A support-free medium-length prefabricated rib truss reinforcement composite plate structure and its preparation method

Abstract

The present invention discloses a support-free medium-length prefabricated rib truss reinforcement composite plate structure and a preparation method thereof, comprising: a horizontal steel mesh and truss reinforcement bars arranged thereon, the horizontal steel mesh comprising longitudinal reinforcement bars and transverse reinforcement bars overlapped thereon, each truss reinforcement bar comprising an upper chord reinforcement bar, two lower chord reinforcement bars, and a web reinforcement bar, the web reinforcement bar connecting the upper chord reinforcement bar and the two lower chord reinforcement bars to form an umbrella-shaped structural unit, the two lower chord reinforcement bars being respectively arranged parallel to either side of the longitudinal reinforcement bar, a prefabricated concrete rib being arranged between adjacent truss reinforcement bars, a first concrete layer being cast below the horizontal steel mesh and truss reinforcement bars, and a second concrete layer being cast above the truss reinforcement bars. The structure has the characteristics of convenient construction, quick assembly, low carbon and environmental protection, and excellent performance, and is suitable for slab structures and support-free construction of medium- and large-span prefabricated concrete buildings, significantly saving construction costs.

Description

Technical Field

[0001] The present invention relates to the technical field of construction engineering, and in particular to a support-free medium-length prefabricated rib truss reinforcement composite plate structure and a preparation method thereof. Background Art

[0002] Prefabricated concrete structures have seen rapid development in China in recent years, owing to their advantages of fast construction, convenient assembly, energy conservation and environmental protection, and minimal on-site wet work. Currently, steel truss composite slabs are widely used in prefabricated concrete structures. These slabs consist of a precast base plate and a cast-in-place composite layer. The precast base plate includes steel truss reinforcement protruding from its surface, which connects the precast base plate and the cast-in-place layer together. This type of composite slab offers greater integrity than fully precast slabs and requires less formwork than cast-in-place slabs.

[0003] Engineering applications have shown that due to the low rigidity of the precast baseplate, large spans of steel truss composite slabs require additional supports at the bottom of the precast baseplate during construction, significantly increasing construction costs and time. To address this, Liu Xiang et al. invented a "Ribbed Steel Truss Concrete Precast Baseplate (CN206844438U)" and Jiang Lu et al. invented a "Ribbed Truss Concrete Composite Slab." By adding concrete ribs between the truss bars, they increase the rigidity of the precast baseplate and reduce the number of supports required during composite slab construction. The above patent: the ribs are full-length ribs (the rib length is close to or equal to the plate length), and the cast-in-place layer needs to cover the upper surface of the ribs to connect the cast-in-place layers into a whole. Therefore, if the rib height is high, the thickness of the composite plate finally completed by construction will be very large. If the rib height is small, the improvement in the stiffness of the plate will not be obvious. At the same time, the ribs of the above-mentioned composite plate and the prefabricated bottom plate are cast into a whole, which is difficult to manufacture. Most importantly, the rib height of the prefabricated bottom plate of the above-mentioned composite plate cannot be too high due to the plate thickness limitation. Therefore, when the span is large, the above-mentioned composite plate still needs to be supported at the bottom of the plate during construction.

[0004] To address the above issues, a support-free medium-length prefabricated ribbed truss reinforced composite slab structure and its preparation method are proposed. For this composite slab, the rib length is designed based on the bending deformation calculation required during construction, and its length is approximately half the slab length. The cast-in-place layer can be wrapped around the ribs without covering the upper surface of the ribs, thereby meeting the requirements for the composite slab's integrity and effectively solving the problem of increased slab thickness due to the installation of ribs. The ribs of the prefabricated base plate are prefabricated, solving the problem of manufacturing difficulties. A method of bolting I-beams to the prefabricated ribs is proposed to further increase the composite slab's bending stiffness, enabling support-free construction of medium- and large-span composite slabs. Summary of the Invention

[0005] The purpose of the present invention is to provide a support-free medium-long prefabricated rib truss reinforcement composite plate structure and a preparation method thereof that is easy to construct and assemble and is suitable for medium- and large-span building plate structures.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a support-free medium-length prefabricated rib truss reinforcement composite plate structure, comprising: a horizontal steel mesh and truss steel bars arranged thereon, the horizontal steel mesh comprising longitudinal steel bars and transverse steel bars overlapped thereon, each of the truss steel bars comprising an upper chord steel bar, two lower chord steel bars and a web steel bar, the web steel bar connecting the upper chord steel bar and the two lower chord steel bars to form an umbrella-shaped structural unit, the two lower chord steel bars are respectively arranged in parallel on both sides of the longitudinal steel bars, concrete prefabricated ribs are arranged between adjacent truss steel bars, a first concrete layer is cast on the lower part of the horizontal steel mesh and the truss steel bars, and a second concrete layer is cast on the upper part of the truss steel bars.

