A type of zigzag roof truss hoisting structure

Abstract

This utility model relates to the technical field of roof truss hoisting equipment, and more particularly to a zigzag roof truss hoisting structure, comprising: adjustable hoisting point components; a multi-point balancing hoisting system; and auxiliary support components. Therefore, this utility model has a reasonable structure. The vertical adjustment function of the four sets of adjustable hoisting point components adapts to the force characteristics of the zigzag roof truss. Combined with the real-time linkage of the force sensor and hydraulic adjustment module in the multi-point balancing hoisting system, the force deviation of each hoisting point is ≤5%. With intelligent coordination with an 80T truck crane, it effectively solves the problems of uneven force distribution and difficult balance control in traditional hoisting of zigzag structures. The phased coordinated support of the brick stacks and temporary support steel frame in the auxiliary support components ensures the stability of the roof truss turning and positioning process, making the installation position deviation ≤8mm and the verticality deviation ≤12mm, significantly improving hoisting accuracy and efficiency.

Description

Technical Field

[0001] This utility model relates to the technical field of roof truss hoisting equipment, and in particular to a zigzag roof truss hoisting structure. Background Technology

[0002] Traditional large-span roof truss hoisting often uses a fixed hoisting point design, which is difficult to adapt to the stress characteristics of the zigzag structure and has poor coordination with the prestressed system (such as corrugated pipes and steel strands), which can easily lead to local stress concentration and roof truss deformation (deviation exceeding 12mm) during hoisting.

[0003] Meanwhile, conventional hoisting relies on manual experience to adjust balance, which is inefficient and poses high safety risks, especially when operating in narrow spaces inside warehouses, where large equipment is not well-suited for operation.

[0004] Therefore, it is necessary to design a hoisting structure that works in conjunction with the prestressed system, intelligently adjusts and balances, and is suitable for operations inside the silo. Utility Model Content

[0005] This utility model aims to at least partially solve one of the technical problems in the related art.

[0006] Therefore, the purpose of this utility model is to propose a zigzag roof truss hoisting structure. This utility model has a reasonable structure. Through the vertical adjustment function of four sets of adjustable hoisting point components, it adapts to the stress characteristics of the zigzag roof truss. Combined with the real-time linkage of the force sensor and hydraulic adjustment module in the multi-point balance hoisting system, it achieves a stress deviation of ≤5% at each hoisting point. With the intelligent collaboration with an 80T truck crane, it effectively solves the problems of uneven stress and difficulty in balance control of the zigzag structure in traditional hoisting. The phased collaborative support of the brick stacks and temporary support steel frame in the auxiliary support components ensures the stability of the roof truss turning and positioning process, making the installation position deviation ≤8mm and the verticality deviation ≤12mm. It significantly improves the hoisting accuracy and efficiency, saves 30% of the construction period compared with traditional processes, and reduces the hoisting cost of a single roof truss by about 1,000 yuan. It is also suitable for warehouse construction scenarios with 18-30 meter span roof trusses, which is in line with the concept of low-carbon environmental protection and green construction.

[0007] To achieve the above objectives, this utility model proposes a zigzag roof truss hoisting structure, comprising:

[0008] Adjustable suspension point assembly: includes a pre-embedded hook, a vertical adjustment rod, and a connecting lug plate. The pre-embedded hook is pre-embedded at a preset suspension point position on the roof truss. One end of the vertical adjustment rod is connected to the pre-embedded hook, and the other end is connected to the connecting lug plate.

[0009] Multi-point balancing hoisting system: includes hoisting wire rope, force sensor, controller and hydraulic adjustment module. The hoisting wire rope is connected to the connecting lug plate through the force sensor. The controller is set on the surface of the rectangular part of the vertical adjustment rod. The hydraulic adjustment module is set inside the rectangular part. The output end of the hydraulic adjustment module extends through the top of the rectangular part and is hinged and fixed to one end of the connecting lug plate. The force sensor and the hydraulic adjustment module are respectively connected to the controller. The controller realizes data interaction with the truck crane control system through a wireless communication module.

