Steel-concrete mixed steel tower drum and concrete tower drum switching node device

Abstract

The invention discloses a steel-concrete mixed type steel tower drum and concrete tower drum switching node device. Comprising the steps that prestressed long bolts penetrating from the outside to the inside and internal prestressed steel strands are jointly stressed, the prying force is small, the node rigidity is high, and the node can be maintained in the wall of the steel tower tube and the concrete tower tube of the steel-concrete mixed wind power generation tower. The problems that two common conversion nodes in the current industry are insufficient in torsional shear resistance bearing capacity, have defects in structure, and are complex in force transmission of an anchor bolt and an anchor plate can be solved. According to the invention, one end of the prestressed long bolt in the conversion node is located outside the steel tower drum, and the other end is located inside the drum wall of the conversion section, so that the prying force between the bottom section flange of the steel tower drum and the upper surface of the conversion section can be reduced through combined action with the prestressed steel strand, and the rigidity of the conversion node is ensured.

Description

Technical Field

[0001] This invention relates to the technical field of structural engineering, and in particular to a steel-concrete hybrid steel tower and concrete tower conversion node device. Background Technology

[0002] The steel-concrete hybrid wind turbine tower consists of a traditional steel tower upper section and a precast concrete tower lower section. It offers excellent structural rigidity and economy, making it a preferred solution for high-wind-power towers in low-wind-speed areas. Steel and concrete are two building materials with significantly different physical properties; steel's modulus of elasticity and specific strength are much higher than concrete's. Therefore, a transfer node is crucial for smoothly and effectively transferring the load from the upper steel tower to the lower concrete tower, ensuring that the two materials can work together to bear the load. This transfer node is the most critical and core part of the entire hybrid tower design. Currently, there are two common types of transfer node structures in the industry, one for steel towers and one for concrete towers. (See below for details.) Figure 1 and Figure 2 . Figure 1 The node shown has been used for the longest time in the mixed-use tower industry. A thick steel plate is placed at the top of the concrete transfer section, directly contacting the bottom flange of the steel tower. The upper end of the prestressed steel strands of the concrete tower is anchored to the bottom flange of the steel tower, and the lower end is anchored to the foundation, thus connecting the two different building materials, steel and concrete. Because the wall thicknesses of the steel tower, concrete tower, and transfer section are all different, a cone angle of approximately 15 degrees is needed on the inner side of the transfer section wall for smooth force transmission and to reduce stress concentration. This connection method is simple in structure, convenient in construction, and provides direct force transmission; therefore, many early mixed-use towers adopted this connection method.

[0003] However, as the unit capacity increases, the tower height also increases, and the bending moment and torque at the transfer node become larger. Under extreme load conditions, the bottom flange of the steel tower may detach from the top steel plate of the transfer section, causing a significant decrease in the torsional shear bearing capacity of the contact surface and resulting in slippage. Therefore, the industry has seen... Figure 2 The connection method shown refers to ensuring a reliable connection at the transition node using anchor bolts. In this method, the upper end of the anchor bolt is anchored to the bottom flange of the steel tower section, and the lower end has an anchor plate pre-embedded in the concrete transition section. The anchoring force of the anchor bolt is provided by the contact pressure between the anchor plate and the concrete, resulting in significant stress concentration near the anchor plate. Under ultimate load conditions, rainwater may enter the anchor bolt hole after the contact surface opens, and long-term operation of the wind turbine may wear down the concrete near the anchor plate, leading to anchor failure. Similarly, since the wall thicknesses of the steel tower, concrete tower, and transition section are different, a similar anchor is generally placed on the inner side of the transition section wall to ensure smooth stress transfer and reduce stress concentration. Figure 1 The conversion is performed using the cone angle in node 1, typically around 45 degrees. This approach is consistent with [previous methods] in terms of construction and force transmission mechanism. Figure 3 The foundation ring foundation shown is very similar to those that have been phased out in the industry and suffer from widespread quality problems. Furthermore, this type of anchor plate divides the concrete tower into inner and outer sections. During factory prefabrication, long shrinkage cracks often appear on the outer side of the tower wall. Many tower manufacturers can only use carbon fiber to completely wrap the concrete transition section, but in reality, the stress in this area is very complex. This method of external carbon fiber wrapping can only cover the cracks on the outer wall of the transition section, but it cannot solve the structural and force transmission defects near the lower anchor plate. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a steel-concrete hybrid steel tower and concrete tower transition joint device, which solves the industry pain points such as insufficient torsional shear bearing capacity, structural defects, and complex force transmission of anchor plates under anchor bolts in the two common transition joints currently used in the industry. To achieve the above-mentioned objectives and other advantages of the present invention, a steel-concrete hybrid steel tower and concrete tower transition joint device is provided, comprising: The steel tower, the transition section fixedly connected to the steel tower, and the stress connection assembly for connecting the steel tower and the transition section, wherein the stress connection assembly includes a long bolt PVC sleeve pre-embedded in the transition section, a prestressed long bolt matching the long bolt PVC sleeve, and a pre-embedded steel plate pre-embedded in the transition section. The fixed anchoring end of the prestressed long bolt extends from the inside of the cylinder wall of the transition section and is located on the outside of the cylinder wall of the steel tower, while the other end, the nut anchoring end, is located on the inside of the cylinder wall of the transition section, thereby making the prestressed long bolt tilted relative to the vertical direction during installation. The inner side of the cylinder wall of the conversion section is provided with multiple prestressed steel strands.

