A method of installing a building tower crown to overcome wind-induced vibrations

Abstract

The present application relates to the field of on-site preparation, handling or processing of building materials or building components, and discloses a building tower crown installation method for overcoming wind-induced vibration, which is characterized by setting column-circumference cables around a main column to resist bending of the main column, so that the main column exhibits the characteristics of a rigid structure. When wind-induced vibration occurs, the position with the largest amplitude is fixed, and then a tuned mass damper is installed at the position with the largest amplitude, so that the damper can play a more effective role, and the required volume and self-weight are greatly reduced. Because the damper is small and light, and two sets of energy dissipation systems respectively for low-frequency vibration of the main column are built by using prestressed cables and components of the tower crown itself, the building tower crown can resist wind without increasing weight. The entire building tower crown is very light, allowing the annular horse path and the damper to be pre-installed in the main column and the main column to be hoisted in sections, and then using the annular horse path and its guardrails as a work platform, without the need for additional high-altitude work platforms and protective structures.

Description

Technical Field

[0001] This invention relates to the field of on-site preparation, handling or processing of building materials or building components, and in particular to a method for installing building tower crowns to overcome wind-induced vibrations. Background Technology

[0002] A tower crown, as the name suggests, is the "hat" of a tower-style high-rise building, placed on top of the building for decorative purposes. An antenna tower crown is a type of tower crown that combines the functions of a tower crown and an antenna. The main body of an antenna tower crown consists of one or more steel structural columns mounted on a base, sometimes with additional crossbeams.

[0003] Due to the significant wind load on the tops of high-rise buildings, antenna tower crowns require a series of prestressed cables and other structures to resist wind. Sometimes, the structure alone is insufficient to withstand the wind load, necessitating the use of dampers. The most commonly used damper in buildings is the tuned mass damper (TMD damper), characterized by its heavy counterweight. When used in antenna tower crowns, it is typically installed at the base of the antenna or even inside the building.

[0004] With the development of modern fluid dynamics technologies such as CFD, the vibrations caused by wind loads on antenna tower crowns have been studied more thoroughly. Taking the Hytera Global Headquarters Tower crown, as an example, this invention utilizes CFD technology and wind tunnels to accurately calculate the amplitude of wind-induced vibrations at different locations and potential extreme situations, allowing for the targeted installation of dampers. By calculating and placing the damper at the location of maximum amplitude, and combining it with a frequency-adjustable eddy current damper, the required size and weight of the damper can be significantly reduced. This theoretically allows the damper to be integrated with the building's tower crown assembly, eliminating the need for separate installation and significantly lowering costs.

[0005] However, the location of the maximum wind-induced vibration amplitude on the antenna tower crown is not necessarily fixed. If the main body of the antenna tower crown were a rigid rod, then the location of the maximum wind-induced vibration amplitude would be fixed, and usually at the top. However, the excessive length of the antenna tower crown means that it cannot be considered a rigid rod, which means that the location of the maximum vibration amplitude may be different each time, making it impossible to accurately install the damper at the location of the maximum amplitude.

[0006] Relying solely on the structural strength of the antenna tower crown to resist wind loads without dampers presents another challenge. The antenna tower crown already houses numerous electronic devices, as well as walkways, ladders, and other auxiliary structures for easy maintenance. These components result in a significant overall weight for the antenna tower crown, making it difficult to hoist as a whole; it requires either in-situ assembly at height or assembly at height followed by jacking into place. If the antenna tower crown's structural strength is relied upon to resist wind loads, further reinforcement is needed, increasing its weight and raising the requirements for high-altitude work platforms and corresponding protective measures. Summary of the Invention

[0007] This invention provides a method for installing building tower crowns to overcome wind-induced vibrations.

