Steel-concrete composite structure cone shell and construction method

Abstract

This application relates to a steel-concrete composite conical shell structure and its construction method, belonging to the field of silo construction technology. The structure comprises a steel-concrete composite conical shell, including: a frame made of large square steel pipes, small square tube purlins welded to the bottom of the frame, a galvanized steel plate bottom formwork fixed below the small square tube purlins, and a concrete filling layer covering the inside and outside of the frame. The construction method employs a process of factory prefabrication, ground assembly, overall hoisting, and high-altitude pouring. It solves the problems of difficult support system erection, high risk of high-altitude operations, and slow construction speed in traditional large-diameter silo roof construction, achieving formwork-free concrete support system construction for the silo roof conical shell. This application eliminates the central column, which is beneficial for improving the smooth flow of coal inside the silo and reducing the risk of spontaneous combustion of stored bulk materials. This application has significant technical advantages such as high construction efficiency, structural stability, and long maintenance-free period, and is particularly suitable for the roof construction of large-diameter bulk silos.

Description

Technical Field

[0001] This invention relates to the field of silo construction technology, and in particular to a steel-concrete composite conical shell structure and its construction method. Background Technology

[0002] Silos, as important bulk material storage structures, are widely used in industries such as power, coal, building materials, and grain. With the continuous expansion of industrial production scale, the demand for silo diameter and capacity is increasing, leading to higher requirements for silo roof structures. The roof structure not only needs sufficient load-bearing capacity to support the upper bridge and conveying equipment, but also requires excellent sealing performance and durability to ensure the safety of the stored materials.

[0003] In the construction of existing medium and large-sized silo roofs, steel space frames or cast-in-place reinforced concrete conical shells are commonly used. For cast-in-place concrete structures, traditional construction methods often require the erection of large-area full-span scaffolding or the installation of central support columns to provide the formwork support system needed for concrete pouring. When dealing with large-diameter silos, this approach results in extremely high and wide support systems, consuming significant amounts of materials and labor, leading to long construction periods and extremely high risks associated with working at heights. Furthermore, the presence of a central column inside the silo often restricts the flow of bulk materials, increasing the risk of spontaneous combustion due to material accumulation. Moreover, in the construction of ultra-large diameter silos (e.g., over 50 meters), the stability of traditional support systems is difficult to guarantee.

[0004] As silo diameters increase to the 80-meter level, existing methods face serious bottlenecks in structural safety and construction efficiency. The difficulty of high-altitude formwork supports limits the widespread adoption of large-diameter silo roofs, while simple steel space frames have disadvantages in terms of corrosion prevention and subsequent maintenance. Therefore, how to eliminate central supports while ensuring structural strength and durability, and solve the problem of supporting large-span formwork at high altitudes, has become a key issue restricting the technological development of ultra-large silos. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a steel-concrete composite conical shell structure and its construction method.

[0006] In a first aspect, this application provides a steel-concrete composite conical shell structure, which adopts the following technical solution: A steel-concrete composite conical shell structure includes: a steel frame, shaped like a frustum of a cone, formed by multiple large square steel tubes connected by nodes; the steel frame includes a bottom ring beam, a top ring beam, and longitudinal main inclined beams, horizontal circumferential members, and web members connecting the bottom and top ring beams; a purlin layer, including multiple small square tube purlins arranged circumferentially, the small square tube purlins being welded to the inner side of the members of the steel frame and spaced along the generatrix of the frustum of a cone; a bottom formwork, which is a galvanized steel plate laid on the bottom surface of the purlin layer, the galvanized steel plate being connected to the small square tube purlins by fasteners; a reinforcing mesh, including a double-layer bidirectional reinforcing mesh tied inside and outside the steel frame; and a concrete filling layer, poured onto the bottom formwork and covering the steel frame and the reinforcing mesh.

[0007] By adopting the above technical solution, using the steel structure frame itself as the load-bearing system, and combining it with a permanent bottom formwork, the erection of high-altitude scaffolding is eliminated, which greatly improves construction efficiency and ensures the safety of high-altitude operations.

[0008] Preferably, the horizontal circumferential members, longitudinal main inclined beams, and web members of the steel structure frame intersect each other, dividing the side of the truncated cone into multiple triangular regions.

[0009] By adopting the above technical solution and utilizing the geometric stability of triangles, the silo roof structure has extremely high spatial stiffness and overall stability when bearing the huge self-weight of concrete and external loads.