[0010] Auxiliary support components include brick stacks and temporary support steel frames. The brick stacks are located at the bottom of both ends of the roof truss, and the temporary support steel frames are located on the column top ring beams.

[0011] In addition, the polygonal roof truss hoisting structure proposed in the above application may also have the following additional technical features:

[0012] Specifically, the adjustable suspension point assembly consists of four sets. The pre-embedded hooks in these four sets are embedded at the upper chord nodes of the roof truss and symmetrically distributed at the bends and both ends of the fold line. The pre-embedded hooks are made of Q355 steel and are welded and fixed to the roof truss reinforcing steel frame. Each pre-embedded hook has an arc-shaped transition section at its top. An M30 threaded hole with a depth ≥50mm is pre-drilled at the connection point between the top of the arc-shaped transition section and the vertical adjusting rod. The vertical adjusting rod is a threaded rod with an adjustment range of 0-50cm. An anti-loosening nut is provided at the connection point between the vertical adjusting rod and the arc-shaped transition section. The outer surface of the vertical adjusting rod is coated with an anti-corrosion layer with graduated markings. The connecting lug is made of 16mm thick Q235 steel plate. A Φ25mm pin hole is opened on the surface of the connecting lug, and a wear-resistant bushing is installed inside the pin hole. Reinforcing ribs are also provided on the surface of the connecting lug.

[0013] Specifically, the force sensor is a pin-type structure with a pin hole in the middle that matches the connecting ear plate. A 24mm diameter 40Cr material pin passes through the rope loop hole of the hoisting wire rope, the center hole of the force sensor, and the pin hole of the connecting ear plate in sequence, forming a series structure of one pin and three holes.

[0014] The hydraulic adjustment module includes a miniature hydraulic jack and a solenoid valve.

[0015] Specifically, the brick stack has a size of 370mm×1000mm and is constructed of MU10 shale bricks and M5 cement mortar. It is used for temporary support when the roof truss is overturned, and a 50mm thick rubber pad is laid on top.

[0016] Specifically, the temporary support steel frame includes vertical support rods and horizontal adjustment rods. The bottom of the vertical support rods is welded and fixed to the embedded parts of the column top ring beam. The surface of the vertical support rods is fixedly connected to the surface of the roof truss by bolts. One end of the horizontal adjustment rod is fixedly connected to the surface of the roof truss, and the other end is fixedly connected to the surface of the column top ring beam.

[0017] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] 1. Stress Coordination: The hook and prestressing system are designed to be collinear, the lifting force is in the same direction as the prestress, and the roof truss deformation is ≤L / 500 (L is the span), which solves the problem of local stress concentration.

[0020] 2. Precise and controllable: The intelligent adjustment system achieves a force deviation of ≤5% at the lifting points and an installation accuracy of 8mm, which is superior to traditional processes (deviation >15mm);

[0021] 3. Warehouse adaptability: The 80T truck crane with a 24-meter boom is suitable for warehouse operations, eliminating the need for large equipment, reducing the lifting time per unit by 30%, and saving approximately 1,000 yuan per unit in costs;

[0022] 4. Safe and reliable: The brick stacks and temporary supports work together to ensure the stability of the machine during turning and positioning, and the emergency stop mechanism reduces the risk of accidents, which meets the JGJ59-2011 safety standard;

[0023] 5. Green and environmentally friendly: Reduces energy consumption in transportation and large equipment, conforms to the concept of low-carbon construction, and contributes to the industrialization of green building. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this utility model will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, in which:

[0025] Figure 1 This is a schematic diagram of a zigzag roof truss hoisting structure according to the present invention;

[0026] Figure 2 This is a schematic diagram of a temporary support steel frame structure in a polygonal roof truss hoisting structure according to the present invention;

[0027] Figure 3 This is a schematic diagram of the pre-embedded hook structure in a zigzag roof truss hoisting structure according to the present invention.