[0008] The technical problem to be solved is that the auxiliary structure results in a large overall weight of the antenna tower crown. At the same time, in order to meet the wind resistance requirements, the antenna tower crown must either be equipped with a heavy damper or its strength must be significantly increased, which greatly increases the construction cost of the antenna tower crown.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for installing a building tower crown to overcome wind-induced vibration, which is used to avoid harmful vibrations, including vortex-induced vibrations, of the building tower crown under wind load. The building tower crown is an antenna tower crown, which includes a base and a main column inserted into the middle of the base and fixedly connected to the base.

[0010] The installation method includes the following steps:

[0011] Step 1: Determine the location with the largest vibration amplitude in the tower crown through simulation, and record it as the installation location of the damper;

[0012] Step 2: Design and install a maintenance system on the main column. The maintenance system includes a ring-shaped walkway that is spaced vertically on the main column and fixedly connected to the main column, and a ladder that is set between two adjacent ring-shaped walkways to connect the two ring-shaped walkways. The ring-shaped walkway is an elastic element. Multiple column-circumferential cables are set between two adjacent ring-shaped walkways and spaced around the main column. The column-circumferential cables are prestressed cables whose upper and lower ends are respectively connected to the upper and lower ring-shaped walkways.

[0013] Step 3: Design the main column segmentation scheme, dividing the main column and installation and maintenance system into multiple prefabricated sections, with the self-weight of each section not exceeding the maximum lifting capacity of the hoisting equipment;

[0014] Step 4: Pre-install the tuned mass damper at the damper installation location, and assemble the main column and installation and maintenance system into prefabricated segments on the ground according to the cutting plan in Step 3.

[0015] Step 5: Assemble the base:

[0016] Step Six: Install the main columns segment by segment, and use the installation and maintenance system as a work platform to complete the connection of the main columns. Then, use the installation and maintenance system as a work platform to install the column circumferential cables between the prefabricated segments, and complete the tensioning of all column circumferential cables.

[0017] Furthermore, the annular walkway is fixedly connected to the main column by connecting rods. Each connecting rod has ear plates welded to its upper and lower surfaces, which serve as both lifting lugs and connection points for prestressed cables. The number of connecting rods in each layer of the annular walkway is the same and they are aligned vertically.

[0018] Furthermore, the stay cables located in the prefabricated segments are tensioned during the ground assembly stage, and the column-circumferential stay cables between the prefabricated segments are tensioned in situ.

[0019] Furthermore, the main column is a variable-diameter steel column whose cross-section gradually decreases from bottom to top. The variable-diameter steel column contains three segments with different cross-sections, which are respectively called the foundation segment, the limiting segment, and the top segment from bottom to top.

[0020] In step three, the portion of the base section above the base is divided into a prefabricated segment;

[0021] In step four, when assembling the prefabricated segments corresponding to the base section, only the connecting rods and lugs are installed;

[0022] In step six, after the foundation section is hoisted and connected to the base, the circular walkway is assembled layer by layer in situ from bottom to top. Then, the column circumferential cables are installed and tensioned. When assembling the circular walkway, the circular walkway or base below is used as a construction platform.

[0023] Furthermore, the base is divided into upper and lower layers, which are connected by columns around the base. The upper part of the base is a three-dimensional truss composed of elastic rods, and is referred to as the elastic suspended layer. The limiting section is connected to the edge of the elastic suspended layer by a stay cable. The stay cable is a prestressed cable arranged radially around the main column. The stay cable, the elastic suspended layer and the main column are combined to form an energy dissipation system for converting the vibration of the main column into deformation in the elastic suspended layer.

[0024] Furthermore, in step five, the portion of the main column's foundation section located in the base is assembled together with the base as a whole. During the assembly of the base, temporary supports are installed below the elastic suspension layer, and these supports are removed immediately after the base is assembled.

[0025] The stay cables are installed in step six. The stay cables are installed immediately after the prefabricated sections at their upper ends are installed, and tensioning is completed after all the components of the tower crown are installed.