[0008] The cross section of the umbrella-shaped structural unit is triangular, one end of the web reinforcement is overlapped with the upper chord reinforcement, and the other end is overlapped with the intersection of the lower chord reinforcement and the transverse reinforcement.

[0009] I-shaped steel is arranged on the prefabricated concrete rib.

[0010] A first bolt hole is provided on the precast concrete rib, and a second bolt hole is provided on the flange portion of the I-shaped steel. Bolts are inserted into the first and second bolt holes to fix the I-shaped steel to the precast concrete rib.

[0011] The cross section of the prefabricated concrete rib is rectangular or drum-shaped.

[0012] The longitudinal steel bars are longitudinal stress-bearing steel bars.

[0013] The longitudinal steel bars are longitudinal prestressed steel bars, and the longitudinal prestressed steel bars are prestressed by stretching.

[0014] The longitudinal steel bars and the transverse steel bars are fixed by binding with steel bar wires.

[0015] The method for preparing the above-mentioned support-free medium-length prefabricated rib truss reinforcement composite plate structure has the following specific steps:

[0016] Step 1: Lay the bottom formwork at a predetermined position, and fix the longitudinal reinforcement on the upper end surface of the bottom formwork;

[0017] Step 2: Overlap the transverse steel bars on the fixed longitudinal steel bars, and tie and fix the steel bars at the intersection of the longitudinal steel bars and the transverse steel bars to form a horizontal steel mesh;

[0018] Step 3: Prefabricate truss reinforcement, wherein the truss reinforcement includes an upper chord reinforcement, two lower chord reinforcements, and a web reinforcement, wherein the web reinforcement connects the upper chord reinforcement and the two lower chord reinforcements to form an umbrella-shaped structural unit;

[0019] Step 4: Install the truss steel bars on the horizontal steel bar mesh, and the two lower chord steel bars of the truss steel bars are respectively arranged in parallel on both sides of the longitudinal steel bars;

[0020] Step 5: Set up templates around the horizontal reinforcement mesh where the truss reinforcement is installed to form a mouth-shaped structure;

[0021] Step 6: hoisting the prefabricated concrete ribs onto the transverse steel bars between adjacent truss steel bars;

[0022] Step 7: pouring concrete into the mouth-shaped structure with the precast concrete ribs hoisted to form a first concrete layer, which covers the lower part of the truss steel bars. The poured first concrete layer is compacted, the surface is smoothed and roughened, and the formwork is removed when the strength requirement is met to obtain a precast base plate structure.

[0023] Step 8: Transport the prefabricated base plate structure of step 7 to the predetermined location of the construction site for installation, perform formwork support, pour concrete into the prefabricated base plate structure to form a second concrete layer, the second concrete layer covers the upper part of the truss steel bars, and compacts and smoothes the surface of the poured second concrete layer. When the strength requirements are met, remove the formwork to obtain a composite plate structure.

[0024] When the longitudinal reinforcement is longitudinal prestressed reinforcement, in step one, prestressed tensioning pedestals are also installed at both ends of the laid base plate, and prestress is applied to the longitudinal reinforcement fixedly installed on the upper end surface of the bottom template through the tensioning pedestals.

[0025] In step seven, an I-shaped steel can be further provided on the precast concrete rib to form a precast base plate structure with the I-shaped steel. After the pouring and curing of the second concrete layer in step eight is completed, the I-shaped steel is removed to complete the production of the composite plate structure.

[0026] The beneficial effects of the support-free medium-length prefabricated rib truss reinforcement composite plate structure and the preparation method thereof of the present invention are:

[0027] 1. Compared with ordinary cast-in-place slabs, this composite slab structure has the characteristics of saving formwork, low carbon and environmental protection.