[0010] Preferably, the steel structure frame is provided with connecting reinforcing plates at the nodes, and the connecting reinforcing plates are fixed to the adjacent members by bolt welding.

[0011] By adopting the above technical solution, rapid positioning and temporary fixing are achieved through bolts during the ground assembly stage, followed by full welding to ensure strength, effectively controlling the spatial dimensional accuracy of the intersection nodes of multiple rods.

[0012] Preferably, the small square tube purlins are arranged every 250mm along the radial height direction of the steel structure frame, and each small square tube purlin is welded and fixed to the members of the steel structure frame by a connecting plate.

[0013] By adopting the above technical solution, the high-density purlin arrangement provides uniform support for the bottom formwork, preventing severe local deflection deformation of the bottom formwork during concrete pouring.

[0014] Preferably, the galvanized steel sheet has a thickness of 2mm, the overlap length between adjacent galvanized steel sheets is not less than 50mm, and the fastener uses galvanized dovetail wire in conjunction with a gasket. By adopting the above technical solution, the sealing performance of the bottom mold is ensured, preventing grout leakage, and the galvanized layer provides excellent durability, allowing the bottom mold to serve the structure for a long time without removal.

[0015] Preferably, the top ring beam is a box beam, which is formed by welding high-strength thick plates into a rectangle, and then splicing multiple rectangular beams together, and is bolted and welded to the longitudinal main inclined beam and web members.

[0016] By adopting the above technical solution, the construction process of the top platform is simplified, and the connection reliability between the silo top and the upper process equipment is enhanced.

[0017] Secondly, this application provides a construction method for a steel-concrete composite conical shell structure, employing the following technical solution: A construction method for a steel-concrete composite conical shell structure includes the following steps: S1: Steel component factory processing and installation of embedded parts on the silo roof; S2: Ground assembly of steel structure frame, bolting and positioning the large square steel pipes according to the design nodes and then welding the nodes; S3: Install the purlin layer and bottom formwork, weld the small square tube purlins to the inside of the steel structure frame on the ground, and install galvanized steel plates at the bottom of the purlins; S4: Overall hoisting, using lifting equipment to lift the assembled steel cone shell to the top elevation of the warehouse, lower it into place, and weld it to the embedded parts; S5: Lay out the steel mesh and tie a double layer of bidirectional steel mesh on both the inner and outer sides of the steel cone shell; S6: Concrete pouring, concrete is poured continuously in layers along the circumference to form a concrete filling layer.

[0018] By adopting the above technical solutions, the process of "ground prefabrication, overall hoisting, and suspended formwork construction" was realized, transforming a large number of high-risk high-altitude formwork operations into safe ground operations.

[0019] Preferably, in step S2, a counter-pull device is used to adjust the position of the rod. The counter-pull device includes a steel wire rope and a guide chain, and is accurately positioned by measuring the coordinates and elevation of the node on each horizontal circle.

[0020] By adopting the above technical solution, it is possible to dynamically correct minor geometric deviations in the assembly process of large-span steel structures, thus ensuring the roundness of the conical structure.

[0021] Preferably, in step S6, the concrete pouring thickness is 320mm-400mm, and the concrete covers the steel structure frame with a protective layer of not less than 60mm on both the top and bottom.

[0022] By adopting the above technical solutions, a robust steel-concrete composite structure was formed, which not only improved the compressive strength of the structure, but also solved the fire prevention and corrosion prevention problems of the steel structure by utilizing the concrete protective layer.

[0023] In summary, this application includes at least one of the following beneficial technical effects: By using a steel frame as a permanent construction support and combining it with a permanent bottom formwork, the complex support system in the traditional construction of large-diameter silos was eliminated, which greatly reduced construction costs, shortened the construction period, and reduced the safety hazards of working at heights. The use of ground assembly, overall hoisting, and anti-tension adjustment devices ensures the geometric accuracy of the ultra-large diameter conical shell structure. Combined with the triangular stable grid design, and verified by the specific design of the bottom ring beam 12 with a diameter of 52m and a total height of 18.45m at the center of the cone in the embodiment, the silo top structure can meet the span requirements of ultra-large diameter (52 meters or more) silos without the need for central column support, thus optimizing the internal space of the silo. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the steel frame.

[0025] Figure 2 yes Figure 1 An enlarged schematic diagram of part A in the middle.

[0026] Figure 3 This is a schematic diagram highlighting the bottom mold.

[0027] Figure 4 This is a schematic diagram highlighting the purlin layer.

[0028] Figure 5 This is a schematic diagram of the steel mesh on one side of the steel structure frame.