[0026] Furthermore, when the damper is installed at the top of the main column, the tuned mass damper is an eddy current damper and is pre-installed inside the main column.

[0027] The present invention provides a method for installing building tower crowns to overcome wind-induced vibrations, which has the following advantages compared with the prior art:

[0028] In this invention, by setting a circumferential cable around the main column to resist the bending of the main column, the main column exhibits the characteristics of a rigid structure. When wind-induced vibration occurs, the position with the largest amplitude is fixed, and then a tuned mass damper is installed at the position with the largest amplitude, so that the damper can play a more effective role, and the required volume and self-weight are greatly reduced.

[0029] In this invention, the column-circumferential cables and the elastic ring-shaped walkway are combined to form an energy-dissipating system that converts the high-frequency vibration of the main column (small amplitude and high frequency in a single energy-dissipating system) into elastic deformation in the ring-shaped walkway. The inclined cables, the elastic suspension layer, and the main column are combined to form an energy-dissipating system that converts the low-frequency vibration of the main column (large amplitude and low frequency in a single energy-dissipating system) into elastic deformation in the elastic suspension layer. This significantly improves the ability of the building's tower crown to resist wind-induced vibrations without increasing its weight.

[0030] In this invention, because the damper is small and light, and the energy is dissipated by the prestressed cables and the components of the tower crown itself, the entire tower crown is very light. This allows the circular walkway and damper to be pre-installed in the main column and the main column to be hoisted in sections. Then, the circular walkway and its guardrails are used as a working platform, eliminating the need to build an additional high-altitude working platform and protective structure. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the building's tower crown;

[0032] Figure 2 This is a schematic diagram of the base assembly.

[0033] Figure 3 This is a schematic diagram of the basic section installation. To more clearly show its main structure, the guardrails and ladders have been removed from the diagram. The same applies below.

[0034] Figure 4 This is a schematic diagram showing the connection between the basic segment and the limiting segment;

[0035] Figure 5 This is a schematic diagram of the installation of the stay cables;

[0036] Figure 6 This is a schematic diagram showing the completed assembly of the building's tower crown.

[0037] Figure 7 This is a schematic diagram of prefabricated segments being assembled on the ground.

[0038] Figure 8 This is a schematic diagram showing the relative positions of the circular walkway and the perimeter cables.

[0039] In the diagram, 1-base, 11-elastic suspended layer, 2-main column, 3-circular walkway, 4-column cable, 5-stayed cable, 6-tuned mass damper, 7-guardrail, 8-connecting rod, 9-ladder. Detailed Implementation

[0040] Taking Hytera's global headquarters building as an example, a method for installing a building crown to overcome wind-induced vibration is used to avoid harmful vibrations, including vortex-induced vibrations, in the building crown under wind load. The building crown is an antenna crown, including a base 1 and a main column 2 inserted in the middle of the base 1 and fixedly connected to the base 1. Note that the main column 2 cannot penetrate into the lower layer of the base 1, otherwise it will affect energy consumption.

[0041] The installation method includes the following steps:

[0042] Step 1: Determine the location with the largest vibration amplitude in the tower crown through simulation, and record it as the installation location of the damper;

[0043] In this embodiment, a wind tunnel was used to simulate the acceleration of the Hytera building's crown under common wind speeds. The results show that at four common wind speeds on the building's roof, the peak acceleration of the crown ranged from approximately 0.25 to 0.5 m / s², indicating significant vibration. Furthermore, vortex-induced vibration may also occur under extreme wind conditions. The largest amplitude vibration was observed at the top section of the crown.

[0044] Step 2: Design and install an inspection system on the main column 2. The inspection system includes a ring-shaped walkway 3 that is spaced vertically on the main column 2 and fixedly connected to the main column 2, and a ladder 9 that is set between two adjacent ring-shaped walkways 3 and used to connect the two ring-shaped walkways 3. The ring-shaped walkway 3 is an elastic element. Multiple column-circumferential cables 4 are set between two adjacent ring-shaped walkways 3 and spaced around the main column 2. The column-circumferential cables 4 are prestressed cables whose upper and lower ends are respectively connected to the upper and lower ring-shaped walkways 3.