[0028] 2. Compared with truss reinforced concrete composite slabs, this composite slab structure has the advantages of larger span, low construction support cost, greater rigidity, better integrity, and good crack resistance. It is suitable for support-free construction of medium and large span building slab structures.

[0029] 3. Compared with ordinary ribbed truss reinforced concrete composite slabs: the rib length of the composite slab structure is designed according to the calculation requirements of the bending deformation during construction, and its length is about half of the slab length. The cast-in-place layer can be wrapped around the ribs without covering the upper surface of the ribs, which can meet the integrity requirements of the composite slab and effectively solve the problem of increasing the slab thickness due to the setting of ribs; the ribs of the prefabricated base plate are prefabricated, which solves the problem of difficulty in manufacturing the prefabricated base plate; a method of connecting I-beams to the prefabricated ribs with bolts is proposed to further increase the bending stiffness of the composite slab, which can realize the support-free construction of medium and large span composite slabs.

[0030] Force Transmission Mechanism: During the construction phase of a composite slab, the live load and the weight of the cast-in-place concrete layer are primarily borne by the precast base plate. This precast base plate is also required to have a certain degree of flexural rigidity to prevent cracks from forming on its underside during construction. The flexural rigidity of the precast base plate can be increased by installing precast concrete ribs on the precast base plate. As the span increases, if the increased rigidity achieved by these methods alone fails to meet the requirements, the flexural rigidity of the precast base plate can be further increased by applying prestress to the load-bearing steel bars of the precast base plate or by connecting detachable I-beams to the upper portions of the precast concrete ribs of the precast base plate, thereby meeting the support-free construction requirements of medium- and large-span composite slabs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural diagram of the longitudinal stress reinforcement;

[0032] Figure 2 It is a schematic diagram of the structure of longitudinal prestressed steel bars;

[0033] Figure 3 It is a schematic diagram of the structure with truss reinforcement installed;

[0034] Figure 4 for Figure 3 Enlarged schematic diagram of the middle truss reinforcement structure;

[0035] Figure 5 It is a schematic diagram of the structure of the enclosed steel formwork;

[0036] Figure 6 It is a structural diagram of precast concrete ribs;

[0037] Figure 7 It is a structural diagram of the anchor bolt;

[0038] Figure 8 This is a structural diagram of a precast concrete rib with bolt holes;

[0039] Figure 9 It is a structural diagram of I-beam;

[0040] Figure 10This is a structural diagram of I-beams installed on precast concrete ribs;

[0041] Figure 11 It is a structural diagram of the arrangement of precast concrete ribs;

[0042] Figure 12 This is a structural diagram of the arrangement of precast concrete ribs with I-shaped steel;

[0043] Figure 13 It is a schematic diagram of the structure for pouring the first concrete layer;

[0044] Figure 14 It is a schematic diagram of a structure with I-shaped steel installed;

[0045] Figure 15 It is a structural diagram of pouring the second concrete layer;

[0046] Figure 16 It is a structural diagram of the composite plate;

[0047] In the figure, 1-longitudinal stress-bearing steel bars; 2-longitudinal prestressed stress-bearing steel bars; 3-transverse steel bars; 4-lower chord steel bars; 5-upper chord steel bars; 6-web bar steel bars; 7-truss steel bars; 8-steel formwork; 9-precast concrete ribs; 10-first bolt hole; 11-screw; 12-nut; 13-bolt; 14-second bolt hole; 15-I-beam, 16-first concrete layer, 17-second concrete layer. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0050] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] Example 1:

[0052] The present invention provides a support-free medium-length prefabricated rib truss reinforcement composite plate structure, such as Figure 3 、 Figure 4 and Figure 5 As shown, it includes: a horizontal steel mesh and a truss steel bar 7 arranged thereon, the horizontal steel mesh includes a longitudinal steel bar and a transverse steel bar 3 overlapped thereon, each of the truss steel bars 7 includes an upper chord steel bar 5, two lower chord steel bars 4 and a web steel bar 6, the web steel bar 6 connects the upper chord steel bar 5 and the two lower chord steel bars 4 to form an umbrella-shaped structural unit, and the two lower chord steel bars 4 are respectively arranged in parallel on both sides of the longitudinal steel bar, as shown in FIG. Figure 11 As shown, precast concrete ribs 9 are arranged between adjacent truss steel bars 7, a first concrete layer 16 is cast on the lower part of the horizontal steel mesh and the truss steel bars 7, and a second concrete layer 17 is cast on the upper part of the truss steel bars 7. The concrete in the overall structure is poured twice. The first concrete layer 16 is poured in the factory, which is suitable for industrial mass production to ensure the pouring quality. The second concrete layer 17 is poured at the construction site, and the truss steel bars 7 are laid on the horizontal steel mesh, and precast concrete ribs 9 are added in between, which is suitable for large-span building panel structures.