[0028] As shown in the figure:

[0029] 10. Roof truss; 20. Column top ring beam;

[0030] 1. Adjustable lifting point assembly; 11. Embedded hook; 12. Vertical adjusting rod; 13. Connecting lug; 2. Multi-point balanced lifting system; 21. Lifting wire rope; 22. Force sensor; 221. Pin; 23. Controller; 24. Hydraulic adjustment module; 3. Auxiliary support components; 31. Brick stack; 32. Temporary support steel frame;

[0031] 111. Arc-shaped transition section; 121. Rectangular section; 122. Anti-loosening nut; 311. Rubber pad; 321. Vertical support rod; 322. Horizontal adjustment rod. Detailed Implementation

[0032] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. Rather, the embodiments of the present invention include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0033] The following description, in conjunction with the accompanying drawings, describes the zigzag roof truss hoisting structure of an embodiment of this utility model.

[0034] like Figures 1-3 As shown, an embodiment of the present invention provides a zigzag roof truss hoisting structure, comprising:

[0035] Adjustable suspension point assembly 1: includes a pre-embedded hook 11, a vertical adjustment rod 12 and a connecting ear plate 13. The pre-embedded hook 11 is pre-embedded in the preset suspension point position of the roof truss 10. One end of the vertical adjustment rod 12 is connected to the pre-embedded hook 11 and the other end is connected to the connecting ear plate 13.

[0036] Multi-point balancing hoisting system 2: includes hoisting wire rope 21, force sensor 22, controller 23 and hydraulic adjustment module 24. Hoisting wire rope 21 is connected to connecting lug 13 through force sensor 22. Controller 23 is set on the surface of rectangular part 121 of vertical adjustment rod 12. Hydraulic adjustment module 24 is set inside rectangular part 121. The output end of hydraulic adjustment module 24 passes through the top of rectangular part 121 and is hinged to one end of connecting lug 13. Force sensor 22 and hydraulic adjustment module 24 are respectively connected to controller 23. Controller 23 realizes data interaction with truck crane control system through wireless communication module.

[0037] Auxiliary support component 3: includes brick stacks 31 and temporary support steel frame 32. The brick stacks 31 are set at the bottom of both ends of the roof truss 10, and the temporary support steel frame 32 is set on the column top ring beam 20.

[0038] It should be noted that the pre-embedded hook 11 described in this embodiment has a pre-embedded depth of ≥200mm, and the center line of the pre-embedded hook 11 deviates from the center line of the φ55 metal corrugated pipe (prestressed duct) built into the roof truss 10 by ≤5mm. It is collinear with the center of the M15-4 anchor, forming a "three-center-one-line" force system to ensure that the lifting force is consistent with the prestress direction and to avoid the roof truss 10 being torsion.

[0039] It should be noted that the hoisting wire rope 21 described in this embodiment is a 6x19+1 fiber core wire rope with a diameter of 24mm (breaking strength of 28.8 tons), each rope is 25 meters long, and the double ropes are connected to 4 hoisting points to ensure that the horizontal angle with the roof truss 10 is ≥60° when turning over and ≥45° when in place.

[0040] It should also be noted that the controller 23 interacts with the truck crane control system via a wireless communication module (transmission distance ≥ 50 meters, delay ≤ 100 ms). The specific linkage method is as follows:

[0041] Lifting speed adjustment: When the force sensor 22 detects a sudden increase in tension at a certain lifting point (e.g., deviation > 5%), the controller 23 sends a deceleration signal, and the lifting speed of the crane on the corresponding side is reduced by 0.5 m / min to avoid local overload;

[0042] Steering angle correction: If the roof truss 10 deviates due to uneven force (such as the deviation between the center line and the installation axis > 5mm), the controller 23 calculates the steering compensation amount (≤ 3°), and the crane rotation mechanism finely adjusts the angle to ensure positioning accuracy;

[0043] Emergency shutdown protection: When the tension at any lifting point reaches 80% of the breaking tension (i.e., 23 tons), or the force sensor 22 data is abnormal (such as wire breakage, error > 3%), the controller 23 immediately sends a shutdown command, the crane stops all operations and alarms.