[0045] In this embodiment, the circular walkway 3 uses an elastic circular steel pipe beam as the main load-bearing component, with planks welded on top and guardrails 7 welded around its perimeter. When the main column 2 experiences small vibrations, the circular steel pipe beam undergoes periodic elastic deformation under the traction of the perimeter cables 4, converting mechanical energy into the internal energy of the circular steel pipe beam. Note that expansion joints must be provided for both the guardrails 7 and the planks to prevent damage to the circular steel pipe beam during deformation.

[0046] Step 3: Design a segmentation scheme for main column 2, dividing main column 2 and the installation and maintenance system into multiple prefabricated segments, with the self-weight of each segment not exceeding the maximum lifting capacity of the hoisting equipment;

[0047] The maximum lifting capacity of all hoisting equipment that can reach the roof is relatively small. In this embodiment, a small tower crane on the roof is used as the hoisting equipment. However, due to the limited load-bearing capacity of the roof, it cannot meet the requirement of hoisting the entire main column 2 at one time. Therefore, it is necessary to assemble each prefabricated segment on the ground, and then transport them to the roof with the help of a ground tower crane or construction elevator, and then hoist them with the help of the tower crane on the roof.

[0048] like Figure 7As shown, step four: pre-install the tuned mass damper 6 at the damper installation location, and according to the cutting scheme in step three, assemble the main column 2 and the installation and maintenance system into prefabricated segments on the ground; here, the circular walkway 3 and other auxiliary components are pre-placed on the main column 2 on the ground.

[0049] like Figure 2 As shown, Step 5: Assemble base 1:

[0050] The base 1 is assembled in situ, but due to its low height, no high-altitude work platform is needed. However, for the subsequent tensioning of the stay cables 5, a small temporary support frame needs to be installed between the upper and lower layers of the base 1, such as... Figure 2 As shown, the temporary support frame is set below the main column 2.

[0051] like Figure 3-6 As shown, step six: install the main column 2 segment by segment, and use the installation and maintenance system as the work platform to complete the connection of the main column 2. Then, use the installation and maintenance system as the work platform to install the prefabricated column circumferential cables 4 between the segments, and complete the tensioning of all column circumferential cables 4.

[0052] Of the column-circumferential cables 4 here, the one located between the two prefabricated sections is tensioned in situ at high altitude, while the remaining cables 4 are tensioned during the ground assembly stage. Although there is a circular walkway 3 serving as a working platform for high-altitude tensioning, it is still more convenient to perform tensioning on the ground. The connection of the main columns 2 uses a conventional steel column connection method, with double-clamp plates for fixing and then butt welding. If necessary, temporary support frames can be erected on the walkway to assist in fixation.

[0053] like Figure 8 As shown, the circular walkway 3 is fixedly connected to the main column 2 by connecting rods 8. Each connecting rod 8 has ear plates welded to its upper and lower surfaces, which serve as both lifting lugs and prestressed cable connection points. The number of connecting rods 8 in each layer of the circular walkway 3 is the same and they are aligned vertically.

[0054] The "ear plate, which simultaneously serves as a lifting lug and a connection point for prestressed cables," means that during the precast segment hoisting, the upper ear plate is used as a lifting lug, and also as a connection point for the prestressed cables such as the column-circumferential cables 4 and the inclined cables 5. The connecting rod 8 needs to be aligned vertically to ensure that the column-circumferential cables 4 are aligned vertically.

[0055] Main column 2 is a variable diameter steel column whose cross-section gradually decreases from bottom to top. The variable diameter steel column contains three segments with different cross-sections, which are respectively called the foundation segment, the limiting segment, and the top segment from bottom to top.