[0053] Furthermore, in this embodiment, the cross-section of the umbrella-shaped structural unit is triangular, one end of the web reinforcement 6 is overlapped with the upper chord reinforcement 5 , and the other end is overlapped with the intersection of the lower chord reinforcement 4 and the transverse reinforcement 3 .

[0054] Furthermore, in this embodiment, Figure 6 As shown, the cross section of the precast concrete rib 9 is rectangular, or a drum-shaped rectangular cross section with two sides having inwardly concave arcs, or other shapes that can achieve the same function.

[0055] Further, if Figure 1 and Figure 2As shown, in one embodiment, the longitudinal reinforcement is a longitudinal stress-bearing reinforcement 1; in another embodiment, the longitudinal reinforcement is a longitudinal prestressed stress-bearing reinforcement 2, and the longitudinal prestressed stress-bearing reinforcement 2 is prestressed by stretching. Before prefabrication, prestressed tension is applied to the bottom stress-bearing reinforcement of the composite plate structure, and other prefabrication processes remain unchanged. It is suitable for larger span building plate structures. In one specific example, the longitudinal prestressed stress-bearing reinforcement 2 can be composed of steel bars or steel wire windings.

[0056] Furthermore, in this embodiment, the longitudinal steel bars and the transverse steel bars 3 are fixed by binding with steel bar wires.

[0057] The method for preparing the above-mentioned support-free medium-length prefabricated rib truss reinforcement composite plate structure has the following specific steps:

[0058] Step 1: Lay the bottom formwork at a predetermined position, and fix longitudinal reinforcements at equal intervals on the upper end surface of the bottom formwork;

[0059] Step 2: Overlap the transverse steel bars 3 on the fixed longitudinal steel bars, and tie and fix the intersection of the longitudinal steel bars and the transverse steel bars 3 with steel wire to form a horizontal steel mesh;

[0060] Step 3: Prefabricate truss steel bars 7, wherein the truss steel bars 7 include an upper chord steel bar 5, two lower chord steel bars 4, and a web steel bar 6. The web steel bar 6 is welded to connect the upper chord steel bar 5 and the two lower chord steel bars 4 to form an umbrella-shaped structural unit.

[0061] Step 4: Install the truss steel bar 7 on the horizontal steel bar mesh and fix it. The two lower chord steel bars 4 of the truss steel bar 7 are respectively arranged in parallel on both sides of the longitudinal steel bar;

[0062] Step 5: Set up steel templates 8 around the horizontal steel mesh where the truss reinforcement 7 is installed, and then use bar magnets to connect and fix the steel templates 8 to complete the arrangement of the steel templates 8 to form a mouth-shaped structure;

[0063] Step 6: If Figure 11 As shown, the prefabricated concrete ribs 9 are hoisted onto the transverse reinforcements 3 between the adjacent truss reinforcements 7;

[0064] Step 7: If Figure 13As shown, concrete is poured into the mouth-shaped structure where the precast concrete ribs 9 are hoisted to form a first concrete layer 16, which is generally not less than 60 mm thick. The first concrete layer 16 covers the lower part of the truss steel bars 7. The poured first concrete layer 16 is compacted, smoothed, and roughened so that the depth of the roughness on its surface is not less than 4 mm. When the strength requirement is met (the strength of the test block cured under the same conditions reaches 75% of the designed concrete cube compressive strength), the formwork is removed to obtain a precast base plate structure.

[0065] Step 8: transport the prefabricated floor structure of step 7 to the predetermined location of the construction site for installation, perform formwork support, pour concrete into the prefabricated floor structure to form a second concrete layer 17, the second concrete layer 17 covers the upper part of the truss steel bar 7, and perform tamping and surface smoothing on the poured second concrete layer 17. When the strength requirement is met, remove the formwork. Figure 16 As shown, a composite plate structure is obtained.