[0044] It should also be noted that the controller 23 is equipped with a touch screen display, which displays the force curves (horizontal axis is time, vertical axis is tension value), angle parameters (angle between the sling and the horizontal line) and deviation percentage of the four lifting points in real time. At the same time, it automatically stores the data (saves for ≥3 months) and can be exported as a basis for construction acceptance, which fully meets the technical requirements of "precise control and safe hoisting" in the construction method.

[0045] Specifically, this utility model has a reasonable structure. The vertical adjustment function of the four sets of adjustable lifting point components 1 is adapted to the force characteristics of the broken-line roof truss 10. Combined with the real-time linkage of the force sensor 22 and the hydraulic adjustment module 24 in the multi-point balance lifting system 2, the force deviation of each lifting point is ≤5%. With the intelligent collaboration with the 80T truck crane, it effectively solves the problems of uneven force and difficulty in balance control of broken-line structures in traditional lifting. The phased collaborative support of the brick stack 31 and the temporary support steel frame 32 in the auxiliary support component 3 ensures the stability of the roof truss 10 during the turning and positioning process, so that the installation position deviation is ≤8mm and the verticality deviation is ≤12mm. It significantly improves the lifting accuracy and efficiency, saves 30% of the construction period compared with the traditional process, and reduces the lifting cost of a single roof truss 10 by about 1,000 yuan. It is also suitable for the in-warehouse construction scenario of 18-30 meter span roof trusses 10, which is in line with the concept of low-carbon environmental protection and green construction.

[0046] Its working principle is as follows:

[0047] Lifting preparation: Four sets of pre-embedded hooks 11 are pre-embedded during the prefabrication of the roof truss 10 to ensure that they are aligned with the prestressed ducts. Before lifting, the lifting point position is preset by the vertical adjustment rod 12 so that the lifting wire rope 21 matches the angle of the broken line.

[0048] Turning-over phase: The 80T truck crane lifts at four points, with the lifting wire rope 21 at an angle of ≥60° to the horizontal line. The brick stack 31 serves as a fulcrum to support the lower chord. The controller 23 monitors the force in real time to avoid unilateral overload.

[0049] Lifting and positioning: The crane is located on the central axis inside the warehouse (24 meters out of the boom). Before lifting, the roof truss 10 is lifted 20-30cm off the ground to check its stability. When positioning, the position is finely adjusted by the temporary support steel frame 32 to control the position deviation ≤8mm and the verticality deviation ≤12mm.

[0050] Taking the 30-meter span prestressed polygonal roof truss of the Changji Prefecture local grain reserve construction project as an example:

[0051] The roof truss 10 is made of C55 precast concrete, with built-in φ55 metal corrugated pipe and 1*7-1860-15.2 steel strand. Four sets of pre-embedded hooks 11 are welded to the upper chord steel bars (weld length 100mm).

[0052] An 80T truck crane (24-meter boom) was used for hoisting. The hoisting wire rope 21 is a 6x19+1 fiber core structure with a diameter of 24mm. The angle between the hoisting wire rope 21 and the horizontal line is 60° when turning and 45° when in place.

[0053] The controller 23 displays the force on each lifting point in real time (deviation ≤3%), and compensates for minor imbalances during the lifting process through the hydraulic adjustment module 24; the temporary support steel frame 32 controls the verticality within 10mm.

[0054] The project involved the hoisting of 90 roof trusses with no deformation or safety incidents, saving 20 days of construction time and a total cost saving of 90,000 yuan, thus verifying the practicality of the structure.