[0056] Unlike conventional steel columns, the various loads on main column 2 are not located at the top of main column 2, but on its side. Therefore, the load-bearing capacity requirements at different locations on main column 2 vary, necessitating the use of variable-diameter steel columns. Of the three sections, the limiting section needs to be connected to the stay cable 5, hence its name.

[0057] In step three, the portion of the foundation section above base 1 is divided into a prefabricated segment; in step four, when assembling the prefabricated segment corresponding to the foundation section, only the connecting rod 8 and ear plate are installed; in step six, after the foundation section is hoisted and connected to base 1, the circular walkway 3 is assembled layer by layer from bottom to top in situ, and then the column circumferential cable 4 is installed and tensioned. When assembling the circular walkway 3, the circular walkway 3 below or base 1 is used as the construction platform.

[0058] The steel columns of the foundation section and the accompanying circular walkway 3 are very large. If the circular walkway 3 is pre-installed in the prefabricated section, it needs to be cut very short, which is not as advantageous as high-altitude in-situ assembly, since the foundation section can be directly assembled using the base 1 as a working platform. However, the connecting rod 8 and the ear plate still need to be pre-installed in the prefabricated section to meet the hoisting requirements.

[0059] The base 1 is divided into upper and lower layers, which are connected by columns around the base 1. The upper part of the base 1 is a three-dimensional truss made of elastic rods, and is referred to as the elastic suspended layer 11. The limiting section is connected to the edge of the elastic suspended layer 11 by a cable 5. The cable 5 is a prestressed cable arranged radially with the main column 2 as the center. The cable 5, the elastic suspended layer 11 and the main column 2 are combined to form an energy dissipation system for converting the vibration of the main column 2 into the deformation of the elastic suspended layer 11.

[0060] To meet the stress characteristics of the upper part of the base 1, the rods of the upper part of the base 1 need to be arranged in a radial, obliquely upward pattern with the main column 2 as the center.

[0061] In step five, the portion of the main column 2 located in the base 1 is assembled together with the base 1 as a whole. During the assembly process, temporary supports are set under the elastic suspension layer 11 of the base 1, and these supports are removed immediately after the base 1 is assembled, so that the elastic suspension layer 11 is suspended, which facilitates subsequent tensioning.

[0062] The stay cable 5 is installed in step six. The stay cable 5 is installed immediately after the prefabricated segment at its upper end is installed, and tensioning is completed after all the components of the tower crown are installed.

[0063] Here, the stay cables 5 act as guy ropes before tensioning is complete; they only need to be tightened, and tensioning them to the set tension should be done last. At this time, it is also necessary to check the tension of each column-circumferential cable 4. If any does not meet the set value, it should be adjusted to the set value. Note that the column-circumferential cables 4 located in the foundation section should be installed and tensioned segment by segment from top to bottom to avoid excessive deformation of the base 1 during the installation and tensioning process.

[0064] When the damper is installed at the top of the main column 2, the tuned mass damper 6 is an eddy current damper and is pre-installed inside the main column 2.

[0065] Here, the eddy current damper is suspended under the bracket inside the top of the main column 2, and sealed with a head above.