[0066] Furthermore, in another embodiment, the longitudinal steel bars are longitudinal prestressed steel bars 2, and the longitudinal prestressed steel bars 2 are prestressed by stretching. Specifically, when the longitudinal steel bars are longitudinal prestressed steel bars 2, in step one, prestressed tensioning pedestals are also installed at both ends of the laid base plate, and the longitudinal steel bars fixedly installed on the upper end surface of the bottom formwork are stretched and prestressed by the tensioning pedestals. Correspondingly, shear reinforcement needs to be tensioned during dismantling.

[0067] Example 2

[0068] The present invention provides a support-free medium-length prefabricated rib truss reinforcement composite plate structure, such as Figure 3 、 Figure 4 and Figure 5 As shown, it includes: a horizontal steel mesh and a truss steel bar 7 arranged thereon, the horizontal steel mesh includes longitudinal steel bars and transverse steel bars 3 overlapped thereon, each of the truss steel bars 7 includes an upper chord steel bar 5, two lower chord steel bars 4 and a web steel bar 6, the web steel bar 6 connects the upper chord steel bar 5 and the two lower chord steel bars 4 to form an umbrella-shaped structural unit, the two lower chord steel bars 4 are respectively arranged in parallel on both sides of the longitudinal steel bars, and a precast concrete rib 9 is arranged between adjacent truss steel bars 7, a first concrete layer 16 is cast at the bottom of the horizontal steel mesh and the truss steel bar 7, and a second concrete layer 17 is cast at the top of the truss steel bar 7, and the concrete in the overall structure is poured twice, the first concrete layer 16 is poured in the factory, which is suitable for industrialized mass production to ensure pouring quality, and the second concrete layer 17 is poured at the construction site, and an I-shaped steel 15 is provided on the precast concrete rib 9, specifically, as Figures 7 to 10As shown, a first bolt hole 10 is provided on the precast concrete rib 9, and a second bolt hole 14 is provided on the flange portion of the I-shaped steel 15. In one embodiment, four first bolt holes 10 are provided on the precast concrete rib 9, and four second bolt holes 14 are correspondingly provided on the flange portion of the I-shaped steel 15. The four first bolt holes 10 and the four second bolt holes 14 are all distributed in a rectangular shape. According to actual use needs, the force transmission needs of the mutual displacement between the I-shaped steel and the precast concrete rib can be met. In addition, bolt holes and bolts are added to ensure a stable connection between the I-shaped steel and the precast concrete rib. Bolts 13 are inserted into the first bolt holes 10 and the second bolt holes 14. The bolts 13 include a screw rod 11 with threads. A nut is fixed to one end of the screw rod 11 so that the I-beam 15 is fixed to the precast concrete rib 9. In order to use a larger span and increase the rib cross-sectional height, when prefabricating the composite slab in the prefabricated component factory, the I-beam is processed on the rib and connected to the precast concrete rib 9 through bolts 13. Other prefabrication processes remain unchanged, which is suitable for support-free large-span building panel structures.

[0069] Furthermore, in this embodiment, the cross-section of the umbrella-shaped structural unit is triangular, one end of the web reinforcement 6 is overlapped with the upper chord reinforcement 5 , and the other end is overlapped with the intersection of the lower chord reinforcement 4 and the transverse reinforcement 3 .

[0070] Furthermore, in this embodiment, the cross section of the precast concrete rib 9 is rectangular, or a drum-shaped rectangular cross section with two sides having inwardly concave arcs, or other shapes that can achieve the same function.

[0071] Furthermore, in one embodiment, the longitudinal reinforcement is a longitudinal stress-bearing reinforcement 1; in another embodiment, the longitudinal reinforcement is a longitudinal prestressed stress-bearing reinforcement 2, and the longitudinal prestressed stress-bearing reinforcement 2 is prestressed by stretching. Before prefabrication, prestressed tension is applied to the bottom stress-bearing reinforcement of the composite plate structure, and other prefabrication processes remain unchanged, which is suitable for larger support-free and large-span building plate structures.

[0072] Furthermore, in this embodiment, the longitudinal steel bars and the transverse steel bars 3 are fixed by binding with steel bar wires.