[0029] Figure 6 This is a schematic diagram of the steel mesh on the other side of the steel structure frame.

[0030] Figure 7 This is a schematic diagram highlighting the concrete infill layer.

[0031] Figure 8 This is a schematic diagram of the installation of a steel-concrete composite conical shell structure.

[0032] Explanation of reference numerals in the attached drawings: 1. Steel frame; 11. Large square steel pipe; 12. Bottom ring beam; 13. Top ring beam; 14. Longitudinal main inclined beam; 15. Horizontal circumferential member; 16. Web member; 2. Purlin layer; 21. Small square tube purlin; 3. Bottom formwork; 4. Steel mesh; 5. Concrete filling layer. Detailed Implementation

[0033] The present application will be further described in detail below with reference to all the accompanying drawings.

[0034] This application discloses a steel-concrete composite conical shell structure.

[0035] Reference Figures 1-8 A steel-concrete composite cone shell structure includes a steel frame 1, a purlin layer 2, a bottom formwork 3, a steel mesh 4, and a concrete filling layer 5.

[0036] Reference Figure 1 and Figure 2 The steel frame 1 is shaped like a frustum of a cone, serving as the load-bearing framework for the entire warehouse roof. This framework is constructed from multiple high-strength large square steel pipes 11 (such as Q355B grade square steel pipes with specifications of TUB200x300x10 or TUB300x300x10) connected at joints. Specifically, the steel frame 1 includes a bottom ring beam 12 at the bottom and a top ring beam 13 at the top. A longitudinal main inclined beam 14, horizontal circumferential members 15, and web members 16 connect the bottom ring beam 12 and the top ring beam 13. In this embodiment, the lower diameter of the bottom ring beam 12 is 52m, the upper diameter of the top ring beam 13 is 14.5m, the total height of the cone center is approximately 18.45m, and the slope angle is designed to be 45 degrees. The horizontal circumferential members 15 are divided into six zones and seven sections along the height direction, with each layer approximately 3.075m high. The longitudinal main inclined beam 14, the horizontal circumferential members 15, and the web members 16 intersect each other, dividing the side of the truncated cone into multiple triangular regions. This triangular grid structure can effectively transfer the huge load from the upper part to the silo wall.

[0037] At the nodes of steel frame 1, specialized connecting reinforcement plates are installed to ensure structural strength when multi-directional members intersect. The thickness of the connecting reinforcement plates can be either 12mm or 15mm. The nodes are fixed using a bolt-weld combination: during ground assembly, the reinforcement plates are first bolted to the square steel pipes through the bolt holes, followed by full welding from all sides. For inner gaps that cannot be directly welded due to obstruction by the connecting plates, the connecting plates are removed, the inner gaps are welded, and then the connecting plates are reinstalled and surrounded by welding. The weld width is designed to be 15mm.

[0038] Reference Figure 3 and Figure 4The purlin layer 2 includes multiple small square tube purlins 21 arranged circumferentially. These small square tube purlins 21 are made of square steel pipe with specifications of 60×40×2mm and material of Q355. The small square tube purlins 21 are welded to the lower inner side of the members of the steel structure frame 1, and are set at intervals of 250mm along the generatrix direction of the truncated cone (i.e., the radial height direction). Each small square tube purlin 21 is welded and fixed to the large square steel pipe 11 member of the steel structure frame 1 by a connecting plate. The connecting plate is Z-shaped, clamping the purlin in the middle of the connecting plate and welding it firmly to the square pipe of the frame.

[0039] The bottom formwork 3 is a galvanized steel sheet laid on the bottom surface of the purlin layer 2. The galvanized steel sheet is 2mm thick and can be made of Q235 or Q355 grade material. The galvanized steel sheet is connected to the small square tube purlin 21 by fasteners. To ensure sealing, the overlap length between adjacent galvanized steel sheets is controlled between 50mm and 80mm. The fasteners use M6.3×55 galvanized dovetail screws (self-tapping screws) with 30mm diameter washers, and the fixing spacing is strictly controlled within 200mm to prevent the bottom formwork 3 from sagging or leaking grout due to its own weight during concrete pouring.

[0040] Reference Figure 5 and Figure 6 The reinforcing mesh 4 comprises a double-layered, bidirectional reinforcing mesh tied to both the inner and outer sides of the steel structure frame 1. The reinforcing mesh uses HRB400 grade steel bars and is fixed to the steel structure frame 1 by positioning brackets.