[0066] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for installing a building tower crown to overcome wind-induced vibration, used to prevent harmful vibrations, including vortex-induced vibrations, from occurring on the building tower crown under wind load, characterized in that: The building tower crown is an antenna tower crown, including a base (1) and a main column (2) inserted in the middle of the base (1) and fixedly connected to the base (1). The installation method includes the following steps: Step 1: Determine the location with the largest vibration amplitude in the tower crown through simulation, and record it as the installation location of the damper; Step 2: Design and install a maintenance system on the main column (2). The maintenance system includes a ring-shaped walkway (3) that is vertically spaced on the main column (2) and fixedly connected to the main column (2), and a ladder (9) that is set between two adjacent ring-shaped walkways (3) and used to connect the two ring-shaped walkways (3). The ring-shaped walkway (3) is an elastic element. Multiple column-circumferential cables (4) are set between two adjacent ring-shaped walkways (3) and spaced around the main column (2). The column-circumferential cables (4) are prestressed cables whose upper and lower ends are respectively connected to the upper and lower ring-shaped walkways (3). The lowest column-circumferential cable (4) extends downward and connects to the base (1). Step 3: Design the main column (2) segmentation scheme, divide the main column (2) and the installation and maintenance system into multiple prefabricated segments as a whole, and the self-weight of each segment shall not exceed the maximum lifting weight of the hoisting equipment; Step 4: Pre-install tuned mass dampers (6) at the damper installation location, and assemble the main column (2) and the installation and maintenance system into prefabricated segments on the ground according to the segmentation scheme in Step 3; Step 5: Assemble the base (1): Step 6: Install the main column (2) segment by segment, and use the installation and maintenance system as the working platform to complete the connection of the main column (2). Then, use the installation and maintenance system as the working platform to install the column circumferential cables (4) between the prefabricated segments, and complete the tensioning of all column circumferential cables (4).

2. The method for installing a building tower crown to overcome wind-induced vibration according to claim 1, characterized in that: The circular walkway (3) is fixedly connected to the main column (2) by connecting rods (8). Each connecting rod (8) has ear plates welded to its upper and lower surfaces, which serve as both lifting lugs and prestressed cable connection points. The number of connecting rods (8) in each layer of the circular walkway (3) is the same and they are aligned vertically.

3. The method for installing a building tower crown to overcome wind-induced vibration according to claim 2, characterized in that: The stay cables (5) located in the prefabricated segments are tensioned during the ground assembly stage, and the circumferential stay cables (4) between the prefabricated segments are tensioned in situ.

4. The method for installing a building tower crown to overcome wind-induced vibration according to claim 2, characterized in that: The main column (2) is a variable diameter steel column whose cross-section gradually decreases from bottom to top. The variable diameter steel column contains three segments with different cross-sections, which are respectively called the foundation segment, the limiting segment, and the top segment from bottom to top. In step three, the portion of the base segment above the base (1) is divided into a prefabricated segment; In step four, when assembling the prefabricated segments corresponding to the base section, only the connecting rod (8) and the ear plate are installed; In step six, after the foundation section is hoisted and connected to the base (1), the ring walkway (3) is assembled in situ layer by layer from bottom to top. Then, the column circumferential cables (4) are installed and tensioned. When assembling the ring walkway (3), the ring walkway (3) below or the base (1) is used as the construction platform.

5. The method for installing a building tower crown to overcome wind-induced vibration according to claim 4, characterized in that: The base (1) is divided into upper and lower layers, which are connected by columns around the base (1). The upper part of the base (1) is a three-dimensional truss made of elastic rods and is called the elastic suspended layer (11). The limiting section is connected to the edge of the elastic suspended layer (11) by a cable (5). The cable (5) is a prestressed cable arranged radially with the main column (2) as the center. The cable (5), the elastic suspended layer (11) and the main column (2) are combined to form an energy dissipation system for converting the vibration of the main column (2) into the deformation in the elastic suspended layer (11).

6. A method for installing a building tower crown to overcome wind-induced vibration according to claim 5, characterized in that: In step five, the part of the base section of the main column (2) located in the base (1) is assembled together with the base (1) into a whole. During the assembly process, temporary support is set under the elastic suspension layer (11) of the base (1), and it is removed immediately after the base (1) is assembled. The stay cable (5) is installed in step six. The stay cable (5) is installed and tensioned immediately after the prefabricated segment at its upper end is installed.

7. The method for installing a building tower crown to overcome wind-induced vibration according to claim 1, characterized in that: When the damper is installed at the top of the main column (2), the tuned mass damper (6) is an eddy current damper and is pre-installed inside the main column (2).

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