[0073] The method for preparing the above-mentioned support-free medium-length prefabricated rib truss reinforcement composite plate structure has the following specific steps:

[0074] Step 1: Lay the bottom formwork at a predetermined position, and fix longitudinal reinforcements at equal intervals on the upper end surface of the bottom formwork;

[0075] Step 2: Overlap the transverse steel bars 3 on the fixed longitudinal steel bars, and tie and fix the intersection of the longitudinal steel bars and the transverse steel bars 3 with steel wire to form a horizontal steel mesh;

[0076] Step 3: Prefabricate truss steel bars 7, wherein the truss steel bars 7 include an upper chord steel bar 5, two lower chord steel bars 4, and a web steel bar 6. The web steel bar 6 is welded to connect the upper chord steel bar 5 and the two lower chord steel bars 4 to form an umbrella-shaped structural unit.

[0077] Step 4: Install the truss steel bar 7 on the horizontal steel bar mesh and fix it. The two lower chord steel bars 4 of the truss steel bar 7 are respectively arranged in parallel on both sides of the longitudinal steel bar;

[0078] Step 5: Set up steel templates 8 around the horizontal steel mesh where the truss reinforcement 7 is installed, and then use bar magnets to connect and fix the steel templates 8 to complete the arrangement of the steel templates 8 to form a mouth-shaped structure;

[0079] Step 6: If Figure 11 As shown, the prefabricated concrete ribs 9 are hoisted onto the transverse reinforcements 3 between the adjacent truss reinforcements 7;

[0080] Step 7: If Figure 12 As shown, an I-shaped steel 15 is installed on the precast concrete rib 9. Figure 14 As shown, concrete is poured into the mouth-shaped structure where the precast concrete ribs 9 are hoisted to form a first concrete layer 16, which is generally not less than 60 mm thick. The first concrete layer 16 covers the lower part of the truss steel bars 7. The poured first concrete layer 16 is compacted, smoothed, and roughened to ensure that the depth of the roughness on its surface is not less than 4 mm. When the strength requirement is met (the strength of the test block under the same curing conditions reaches 75% of the designed concrete cube compressive strength), the formwork is removed to obtain a precast bottom plate structure with I-shaped steel 15.

[0081] Step 8: If Figure 15 As shown, the prefabricated base plate structure of step seven is transported to the predetermined location of the construction site for installation, and formwork support is performed. Concrete is poured into the prefabricated base plate structure to form a second concrete layer 17. The second concrete layer 17 covers the upper part of the truss steel bar 7. The poured second concrete layer 17 is compacted and the surface is smoothed. When the strength requirement is met, the I-beam 15 is dismantled and the formwork is removed. Figure 16 As shown, a composite plate structure is obtained.

[0082] Furthermore, in another embodiment, the longitudinal steel bars are longitudinal prestressed steel bars 2, and the longitudinal prestressed steel bars 2 are prestressed by stretching. Specifically, when the longitudinal steel bars are longitudinal prestressed steel bars 2, in step one, prestressed tensioning pedestals are also installed at both ends of the laid base plate, and the longitudinal steel bars fixedly installed on the upper end surface of the bottom formwork are stretched and prestressed by the tensioning pedestals. Correspondingly, shear reinforcement needs to be tensioned during dismantling.

[0083] The present invention provides a support-free medium-length prefabricated rib truss reinforcement composite plate structure and its preparation method. Its force transmission mechanism is as follows: during the pouring of the cast-in-place composite layer at the construction site, under the action of secondary force, the prefabricated bottom plate bends downward as a whole. Since the prefabricated bottom plate is provided with prefabricated concrete ribs, the height of the cross section is increased, the lower longitudinal steel bars are pulled, and the upper prefabricated concrete ribs are compressed, which resist the downward bending of the prefabricated bottom plate and increase the bending rigidity, thereby achieving the purpose of support-free on-site construction. It has the advantages of large span, low construction support cost, large rigidity, good integrity, and good crack resistance. According to its force performance, spatial span, production and transportation, and hoisting capacity, a lightweight concrete cast-in-place composite layer can be used to reduce the weight of the plate. Its prefabricated concrete ribs do not completely penetrate the entire composite plate structure, which meets the secondary force conditions of the composite plate during construction and meets the requirements of the two-way pipeline arrangement of the structure.

[0084] The implementation results show that the medium-length prefabricated rib truss reinforced composite plate structure proposed in the present invention is suitable for the construction of prefabricated concrete floor slabs of different spans, greatly saving the construction support cost and effectively improving the construction progress.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the present claims.