[0005] Preferably, the steel tower and the transition section are fixedly connected by a specially made high-neck flange, and the upper surface of the specially made high-neck flange has an inclined surface at the position of the prestressed long bolt, the inclined surface being used for anchoring one end of the prestressed long bolt.

[0006] Preferably, the lower end of the inner wall of the transition section is provided with a tapered angle.

[0007] Preferably, a pre-embedded steel plate and a wedge-shaped gasket are pre-embedded at the lower end of the inner wall of the transition section, at the location of the prestressed long bolt.

[0008] Preferably, the prestressed long bolts and prestressed steel strands are not bonded within the transition section.

[0009] Preferably, the prestressed steel strand is located inside the steel tower, and the transition section has a plurality of evenly arranged bolt holes, which are located on the outside of the steel tower.

[0010] Compared with the prior art, the advantages and positive effects of the present invention are: 1. The proposed novel conversion node between the steel and concrete tower sections of a steel-concrete hybrid wind power generation tower completely solves the problems of structural defects, stress concentration, and shrinkage cracks that may occur during the prefabrication process of current conversion nodes with anchor bolts.

[0011] 2. The proposed novel conversion node between the steel tower and the concrete tower in the steel-concrete hybrid wind power generation tower uses prestressed long bolts with the upper end on the outside of the steel tower and the lower end on the inside of the hybrid tower, which is convenient to install and allows for maintenance inside the tower.

[0012] 3. The proposed novel conversion node for steel-concrete hybrid wind power towers, which combines the steel tower and concrete tower sections, exhibits low prying force between the flange surface and the conversion section surface, resulting in high node stiffness. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of a common conversion node 1 in the steel-concrete hybrid steel tower and concrete tower conversion node device according to the present invention; Figure 2 This is a schematic diagram of a common conversion node 2 in the steel-concrete hybrid steel tower and concrete tower conversion node device according to the present invention; Figure 3 This is a schematic diagram of the ring foundation of the steel-concrete hybrid steel tower and concrete tower conversion node device according to the present invention; Figure 4 A schematic diagram of a novel conversion node for the steel-concrete hybrid steel tower and concrete tower conversion node device according to the present invention; Figure 5 This is a schematic diagram of the prestressed long bolt of the steel-concrete hybrid steel tower and concrete tower conversion node device according to the present invention; Figure 6 This is a schematic diagram showing the relative relationship between the bottom flange of the steel tower and the upper surface of the transition section in the steel-concrete hybrid steel tower and concrete tower conversion node device according to the present invention.