[0041] Reference Figure 1 , Figure 6 and Figure 7 The concrete filling layer 5 is poured onto the bottom formwork 3, completely covering the steel structure frame 1 and the reinforcing mesh 4. In this embodiment, C40 grade micro-expansion compensating shrinkage concrete is selected to improve crack resistance. The total thickness of the concrete pouring is 400mm, of which the large square steel pipe 11 frame (200mm high) is located in the middle, and the concrete covers the upper and lower parts of the frame with a 100mm thick protective layer (Note: the thickness of the protective layer is not less than 60mm depending on the location).

[0042] Reference Figure 8 The top ring beam 13 is a box beam. The top box beam is made of high-strength thick plates welded into a rectangle, and then spliced ​​together from multiple rectangular beams. In this embodiment, the dome box beam has a diameter of 14.5m and is composed of 16 rectangular beams. Every 4 beams are assembled into a group, for a total of 4 groups.

[0043] The working principle of the steel-concrete composite conical shell structure in this application embodiment is as follows: It upgrades traditional pure concrete or pure steel structures to a "steel-concrete composite thin-walled conical shell structure." Its core principle utilizes a triangular grid steel frame 1 with extremely high spatial stiffness as a self-supporting system during construction, completely eliminating the reliance on full-span scaffolding or central support columns in traditional processes. During construction, the bottom formwork 3 is directly fixed to the steel frame 1 and hoisted along with the frame as a whole, achieving high-altitude formwork-free operation through the "ground assembly, integrated formwork hoisting" technique. In terms of geometric precision control, the use of a total station combined with a wire rope guide chain anti-pull device solves the problems of easy deformation and difficult alignment of large-span steel structures. In terms of structural stress, the steel frame 1 and concrete are combined through encapsulation, forming a collaborative whole. The steel provides tensile strength, while the concrete provides compressive strength and corrosion and fire protection, enabling the structure to withstand the enormous dynamic load of the upper trestle. The entire solution achieves efficient and safe construction of the roof of an ultra-large diameter silo.

[0044] This application also discloses a construction method for a steel-concrete composite conical shell structure.

[0045] A construction method for a steel-concrete composite conical shell structure includes the following steps: S1: Steel component factory processing and installation of embedded parts in the silo roof. In the factory, components such as square steel pipes, connecting plates, and purlins are cut, welded, rust-removed, and coated with anti-corrosion paint according to the design drawings. Simultaneously, when the silo wall construction reaches an elevation of 68.5m, the bottom embedded iron parts are precisely installed, and the elevation and position are verified.

[0046] S2: Ground assembly of the steel structure frame 1. Due to the 52m diameter of the steel conical shell, assembly was carried out on a leveled site below the warehouse. First, the bottom two layers of horizontal circumferential members 15 were installed, connected and positioned using bolts. Then, the longitudinal main diagonal beams 14 and web members 16 were installed. During assembly, a counter-tensioning device was used to adjust the position of the members. The counter-tensioning device consisted of an 8mm steel wire rope and a 1-ton manual chain guide. Construction personnel used a total station to measure the spatial coordinates and elevation of each node on each horizontal circle. If roundness deviations or elevation errors were found, radial or circumferential tension was generated by pulling the steel wire rope with the chain guide to make minor corrections to the member positions. After the total station verified that all node coordinates met the error requirements, formal welding of the nodes was carried out, ensuring "full weld within the node seam".

[0047] S3: Install purlin layer 2 and bottom formwork 3. After the steel structure frame 1 is welded, small square tube purlins 21 are welded to the inside of the frame at 250mm intervals. Then, a 2mm thick galvanized steel plate is laid at the bottom of the purlins. During laying, the steel plates overlap by 50mm, and an electric drill, galvanized dovetail wire, and shims are used to secure the steel plates to the purlins. This step is completed on the ground, avoiding extensive high-altitude formwork work.

[0048] S4: Overall Lifting. A 1600-ton crawler crane will be selected. A multi-point lifting method will be used, selecting multiple points around the top ring beam 13 for lifting. Before lifting, a support structure can be installed on the top ring beam 13 to increase its support capacity. The total lifting weight (including steel structure frame 1, purlins, bottom formwork 3, and lifting equipment) is approximately 300 tons. The assembled steel cone shell will be lifted as a whole to the top elevation of the silo. When the bottom ring beam 12 of the steel cone shell approaches the top of the silo, the guide frame will be lowered into place. After positioning, the bottom ring beam 12 will be firmly welded to the embedded parts of the silo top.

