the prefabricated composite slab floor is made by combining SMA strands and steel strands with ECC. ECC has good crack control ability and crack dispersion performance. When used in combination with SMA strand prestressing, it can effectively reduce the deflection of the prefabricated composite slab during the construction stage, thereby avoiding early cracking damage at the bottom of the large-span prefabricated composite slab during construction and normal use, and improving the crack resistance of the large-span prefabricated composite slab; the use of recycled concrete meets the application requirements of large-span and high-load structures while taking into account resource recycling and environmental protection.

[0052] Of course, the above description is only a preferred embodiment of the present invention and does not constitute a limitation of the present invention. Under the guidance of the prior art, those skilled in the art can make other modifications to the implementation of the present invention without creative work, and any modification made within the spirit and principle of the present invention or simple replacement or equivalent replacement using conventional technical means in the field should be included in the protection scope of the present invention.

Claims

1. A prestressed long-span composite slab of prefabricated ECC base slab-post-cast GRC composite layer, comprising a base slab (1) and a post-cast layer (2), characterized in that: The base plate (1) is formed by integrally casting an ECC material and a base plate stranded wire mesh, wherein the base plate stranded wire mesh is formed by transverse stranded wires and longitudinal stranded wires fixed on a base plate template; The bottom plate (1) is provided with a rectangular rib (103), and the rectangular rib (103) is formed by integrally casting the truss steel bars (104) and the bottom plate; the truss steel bars (104) and the bottom plate stranded wire mesh are bound together by binding wires; The post-cast layer (2) is located above the base plate (1) and is cast using concrete or recycled concrete.

2. The prestressed large-span composite slab of prefabricated ECC bottom slab-post-cast GRC composite layer according to claim 1 is characterized in that: The bottom plate stranded wire mesh is made of high-strength stainless steel stranded wires; or is made of high-strength stainless steel stranded wires and SMA stranded wires in combination at intervals.

3. The prestressed large-span composite slab of prefabricated ECC bottom slab-post-cast GRC composite layer according to claim 1 is characterized in that: The rectangular rib (103) has a width of 100-250 mm and a height of 40 mm; the number of rectangular ribs on the one-way plate is not less than 3, and the spacing between the rectangular ribs is 400 mm-700 mm; the number of rectangular ribs on the two-way plate is not less than 4, and the spacing between the rectangular ribs is not greater than 500 mm; the outermost rectangular ribs of the one-way plate and the two-way plate are not greater than 200 mm from the edge of the composite plate.

4. The prestressed large-span composite slab of prefabricated ECC bottom slab-post-cast GRC composite layer according to claim 3 is characterized by: The truss steel bars are 10 to 20 mm higher than the rectangular ribs.

5. The prestressed long-span composite slab of prefabricated ECC bottom slab-post-cast GRC composite layer according to any one of claims 1 to 4, characterized in that: The diameter of the high-strength stainless steel stranded wire and the SMA stranded wire is not less than 3.6 mm and not more than 6 mm. The diameter of the transverse stranded wire of the one-way plate bottom plate is smaller than the diameter of the longitudinal stranded wire of the bottom plate. The diameter of the transverse stranded wire of the two-way plate bottom plate is the same as the longitudinal stranded wire of the bottom plate.

6. The prestressed large-span composite slab of prefabricated ECC bottom slab and post-cast GRC composite layer according to claim 5 is characterized in that: The one-way slab is arranged with truss steel bars and rectangular ribs in the longitudinal direction, and the two-way slab is arranged with truss steel bars and rectangular ribs in both the transverse direction and the longitudinal direction.

7. The prestressed long-span composite slab of prefabricated ECC bottom slab-post-cast GRC composite layer according to claim 1, 2, 3, 4 or 6, characterized in that: The bottom plate template (3) comprises a steel plate, a limiting angle steel and a fixed angle steel, wherein the limiting angle steel and the fixed angle steel are fixed to the steel plate by bolts, the limiting angle steel is provided with a limiting hole, the fixed angle steel is provided with a fixing slot, and the fixed angle steel is arranged along the periphery of the limiting angle steel and a spacing of not less than 80 mm is left between the two.

8. A construction method for a prestressed large-span composite slab as claimed in claim 1, characterized in that: The process includes the following steps: Step S1: fix the limiting angle steel and the fixed angle steel on the steel plate according to the design size, pass the stranded wire end through the limiting hole of the limiting angle steel, and fix the stranded wire end to the fixed slot on the fixed angle steel with an aluminum buckle and a slipknot bolt. In this way, the transverse stranded wires and the longitudinal stranded wires of the bottom plate are alternately fixed on the bottom plate template, and finally the truss steel bars and the bottom plate stranded wire mesh are tied with wire ties; Step S2: Place a concrete protective layer pad at the bottom of the bottom plate stranded wire mesh. After confirming that it is correct, pour the prepared ECC to the height of the bottom plate, fill the remaining positions of the bottom plate where the rectangular ribs are set with long wooden strips, and finally pour the prepared ECC to the height of the rectangular ribs in the vacant positions of the long wooden strips; Step S3: After the initial setting of the ECC surface, the surface of the specimen is artificially roughened using a wooden sawtooth brush to meet the rough surface requirements in the design specifications; Step S4: Use the prefabricated bottom plate as the bottom formwork, and place side formwork around it as the formwork for pouring the post-casting layer concrete, then tie and fix the structural steel mesh in the post-casting layer, and pour the mixed recycled concrete on the bottom plate.

9. The construction method of the prestressed large-span composite slab according to claim 8, characterized in that: The bottom plate adopts a combination of ECC and stranded wire mesh, and the stranded wire mesh is made of high-strength stainless steel stranded wire; or a combination of high-strength stainless steel stranded wire and SMA stranded wire is adopted; the number of SMA stranded wires used is adjusted according to specific design requirements; the area design of SMA stranded wire adopts the method of replacing steel stranded wire with equal area or equal strength. When replacing with equal area, SMA stranded wire is preferably selected with the same diameter as steel stranded wire, and the replacement area is not more than 50%. When replacing steel stranded wire with strength, the diameter of SMA stranded wire should be larger than the diameter of steel stranded wire to ensure the consistency of the number of replacements.

10. The construction method of the prestressed large-span composite slab according to claim 8 or 9, characterized in that: The rectangular ribs run through the entire upper part of the base plate, and the rectangular ribs are used in combination with truss steel bars; the spacing between the rectangular ribs is 400mm-700mm, the number of rectangular ribs on the one-way plate is not less than 3, the rectangular ribs in the main force direction of the two-way plate are appropriately increased, the spacing between the rectangular ribs is not more than 500mm, and the number is not less than 4, and the outermost rectangular ribs of the one-way plate and the two-way plate are not more than 200mm away from the edge of the composite plate.

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