[0055] In one embodiment of this utility model, such as Figure 3 As shown, the adjustable suspension point assembly 1 has four sets. The pre-embedded hooks 11 in the four sets of adjustable suspension point assemblies 1 are pre-embedded at the upper chord nodes of the roof truss 10, and are symmetrically distributed at the bends and both ends of the fold line. The pre-embedded hooks 11 are made of Q355 steel and are welded and fixed to the steel reinforcement frame of the roof truss 10. The top of the pre-embedded hook 11 has an arc-shaped transition section 111. An M30 threaded hole with a depth ≥50mm is reserved at the connection point between the top of the arc-shaped transition section 111 and the vertical adjusting rod 12. The adjusting rod 12 is a threaded rod with an adjustment range of 0-50cm. An anti-loosening nut 122 is provided at the connection node between the vertical adjusting rod 12 and the arc transition section 111. The outer surface of the vertical adjusting rod 12 is provided with an anti-corrosion coating, and the anti-corrosion coating is provided with scale markings. The connecting ear plate 13 is made of 16mm thick Q235 steel plate. A Φ25mm pin hole is opened on the surface of the connecting ear plate 13, and a wear-resistant bushing is provided in the pin hole. The surface of the connecting ear plate 13 is provided with reinforcing ribs.

[0056] Specifically, the structure and material of the adjustable suspension point assembly 1 will be further explained.

[0057] In one embodiment of this utility model, such as Figure 3 As shown, the force sensor 22 has a pin-type structure with a pin hole in the middle that matches the connecting ear plate 13. A 40Cr pin 221 with a diameter of 24mm passes through the rope loop hole of the hoisting wire rope 21, the center hole of the force sensor 22, and the pin hole of the connecting ear plate 13 in sequence, forming a series structure of one pin and three holes.

[0058] The hydraulic adjustment module 24 includes a miniature hydraulic jack and a solenoid valve.

[0059] Specifically, the linkage between the force sensor 22, the connecting ear plate 13 and the hoisting wire rope 21 is achieved through the through connection of the pin shaft 221, which not only conforms to the scientific principle of force line transmission, but also simplifies the structural design and fully matches the hoisting requirements of accurate monitoring and balanced force distribution.

[0060] In one embodiment of this utility model, such as Figure 1 As shown, the brick stack 31 has a size of 370mm×1000mm and is constructed of MU10 shale bricks and M5 cement mortar. It is used for temporary support when the roof truss 10 is overturned, and a 50mm thick rubber pad 311 is laid on top.

[0061] Specifically, the structure and materials of the brick stack 31 will be further explained.

[0062] In one embodiment of this utility model, such as Figure 2 As shown, the temporary support steel frame 32 includes a vertical support rod 321 and a horizontal adjustment rod 322. The bottom of the vertical support rod 321 is welded and fixed to the embedded part of the column top ring beam 20. The surface of the vertical support rod 321 is fixedly connected to the surface of the roof truss 10 by bolts. One end of the horizontal adjustment rod 322 is fixedly connected to the surface of the roof truss 10, and the other end is fixedly connected to the surface of the column top ring beam 20.

[0063] Specifically, the structure and connection relationship of the temporary support steel frame 32 will be further explained.

[0064] In summary, the proposed embodiment of the zigzag roof truss hoisting structure is structurally sound. The vertical adjustment function of four sets of adjustable hoisting point components 1 adapts to the force characteristics of the zigzag roof truss 10. Combined with the real-time linkage of the force sensor 22 and hydraulic adjustment module 24 in the multi-point balance hoisting system 2, the force deviation at each hoisting point is ≤5%. With intelligent collaboration with an 80T truck crane, it effectively solves the problems of uneven force distribution and difficult balance control in traditional hoisting methods for zigzag structures. The phased collaborative support of the brick stack 31 and temporary support steel frame 32 in the auxiliary support component 3 ensures the stability of the roof truss 10 during its turning and positioning process, resulting in an installation position deviation of ≤8mm and a verticality deviation of ≤12mm. This significantly improves hoisting accuracy and efficiency, saves 30% of the construction period compared to traditional methods, and reduces the hoisting cost of a single roof truss 10 by approximately 1000 yuan. Furthermore, it is suitable for in-warehouse construction scenarios with 18-30 meter span roof trusses 10, conforming to the concepts of low-carbon environmental protection and green construction.