[0049] The supporting structure can be a grid beam, an I-beam, or a double-beam, which can increase the supporting force of the top ring beam.

[0050] S5: Lay the steel mesh 4. Tie a double-layer bidirectional steel mesh on both the inner and outer sides of the already positioned steel cone shell.

[0051] S6: Concrete Pouring. Concrete is delivered to the top of the formwork using a pump truck. Concrete is poured continuously and symmetrically in layers along the circumference to form the concrete filling layer 5. During pouring, the thickness is strictly controlled between 320mm and 400mm, ensuring that the concrete covers the steel frame 1 with a protective layer of at least 60mm on both the top and bottom. The concrete is formed using the supporting force of the galvanized steel plate bottom formwork 3.

[0052] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A steel-concrete composite conical shell structure, characterized in that, include: The steel structure frame (1) is shaped like a frustum and is made of multiple large square steel pipes (11) connected by nodes. The steel structure frame (1) includes a bottom ring beam (12), a top ring beam (13), and longitudinal main inclined beams (14), horizontal circumferential members (15), and web members (16) connected between the bottom ring beam (12) and the top ring beam (13). The purlin layer (2) includes multiple small square tube purlins (21) arranged in a circumferential direction. The small square tube purlins (21) are welded to the inner side of the members of the steel structure frame (1) and are spaced along the generatrix direction of the truncated cone. The bottom mold (3) is a galvanized steel plate laid on the bottom surface of the purlin layer (2), and the galvanized steel plate is connected to the small square tube purlin (21) by fasteners; The steel mesh (4) includes a double-layer bidirectional steel mesh tied inside and outside the steel structure frame (1); A concrete filling layer (5) is poured onto the bottom formwork (3) and covers the steel structure frame (1) and the steel mesh (4).

2. The steel-concrete composite conical shell structure according to claim 1, characterized in that, The horizontal circumferential members (15), longitudinal main inclined beams (14), and web members (16) of the steel structure frame (1) intersect each other, dividing the side of the truncated cone into multiple triangular regions.

3. A steel-concrete composite conical shell according to claim 1, characterized in that, The steel structure frame (1) is provided with connecting reinforcement plates at the nodes, and the connecting reinforcement plates are fixed to the adjacent members by bolt welding.

4. A steel-concrete composite conical shell according to claim 1, characterized in that, The small square tube purlins (21) are installed every 250 mm along the radial height direction of the steel structure frame (1), and each small square tube purlin (21) is welded to the member of the steel structure frame (1) by a connecting plate.

5. A steel-concrete composite conical shell according to claim 1, characterized in that, The thickness of the galvanized steel sheet is 2mm, the overlap length between adjacent galvanized steel sheets is not less than 50mm, and the fastener uses galvanized dovetail wire in conjunction with a gasket.

6. A steel-concrete composite conical shell according to claim 1, characterized in that, The top ring beam (13) is a box beam, which is made of high-strength thick plates welded into a rectangle, and then spliced ​​together by multiple rectangular beams, and is bolted and welded to the longitudinal main inclined beam (14) and the web member (16).

7. A construction method for a steel-concrete composite conical shell structure, used for fabricating a steel-concrete composite conical shell structure as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Steel component factory processing and installation of embedded parts on the silo roof; S2: Steel structure frame (1) Ground assembly, the large square steel pipe (11) is bolted and positioned according to the design nodes and then corrected, and then the nodes are welded; S3: Install the purlin layer (2) and the bottom formwork (3), weld the small square tube purlins (21) to the inside of the steel structure frame (1) on the ground, and install galvanized steel plates at the bottom of the purlins; S4: Overall hoisting, using lifting equipment to lift the assembled steel cone shell to the top elevation of the warehouse, lower it into place, and weld it to the embedded parts; S5: Lay out the steel mesh (4), and tie a double layer of bidirectional steel mesh on both the inner and outer sides of the steel cone shell; S6: Concrete pouring, concrete is poured continuously in layers along the circumference to form a concrete filling layer (5).

8. The construction method for a steel-concrete composite conical shell structure according to claim 7, characterized in that, In step S2, a counter-pull device is used to adjust the position of the rod. The counter-pull device includes a steel wire rope and a guide chain. The precise positioning is achieved by measuring the coordinates and elevation of the nodes on each horizontal circle.

9. The construction method of a steel-concrete composite conical shell structure according to claim 7, characterized in that, In step S6, the concrete pouring thickness is 320mm-400mm, and the concrete covers the steel structure frame (1) with a protective layer of not less than 60mm on both the top and bottom.

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