Claims

1. A support-free medium-length prefabricated rib truss reinforcement composite plate structure, characterized in that: include: A horizontal steel mesh and truss steel bars arranged thereon, the horizontal steel mesh includes longitudinal steel bars and transverse steel bars overlapped thereon, each of the truss steel bars includes an upper chord steel bar, two lower chord steel bars and a web steel bar, the web steel bar connects the upper chord steel bar and the two lower chord steel bars to form an umbrella-shaped structural unit, the two lower chord steel bars are respectively arranged in parallel on both sides of the longitudinal steel bars, concrete precast ribs are arranged between adjacent truss steel bars, and detachable I-shaped steel bars are arranged on the concrete precast ribs, a first concrete layer is cast on the lower part of the horizontal steel mesh and the truss steel bars, a second concrete layer is cast on the upper part of the truss steel bars, and one end of the web steel bar is overlapped on the upper chord steel bar, and the other end is overlapped on the intersection of the lower chord steel bar and the transverse steel bar.

2. The support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 1, characterized in that: A first bolt hole is provided on the precast concrete rib, and a second bolt hole is provided on the flange portion of the I-shaped steel. Bolts are inserted into the first and second bolt holes to fix the I-shaped steel to the precast concrete rib.

3. The support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 1, characterized in that: The cross section of the prefabricated concrete rib is rectangular or drum-shaped.

4. The support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 1, characterized in that: The longitudinal steel bars are longitudinal stress-bearing steel bars.

5. The support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 1, characterized in that: The longitudinal steel bars are longitudinal prestressed steel bars, and the longitudinal prestressed steel bars are prestressed by stretching.

6. The method for preparing a support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 1, characterized in that: The specific steps are as follows: Step 1: Lay the bottom formwork at a predetermined position, and fix the longitudinal reinforcement on the upper end surface of the bottom formwork; Step 2: Overlap the transverse steel bars on the fixed longitudinal steel bars, and tie and fix the steel bars at the intersection of the longitudinal steel bars and the transverse steel bars to form a horizontal steel mesh; Step 3: Prefabricate truss reinforcement, wherein the truss reinforcement includes an upper chord reinforcement, two lower chord reinforcements, and a web reinforcement, wherein the web reinforcement connects the upper chord reinforcement and the two lower chord reinforcements to form an umbrella-shaped structural unit; Step 4: Install the truss steel bars on the horizontal steel bar mesh, and the two lower chord steel bars of the truss steel bars are respectively arranged in parallel on both sides of the longitudinal steel bars; Step 5: Set up templates around the horizontal reinforcement mesh where the truss reinforcement is installed to form a mouth-shaped structure; Step 6: hoisting the prefabricated concrete ribs onto the transverse steel bars between adjacent truss steel bars; Step 7: pouring concrete into the mouth-shaped structure with the precast concrete ribs hoisted to form a first concrete layer, which covers the lower part of the truss steel bars. The poured first concrete layer is compacted, the surface is smoothed and roughened, and the formwork is removed when the strength requirement is met to obtain a precast base plate structure. Step 8: Transport the prefabricated base plate structure of step 7 to the predetermined location of the construction site for installation, perform formwork support, pour concrete into the prefabricated base plate structure to form a second concrete layer, the second concrete layer covers the upper part of the truss steel bars, and compacts and smoothes the surface of the poured second concrete layer. When the strength requirements are met, remove the formwork to obtain a composite plate structure.

7. The method for preparing a support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 6, characterized in that: When the longitudinal steel bars are longitudinal prestressed steel bars, in step one, prestressed tensioning pedestals are installed at both ends of the laid base plate, and prestress is applied to the longitudinal steel bars fixedly installed on the upper end surface of the bottom formwork through the tensioning pedestals. In step seven, after the pouring and curing of the first concrete layer is completed, the reinforcement is sheared and tensioned. When the strength requirements are met, the formwork is removed to obtain a prefabricated base plate structure.

8. The method for preparing a support-free medium-length prefabricated rib truss reinforcement composite plate structure according to claim 6, characterized in that: In step seven, an I-beam may be further provided on the precast concrete rib to form a precast base plate structure with an I-beam. After the pouring and curing of the second concrete layer is completed in step eight, the formwork is removed and the I-beam is disassembled when the strength requirement is met, thereby completing the production of the composite plate structure.

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