[0065] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0066] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0067] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A folded line roof truss hoisting structure, characterized by, include: Adjustable suspension point assembly (1): includes a pre-embedded hook (11), a vertical adjustment rod (12) and a connecting ear plate (13). The pre-embedded hook (11) is pre-embedded at a preset suspension point position of the roof truss (10). One end of the vertical adjustment rod (12) is connected to the pre-embedded hook (11), and the other end is connected to the connecting ear plate (13). Multi-point balancing hoisting system (2): includes hoisting wire rope (21), force sensor (22), controller (23) and hydraulic adjustment module (24). The hoisting wire rope (21) is connected to the connecting lug (13) through the force sensor (22). The controller (23) is set on the surface of the rectangular part (121) of the vertical adjustment rod (12). The hydraulic adjustment module (24) is set inside the rectangular part (121). The output end of the hydraulic adjustment module (24) passes through the top of the rectangular part (121) and is hinged to one end of the connecting lug (13). The force sensor (22) and the hydraulic adjustment module (24) are respectively connected to the controller (23). The controller (23) realizes data interaction with the truck crane control system through a wireless communication module. Auxiliary support components (3): include brick stacks (31) and temporary support steel frames (32), wherein the brick stacks (31) are located at the bottom of both ends of the roof truss (10), and the temporary support steel frames (32) are located on the column top ring beam (20).

2. The folded-line roof truss hoisting structure according to claim 1, wherein The adjustable suspension point assembly (1) is provided in four sets. The pre-embedded hooks (11) in the four sets of adjustable suspension point assemblies (1) are pre-embedded at the upper chord nodes of the roof truss (10) and symmetrically distributed at the bends and both ends of the fold line. The pre-embedded hooks (11) are made of Q355 steel and are welded and fixed to the steel reinforcement skeleton of the roof truss (10). The top of the pre-embedded hooks (11) is provided with an arc-shaped transition section (111). An M30 threaded hole with a depth ≥50mm is reserved at the connection between the top of the arc-shaped transition section (111) and the vertical adjustment rod (12). The vertical adjustment rod (12) is a threaded rod with an adjustment range of 0-50cm. A locking nut (122) is provided at the connection node between the vertical adjustment rod (12) and the arc transition section (111). The outer surface of the vertical adjustment rod (12) is provided with an anti-corrosion coating, and the anti-corrosion coating is provided with scale markings. The connecting ear plate (13) is made of 16mm thick Q235 steel plate. The surface of the connecting ear plate (13) is provided with a Φ25mm pin hole, and a wear-resistant bushing is provided in the pin hole. The surface of the connecting ear plate (13) is provided with reinforcing ribs.

3. The folded-line roof truss hoisting structure according to claim 1, wherein The force sensor (22) is a pin-type structure with a pin hole in the middle that matches the connecting ear plate (13). A 40Cr pin (221) with a diameter of 24mm passes through the rope loop hole of the hoisting wire rope (21), the center hole of the force sensor (22), and the pin hole of the connecting ear plate (13) in sequence, forming a series structure of one pin and three holes. The hydraulic adjustment module (24) includes a miniature hydraulic jack and a solenoid valve.

4. The folded-line roof truss hoisting structure according to claim 1, wherein The brick stack (31) has a size of 370mm×1000mm and is constructed of MU10 shale bricks and M5 cement mortar. It is used for temporary support when the roof truss (10) is turned over, and a 50mm thick rubber pad (311) is laid on top.

5. The folded-line roof truss hoisting structure according to claim 1, wherein The temporary support steel frame (32) includes a vertical support rod (321) and a horizontal adjustment rod (322). The bottom of the vertical support rod (321) is welded and fixed to the embedded part of the column top ring beam (20). The surface of the vertical support rod (321) is fixedly connected to the surface of the roof truss (10) by bolts. One end of the horizontal adjustment rod (322) is fixedly connected to the surface of the roof truss (10), and the other end is fixedly connected to the surface of the column top ring beam (20).

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