[0014] The following are the labels in the diagram: 1. Steel tower, 2. Concrete tower, 3. Transfer section, 4. Prestressed long bolt, 5. Long bolt PVC sleeve, 6. Prestressed steel strand, 7. Special high neck flange, 8. Flange conical surface, 9. Inner bottom conical surface of transfer section, 10. Embedded steel plate, 11. Equal thickness round steel gasket, 12. Variable thickness wedge gasket, 13. Nut, 14. Prestressed steel strand hole, 15. Prestressed long bolt hole. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Reference Figure 4 The conversion node proposed in this invention is mainly in Figure 2 Based on the existing design, the anchor bolts that needed to be pre-embedded in the concrete were replaced with prestressed long bolts 4 that do not require pre-embedding. However, a PVC sleeve 5 needs to be pre-embedded in the transition section 3 at the location of the prestressed long bolts 4. A steel-concrete hybrid steel tower and concrete tower transition node device includes: The steel tower 1, the transition section 3 fixedly connected to the steel tower 1, and the stress connection assembly for connecting the steel tower 1 and the transition section 3, wherein the stress connection assembly includes a long bolt PVC sleeve 5 pre-embedded in the transition section 3, a prestressed long bolt 4 matching the long bolt PVC sleeve 5, and a pre-embedded steel plate 10 pre-embedded in the transition section 3. The fixed anchoring end of the prestressed long bolt 4 extends from the inside of the cylinder wall of the transition section 3 and is located on the outside of the cylinder wall of the steel tower cylinder 1, while the nut anchoring end is located on the inside of the cylinder wall of the transition section 3, thereby making the prestressed long bolt 4 tilted relative to the vertical direction during installation. Multiple prestressed steel strands 6 are arranged around the inner side of the cylinder wall of the transition section 3. The steel tower 1 and the transition section 3 are connected by a specially made high-neck flange 7. The upper end of the prestressed steel strand 6 is anchored to the specially made high-neck flange 7 of the steel tower 1 and located on the inner side of the cylinder wall. The prestressed long bolts 4 and the prestressed steel strands 6 are respectively set on the inner and outer sides of the cylinder wall of the steel tower 1, which can improve the stress state of the flange 7 and ensure that the specially made high-neck flange 7 will not detach from the top surface of the transition section on a large scale under the ultimate load condition, thereby improving the stiffness and torsional shear bearing capacity of the transition node.

[0017] Furthermore, in order to anchor the upper end of the prestressed long bolt 4 to the outside of the steel tower 1 and the lower end to the inside of the transition section 3, the upper surface of the specially made high neck flange 7 has an inclined surface 8 at the position of the prestressed long bolt 4. The inclined surface 8 is used for the anchoring installation of one end of the prestressed long bolt 4.

[0018] Furthermore, the lower end of the inner wall of the transition section 3 is provided with a cone angle 9 to alleviate stress concentration and to anchor the nut at the lower end of the prestressed long bolt 4.

[0019] like Figure 5As shown, a uniform thickness round steel pad 11 is provided at the upper end of the prestressed long bolt 4. The uniform thickness round steel pad 11 is located between the upper end of the prestressed long bolt 4 and the inclined surface 8. At the lower end of the inner wall of the transition section 3, at the position of the prestressed long bolt 4, a pre-embedded steel plate 10 and a wedge-shaped washer 12 are pre-embedded. The inclination angle of the wedge-shaped washer 12 needs to be controlled within a certain angle according to the friction coefficient of the friction surface to achieve self-locking, or the angle of the wedge-shaped washer 12 needs to be determined according to the inclination angle of the prestressed long bolt. The lower end of the prestressed long bolt 4 also includes a nut 13, which is fixed to the inner side of the cylinder wall of the transition section 3 to facilitate the installation and maintenance of the prestressed long bolt 4.

[0020] like Figure 6 As shown, a ring of evenly spaced bolt holes 15 is provided on the transition section 3 and on the outer side of the steel tower 1, and a ring of prestressed steel strand holes 14 is provided on the transition section 3 and on the inner side of the steel tower 1.

[0021] Furthermore, the prestressed long bolt 4 and the prestressed steel strand 6 are not bonded together within the transition section 3.

[0022] In summary, the prestressed long bolts in the transition node of this application have one end located on the outside of the steel tower and the other end located on the inside of the transition section wall. Together with the prestressed steel strands, they can reduce the prying force between the bottom flange of the steel tower and the upper surface of the transition section, thus ensuring the rigidity of the transition node.

[0023] Example: In specific implementation, the shapes of the steel tower 1 and concrete tower 2 of the steel-concrete hybrid wind turbine tower should first be determined through calculation and analysis based on the load provided by the main engine manufacturer. Then, the geometric dimensions of the transition section 3 should be determined based on the load at the transition node. The diameter and number of prestressed long bolts 4 should be determined through finite element analysis, and the inclination angle of the prestressed long bolts 4, the inclination angle of the outer conical surface of the special high-neck flange 7, and the inclination angle of the inner wall conical surface 9 of the transition section should be determined through spatial layout. In practice, the diameter and number of bolts will vary depending on the wind turbine model, and the relevant calculations should follow the general calculation method for flange bolts. During the prefabrication of the transition section 3 in the factory, the long bolts 4 and the PVC sleeves 5 and wedge gaskets 12 on the outside of the prestressed steel strands 6 should be pre-embedded, and the position of the reserved ducts should be ensured by special tooling. The special high-neck flange 7 is a high-neck flange with the outer side ground. It needs to be welded to the steel tower 1 in the steel structure processing plant and subjected to anti-corrosion treatment before being transported to the site.

[0024] Furthermore, after the transition section 3 is transported to the site, it is positioned on the ground fixtures. Then, the bottom steel tower section 1 is lifted for the transition node assembly. First, the equal-thickness round steel pads 11 are fitted onto the prestressed long bolts 4. Then, they are inserted into the inner wall of the transition section 3 through the bolt holes 15. Next, wedge-shaped washers 12 are fitted and the angle is adjusted. Nuts 13 are then tightened. After all the prestressed long bolts 4 are installed, pre-tensioning of the prestressed long bolts 4 begins, with a tension force of 60-70% of the design value. Then, the prestressed steel strands 6 are threaded from top to bottom through the prestressed steel strand holes 14 pre-embedded in the transition section 3 on the ground. The installation of the concrete tower 2 can be carried out simultaneously with the assembly of the transition node. After the concrete tower 2 is assembled, epoxy resin adhesive or grout is applied to the upper horizontal joint for leveling. Then, the entire transition node is lifted onto the concrete tower 2 and positioned. The bottom end of the prestressed steel strands 6 is anchored to the bottom foundation, and then the prestressed steel strands 6 are tensioned. After the prestressed steel strands 6 are tensioned, the prestressed long bolts 4 are tensioned a second time to the design preload. This completes the construction of the entire transfer node.

[0025] The number of devices and processing scale described herein are for simplification of the invention. Applications, modifications, and variations of this invention will be readily apparent to those skilled in the art. Although embodiments of the invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for this invention, and further modifications can be readily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, this invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A steel-concrete hybrid steel tower and concrete tower transition node device, characterized in that, include: The steel tower (1), the transition section (3) fixedly connected to the steel tower (1), and the stress connection assembly for connecting the steel tower (1) and the transition section (3) include a long bolt PVC sleeve (5) pre-embedded in the transition section (3), a prestressed long bolt (4) matching the long bolt PVC sleeve (5), and a pre-embedded steel plate (10) pre-embedded in the transition section (3). The fixed anchoring end of the prestressed long bolt (4) extends from the inside of the cylinder wall of the transition section (3) and is anchored to the outside of the cylinder wall of the steel tower (1), while the other end, the nut anchoring end, is located inside the cylinder wall of the transition section (3), thereby making the prestressed long bolt (4) tilted relative to the vertical direction during installation. Multiple prestressed steel strands (6) are arranged around the inner side of the cylinder wall of the transition section (3).

2. The steel-concrete hybrid steel tower and concrete tower transition node device as described in claim 1, characterized in that, The steel tower (1) and the transition section (3) are fixedly connected by a special high neck flange (7), and the upper surface of the special high neck flange (7) has an inclined surface at the position of the prestressed long bolt (4), which is used for the anchoring installation of one end of the prestressed long bolt (4).

3. The steel-concrete hybrid steel tower and concrete tower transition node device as described in claim 1, characterized in that, The lower end of the inner wall of the transition section (3) is provided with a cone angle (9).

4. The steel-concrete hybrid steel tower and concrete tower transition node device as described in claim 1, characterized in that, The lower end of the inner wall of the transition section (3) is pre-embedded with a steel plate (10) and a wedge-shaped gasket (12) at the position of the prestressed long bolt (4).

5. The steel-concrete hybrid steel tower and concrete tower transition node device as described in claim 1, characterized in that, The prestressed long bolt (4) and the prestressed steel strand (6) are not bonded within the transition section (3).

6. The steel-concrete hybrid steel tower and concrete tower conversion node device as described in claim 1, characterized in that, The prestressed steel strand (6) is located inside the steel tower (1), and the transition section (3) is provided with a plurality of evenly arranged bolt holes (15), which are located on the outside of the steel tower (1).

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